The Experiential Turn in Eighteenth-Century German Philosophy (Routledge Studies in Eighteenth-Century Philosophy) [1 ed.] 1138606839, 9781138606838

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The Experiential Turn in Eighteenth-Century German Philosophy

This collection of essays challenges the prevailing assumption that eighteenth-century German philosophy prior to Kant was largely defned by post-Leibnizian rationalism and, accordingly, a low esteem of the cognitive function of the senses. It does so by highlighting the various ways in which eighteenth-century German philosophers reconceived the notion and role of experience in their efforts to identify, defend, and contest the contribution of sensibility to disciplines such as metaphysics, theology, the natural sciences, psychology, and aesthetics. Engaging in depth with Tschirnhaus, Wolff, the Wolffans, eclecticism, Popularphilosophie, the Berlin Academy, Tetens, and Kant, its thirteen chapters present a more nuanced understanding of the German reception of British and French ideas and dismiss the prevailing view that German philosophy was largely isolated from European debates. Moreover, the book introduces a number of relatively unknown, but highly relevant philosophers and developments to non-specialized scholars and contributes to a better understanding of the richness and complexity of the German Enlightenment. Karin de Boer is Professor of Philosophy at the University of Leuven. She is the author of Thinking in the Light of Time: Heidegger’s Encounter with Hegel (2000), On Hegel: The Sway of the Negative (2010), and Kant’s Reform of Metaphysics: The Critique of Pure Reason Reconsidered (2020). Tinca Prunea-Bretonnet is researcher at the Research Institute of the University of Bucharest (Humanities Division). She is the author of L’avènement de la métaphysique kantienne. Prémisses et enjeux d’une réception au XXe siècle (forthcoming) and coeditor of Kant et Wolff: Héritages et ruptures (2011).

Routledge Studies in Eighteenth-Century Philosophy

Kant and the Problem of Self-Knowledge Luca Forgione Kant on Intuition Western and Asian Perspectives on Transcendental Idealism Edited by Stephen R. Palmquist Hume on Art, Emotions, and Superstition A Critical Study of the Four Dissertations Amyas Merivale A Guide to Kant’s Psychologism via Locke, Berkeley, Hume, and Wittgenstein Wayne Waxman Kant and the Continental Tradition Sensibility, Nature, and Religion Edited by Sorin Baiasu and Alberto Vanzo Beyond Autonomy in Eighteenth-Century British and German Aesthetics Edited by Karl Axelsson, Camilla Flodin, and Mattias Pirholt Kant’s Critical Epistemology Why Epistemology Must Consider Judgment First Kenneth R. Westphal The Experiential Turn in Eighteenth-Century German Philosophy Edited by Karin de Boer and Tinca Prunea-Bretonnet For more information about this series, please visit: https://www. routledge.com/Routledge-Studies-in-Eighteenth-Century-Philosophy/ book-series/SE0391

The Experiential Turn in Eighteenth-Century German Philosophy Edited by Karin de Boer and Tinca Prunea-Bretonnet

First published 2021 by Routledge 52 Vanderbilt Avenue, New York, NY 10017 and by Routledge 2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN Routledge is an imprint of the Taylor & Francis Group, an informa business © 2021 Taylor & Francis The right of Karen de Boer and Tinca Prunea-Bretonnet to be identifed as the authors of the editorial material, and of the authors for their individual chapters, has been asserted in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identifcation and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data A catalog record for this title has been requested ISBN: 978-1-138-60683-8 (hbk) ISBN: 978-1-032-00285-9 (pbk) ISBN: 978-0-429-46749-3 (ebk) Typeset in Sabon by codeMantra

Contents

List of Abbreviations Introduction

vii 1

K A R I N D E B O E R A N D T I N C A P RU N E A - B R E T O N N E T

PART I

Wolff and Wolffanism 1 Before and Beyond Leibniz: Tschirnhaus and Wolff on Experience and Method

15 17

C O R E Y W. DYC K

2 The Role of Experience in Wolff’s General Cosmology

37

CHR IST I A N LEDUC

3 Aesthetica Experimentalis: Baumgarten and the Aesthetic Dimension of Experience

55

A L E S S A N D RO N A N N I N I

PART II

Eclecticism and Popularphilosophie 4 The Thomasian Context: Crusius on Experience

79 81

S T E FA N H E ß B RÜ G G E N -WA LT E R

5 Experience and Inner Sense: Feder–Lossius–Kant UDO THIEL

98

vi

Contents

6 Christoph Meiners’s Empiricist ‘Revision’ of Philosophy and Michael Hißmann’s Anti-Speculative Materialism

119

FA L K W U N D E R L I C H

PART III

The Berlin Academy 7 Contingency and Experience in Maupertuis’s Essay on Cosmology

139 141

AN NE-LISE REY

8 The Role of Reason, Experience, and Physiology in J.H.S. Formey’s Essay on Dreams

158

A N N E L I E G RO S S E

9 Lambert on Experience and Deduction

181

PAO L A B A S S O

10 On the Mitigated Phenomenalism of J.-B. Merian

203

T I N C A P RU N E A - B R E T O N N E T

PART IV

Tetens and Kant

229

11 The Role of Experience in Kant’s Prize Essay

231

C O U RT N E Y D. F U G AT E

12 Tetens on the Nature of Experience: Between Empiricism and Rationalism

254

C L I N T O N T O L L E Y A N D R . B R I A N T R AC Z

13 Kant’s Inquiries into a New Touchstone for Metaphysical Truths

274

K A R I N DE BOER

List of Contributors

297

Index

301

Abbreviations

Bacon, Francis AS The Dignity and Advancement of Learning / De dignitate et augmentis scientiarum, in The Works of Francis Bacon, vol. 4, ed. by J. Spedding, R.L. Ellis and D.D. Heath, London: Longman, 1860; repr. Stuttgart-Bad Cannstatt: Fromann-Holzboog 1986. Basedow, Johann Bernhard Phil Philalethie. Neue Aussichten in die Wahrheiten und Religion der Vernunft bis in die Gränzen der glaubwürdigen Offenbarung, vol. 2, Altona: Iversen 1964. Baumgarten, Alexander Gottlieb Aesth Aesthetica, Frankfurt: Kleyb 1750. AL Acroasis logica, Halle: Hemmerde 1761. EP Ethica philosophica, Halle: Hemmerde 1740. Koll ‘Kollegium über die Ästhetik’, in B. Poppe (ed.), Alexander Gottlieb Baumgarten. Seine Bedeutung und Stellung in der Leibniz-Wolffschen Philosophie und seine Beziehungen zu Kant. Nebst Veröffentlichung einer bisher unbekannten Handschrift der Ästhetik Baumgartens, Borna/Leipzig: Noske 1907. M Metaphysica, Halle: Hemmerde 1739 / Metaphysics, transl. and ed. by C.D. Fugate and J. Hymers, London: Bloomsbury 2013. PBA Philosophische Brieffe von Aletheophilus, Frankfurt/ Leipzig: [s.n.] 1741. Crusius, Christian August Entwurf Entwurf der nothwendigen Vernunft-Wahrheiten, Leipzig: Gleditsch 1745; repr. in Die philosophische Werke, vol. 2, Hildesheim: Olms 1964. Weg Weg zur Gewißheit und Zuverläßigkeit der menschlichen Erkenntnis, Leipzig: Gleditsch 1747; repr. in Die philosophische Werke, vol. 3, Hildesheim: Olms 1965.

viii Abbreviations Feder, Johann Georg Heinrich DSI De sensu interno, Göttingen: Schulz 1768. LM Logik und Metaphysik, Göttingen/Gotha: Dieterich 1769. UMG ʻÜber das moralische Gefühl’, in Deutsches Museum, 1776–1777; repr. Kopenhagen/Leipzig: Faber und Nitschke 1792. Formey, Jean Henri Samuel ED ʻEssai sur les songesʼ, Histoire de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1746), Berlin: Haude & Spener 1748. Hanov, Michael Christoph EEK Entwurf der Erfndungs-Kunst, vol. 1, Danzig: Schreiber 1739. Hißmann, Michael PsV Psychologische Versuche, ein Beytrag zur esoterischen Logik, Frankfurt/Leipzig: [s.n.] 1777. FU ʻVersuch über das Fundament der Kräfte. Bey Gelegenheit der von der Königlichen Akademie der Wissenschaften in Berlin für das Jahr 1779 aufgegebenen Preisfrageʼ, ed. by M. Hißmann, Magazin für die Philosophie und ihre Geschichte, vol. 6, Göttingen/Lemgo: Meyer 1783. Hofmann, Adolph Friedrich Gedancken Gedancken über Hn. Christian Wolffens […] Logic oder sogenannte Philosophiam rationalem, Leipzig: Heinsius 1729. Vernunftlehre, Leipzig: bei dem Autore 1737. VL Hume, David EHU Enquiry Concerning Human Understanding, ed. by P. Millican, Oxford: Oxford University Press 2007. T A Treatise of Human Nature, ed. by P.H. Nidditch, Oxford: Clarendon Press 1978. Kant, Immanuel Anthr Anthropology from a Pragmatic Point of View, in Anthropology, History, and Education, ed. by G. Zöller and R.B. Louden, transl. by R. B. Louden, Cambridge: Cambridge University Press 2007. CPR Critique of Pure Reason, transl. and ed. by P. Guyer and A. Wood, Cambridge: Cambridge University Press 1998. Corr Correspondence, transl. and ed. by A. Zweig, Cambridge: Cambridge University Press 2010. Dreams Dreams of a Spirit-Seer Elucidated by Dreams of Metaphysics, in Theoretical Philosophy, 1755–1770,

Abbreviations

ix

transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press 1992. FS The False Subtlety of the Four Syllogistic Figures, in Theoretical Philosophy, 1755–1770, ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press 2002. Inq Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality, in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press 1992. LM Herder Lectures on Metaphysics Herder, in Lectures on Metaphysics, transl. and ed. by K. Ameriks and S. Naragon, Cambridge: Cambridge University Press 1997. NM Attempt to Introduce the Concept of Negative Magnitudes into Philosophy, in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press 1992. OPA The Only Possible Argument in Support of a Demonstration of the Existence of God, in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press 1992. Prol Prolegomena to any Future Metaphysics that Will Be Able to Come Forward as Science, transl. by G. Hatfeld, Cambridge: Cambridge University Press 2004. Lambert, Johann Heinrich Arch Anlage zur Architectonic, oder Theorie des Einfachen und des Ersten in der philosophischen und mathematischen Erkenntniß, 2 vols., Riga: Hartknoch 1771; repr. in Philosophische Schriften, vols. 3–4, Hildesheim: Olms 1965. CV Abhandlung vom Criterium veritatis, ‘Abhandlung vom Criterium veritatis’, ed. by K. Bopp, Kant-Studien, 36, 1915; repr. in Philosophische Schriften, vol. 10.2, Hildesheim: Olms 2008. DR ‘Discours de réception’ (‘Sur la liaison des connaissances qui sont l’objet des quatre classes de l’Académie’), Histoire de l’Académie Royale de Berlin (1765), Berlin: Haude & Spener 1767. NO Neues Organon, oder Gedanken über die Erforschung und Bezeichnung des Wahren und dessen Unterscheidung von Irrthum und Schein, 2 vols., Leipzig: Wendler 1764; repr. in Philosophische Schriften, vols. 1–2, Hildesheim: Olms 1965.

x

Abbreviations

Leibniz, Gottfried Wilhelm BLW Leibniz, Gottfried Wilhelm, and Wolff, Christian, Briefwechsel zwischen Leibniz und Christian Wolff, ed. by C. I. Gerhardt, Halle: Schmidt 1860; repr. Hildesheim: Olms 1971. Locke, John Essay An Essay Concerning Human Understanding, ed. by P.H. Nidditch, Oxford: Clarendon Press 1975. Lossius, Johann Christian PU Physische Ursachen des Wahren, Gotha: Ettinger 1775. Maupertuis, Pierre-Louis Moreau de DFA Discours sur les différentes fgures des astres, Paris: Imprimerie Royale 1732. EC Essai de cosmologie, Leiden: Luzac 1751. EP ‘Examen philosophique de la preuve de l’existence de Dieu employée dans l’Essai de cosmologie’, Histoire de l’Académie Royale des Sciences et des Belles Lettres (1756), Berlin: Haude & Spener 1758. LA ‘Sur les lois de l’attraction’, Mémoires de l’Académie royales des sciences 1732. Meier, Georg Friedrich ASW Anfangsgründe aller schönen Wissenschaften, vol. 2, Halle: Hemmerde 1749. Meiners, Christoph REV Revision der Philosophie. Erster Theil, Göttingen/Gotha: Dieterich 1772. Merian, Jean-Bernard APE Mémoire sur l’apperception de notre propre existence, in Histoire de l’Académie Royale des Sciences et des BellesLettres de Berlin (1749), Berlin: Haude & Spener 1751. APID Mémoire sur l’apperception considérée relativement aux idées, ou, sur l’existence des idées dans l’âme, in Histoire de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1749), Berlin: Haude & Spener 1759. DM Discours sur la métaphysique, Berlin: Voss, 1765. PHPN Parallèle historique entre nos deux philosophies nationales, in Mémoires de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1797), Berlin: Decker 1800. MLP [Review of] D. Hume, Philosophical Essays on Human Understanding [An Enquiry Concerning Human Understanding], Mélanges littéraires et philosophiques, 1755 (MLP1)–1756 (MLP2).

Abbreviations PH

RPR

xi

Sur le phénoménisme de David Hume, in Mémoires de l’Académie Royale des Sciences et des Belles-Lettres depuis l’avènement de Frédéric Guillaume II au thrône (1793), Berlin: Decker 1798 / On the Phenomenalism of David Hume, transl. by P. Briscoe, Hume Studies, 23/1, 1997. Réfexions philosophiques sur la ressemblance, in Histoire de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1751), Berlin: Haude & Spener 1753.

Newton, Isaac PM The Principia: Mathematical Principles of Natural Philosophy, transl. by I.B. Cohen and A. Whitman, Berkeley: University of California Press 1999. Rüdiger, Andreas SVF De sensu veri et falsi, Halle: Gruner 1709. Syrbius, Johann Jacob IP Institutiones philosophiae rationalis eclecticae, Jena: Bielcke 1717. Tetens, Johann Nicolas ASP Über die allgemeine speculativische Philosophie, Bützow/ Wismar: Berger & Boedner 1775; repr. in Neudrucke seltener philosophischer Werke, vol. 4, ed. by W. Uebele, Berlin: Reuther and Richard 1913. PV Philosophische Versuche über die menschliche Natur und ihre Entwickelung, Leipzig: Weidmann und Reich 1777; ed. by U. Roth and G. Stiening, Berlin: De Gruyter 2014. Tschirnhaus, Ehrenfried Walter von MM Medicina mentis et corporis sive artis inveniendi praecepta generalia, Leipzig: Fritsch 1695; repr. Hildesheim: Olms 1964. Wolff, Christian BC ‘De methodo mathematica brevis commentatio’, Elementa matheseos universae, Halle: Renger 1713; repr. in Gesammelte Werke, II.29, Hildesheim: Olms 2003. CG Cosmologia generalis, Frankfurt/Leipzig: Renger 1731; repr. in Gesammelte Werke, II.4, Hildesheim: Olms 1964. CR Cogitationes rationales de viribus intellectus humani, Leipzig: Renger 1740; repr. in Gesammelte Werke, II. 2, Hildesheim: Olms 1983. DP Discursus praeliminaris de philosophia in genere / Einleitende Abhandlung über Philosophie im Allgemeinen, ed. by G. Gawlick and L. Kreimendahl, Stuttgart-Bad Cannstatt: Frommann-Holzboog 1963 /

xii

Abbreviations

ELB GL

GM

GPh GPhys

KU

LL ML MMP PE PPO PR PPU

Preliminary Discourse on Philosophy in General, transl. by R.J. Blackwell, Indianapolis/New York: Bobbs-Merill 1996. Christian Wolffs eigene Lebensbeschreibung, ed. by H. Wuttke, Leipzig: Weidmann 1841; repr. in Gesammelte Werke, I.10, Hildesheim: Olms 1980. Vernünfftige Gedancken von der Kräfften des menschlichen Verstandes (German Logic), Halle: Renger 1713; repr. in Gesammelte Werke, I.1, Hildesheim: Olms 1978. Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt (German Metaphysics), Halle: Renger 1720; repr. in Gesammelte Werke, I.2, Hildesheim: Olms 1983. Vernünfftige Gedancken von den Würckungen der Natur (German Physics), Halle: Renger 1723; repr. in Gesammelte Werke, I.6, Hildesheim: Olms 1981. Vernünfftige Gedanken von dem Gebrauche der Theile in Menschen, Thieren und Pfantzen (German Physiology), Frankfurt/Leipzig: Renger 1725; repr. in Gesammelte Werke, I.8, Hildesheim: Olms 1980. ‘Kurzer Unterricht von der mathematischen Methode’, in Die Anfangsgründe aller mathematischen Wissenschaften, Halle: Renger 1710; repr. in Gesammelte Werke, I.15.1, Hildesheim: Olms 1999. Philosophia rationalis sive Logica (Latin Logic), Frankfurt/Leipzig: Renger 1728; repr. in Gesammelte Werke, I.1.1–3, Hildesheim: Olms 1983. Mathematisches Lexicon, Leipzig: Gleditsch 1716; repr. in Gesammelte Werke, I.11, Hildesheim: Olms 1965. Meletemata mathematico-philosophica, Halle: Renger 1755; repr. in Gesammelte Werke, II.35, Hildesheim: Olms 2003. Psychologia empirica, Frankfurt/Leipzig: Renger 1732; reprint in Gesammelte Werke, II.5, Hildesheim: Olms 1968. Philosophia prima sive Ontologia, Frankfurt/Leipzig: Renger 1729; repr. in Gesammelte Werke, II.3, Hildesheim: Olms 1962. Psychologia rationalis, Frankfurt/Leipzig: Renger 1734; repr. in Gesammelte Werke, II.6, Hildesheim: Olms 1994. Philosophia practica universalis. Pars posterior, Frankfurt/Leipzig: Renger 1739; repr. in Gesammelte Werke, II.11, Hildesheim: Olms 1979.

Introduction Karin de Boer and Tinca Prunea-Bretonnet

The thirteen essays collected in this volume seek to counter the widespread assumption that eighteenth-century German philosophy up to the publication of Kant’s Critique of Pure Reason was largely defned by Leibnizian and Wolffan brands of rationalism and, thus, lagging behind contemporaneous responses to the scientifc revolution by philosophers in France, England, Scotland, and elsewhere. This prevailing image is due at least in part to Kant’s own assertion that the “critical path” he had opened put an end to Wolffan dogmatism and Humean skepticism alike.1 We do not want to suggest that this assertion is false in all respects. Yet we maintain that the way Kant and his early followers framed the history of modern philosophy up to 1781 covers over the efforts of their predecessors to come to terms with the epistemological implications of the modern shift toward experimentation in sciences such as physics and astronomy. Challenging the textbook accounts, the aim of this volume is to show how eighteenth-century German philosophers—including the French-speaking members of the Berlin Academy—sought to emancipate experience from its classical subordination to the intellect, and this with regard to its role in the natural sciences, psychology, religion, art, and the various branches of philosophy itself. Evidently, this ‘experiential turn,’ as we propose to call it, did not occur independently of the international context, in particular the works of Locke and Newton, which had an impact on the developments within German philosophy from the publication of Wolff’s German Logic (1713) to Merian’s Historical Parallel between Our Two National Philosophies (1797). For various reasons, however, we hold that the effects of Lockean and Newtonian ideas on these debates cannot be properly understood by means of the worn-out historiographical opposition between empiricism and rationalism. 2 First, insofar as this opposition is strongly associated with the distinction between England and Scotland on the one hand and Germany on the other, it ignores the extent to which German philosophers drew on native resources, including Pietism, to reassess the epistemological function of experience in nonphilosophical and philosophical pursuits of truth, beauty, and wisdom. Second, as has been argued in most detail by Engfer, seventeenth- and

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eighteenth-century philosophy defes a binary classifcation because its representatives held views on particular epistemological questions at odds with their overt prioritization of the role of either the intellect or the senses. Third, philosophers such as Descartes, Leibniz, or Hume did not refer to themselves or their interlocutors as rationalists or empiricists, since the meaning of these terms only became fxed shortly after Kant’s occasional use of them.3 In line with Engfer’s study, we propose to frame the developments in eighteenth-century German philosophy in terms of its successive attempts to reassess the role of experience in non-philosophical and philosophical types of cognition.4 In many cases, these attempts emerged from the perceived challenge posed by the mathematico-empirical method made famous by Newton’s Principia Mathematica (1687).5 For some of the philosophers under consideration, Newton’s defense of experimentation against more speculative approaches to nature provided a useful weapon against speculations about the soul and God that were considered sterile and vain. Others reacted to the increasing prominence of the Newtonian model by trying to incorporate its principles into their epistemological accounts of science and cognition. More often than not, these appeals to Newton were based on a superfcial image of the scientist rather than a careful study of his actual works.6 Throughout Europe, philosophical responses to Newton often went hand in hand with the appraisal or (partial) emulation of the theory of human cognition elaborated in Locke’s Essay Concerning Human Understanding, which was published two years after the Principia.7 Locke’s Essay was frst translated into French in 1700, into Latin in 1701, and into German in 1757. While his thought became particularly infuential in the second half of the eighteenth century, his ideas were already known and discussed by Thomasians and other early enlightened thinkers.8 Although we acknowledge the impact of the scientifc, methodological, and epistemological principles associated with the names of Newton and Locke on eighteenth-century German philosophy, the main aim of the present collection is not to spell out this infuence. We rather focus on how eighteenth-century German philosophers with very different backgrounds and aims conceived of the role of experience in both the generation of knowledge and the assessment of questionable truth claims. By examining their accounts of non-philosophical and philosophical cognition through the lens of the notion of experience, we hope to cast new light on this underinvestigated episode. However, this endeavor is somewhat complicated by the fact that, throughout the history of philosophy, the concept of experience has been a notoriously polysemous one.9 Accordingly, we cannot take it for granted that eighteenth-century German philosophers had the same thing in mind when they treated of experience in affrmative or negative

Introduction 3 terms. While a full answer to this question exceeds the scope of this introduction, it might be useful to recall the main features associated with the concept of experience, many of which found their way to modern philosophy through their codifcation in Aristotle’s works.10 Starting with the common acceptance of the term ‘experience,’ we can say that someone who appeals to experience in order to recommend a certain remedy does so by drawing on his or her recollection of a number of similar cases in which this remedy appeared to be successful. This common-sense notion of experience contains two elements. It pertains (1) to the act of grasping a number of cases as similar and (2) to the act of relying on this perceived similarity to draw an inference and/or decide on a particular course of action. In the latter case, experience is a crucial source of ‘know-how’ that often suffces to achieve a certain end.11 In the former case, the inference drawn from experience—according to its commonsense understanding—can be considered an explicit articulation of the insight obtained and, thus, an instance of experiential or empirical cognition. On this account, propositions such as ‘x is a good remedy against y’ amount to instances of experience.12 The common-sense notion of experience is relevant to philosophy at least insofar as it seeks to determine the origin, grounds, and validity of both non-philosophical and philosophical types of cognition. According to Aristotle and the tradition he initiated, the epistemological value of experiential cognition is limited in that it fails to provide the knower with the reason or ground of its validity.13 For this reason, experience has traditionally been subordinated to the purely intellectual cognitions pursued in mathematics and philosophy itself insofar as it starts from self-evident principles and proceeds by means of syllogistic reasoning. As will be shown throughout the present volume, eighteenth-century philosophy was faced with a far more complex—and more ambivalent— understanding of experience, one that breached the Aristotelian premises in various respects.14 Put briefy, in the wake of the success and increasing acceptance of modern scientifc practices, philosophers came to put more weight on the role of controlled and verifable experiences, i.e., experiments. The idea that scientifc knowledge ought to be verifable by means of empirical observations was increasingly deployed as a means to debunk the speculative claims put forward in disciplines such as natural philosophy and metaphysics. On the positive side, the idea that scientifc knowledge ought to rest on experiments was carried over from the natural sciences to emerging disciplines such as psychology and aesthetics. Moreover, in the wake of the German Pietist tradition as well as Descartes’s and Locke’s innovative investigations into the human mind, the traditional focus on outer experience was complemented by the idea of inner experience, or observation, as a privileged means to gain insight into the mind’s own cognitive capacities and workings.15 By conceiving

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of inner experience as analogous to outer experience, philosophers thought they could align themselves with the success of the natural sciences.16 As we will see, however, the idea that psychologists and philosophers could achieve their aims by relying on this type of cognition had both supporters and critics. Locke’s Essay also added a new dimension to the debate by using the term ‘experience’ to denote the basic mental operation that supplies the understanding “with all materials of thinking.”17 Locke considered experience in this sense—also called ‘observation’—to draw these materials from either sensation or the mind’s own operations and, ultimately, from either the external objects that give rise to sensations or the mind itself.18 Thus, Locke uses the term ‘experience’ not as an equivalent of ‘empirical cognition,’ but to identify the so-far anonymous act by means of which the mind frst turns both sensations and thoughts into ideas that, hence, constitute the content of its cognitions. From Tschirnhaus and Wolff onward, German philosophers engaged with the experimental scientifc practices of their contemporaries as well as with Baconian, Newtonian, Lockean, and—later on—Humean, conceptions of sensation, outer experience, inner experience, and experiments. One way or another, they tried to accommodate (elements of) their insights, criticisms, and methodologies. As was mentioned above, some of them also drew on the resources offered by German Pietism to challenge what they perceived as the intellectualist bias of the Leibnizian and Wolffan philosophical systems. However, eighteenth-century German philosophers predominantly sought to integrate or harmonize the insights obtained by Newton, Locke, Leibniz, and their followers. Regardless of the widely divergent results of their efforts, this meant they sought to navigate the tension between, on the one hand, a variety of anti-speculative and anti-intellectualist appeals to sensation, inner experience, and the experimental method and, on the other hand, the classical ideal of scientifc knowledge as the sum total of universal truths to be discovered by the intellect. Arguably, the challenge they were facing came down to deciding whether philosophy should aspire to the type of reasoning carried out in mathematics, emulate the method employed in the experimental sciences, combine elements of both, or move beyond both models.19 The tension between these models was played out preeminently within the circle of philosophers and scientists associated with the Berlin Academy, especially after its reorganization by Frederick II between 1744 and 1746. The King appointed the French scientist and philosopher Maupertuis as the head of the Academy, which was endowed with a class of speculative philosophy—the frst of its kind among European Academies—and frmly encouraged exchanges with English and French philosophical currents. As a result, the debates fostered by the Berlin Academy were largely defned by the real and perceived opposition

Introduction 5 between Wolffanism, Newtonianism, and Lockeanism.20 However, we hold that these debates brought to the fore a tension that ran much deeper and, in fact, largely shaped the philosophical positions and movements treated in the present collection of essays. While most of these essays examine the work of a single philosopher, we hope that the collection as a whole clarifes how this tension informed their accounts and appraisal of experiential cognition and, thus, bring out a thread that inconspicuously runs through eighteenth-century German philosophy as such. Obviously, the problem that we consider to unite the philosophers treated in this collection already played a crucial role in seventeenthcentury European philosophy. Accordingly, some of the contributions take into account the impact of late seventeenth-century authors such as Leibniz, Thomasius, and Tschirnhaus.21 As far as studies of eighteenth-century philosophy are concerned, we believe that the present collection complements existing research—including a number of very recent publications—in various ways. It shares common ground with a recent collection devoted to eighteenth-century European empiricism titled What Does It Mean to Be an Empiricist? Empiricisms in Eighteenth-Century Science, which, however, deals with philosophical accounts of the experimental sciences rather than developments within philosophy itself. 22 Rydberg (2017), conversely, highlights the crucial role that philosophers and theologians who taught in Halle between the late seventeenth and the mid-eighteenth century assigned to inner experience and related concepts. Yet Rydberg’s study is concerned with the history of the idea of inner experience rather than the history of philosophy more narrowly defned. Various essays in our collection deal with philosophers who are seriously underinvestigated or even unknown outside small circles of specialists. In this regard, we agree with the recent trend in the historiography of philosophy to put canonical fgures into perspective23 and, more generally, to avoid entrenched generalizations that obscure the complexity of the developments under consideration. 24 Another historiographical pitfall we hope to have avoided is the assumption that the tale of eighteenth-century German philosophy is that of a progressive development that culminated in Kant’s radical break with Wolffanism. While it is certainly warranted to examine the period between Wolff and Tetens in order to shed light on Kant’s philosophy, as is done in a number of recent studies, the present collection seeks to account for that which unites the philosophers under discussion without casting their achievements and disagreements into a teleological mold.25 In a sense, the essays gathered here aim to observe the successive effects of the tension between, on the one hand, the ideal of intellectual purity and, on the other, the objectivity to which experiential cognition lays claim, and this insofar as this tension unfolded in the element of early post-Leibnizian philosophy. As we will see, many of the philosophers

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treated in this volume attempted to reconcile rationalist and empiricist accounts of cognition rather than endorsing the one or the other position. Taken together, these successive effects might be considered to amount to the experiential turn of modern German philosophy. The essays resulting from this project are ordered according to the partly overlapping movements that defned German eighteenth-century philosophy: Wolff and Wolffanism, eclecticism and Popularphilosophie, and the Berlin Academy. Tetens and Kant are treated together in the fnal section. In the remaining part of this introduction, we provide a brief outline of the book’s thirteen chapters. The frst chapter, by Corey Dyck, sets the scene by examining the largely overlooked infuence of Tschirnhaus’s treatise on method, the Medicina mentis, on Wolff’s early conception of the mathematical method in the Philosophia practica universalis, mathematica methodo conscripta (1703) and other treatises. Dyck shows that Wolff was deeply indebted to Tschirnhaus’s insistence that scientifc investigations rest on principles gained from experience, yet did not accept Tschirnhaus’s position in all regards. On Dyck’s account, Tschirnhaus’s methodological principles not only informed Wolff’s earliest philosophical works but also had an impact on his major works on logic and mathematics. Accordingly, the chapter brings out features of Wolff’s understanding of the method to be employed in all sciences that defy the characterization of Wolff’s methodology as rationalist in the accepted sense of the term. Turning to Wolff’s mature works, Christian Leduc’s chapter considers Wolff’s innovative yet somewhat ambivalent understanding of the relationship between ontology, cosmology, and experimental physics. Focusing on the Cosmologia generalis (1731), Leduc does so in particular by comparing Wolff’s stated views on the role of the analytic and synthetic methods in scientifc enquiries with the way he actually proceeds to generate cosmological truths. As Leduc points out, Wolff maintains in the Cosmologia generalis that all cosmological truths must be grounded on experimental physics, but actually demonstrates the properties of matter and the laws of motion by relying on the results of ontology, which purports to prove the frst general and common concepts and propositions a priori or by means of the synthetic method. On this reading, Wolff’s general cosmology suffers from a tension that characterizes Wolff’s system as a whole, namely, the tension between his appreciation of Newton’s methodology and the ideal represented by Euclidian mathematics. The third chapter, by Alessandro Nannini, addresses Wolff’s wellknown successor Alexander Gottlieb Baumgarten in view of a dimension left untouched by Wolff, namely, the aesthetic dimension of experience. While Baumgarten can rightly be said to have founded modern aesthetics, Nannini contextualizes the Aesthetica (1750) by relating its innovations not only to early-eighteenth-century developments in the natural sciences but also to the increasing prominence

Introduction 7 granted to sensibility, experience, and experiments in Lutheran theology. In the latter tradition, spiritual experience became aligned with knowledge acquired by the senses and other lower cognitive powers. Drawing on this analysis, Nannini argues that Baumgarten’s aesthetics aims to achieve a twofold goal. On the one hand, he took the discipline to provide the various types of experimentalism, ranging from natural science to theology, with a unifed epistemological framework. On the other hand, he took his aesthetics to teach aestheticians how to achieve the highest goal of aesthetics—beauty—by conducting a range of aesthetic experiments. Stefan Heßbrüggen-Walter’s contribution examines Wolff’s main opponent during the 1740s, Christian August Crusius, in view of his relationship to both Wolff and the Thomasian tradition. As HeßbrüggenWalter explains, the various meanings of the concept of experience became an explicit subject of debate among Thomasius’s followers. Rüdiger, Syrbius, and Budde considered experience to consist in multiple sensations of the same object, whereas Hofmann and Crusius conceived of experiences as propositions based on sensations. The chapter argues that Crusius’s analysis of the concept of experience in Entwurf der nothwendigen Vernunft-Wahrheiten (1745) follows in the footsteps of Rüdiger and Hofmann by prioritizing the role of experience in scientifc investigations and, accordingly, abandoning the emphasis of radical Pietism on spiritual experiences. According to Heßbrüggen-Walter, Crusius mainly moved beyond his teachers by integrating their ideas into a coherent theory. Udo Thiel’s chapter is aligned with Nannini’s to the extent that it engages with eighteenth-century accounts of inner experience. However, the two philosophers he puts center stage, Johann Georg Heinrich Feder and Johann Christian Lossius, represent a very different tradition, namely, one that took its bearings from Locke. According to Thiel, both Feder and Lossius sought to provide systematic accounts of how the human mind obtains experience of its own mental states and activities. Unlike Locke’s Essay, as Thiel explains, Feder’s textbook Logik und Metaphysik (1769) distinguishes various types of immediate inner sensation, including the feeling he calls Selbstgefühl. Feder also moved beyond Locke’s empiricism by claiming that this non-conceptual feeling grounds any distinct thought of the self and, hence, the thought of a subject that is simple and immaterial. Feder’s account infuenced a range of late-eighteenth-century German philosophers, including Lossius and Tetens. According to Thiel, Kant was also familiar with Feder’s work, but during the 1770s departed from Feder by drawing a clear distinction between inner sense and apperception. Concluding the second section, Falk Wunderlich’s contribution likewise examines two underinvestigated German philosophers with a strong empiricist bent, namely, the Göttingen professors Christoph

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Meiners and Michael Hißmann. After discussing Meiners’s programmatic Revision der Philosophie (1772), Wunderlich offers an analysis of Hißmann’s Psychologische Versuche (1777), a work that builds on both Meiners’s and Feder’s accounts of the human mind. As Wunderlich explains, Hißmann moved beyond these accounts by arguing—along materialist lines—that philosophical investigations into the human mind should rely on the results obtained in physiology and medicine rather than inner experience. The chapter concludes by arguing that Hißmann combined his materialist methodology with agnosticism concerning the nature of the soul and accepted Leibniz’s monadological account of the soul as a consistent hypothesis. Shifting the focus to developments at the Berlin Academy, Anne-Lise Rey’s chapter addresses Maupertuis’s attempt—typical of his circle— to forge a middle path between metaphysics and experimentation, i.e., between the positions represented by Leibniz and Newton. She does so by focusing on the epistemological elements of the physical theology he elaborated in, among other works, his Essai de cosmologie (1750). On Rey’s account, Maupertuis turned against the Cartesian ideal of geometrical truths by giving pride of place to experimentation and, thus, the inability of the human mind to grasp the system of nature by means of the intellect. As she points out, however, Maupertuis’s defense of the role of experiments went hand in hand with the conviction that the laws of nature discovered by means of these experiments demonstrate the existence of God. In her contribution, Annelie Grosse examines the efforts on the part of Jean Henri Samuel Formey, the permanent secretary of the Berlin Academy, to develop a psychology informed by both Wolffan empirical psychology and physiological descriptions of the nervous system. She illustrates Formey’s innovative approach to the soul by analyzing his Essai sur les songes (1746) with particular attention to the methodological refections he elaborates in this context. Grosse argues that Formey’s account of dreaming, despite its Wolffan overtones, turned against Wolff’s strict separation of physiology and metaphysics in order to accommodate the increasing weight that his contemporaries gave to experimentalism. The chapter thus shows how Formey’s complex conception of experience seeks to integrate elements of the methods represented by Wolff and Newton. Paola Basso addresses a further result of the attempts of scholars associated with the Berlin Academy to integrate experimentalism and speculation, namely, Lambert’s original understanding of the a priori and a posteriori elements of the method to be employed in all scientifc investigations, including those carried out in philosophy. As Basso explains, Lambert in Neues Organon (1764) and related texts draws on Locke by arguing that philosophy ought to begin by drawing its basic

Introduction 9 content—simple concepts—from observation, but ought to further proceed by adopting the geometrical method championed by Wolff, i.e., by establishing axioms and postulates and carrying out a priori deductions constrained by the latter. Given their origin in simple concepts derived from observation, the complex concepts and propositions that result from this a priori procedure have a bearing on the actual world. According to Basso, this hybrid method unifes experience and deduction in a novel way. Tinca Prunea-Bretonnet’s chapter examines the role Jean-Bernard Merian granted to experience in the eclectic philosophy he developed between 1749 and 1797. She clarifes the nature of this eclecticism—which dominated the Berlin Academy at the time—by showing how Merian embraced Lockean, Humean, and Newtonian insights, but not without determining the limits of their approaches. Prunea-Bretonnet does so in particular by analyzing Merian’s infuential theory of apperception, his understanding of the relationship between metaphysics and natural philosophy, his reception of Hume’s views on skepticism, and his rejection of what he takes to be Hume’s generalized phenomenalism. Drawing on these elements, she shows how Merian countered Hume’s standpoint by defending the indubitable certainty provided by the apperception of the self as well as the foundational and guiding role played by metaphysics defned as a science of principles. Courtney D. Fugate offers an analysis of the role Kant grants to experience in the Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality (1764) and related early writings. Taking Kant’s references to Newton as a clue, his reading challenges the received view by its emphasis on Kant’s indebtedness to Baconian and Newtonian brands of empiricism. After examining Bacon’s and Newton’s thoughts on the method to be employed in the sciences, Fugate argues that the method Kant expounds in the Inquiry and seeks to apply in other works is akin to Newton’s rather than Wolff’s. On his account, Kant seems to align himself with Wolff but importantly deviates from Wolff’s position by claiming that metaphysics owes its content to empirical sciences rather than the employment of the synthetic method. Clinton Tolley and R. Brian Tracz examine Tetens’s multifaceted account of experience in his Philosophische Versuche über die menschliche Natur und ihre Entwickelung (1777). On their reading, Tetens’s detailed analysis of the various cognitive operations of the human mind is indebted not only to Locke, as is obvious, but also to Leibniz and Wolff. Thus, they point out that Tetens adopts Locke’s observational method to provide a genetic account of the types of cognition the human mind can achieve but casts the results in the mold of Wolffan empirical psychology. They further argue that Tetens, unlike Locke, clearly distinguishes experience from sensation and sides with Leibniz as far as

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the non-empirical origin of elementary concepts such as substance and causality is concerned. After considering Tetens’s view on the philosopher’s experience of the cognitive activities carried out by the human mind themselves, the chapter concludes by comparing Tetens and Kant on this issue. The fnal chapter, by Karin de Boer, ties in with the preceding two by tracing Kant’s successive attempts to come to terms with the role of experience in metaphysics in the Inquiry (1764), Dreams of a Spirit-Seer (1766), and the Critique of Pure Reason (1781). De Boer argues that Kant—in line with many of his contemporaries—embraced the scientifc model represented by Newtonian physics because it provided the means to challenge the assumption on the part of Wolffan metaphysics that a priori cognition of objects could be achieved by the intellect alone. On her account, however, Kant was not prepared to elevate experience into the absolute touchstone of metaphysics, as this would threaten the very possibility of a priori cognition. The chapter argues that Kant’s successive efforts to solve this tension culminated in Kant’s claim, put forward in the Critique of Pure Reason, that the synthetic a priori cognition to which metaphysics aspired is warranted only insofar as it pertains to possible experience.

Notes 1 Kant, CPR, A856/B884. 2 In this regard, our approach is in line with Engfer (1996: 11–32); see also Anstey (2005), Vanzo (2014), Pasini and Rumore (2016), and Bodenmann and Rey (2018). 3 While varieties of the opposition can be found in Kant’s Critique of Pure Reason (cf. A854/B882), it was canonized by Reinhold and Tennemann, both of whom presented Kant as the one who had overcome the onesidedness of the two doctrines. See Engfer (1996: 24–32) and Vanzo (2014: 528–31). According to Vanzo, moreover, it “is only after Kant introduced the new, standard notion of empiricism that self-professed observational philosophers started to be called and to call themselves empiricists or empirical philosophers” (523). 4 Apart from Holzhey (1970), a largely philological German study on Kant and his predecessors, we are not aware of studies that proposes to frame German Enlightenment philosophy in terms of its shifting understanding of experiential cognition. 5 On this, see Schliesser (2011), who claims that eighteenth-century philosophers, in one way or another, had to respond to the assumption that Newton’s natural philosophy could be used to settle debates within philosophy proper. On the European reception of Newton more generally, see Boran and Feingold (2017); Mandelbrote and Pulte (2019). 6 See Puech (2015). 7 As D’Alembert notes in his 1751 Discours préliminaire de l’Encyclopédie: “Locke undertook and successfully carried through what Newton had not dared to do, or perhaps would have found impossible. It can be said that he

Introduction 11

8 9 10 11 12 13 14

15 16

17 18 19

20 21 22 23

24 25

created metaphysics, almost as Newton had created physics. He understood that the abstractions and ridiculous questions which had been debated up to that time and which had seemed to constitute the substance of philosophy were the very part most necessary to proscribe. He sought the principal causes of our errors in those abstractions and in the abuse of signs, and that is where he found them.” (D’Alembert, 1995: 83–84) See Chapter 4 in this volume; see also Fischer (1975). See Gadamer (1960: 329), Holzhey (1970: 13), Engfer (1996: 14, 30–32), and Bodenmann and Rey (2018). For overviews of this development, see ‘Erfahrung’ in Ritter et al. (1972: 609–15) and Holzhey (1970). See Aristotle, Met. 980b–981a; Anal. post. 100a. See Holzhey (1970: 34–64). See Wolff, LL § 664. On this, see Chapter 12 of the present volume. See Aristotle, Met. 981a–b. It goes without saying that these new perspectives on the notion of experience originated in late sixteenth- and seventeenth-century developments in both the sciences and philosophy, frst and foremost Bacon’s Novum organum (1620). On the various meanings of the term ‘experience’ during this period, see Dear (2006). See Rydberg (2017). While he does not explicitly refer to inner experience, a clear point in case is Hume’s alignment of the “scrutiny into the powers and faculties of human nature” undertaken in the Enquiry and Newton’s achievements. Thus, Hume asks rhetorically whether we shall “esteem it worthy the labour of a philosopher to give us a true system of the planets, and adjust the position and order of those remote bodies; while we affect to overlook those, who, with so much success, delineate the parts of the mind, in which we are so intimately concerned?” See Hume, Enquiry, 1.13–14. Locke, Essay, II.i.2. Locke, Essay, II.i.3–5. See Engfer (1996: 15–16). While Engfer describes the two models available to seventeenth- and eighteenth-century philosophers in similar terms, he cautions against identifying them with rationalism and empiricism, if only because many philosophers we identify as empiricists conceived of mathematics as a prime example of indubitable knowledge. See Prunea-Bretonnet (2015). As regards efforts to undercut the opposition between rationalism and empiricism with respect to (late) seventeenth-century philosophy, see Anstey (2005) and Vanzo and Anstey (2019). Bodenmann and Rey (2018). See also Pasini and Rumore (2016) and Tommasi (2019). See, for example, the recent anthology titled Early Modern German Philosophy (1690–1750) (Dyck 2020), a collection of essays titled Women and Philosophy in Eighteenth-Century Germany (Dyck 2021), and the book series Oxford New Histories of Philosophy edited by Christia Mercer and Melvin Rogers. This holds true, as was mentioned above, not only of the terms ‘rationalism’ and ‘empiricism’ but also of the assumption of a unifed ‘Scientifc Revolution’. For criticism of the latter concept, see Shapin (1996). Studies of this period that examine pre-Kantian philosophy in view of Kant include Holzhey (1970), Watkins (2005), Wunderlich (2005), Sturm (2011), Dyck (2014), and Dyck and Wunderlich (2018).

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Bibliography Ahnert, Thomas (2004), ‘Newtonianism in Early Enlightenment Germany, c. 1720–1750’, Studies in History and Philosophy of Science, 35/3, 471–91. Anstey, Peter (2005), ‘Experimental versus Speculative Natural Philosophy’, in P. Anstey and J. Schuster (eds.), The Science of Nature in the Seventeenth Century: Patterns of Changes in Early Modern Natural Philosophy, Dordrecht: Springer, 215–42. Bodenmann, Siegfried and Rey, Anne-Lise (eds.) (2018), What Does It Mean to be an Empiricist? Empiricisms in Eighteenth-Century Science, Boston: Springer. Boran, Elizabethanne and Feingold, Mordechai (eds.) (2017), Reading Newton in Early Modern Europe, Leiden: Brill. D’Alembert, Jean Le Rond (1995), Preliminary Discourse to the Encyclopedia of Diderot, ed. and transl. by R.N. Schwab, Chicago: University of Chicago Press. Dear, Peter (2006), ‘The Meanings of Experience’, in K. Park and L. Daston (eds.), The Cambridge History of Science Volume 3: Early Modern Science, Cambridge: Cambridge University Press, 106–31. Dyck, Corey (2014), Kant and Rational Psychology, Oxford: Oxford University Press. ——— (2020), Early Modern German Philosophy (1690–1750), Oxford: Oxford University Press. ——— (ed.) (2021), Women and Philosophy in Eighteenth-Century Germany, Oxford: Oxford University Press. Dyck, Corey and Wunderlich, Falk (eds.) (2018), Kant and His German Contemporaries, Cambridge: Cambridge University Press. Engfer, Hans-Jürgen (1996), Empirismus versus Rationalismus? Kritik eines philosophie-historischen Schemas, Paderborn: Schöningh. Fischer, Klaus P. (1975), ‘John Locke in the German Enlightenment: An Interpretation’, Journal of the History of Ideas, 36/3, 431–46. Gadamer, Hans-Georg (1960), Wahrheit und Methode, Tübingen: Mohr Siebeck. Hahn, Robert (1988), Kant’s Newtonian Revolution in Philosophy, Carbondale: Southern Illinois University Press. Holzhey, Helmut (1970), Kants Erfahrungsbegriff: Quellengeschichtliche und Bedeutungsanalytische Untersuchungen, Basel-Stuttgart: Schwabe. Lefèvre, Wolfgang (ed.) (2001), Between Leibniz, Newton and Kant: Philosophy and Science in the Eighteenth Century, Dordrecht: Springer. Mandelbrote, Scott and Pulte, Helmut (eds.) (2019), The Reception of Isaac Newton in Europe, London/New York: Bloomsbury. Pasini, Enrico and Rumore, Paola (eds.) (2016), Another Eighteenth-Century German Philosophy? Rethinking German Enlightenment, Quaestio, 16. Prunea-Bretonnet, Tinca (2015), ‘La méthode philosophique en question. L’Académie de Berlin et le concours pour l’année 1763’, Philosophiques, 42/1, 107–30. Puech, M. (2015), ‘Kant voulait-il être le Newton du monde transcendantal? Réfexions sur les conséquences en philosophie du statut de la science’, in R.

Introduction 13 Theis and L. Sosoe (eds.), Les sources de la philosophie kantienne. XVIIe et XVIIIe siècles, Paris: Vrin, 37–46. Ritter, Joachim, Grunder, Karlfried, and Gabriel, Gottfried (eds.) (1972), Historisches Wörterbuch der Philosophie, vol. 2 (D–F), Zürich: Scheidegger and Spiess. Rydberg, Andreas (2017), Inner Experience: An Analysis of Scientifc Experience in Early Modern Germany, Uppsala: Uppsala Universitet. Schliesser, Eric (2011), ‘Newton’s Challenge to Philosophy: A Programmatic Essay’, Hopos: The Journal of the International Society for the History of Philosophy of Science, 1/1, 101–28. Shapin, Steven (1996), The Scientifc Revolution, Chicago: University of Chicago Press. Stan, Marius (2012), ‘Newton and Wolff: The Leibnizian Reaction to the Principia, 1716–1763’, Southern Journal of Philosophy, 50/3, 459–81. Sturm, Thomas (2011), Kant und die Wissenschaften vom Menschen, Paderborn: Mentis. Tommasi, Francesco V. (ed.) (2019), Questioni di metafsica nel settecento tedesco, Archivio di flosofa, 87/1. Vanzo, Alberto (2014), ‘From Empirics to Empiricists’, Intellectual History Review, 24/4, 517–38. Vanzo, Alberto and Anstey, Peter R. (eds.) (2019), Experiment, Speculation and Religion in Early Modern Philosophy, New York/London: Routledge. Watkins, Eric (2005), Kant and the Metaphysics of Causality, Cambridge: Cambridge University Press. Wunderlich, Falk (2005), Kant und die Bewuβtseinstheorien des 18. Jahrhunderts, Berlin/New York: De Gruyter.

Part I

Wolff and Wolffanism

1

Before and Beyond Leibniz Tschirnhaus and Wolff on Experience and Method Corey W. Dyck

Leibniz’s importance for Christian Wolff, both intellectually and professionally, is widely recognized and indisputable. Yet Leibniz is only one of a number of fgures who made an impact on Wolff’s philosophy, especially in the early stages of his intellectual career. It has been recognized for some time, for instance, that Wolff’s metaphysics, and particularly that elaborated in his later Latin series of textbooks, is indebted to scholastic thinkers.1 Less appreciated, however, is Wolff’s frequent engagement with British thinkers such as Clarke, Collins, and Newton, as well as French and Dutch thinkers, in his many reviews and essays published in the learned journal Acta eruditorum. 2 Closer to home, Ehrenfried Walter von Tschirnhaus was a fgure who exercised a direct and decisive, if largely overlooked, infuence on Wolff’s philosophical enterprise. Indeed, Wolff was a Tschirnhaus devotée before he became acquainted with Leibniz, and a careful consideration of Wolff’s early writings reveals a persistent commitment to Tschirnhaus’s views on scientifc methodology even as Wolff identifed, and worked to rectify, its various shortcomings. A focus on Tschirnhaus’s infuence on Wolff can also serve to correct a widespread misconception of the character of Wolff’s rationalism, given that Wolff followed Tschirnhaus in granting a crucial role to experience in scientifc investigation. Accordingly, in this chapter, I will consider Tschirnhaus’s infuence on Wolff, with an eye to the role both grant to experience within their respective methodologies. I will, moreover, focus on the frst ten years of Wolff’s career, during which he worked intensively on refning his (in)famous mathematical method, a project that owes its inception in no small part to Tschirnhaus. In the frst section, I will consider Tschirnhaus’s own outline of this method in his primary text, the Medicina mentis, with emphasis on the central role played by experience, and then show how Wolff’s earliest publications take up various themes relating to it, but also diagnose important defciencies in Tschirnhaus’s exposition. In the second section, I turn to Wolff’s initial encounters with Leibniz and argue that a key part

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of Leibniz’s early signifcance for Wolff lies in the solutions he supplies for the challenges Wolff had identifed in Tschirnhaus’s account of the scientifc method. In the third and fnal section, I turn to Wolff’s complete elaboration of the mathematical method in his German Logic and contend that Tschirnhaus’s infuence is evident, particularly as regards the role he assigns to experience at every stage of its application.

1 Tschirnhaus’s Medicina mentis and Wolff’s Dissertations Tschirnhaus’s philosophy, particularly as detailed in his principal philosophical text, the Medicina mentis et corporis, might best be characterized as an experimental Cartesianism. Tschirnhaus, a Saxon nobleman, studied at the University of Leiden, where the Cartesian Geulincx was active, 3 and was an important member of Spinoza’s circle of friends (among whom Spinoza circulated the Ethics). Tschirnhaus was also an active scientist, mathematician, and inventor, who among other things developed new techniques for casting and polishing glass and played a (perhaps the) key role in the discovery of the secret for making porcelain. Tschirnhaus himself characterizes his aim in the Medicina mentis as outlining a “certain and constant method” for the discovery of all unknown truths. Specifcally, he aims to carve out a “middle way” between the two unsatisfactory options offered by his contemporaries concerning the path to discovering truth, namely, between those who contend that all knowledge is derived a priori solely through reasons and those who claim it is only gained a posteriori through experience (MM 290). The merely rationalistic methodology of the former is presumably vitiated by its reliance on the syllogism, which Tschirnhaus rejects as a means for discovery. He also considers this methodology to err in setting out from metaphysical principles in seeking to obtain knowledge of the natural world.4 Conversely, the latter, purely empirical methodology is wrong to abjure all use of reason or the intellect in discovery and moreover leaves itself open to skeptical challenges inasmuch as it dismisses inquiry into the criterion of truth as a speculative question (MM 38–39).5 Instead, Tschirnhaus claims that “one should at the outset begin a posteriori, but then in what follows everything should only be derived a priori, and then the singular is to be confrmed everywhere through evident experiences [per evidentes experientias]” (MM 290). Regarding the frst, a posteriori step in this methodology, Tschirnhaus indicates that we should start with experiences that can be had by anyone at any moment without considerable effort or possibility of error (MM 290–91). The Cartesian infection of his thought is easily discerned as he lists four such foundational experiences at the outset of the Medicina mentis: (1) “I am conscious of various things”; (2) “I am affected positively by some things and negatively by others”; (3) “I am

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able to conceive of some things […] but I cannot at all conceive of some other things”; and (4) “I notice various objects by means of the external senses and likewise by means of internal images and passions.”6 What makes these “most evident experiences” (experientia evidentissima) indispensable starting points for any attempt at discovery is not that, for instance, analysis of them alone serves to disclose new scientifc truths but rather that refecting upon them yields core epistemological and psychological insights that can be drawn upon in any subsequent investigation (MM 291).7 Most importantly, Tschirnhaus holds that consideration of these experiences supplies the criterion that allows for distinguishing truth from falsehood (cf. MM 34). According to Tschirnhaus, the mark of the true is that it permits of being grasped or thought (concipere), as when we grasp that the whole is greater than the part or that all radii in a circle are equal, whereas the mark of the false is that it cannot be thus conceived, as with the claim that the part is greater than the whole or that all radii of a circle are not equal (MM 34–35). While Tschirnhaus does not specify further what concipere consists in, it is clear that it does not simply amount to the bare thought of some thing (since that would cast too wide of a net) but involves a positive insight into the truth of some claim, such that it is immune to skeptical doubt (MM 34–35). On the basis of these most evident experiences, particularly the experiences gained by means of the (internal and external) senses in accordance with the fourth sort, Tschirnhaus proceeds to elucidate the a priori step in his methodology, which involves the application of a method borrowed from mathematics and geometry in particular.8 As characterized by Tschirnhaus, this method consists in the formation of defnitions through the combination of primary concepts of things, the derivation of axioms from these defnitions, and fnally the combination of defnitions with one another to derive further truths identifed as theorems (MM 67). Tschirnhaus’s understanding of axioms as derived from defnitions is certainly peculiar,9 and his account of theorems, with the related discussions of scholia, problems, and hypotheses, does crucial work for his theory of invention; however, his method really relies upon his theory of defnition. For Tschirnhaus, the aim of a defnition is, quite literally, the “generation” of the thing defned, an aim that is readily realized in the case of geometrical defnitions (i.e., of ‘circle’) but which Tschirnhaus extends to the notion of virtue and, notoriously, to the notion of laughter.10 Tschirnhaus then proceeds to elaborate three detailed rules through which such defnitions can be discovered.11 The frst rule requires surveying our thoughts relating to the various sorts of objects of our mind,12 abstracting from them as many genera as correspond to the different sorts of representations, and then repeating the process for these genera until we arrive at distinguishable “diverse natures” (MM 73).

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The second rule states that we should identify the commonalities among the various genera, which Tschirnhaus calls the ‘elements’ (elementa) of the defnition and through the combination of which a defnition is formed (MM 85–86). Third, and fnally, the resulting defnitions are to be ordered according to which one presupposes the other (either in terms of existential or conceptual dependence), until all elements are accounted for, and indeed until one can demonstrate through indirect proof that no further concepts can be formed of the defned notions (MM 91). The a priori step in Tschirnhaus’s account is completed with the move from defnitions to axioms and theorems, yet this does not signal the end of his account of the rules of invention, as he then returns to experience in search of ‘confrmation’ of what has been thus derived.13 Tschirnhaus understands ‘confrmation’ fairly straightforwardly in terms of offering empirical support for what has been derived a priori through the method just outlined, such that we complete a circle through deriving the very experiences that spurred our investigation at the outset. Yet, Tschirnhaus also contends that experience, particularly in the form of a deliberately enacted experiment, is effective in combating our tendency to err. Since the intellect cannot err on its own, as its function is solely to grasp what is true, Tschirnhaus locates all error in the imagination, where we mistake representations that have their source in it for accurate representations of objects (MM 165–66). Having derived a priori, for instance, that space is not a vacuum, as represented by the imagination, but extension as conceived by the intellect (MM 179), Tschirnhaus claims that we can then turn to instituting experiments designed to render intuitive the truth abstractly cognized by the intellect, with the intention of weakening the power of the images of the imagination and making it tractable to the intellect’s guidance.14 Accordingly, Tschirnhaus concludes, error can be systematically avoided only when, after conducting our a priori derivations, we have confrmed everything through experience and experiments, so that the imagination is altogether purged of erroneous impressions (MM 294). It would be diffcult to overestimate the importance of Tschirnhaus for Wolff.15 Wolff frst gained an interest in the Medicina mentis during his time in gymnasium (ELB 116–17), but it was only after taking up his mathematical studies in Jena in 1699 that he found himself able to proft from reading it (ELB 123–24). Wolff evidently read the text with great interest and care, marking his own copy with comments and queries. Later on, he even prepared an excerpted text for students without the requisite mathematical background (ELB 139). Unsurprisingly, given this, Wolff’s earliest publications betray the unmistakable infuence of the Medicina mentis. Contrary to what some commentators have claimed, however, Wolff was far from interpreting Tschirnhaus “purely rationalistically” (rein rationalistisch)16; rather, in extending Tschirnhaus’s project, Wolff was keen to assign an important role to experience and the senses in

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the generation of cognition. This is nowhere more evident than in the dissertation Wolff wrote for his habilitation at the university of Leipzig in 1703, Philosophia practica universalis, mathematica methodo conscripta which, according to Wolff’s report, Tschirnhaus himself regarded as the fruit of the Medicina mentis (ELB 134). Tschirnhaus’s infuence is clear, for instance, in Wolff’s justifcation of his use of the mathematical method in moral philosophy, because, as he puts it, this method allows us to “accurately distinguish the concepts of the intellect from the perceptions of the imagination” (MMP II 190). Wolff’s regimentation of this mathematical method is also informed throughout by Tschirnhaus’s presentation. Thus, in his own presentation, Wolff likewise sets out from defnitions, proceeds to axioms, which he understands explicitly as truths derived from individual defnitions,17 and takes these axioms to yield propositions and theorems. Most importantly, however, in a nod to Tschirnhaus’s emphasis of the importance of experience at the outset of the application of his method, Wolff presents a set of Observationes after the axioms, where these are observations whose truth is established a posteriori, that is, “through sense experience instituted by the direction of the intellect” (MMP II 199). Many of these same themes are present in Wolff’s next two publications, both in 1703, though neither wears its Tschirnhausian character quite so explicitly on its sleeve. So Wolff’s presentation in the dissertation De rotis dentatis no longer includes a section dedicated to observations, yet he does indicate that experience plays a probative role (MMP II 227). More importantly, the Disquisitio philosophica de loquela (De loquela) takes up an issue fundamental to Tschirnhaus, namely, accounting for the communicability of an idea, which Tschirnhaus viewed as criterial for taking a representation to be a concept of the intellect.18 Unexpectedly, in De loquela Wolff approaches the issue of the communicability of ideas through a metaphysical lens. Thus, proceeding from the principle (which Wolff identifes as Cartesian) that whatever is cognized of some thing is contained in the concept of that thing, he claims that it was Tschirnhaus who made a distinctive employment of this principle inasmuch as he turned to the consideration of a thing’s concept by way of discovering truths about the thing itself (MMP II 245–26). Applying this principle to the Cartesian concept of mind or spirit as a substance which is conscious of everything within it, however, shows that not all representations (such as of external things and their signs) can be deduced from it, and Wolff proposes to remedy this by conceiving of the mind as a being dependent upon God (MMP II 246–47). In the course of surveying our experiences of the mind by way of showing how its representations reveal this dependence upon God, Wolff turns to an account of signs which (for Wolff) raises the issue of how one mind can act (i.e., excite a thought) in another and is accordingly thought to involve a problem analogous to the Cartesian one of accounting for the interaction

22 Corey W. Dyck of mind and body. Wolff contends that this riddle can be resolved if we focus on our dependence on God and His will, in accordance with which alone such affection can be understood to take place (MMP II 252). Despite these various borrowings and emendations, Wolff was also a critical reader of Tschirnhaus at this early stage of his development, with the problems he identifes informing and motivating his subsequent philosophical efforts. Thus, he faults Tschirnhaus for offering only an obscure account of concipere and for failing to show in a detailed way how (real) defnitions should be discovered. Concerning the former, Wolff attempts to clarify concipere by taking it in terms of “mutually positing thoughts” (cogitationes se mutuo ponentes), by which Wolff presumably understands thoughts in which there is no contradiction, as this is contrasted with “mutually cancelling thoughts” (cogitationes se mutuo tollentes) (ELB 124). Regarding the latter issue, Wolff faults Tschirnhaus for a too narrow conception of real defnition and for failing to give any precise guidance as to how the “elements of defnitions”can be found (ELB 125). Indeed, Wolff even sought out Tschirnhaus himself during an Easter book fair in Leipzig in order to get his responses to these concerns. According to Wolff’s report, Tschirnhaus was satisfed with his gloss of concipere, but when questioned about how the elements of defnitions are discovered, Tschirnhaus simply replied that “this would indeed be the main issue” (dieses wäre eben die HauptSache) (ELB 125). As we will see, Wolff continued to be preoccupied with these problems from Tschirnhaus as he worked toward refning the mathematical method, and it is this project that provides the initial context for Wolff’s interaction with and reception of Leibniz.

2 Leibniz and Wolff’s Tschirnhausian Project Wolff’s Habilitationsschrift on practical philosophy (Philosophia practica universalis) proved rather important for his academic prospects and later philosophical development, as it was this text that brought him to the attention of Otto Mencke, the founder of Acta eruditorum (in 1682) and, through him, Leibniz (ELB 133). Mencke, who examined the dissertation, sent it to Leibniz (without his knowledge, Wolff claims, though this has been disputed19) for an appraisal, to which Leibniz responded approvingly, even including a message intended directly for Wolff.20 This was in any case the beginning of Wolff’s correspondence with Leibniz, which would continue until the latter’s death in 1716. It would not be inaccurate to say that it often suffced (at least in the early exchanges) that Leibniz informed Wolff of his own positions on a variety of philosophical issues for Wolff to adopt that position himself. Wolff’s frst letter to Leibniz included his Dissertatio algebraica de algorithmo infnitesimali differentiali, dated December 24, 1704, the same date as Wolff’s letter, and which is dedicated to Leibniz.

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This dissertation, which contains Wolff’s frst published mention of Leibniz, 21 concludes with a diverse set of corollaries, the third of which is “The syllogism is not a medium of the discovery of truth” (MMP II 289). That Wolff should draw this corollary is not surprising, given Wolff’s admiration for Tschirnhaus and the fact that many of his teachers followed the Cartesian rejection of syllogistics (ELB 135–36). In his detailed reply of February 21, 1705, however, Leibniz sharply reproves Wolff for this, saying simply “I would not dare to claim absolutely that the syllogism is not a medium of the discovery of truth” (BLW 18). This sentence was evidently all Wolff required in order to completely rethink his hostility toward the syllogism, as he subsequently identifes his adherence to this opinion as a prejudice founded on the authority of famous men, among whom Tschirnhaus is numbered (ELB 136). Even so, Wolff does not uniformly defer to Leibniz’s authority on these topics, but in some cases adopts a view that better accords with his other commitments and concerns. This is most evident concerning De loquela, which Wolff sent to Leibniz after this initial response and which Leibniz comments on in his next letter of August 20, 1705. It is in this letter that Leibniz frst points Wolff to his writings on the preestablished harmony, specifcally the New System and the exchange with Bayle, and informs Wolff of his rejection of the Cartesian doctrine that the mind is conscious of everything that takes place within it (BLW 32). In his response, Wolff confesses his ignorance of Leibniz’s system and requests more detail since he lacks access to the texts (BLW 39), which Leibniz obligingly provides in his next letter of November 9, 1705. Leibniz’s rejection of the claim that the mind is conscious of everything that it contains, which Wolff had previously endorsed (cf. MMP II 245), allows Wolff to continue to uphold the principle that whatever is cognized of a thing must be “contained” (continetur) in its concept, a principle he claims to borrow from Descartes but that he also fnds in Tschirnhaus (MMP II 246). Consequently, Leibniz’s conception of the (individual) soul as containing all of its perceptual states could only have seemed quite sympathetic, and given this it is not surprising that in his response, dated December 2, 1705, Wolff offers a wholehearted endorsement of Leibniz’s system (BLW 46–47). More importantly (for our purposes), Leibniz intervened concerning various topics of relevance for Wolff’s understanding of Tschirnhaus’s mathematical method. First and foremost among these is Leibniz’s championing of the analysis of concepts into simpler notions, a method that Wolff takes to provide an answer to his challenge to Tschirnhaus concerning the discovery of the elements of defnitions (BLW 39).22 Second, and relatedly, Leibniz complicates the Tschirnhausian picture by arguing that the possibility of concepts must be demonstrated before those concepts can be deployed philosophically. Leibniz makes this point specifcally in relation to his criticism of the Cartesian (and Anselmian)

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ontological argument for God’s existence, which argument Wolff had deployed himself in his dissertation on practical philosophy (MMP II 195–96). As Leibniz writes to Wolff, “the Cartesian demonstration of the existence of God proceeds geometrically if you suppose a God to be possible” (BLW 18—my emphasis). Leibniz’s point, which obviously extends beyond the notion of God, would soon lead Wolff to consider various ways in which the possibility of concepts in general (that is, on his account, their relation to possible things) can be proved. Signifcantly, in making this point to Wolff, Leibniz refers to an essay of his in the Acta eruditorum, namely the ‘Meditations on Knowledge, Truth, and Ideas’ of 1684, and in the same letter to Wolff he brings his attention to his novel hierarchical organization of the Cartesian distinction between ideas in that essay (BLW 18). Yet, Leibniz’s infuence, philosophical and otherwise, on Wolff did not change the fundamental outlines of his project, and around 1707 (in spite of the rigors of his new position at Halle) Wolff wrote a number of short philosophical publications that flled out and extended his conception of the usefulness of the mathematical method. Particularly worthy of note is the Solutio nonnullarum diffcultatum circa mentem humanam obviarum, which nicely illustrates how Wolff sought to integrate and develop Leibniz’s insights within his own, steadfastly Tschirnhausian, framework. The essay presents a treatment of the origin of concepts and an account of the nature of reasoning which are both clearly infuenced by Leibniz, particularly his discussion in the ‘Meditations’ which Wolff had evidently read carefully by this point.23 So, Wolff accounts for how distinct, general concepts are derived from perceptions of individual things through successive abstraction from various determinations in the original representation. Wolff contends that the “reality” (realitas) of the resulting concept is secured given that it contains nothing that cannot be found in the original representation (MMP I 13); however, since these notions can be arbitrarily combined with others, the reality of the resulting representation must be proved either a priori through consideration of the contents of the concept (and the generation of what is represented) or a posteriori through reference to a sensation of what is represented (MMP I 14). Concerning these general concepts, and here the Leibnizian infuence is clearest, Wolff contends that since they are indeterminate they can only be represented through symbols, which are chosen in accordance with a characteristic, and are manipulated in accordance with rules specifed in a combinatoric (MMP I 14). As an example of such a rule, Wolff specifes the mathematical rule of substituting like by like, which he considers in its application to an example from natural science (“the fre melts the lead”). Wolff argues that through progressive substitutions of defnitions for concepts, and careful consideration of their contents, we arrive at a new proposition (this is an example of the demonstration of what Wolff would later call a theorem) (MMP I 15–16).

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A fnal, but important, essay from this period relating to Wolff’s refnement of the mathematical method is his Leges experientiarum fundamentales, originally published in the Acta in 1708, in which he outlines the conditions under which experience can be made serviceable for use in the mathematical method. Evidently, Wolff continued to believe that sense experience, when directed appropriately by the intellect, is a crucial source of cognition. Wolff begins by explaining that we proceed from the perception of individual things by means of the external senses to universal cognition of such objects. With reference to his previous treatment of the origin of concepts, Wolff now makes clear that he takes distinct concepts to originate in the understanding’s refection upon sensory experience. He thus refers to the distinct notions that arise as “original” or “primitive” (primigenias) notions (MMP I 18), which are not subject to doubt as regards their possibility and thereby also indicates that he takes the foundational concepts of scientifc investigation to originate in sensation (even if the concepts are no longer sensitive representations). Wolff goes on to briefy highlight two obvious uses for concepts thus acquired, namely, that they enable the recognition of cognized objects under them and that we can further derive concepts through abstraction from the marks of the original notion or through its composition with others (MMP I 19). However, the bulk of the remainder of the essay concerns the limits of our experience, as Wolff is keen that we should also attend to these in the context of our reliance upon sensory cognition, given that care is required in the distinction between the concepts we draw from it.24 As an example, Wolff considers our experiential cognition that things have a power for altering other things, or that a thing, A, has a power to infuence another, B. Here, Wolff claims, our cognition is ambiguous between three different possibilities, such that the concepts drawn will depend on how we gloss our experience (which Wolff does not call into question). It is possible, frst, that only the actual alterations on the part of A and B are accessible to the senses, second, that the causes of the alterations are also available to the senses, or, third, that the infuence itself is distinctly perceived (MMP I 19). In the course of the essay itself Wolff does not settle which of these options is the case with respect to the interactions among external objects, and much less with respect to that between the soul and the body. However, he does go on to use the example to derive a number of principles that should direct the examination and investigation of our experience. So, if the frst is the case (and only actual alterations are given to the senses), Wolff notes that then we cognize nothing more through experience than that something has happened, and insofar as we want to seek out the cause of this or the conditions under which such a change happens, we need to bring it out through previous experience or further inferences, which must likewise be carefully considered (MMP I 19–20).

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In the second case (where the cause is also given), Wolff warns that in order to be confdent that we have perceived a cause, we must be careful to distinguish a genuine perception of causation from the mere perception that one thing succeeds another or that two things occur at once, for we do not thereby have grounds to infer a causal relation between the two (MMP I 21). Finally, in the third case, where infuence is directly perceived (which Wolff does not here rule out), we must use the resources of physics to investigate the nature of the power involved, but only once we have considered whether perhaps a part of the infuence is not given to our senses. In order to do this, Wolff recommends a thorough experimental investigation of the conditions under which the change occurs (MMP I 20–21). As should be evident from the foregoing discussion, Wolff’s examination of the foundational laws of experience is ultimately motivated by Tschirnhaus’s account of the role of experience in scientifc investigation, and it is a function of the fact that Wolff continues to assign such a role to sensory experience that he also takes care to outline the rules that govern its use and to circumscribe the limits of this use. This is hardly an aberration, or an immature empirical dalliance on his way to a mature and robust philosophical rationalism, as Wolff will continue to lay such an emphasis on experience, not merely in physics but also in metaphysical disciplines such as psychology and natural theology (though we cannot consider these here). 25

3 Refning the Mathematical Method: The German Logic What is in any case foremost on Wolff’s mind during the period until Leibniz’s death in 1716 is the task of refning and systematizing the mathematical method. He accomplishes this in a series of texts, including the ‘Kurzer Unterricht von der Mathematischen Methode oder Lehr-Art’ that opens the Anfangs-Gründe aller Mathematischen Wissenschaften (1710); its Latin counterpart, the ‘De Methodo Mathematica Brevis Commentatio’ in the Elementa matheseos universae (frst volume 1713); and the Mathematisches Lexicon (1716), which includes an entry on the method as well as on each of its principal elements. In these texts, Wolff continues to claim Tschirnhaus as his model; thus, he writes that “no one has explained the mathematical method more skillfully [geschickter] than Tschirnhaus,” and he even claims that his own presentation will help the reader to understand Tschirnhaus’s book better, “something [he] sincerely desires for every lover of truth” (KU 4). The most important and complete presentation of the method, however, is contained in the Vernünfftige Gedancken von den Kräfften des menschlichen Verstandes und ihrem richtigen Gebrauche in Erkäntnis der Wahrheit (German Logic) (1713), a work that Wolff, despite its presentation in a form (roughly) commensurate with traditional treatments in logic, nonetheless identifes as the defnitive presentation of his method. 26 Indeed, the

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German Logic represents the culmination of Wolff’s efforts to refne the mathematical method and revise it in light of his previous criticisms of Tschirnhaus and Leibniz’s interventions. 27 We will consider the essentials of Wolff’s treatment in what follows, beginning with defnitions, with an eye to these complementary infuences. 3.1 Defnitions Wolff’s account in the German Logic of how we form real defnitions begins with a discussion of concepts which serve as the referents of the terms to be defned. This discussion opens in an Aristotelian-Lockean vein, as he contends that our concepts ultimately have their origin in sensation. Sensation (Empfndung) is identifed with the consciousness of something being present to us, and the senses (Sinnen) are the capacity that leads us to the immediate sensation of things that are external to us (GL1, ch. 1, §§ 1–3). And while a concept (Begriff / notio) is simply said to be “any representation of a thing in our thoughts,” Wolff proceeds to claim that, since the senses provide us with representations of things outside of us, the senses also ultimately provide us with concepts (GL1, ch. 1, §§ 4–5). Wolff does not (at this stage at any rate) consider any other source for our concepts of external things (or of anything else for that matter) but instead turns to the question of how we form universal concepts from the singular concepts supplied by the senses. Wolff notes that we can compare (already acquired) concepts with one another with an eye to their similarities and differences, such that we take some concepts to be of the same sort (Art) and, thus, produce a new, universal concept (GL1, ch. 1, §§ 24–26). Alternatively, a general concept can be formed by leaving out determinations in a given concept, though we can also arbitrarily add determinations to a given concept with the result that it becomes less general (GL1, ch. 1, § 28). Following on Leibniz’s previous suggestion that the possibility of concepts must frst be demonstrated, Wolff contends that it is only in the case of the initial concepts supplied by the senses (i.e., our thoughts of sensations) that our possession of the concept amounts to an immediate and indubitable proof of the concept’s possibility, which is to say, of the possible existence of the referent of the representation (GL1, ch. 1, § 29). Likewise, in the case of the second sort of concepts, namely those abstracted from concepts of sensation, Wolff argues that we can be certain of their possibility insofar as they are attained through leaving out determinations of concepts whose possibility is already certain (GL1, ch. 1, § 30). However, the possibility of the fnal sort of concepts—those formed through arbitrary determination—cannot be taken for granted, since “our will can make nothing possible” (GL1, ch. 1, § 31). Wolff considers two ways in which these concepts can be demonstrated, namely through experience or by means of a proof.28 The possibility of an arbitrarily formed concept can be proven from experience insofar as we fnd an example of the

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concept in the world and attend to whether it agrees with the concept (GL1, ch. 1, § 32), and it can be shown through a proof insofar as we show how it can come about or whether something of whose possibility we are already certain is entailed by it (GL1, ch. 1, § 33). General, possible concepts are the objects of the defnitions which constitute the initial step of the mathematical method. The question remains, however, as to how we arrive at the defnitions of these concepts—what are the elements of which the defnitions are composed? It will be recalled that this is the very question Wolff posed to Tschirnhaus himself at their frst meeting. Here, again, Wolff’s interaction with Leibniz comes into play, particularly Leibniz’s hierarchical reorganization of the Cartesian designation of concepts as obscure, clear, or distinct, as well as his method of analysis by which the marks of complex concepts are distinguished from one another. By means of attention to our concepts and to what distinguishes them from one another, we can raise obscure concepts to clear ones (GL1, ch. 1, §§ 8–9), and by carefully distinguishing the marks in a given clear concept we can render it distinct rather than confused or indistinct (GL1, ch. 1, §§ 12, 17). Defnitions, then, are formed through consideration of our distinct concepts (GL1, ch. 1, § 34) and, in fact, the method for rendering our concepts distinct is also that for forming their defnitions, 29 which is why Wolff nearly identifes distinct concepts with defnitions (cf. GL1, ch. 1, § 34). As before, Wolff distinguishes between nominal and real defnitions, or defnitions of words (Wort-Erklärungen) and defnitions of things (Sach-Erklärungen), where the former state suffcient properties by which the concept is distinguished from all other similar ones and the latter show how the concept is possible by showing how an object corresponding to it can be brought about (GL1, ch. 1, § 38). In a departure from Tschirnhaus, however, Wolff allows that nominal defnitions are not only useful for the purposes of everyday life but also indispensable for discovering real defnitions (GL1, ch. 1, § 47), namely, insofar as one considers the marks enumerated in the nominal defnition and compares them with other cognitions to ascertain how the object can be generated (GL1, ch. 1, §§ 51–52). This corresponds to the a priori method of discovering real defnitions, but Wolff also provides a couple of a posteriori methods for discovering them, either (when we know nothing about the thing to begin with) through simple trial-and-error (GL1, ch. 1, §§ 48–49) or through careful investigation of the structure of the given thing (as with a machine—GL1, ch. 1, § 53). 3.2 Axioms, Postulates, and Propositions from Experience The discovery and formulation of defnitions is crucial, as defnitions serve as the “grounds” of demonstrations,30 that is, of chains of valid syllogisms which are linked inasmuch as the conclusions of earlier proofs

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in the series serve as premises in a subsequent proof (ML 501) and the frst premises of which are themselves propositions that are (indemonstrably) certain. Defnitions can serve as these grounds, or frst premises, in demonstrations, though they do so in two different ways. First, they themselves can serve as frst principles in the demonstration, where real defnitions can do so immediately but nominal defnitions must frst have the possibility of their related concept proven (ML 495).31 Second, defnitions can serve as grounds of demonstrations insofar as further propositions are derived directly from one of them. Wolff refers to these derivative propositions generally as ‘principles’ (Grundsätze) (KU § 27), and he divides them into theoretical and practical, where the former assert that something is the case or pertains to some thing and the latter that and how something could be done (GL1, ch. 3, § 12). Theoretical principles are called ‘axioms’ (axioma), though Wolff sometimes simply refers to them as ‘principles’ (Grundsätze) (GL1, ch. 3, § 13) and explicitly understands them in the Tschirnhausian sense (ML 223).32 Practical principles, on the other hand, are called ‘postulates’ (postulata  / Heische-Sätze).33 Since both of these are taken to follow immediately from a defnition, they are identifed as “identical propositions” (ML 224). Wolff maintains that the latter do not require further proof, as they are “clear in themselves” given the defnition, though he comments that such a proof could readily be supplied (GL1, ch. 5, § 2). Signifcantly, however, defnitions and axioms are not the only allowable grounds for demonstrations. Wolff argues that experiences (Erfahrungen / experientiae) can also serve as such grounds. As he writes, “one calls it a demonstration when one can conduct one’s proof so far until, in the last inference, one has nothing else than defnitions, clear experiences, and other identical propositions as premises.”34 Not every (proposition from) experience is suitable for this employment, however, and so Wolff devotes a chapter of the German Logic35 to setting out the conditions for their use in demonstrations. Commensurate with his early essay on the laws of experience, Wolff distinguishes between three different cases of experience that are so usable: frst, the experience of a thing along with its properties; second, the experience of the changes that something undergoes; and third, the experience of a thing’s effects upon another thing (GL1, ch. 4, § 5). He then considers the means by which we might determine, for instance, that our experience is in fact of a property belonging to the thing (such as three-sidedness to triangles), where a property is understood as something “that a thing must retain as long as it remains what it is” (GL1, ch. 4, § 6). Wolff claims that we must investigate whether the (alleged) property pertains to the thing in different circumstances and rule out the possibility that it has that feature only in light of some external ground, which we can do by altering its present circumstances (GL1, ch. 4, § 6). Alternatively, in cases where the thing under consideration cannot be easily moved, we might observe

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it over an extended period of time (GL1, ch. 4, § 7), or we might opt to investigate the matter a priori and, after acquiring a distinct concept of the thing, elaborate the marks of the concept to determine whether the connection between it and the alleged property is found (GL1, ch. 4, § 8). As before, Wolff devotes special attention to our experience of causal connections. While he allows that a causal connection can be known with certainty insofar as an alteration comes to be as soon as one body is introduced to another (GL1, ch. 4, § 9), he cautions that we must take care in our observation to ensure that this is in fact what was perceived. We must ensure, for instance, that one or both of the two objects at issue, or some other factor involved, has not previously undergone some alteration without which the event would not have happened, where this requires a thorough investigation of the state of the things involved (GL1, ch. 4, § 10). Further, Wolff advises that we must undertake to show that a given causal connection is not merely an instance of correlation, “[s]ince two things could always be connected with one another either because they have the same cause or because one or both often occur” (GL1, ch. 4, § 11). We can, however, ascertain that a given connection is mere correlation insofar as we observe a case where the frst event takes place and, in the absence of any hindering conditions, the second fails to occur (GL1, ch. 4, § 11). What all this goes to show is that experience of the sort that is admissible as a premise in a demonstration is to be understood not as the simple deliverance of the senses, but rather as a proposition that is subject to rigorous investigation. Given this, then, it is hardly surprising that he counts as experiences so understood the results of experiments (Experimente / Versuche), which are repeated and varied to ensure the reliability of their results (GL1, ch. 4, §§ 12–13). When these precautions are taken in the examination and confrmation of our singular experiences, Wolff claims that we can “quite easily change them into universal propositions” (GL1, ch. 4, § 15). In an echo of Tschirnhaus’s experientiae evidentissimae, Wolff dubs the latter “clear experiences” in order to distinguish them from the ordinary and unvetted deliverances of the senses and allows them to serve as grounds of demonstrations without any consequent loss of certainty. 3.3 Theorems and Problems While defnitions and propositions from experience provide the starting principles of demonstrations, it is theorems (theorema / Lehrsätze) that constitute the real core of Wolff’s method and the focus of his scientifc project. Following Tschirnhaus, theorems (and problems) are generally identifed by Wolff as propositions that make a claim (affrmative or negative) about what is or can be that can be derived from multiple defnitions.36 According to Wolff, a theorem is discovered through

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“experimentation,” that is, by beginning with simple defnitions and formulating propositions whose correctness is readily apparent (GL1, ch. 5, § 4). In addition, and signifcantly, Wolff takes theorems to have a specifc syntax, dividing them into a condition (hypothesis / Bedingung) and an assertion (thesis / Aussage), where the former states the circumstances under which some feature or property can pertain or not pertain to a thing and the latter asserts that that same feature or property pertains to a thing (or not) (GL1, ch. 3, § 6). An example of a theorem provided by Wolff is “a triangle is half of a parallelogram if both have the same height and base,” where the condition is “both have the same height and base” and the assertion is “a triangle is half of a parallelogram” (KU § 35). Whereas theorems are theoretical propositions, problems are practical propositions (GL1, ch. 3, § 14) which simply state something that is to be done. Wolff divides the task expressed in a problem into two parts—the frst is the ‘proposal’ (propositio / Vortrag), such as “show that a triangle is half of a parallelogram,” and the second is the ‘resolution’ (resolutio / Aufösung) in which the way in which the proposal is accomplished is laid out (ML 1093). While theorems clearly have priority in Wolff’s demonstrative enterprise, he holds that we tend to fnd theorems by arriving frst at problems and resolving them. Wolff’s account of theorems, and his theory of propositions in general, has been dismissed as a mere appendix to his logic, the real focus of which is thought to be his theory of concepts37; in fact, the opposite is the case. Not only do theorems represent the real engine of scientifc discovery for Wolff, with defnitions (and concepts) playing an explicit role in the demonstration of the discovered truths, but in addition Wolff’s account of theorems illustrates his ultimate reply to the ambiguity he initially diagnosed in Tschirnhaus’s understanding of thought (concipere).38 As we saw before, Wolff had trouble understanding what, precisely, grounded the necessity of assent implied in Tschirnhaus’s account of concipere, a failing also diagnosed in the Cartesian account of clear and distinct perception. Rather than relying on a potentially misleading personal conviction, Wolff analyzed this necessity in terms of “mutually positing” or “mutually cancelling” thoughts, such that having one thought either implies or excludes another. Wolff now formulates this account in the context of his analysis of a theorem, where a proposition is thought in the sense of concipere, for instance, when the two components of the theorem are such that the thought of the condition posits the thought of the assertion: Now if two thoughts are so constituted that the second necessarily takes place when one entertains the frst, or that I must necessarily think the second when I think the frst of something, so, in this case the thoughts agree; if however I cannot possibly think the second of

32

Corey W. Dyck something when I think the frst of it, so in this case my thoughts confict with or contradict one another.39

As Wolff proceeds to claim in the former case, where our thoughts agree (übereinstimmen), we say that “we can think the proposition,” whereas in the latter case “we cannot think the proposition,” where Tschirnhaus’s notion of concipere is clearly intended (GL1, ch. 3, § 10).40 Indeed, this is to be contrasted with the much broader account of thought offered earlier in the German Logic, where it is understood simply in terms of the consciousness of a representation.41 Yet the difference in senses of ‘thought’ is clearest in the case in which we cannot think a proposition, since Wolff’s point is obviously not that we are simply not aware of the proposition but rather that the thought of one excludes the thought of the other (with the result being a negative proposition). Wolff rounds out his account of the mathematical method with a discussion of corollaries (Zusätze), or applications of a theorem to a particular case, scholia (Anmerckungen), or further elucidations of something in the defnitions or principles, and of course the syllogism as the primary instrument of discovery (GL1, ch. 7, § 1). Nonetheless, what should be clear is that Wolff recognizes an important, even constitutive role for experience in the crucial initial stages of the application of the method. So, we rely on experience in the form of sensation for the acquisition of concepts; experience is also a source for the discovery (a posteriori) of real defnitions; clear experiences are allowed to serve as principles in demonstrations; and causal connections that are known through observation or experiment can serve as problems and issue in theorems. While this fact serves to rebut those who take the mathematical character of Wolff’s method to imply that it is purely rationalistic, it would nonetheless be equally incorrect to identify Wolff as a thoroughgoing empiricist in this respect, since the initial, singular concepts of the senses are rendered universal and distinct through the operation of the understanding, and the experiences that are ultimately admissible as grounds of demonstrations are the result of a rigorous vetting that serves to distinguish them from the unvarnished deliverances of the senses (GL1, ch. 4, § 8). Similarly to Tschirnhaus, then, Wolff holds that the senses can only reliably contribute to our cognition insofar as they are directed by the understanding.

4 Conclusion I have argued that, in the end, the vital role that Wolff assigns to experience in the defnitive presentation of his scientifc methodology clearly testifes to Tschirnhaus’s legacy. Through the blending of (what Wolff himself terms) a posteriori and a priori methodologies within the context of the mathematical method, we can see that Wolff is aiming, as he

Wolff on Experience and Method

33

had from the outset of his career, at an eminently Tschirnhausian “middle way” between empiricist and rationalist approaches to the discovery and justifcation of knowledge. Moreover, in highlighting Tschirnhaus’s importance for Wolff’s early thought, the foregoing also provides essential context for Leibniz’s infuence on Wolff’s philosophical thought. Well before Wolff had heard of the ‘Leibnizian philosophy,’ he had already carefully studied that of Tschirnhaus, and so, far from it being the case that Wolff’s acquaintance with Leibniz had the effect of “repelling” Tschirnhaus’s infuence,42 it is rather the case that Leibniz’s infuence, particularly in these initial stages, was most effectively exercised within the broader framework provided by Tschirnhaus.

Notes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

See Honnefelder (1990) and, recently, Leduc (2018). These have been collected in Wolff (2001). See Beck (1969: 189). See Tschirnhaus, MM 27–28 and the unpaginated ‘Praefatio authoris ad lectorem.’ For additional discussion of the limits of empiricism according to Tschirnhaus, see Van Peursen (1993: 396, 408). See Tschirnhaus, MM, unpaginated ‘Praefatio.’ De Vleeschauwer (1932: 672) refers to these intuitions as methodological presuppositions. See Tschirnhaus, MM, unpaginated ‘Praefatio.’ On how Tschirnhaus considers his use of this method to depart from the traditional (synthetic) method employed in geometry, see MM 127–28 and Schönfeld (1998: 69). This is noted, for instance, by Schönfeld (1998: 71). For the generative aim of defnitions, see Tschirnhaus, MM 67–68; for the latter examples, see MM 70–71 and Beck (1969: 192). For details, see Verweyen (1905: 89–95). Tschirnhaus identifes three general classes of objects at issue here: imaginabilia, rationalia or mathematica, and realia or physica; cf. Tschirnhaus, MM 74–76 and Schönfeld (1998: 67–68). Contrast, for instance, Beck (1969: 192), who claims that for Tschirnhaus “[e]xperience is useful only in setting us under way.” For criticism of this interpretation, see particularly Wurtz (1988: 194–201). See Tschirnhaus, MM 214, 270, 280. For extended discussion of this sense of ‘confrmation,’ see Wurtz (1988: 198–201). As Wollgast summarizes (1988: 30), there would be “no Christian Wolff without Tschirnhaus.” The phrase is Winter’s (1960: 71). One might also here contrast Schönfeld (1998: 73), who accuses Wolff of an overly rationalistic misinterpretation of the Medicina mentis. See Wolff, MMP II 196 (defnition 23, corollary 2) and 198 (frst scholium of Chapter 2). Inasmuch as everyone is capable of grasping what is true by means of the intellect, whereas imaginings are a function of an individual’s past sensory experience, Tschirnhaus contends that the communicability of some matter of fact reliably indicates that it is an object of the intellect rather than the product of imagination. See Tschirnhaus, MM 45–46.

34 Corey W. Dyck 19 For discussion of this, see Gerhardt’s introduction to Leibniz and Wolff (1860/1971: 8n) and Arnsperger (1897: 24–25). 20 Wolff, ELB 133. For the original note from Mencke (dated Nov. 12, 1704), see BLW 15. 21 Wolff, MMP II 271, § 9; cf. also § 4. 22 On this see Schönfeld (1998: 73) and Arndt (1978: 21). 23 For further discussion of this essay, with a particular focus on its relation to Leibniz’s ‘Meditations,’ see Pelletier (2017: 34–37). 24 Wolff, MMP I 18: “We should be particularly cautious that cognitions through experience are not extended beyond their limits.” 25 Wolff’s continued interest in Tschirnhaus at this time is evident in another, more poignant respect as well. In his autobiography, Wolff notes that Tschirnhaus had informed him during their meeting at the book fair in Leipzig that the Medicina mentis had only been intended as the frst part of a trilogy of works which, Tschirnhaus earnestly explained, would apply his method to mathematics proper and then to physics. Tschirnhaus never published these texts, though after his death in October 1708, only a few months after Wolff’s publication of his essay on experience, Wolff made inquiries regarding these manuscripts in particular so that “his discoveries might be preserved from decay, and to secure his fame for posterity,” only to fnd out that, like his friend Spinoza before him, Tschirnhaus had ordered his papers burned after his death (ELB 126–27). 26 Indeed, Wolff compiled a précis of Tschirnhaus’s Medicina mentis while lecturing on the text in Leipzig, and he reports that he made use of this and other such notes when writing his German works; cf. Arndt (1978: 16) and Wolff, ELB 139–40. 27 I will refer throughout to the frst edition of the German Logic since, as we will have occasion to note, there are non-trivial differences between it and subsequent editions in which the Tschirnhausian infuence on Wolff’s thought is more easily seen. 28 Wolff had already introduced these two methods in his Solutio nonnullarum diffcultatum essay (cf. MMP I 13–14). 29 See Wolff, KU, §§ 12, 17; BC, § 13; and ML 495. 30 Wolff, ML 495; KU § 40. 31 Wolff takes this point from Leibniz’s ‘Meditations’; cf. Leibniz (1989: 293). 32 Contrast Leibniz, who takes credit for Wolff’s claim that axioms can be analyzed into identical propositions and defnitions; cf. BLW 163. While Tschirnhaus does not identify axioms as identical propositions, he does claim that they are derived from defnitions (cf. MM 117–18). 33 Wolff, KU § 28; GL1, ch. 3, § 13; ML 1086. 34 Wolff, GL1, ch. 6, § 19; cf. also Wolff, BC § 2. 35 Wolff, GL1, chs. 4 and 5 in subsequent editions. It is likely by way of emphasizing the fact that clear experiences can serve as grounds of demonstrations that the chapter on experience precedes that on inferences (ch. 6) in the frst edition of the German Logic (note that this follows the order of presentation in the KU: principles [§§ 27–29], followed by experiences [§§ 30–32], theorems [§§ 33–38]—corresponding to ch. 5 in GL1 on the invention of propositions—and fnally proofs and demonstrations [§§ 39–43]). 36 Wolff, GL1, ch. 3, § 13; KU § 33; ML 1377–78. 37 See Arndt (1978: 82). 38 See above. See also Wolff’s letter to Leibniz of December 5, 1705, where he makes this connection clear (BLW 48). 39 Wolff, GL1, ch. 3, § 9; cf. KU § 38.

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40 Thus, in Wolff’s later, Latin translation of GL1, he employs ‘concipere’ in this context; cf. CR, ch. 3, § 83. 41 See Wolff, GL1, ch. 1, § 2, and again, contrast the Latin translation of GL1 which uses ‘cognitio’ rather than ‘concipere’ in the parallel discussion (CR, ch. 1, § 2). 42 Contrast Wundt (1945: 128).

Bibliography Primary Sources Leibniz, Gottfried Wilhelm (1989), Philosophical Papers and Letters, ed. and trans. by L. Loemker, Dordrecht: Kluwer. ——— and Christian Wolff (1860), Briefwechsel zwischen Leibniz und Christian Wolff, ed. by C.I. Gerhardt, Halle: Schmidt; repr. Hildesheim: Olms 1971 (BLW). Tschirnhaus, Ehrenfried Walter von (1695), Medicina mentis et corporis, (2nd revised and expanded edn. 1695 [1st edn. 1687]), Leipzig: Fritsch; repr., with a foreword by W. Risse, Hildesheim: Olms 1964 (MM). Wolff, Christian (1710), Anfangs-Gründe aller mathematischen Wissenschaften, vol. 1, Halle: Renger. The frst volume contains ‘Kurzer Unterricht von der mathematischen Methode’, 5–27; repr. in Gesammelte Werke, I.15.1, Hildesheim: Olms 1999 (KU). ——— (1713a), Vernünfftige Gedancken von den Kräfften des menschlichen Verstandes und ihrem richtigen Gebrauche in Erkänntnis der Wahrheit, Halle: Renger; repr. in Gesammelte Werke, I.1, Hildesheim: Olms 1978 (GL; ‘1’ indicates the frst edition of this work). ——— (1713b, 1715), Elementa matheseos universae, 2 vols., Halle: Renger. The frst volume contains “De methodo mathematica brevis commentatio”, 5–16; repr. in Gesammelte Werke, II.29, Hildesheim: Olms 2003 (BC). ——— (1716), Mathematisches Lexicon, darinnen die in allen Theilen der Mathematick üblichen Kunst-Wörter erkläret, und zur Historie der Mathematischen Wissenschaften dienliche Nachrichten ertheilet, auch die Schrifften, wo iede Materie ausgeführet zu fnden, angeführet werden, Leipzig: Gleditsch; repr. in Gesammelte Werke, I.11, Hildesheim: Olms 1965 (ML). ——— (1740), Cogitationes rationales de viribus intellectus humani, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II. 2, Hildesheim: Olms 1983 (CR). ——— (1755), Meletemata mathematico-philosophica cum erudito orbe literarum commercio communicata. Quibus accedunt dissertationes, Halle: Renger; repr. in Gesammelte Werke, II.35, Hildesheim: Olms 2003 (MMP; ‘I,’ ‘II,’ or ‘III’ indicate the section number). ——— (1841), Christian Wolffs eigene Lebensbeschreibung, ed. by H. Wuttke, Leipzig: Weidmann; repr. in Gesammelte Werke, I.10, Hildesheim: Olms 1980 (ELB). ——— (2001), Sämtliche Rezensionen in den Acta Eruditorum (1705–1731), ed. by H.A. Laeven and L. Laeven-Aretz, in Gesammelte Werke, II.38.1–5, Hildesheim: Olms.

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Secondary Sources Arndt, Hans Werner (1978), ‘Einführung’, in Vernünftige Gedanken von der Kräften des menschlichen Verstandes und ihrem richtigen Gebrauche in Erkenntnis der Wahrheit, in Ch. Wolff, Gesammelte Werke, I.1, Hildesheim: Olms, 7–102. Arnsperger, Walther (1897), Christian Wolff’s Verhältnis zu Leibniz, Weimar: Felber. Beck, Lewis White (1969), Early German Philosophy: Kant and His Predecessors, Cambridge: Belknap. De Vleeschauwer, Herman Jan (1932), ‘La genèse de la méthode mathématique de Wolf. Contribution à l’histoire des idées au XVIIIe siècle’, Revue belge de philologie et d’histoire, 11, 651–77. Honnefelder, Ludger (1990), Scientia transcendens: die formale Bestimmung der Seiendheit und Realität in der Metaphysik des Mittelalters und der Neuzeit (Duns Scotus, Suarez, Wolff, Kant, Peirce), Hamburg: Meiner. Leduc, Christian (2018), ‘Sources of Wolff’s Philosophy: Scholastics/Leibniz’, in R. Theis and A. Aichele (eds.), Handbuch Christian Wolff, Wiesbaden: Springer, 35–53. Pelletier, Arnauld (2017), ‘On the Origin of Concepts: The Cognitive Continuum between the Senses and Understanding in Wolff’s German Logic’, in A. Pelletier (ed.), Christian Wolff’s German Logic: Sources, Signifcance, and Reception, Hildesheim: Olms, 29–51. Schönfeld, Martin (1998), ‘Dogmatic Metaphysics and Tschirnhaus’s Methodology’, Journal of the History of Philosophy, 36/1, 57–76. Stiehler, Georg (1960), ‘Tschirnhaus als Philosoph’, in E. Winter (ed.), E. W. von Tschirnhaus und die Frühaufklärung in Mittel- und Osteuropa, Berlin: Akademie-Verlag, 83–92. Van Peursen, C.A. (1993), ‘E. W. von Tschirnhaus and the Ars Inveniendi’, Journal of the History of Ideas, 54/3, 395–410. Verweyen, Johannes (1905), Ehrenfried Walter von Tschirnhaus als Philosophy (Dissertation) Bonn: Hanstein. Winter, Eduard (1960), ‘Der Bahnbrecher der deutschen Frühaufklärung’, in E. Winter (ed.), E. W. von Tschirnhaus und die Frühaufklärung in Mittel- und Osteuropa, Berlin: Akademie-Verlag, 1–82. Wollgast, Siegfried (1988), Ehrenfried Walther von Tschirnhaus und die deutsche Frühaufklärung, Berlin: Akademie-Verlag. Wundt, Max (1945), Die deutsche Schulphilosophie im Zeitalter der Aufklärung, Tübingen: Mohr. Wurtz, Jean-Paul (1988), ‘Über einige offene oder strittige, die Medicina mentis von Tschirnhaus betreffende Fragen’, Studia Leibnitiana, 20/2, 190–211.

2

The Role of Experience in Wolff’s General Cosmology Christian Leduc

Wolff’s conception of knowledge remains to this day an object of discussion. His own accounts of the matter have undoubtedly contributed to the disagreement and confusion among commentators. On several occasions, Wolff claims that any kind of cognition, including philosophical knowledge, begins with experience and observation. The Discursus praeliminaris to the Philosophia rationalis sive Logica is clear on this matter: knowledge originates from empirical sources, or what was called at that period the historical cognition, but must be completed with mathematical and philosophical demonstrations (DP §§ 9–11). However, it seems evident that many of the philosophical principles that Wolff endorses, in particular in metaphysics, are not based on experience. For example, his proofs for the principle of suffcient reason in the Ontologia do not rely on inner experience: only after having proved this principle by demonstrative means does Wolff point out that we can also perceive, in singular cases, that everything must have its suffcient reason (PPO § 72). It is thus far from clear whether or not his metaphysical positions are entirely based on historical and descriptive cognition. To achieve this, Wolff would have had to establish an experimental ontology that he sometimes mentions but never elaborated.1 At the same time, this confusion results most probably from our own presuppositions regarding the distinction between a priori and a posteriori knowledge, a distinction that we tend to understand in Kantian terms. 2 Some commentators have even argued that experience is required at every level of Wolff’s philosophy and that he cannot simply be characterized as a rationalist or deductivist philosopher.3 The main reasons are that experience and historical knowledge are employed in almost all his texts and that his methodology requires empirical foundations.4 One way of approaching these questions is to examine how Wolff understands the relationship between experience and reason in specifc realms. In this chapter, I propose to analyze the distinction between empirical and demonstrative knowledge in the context of Wolff’s cosmology. This case is particularly interesting, since Wolff affrms that this discipline requires the contribution of both rational demonstration and empirical proof but actually does not always clearly distinguish the

38 Christian Leduc two approaches. This might be surprising, for Wolff is unambiguous on this point in the case of other disciplines. Thus, he maintains in the Psychologia empirica that empirical psychology must precede the rational demonstrations to be carried out in rational psychology (PE § 4), for we need to obtain empirical knowledge of the faculties and affections of the soul in order to be able to defne its essential characteristics (PE § 65). In sum, in the case of psychology Wolff adheres to the real marriage between reason and experience (connubium rationis et experientiae). 5 As was mentioned above, it is much less clear to what extent the principles elaborated in Wolff’s cosmology rely on a priori ontological principles or on experience. In this contribution, I argue that Wolff’s conception of cosmology can be distinctly interpreted with respect to this question. Both the chapter on the world in the German Metaphysics and the later Cosmologia are preceded by metaphysical considerations on principles concerning order, perfection, and connection as well as the principle of suffcient reason. As I hope to show, however, the method Wolff employs in the German Metaphysics hinges much more on experience than the one he employs in the Cosmologia.

1 Wolff’s Division of Philosophy In order to contextualize Wolff’s conception of cosmology, I will begin by examining his discussion of the relationship between ontology, cosmology, and physics in the Discursus. In a section from which many thinkers, in particular Baumgarten and Kant, derived their own divisions of metaphysics, Wolff claims that the various parts of metaphysics should be ordered by moving from the most general part to the more particular ones, that is, from frst philosophy or ontology to cosmology, psychology, and, fnally, natural theology.6 This distinction is inspired by the scholastic division between the metaphysica generalis and the metaphysicae specialis, even though Wolff’s conception of metaphysics is here original.7 This order is mainly axiomatic and demonstrative, since fundamental ontological principles are required in cosmology, whereas cosmological principles are presupposed in psychology and natural theology. Thus, cosmology treats a class of beings the fundamental properties of which must already have been demonstrated in ontology. This conception was certainly very infuential in the history of metaphysics, but it must be noted that Wolff does not employ the same theoretical organization in the German Metaphysics, in which psychology is treated prior to cosmology. The point that I will later emphasize is that Wolff seems to have modifed his views concerning the scope of cosmology. Even though this order of exposition is found in the Discursus, the picture is more complicated when Wolff addresses the defnition of philosophy more generally. Actually, Wolff begins his account not with his

Experience in Wolff’s General Cosmology 39 division of the parts of metaphysics but with a number of more general considerations about philosophy. On his account, philosophy, qua study of all beings, has three objects, namely, God, human souls, and bodies. These objects are studied insofar as they are possible, that is, not insofar as they are actually perceived. Accordingly, physics is defned as “the science of what is possible through bodies” (DP § 59). Since philosophy is understood as the science of possibilium, physics will thus refer to the general study of what can possibly occur in bodies. This also means that the name term ‘physics’ denotes here a general philosophical doctrine through which other disciplines, such as cosmology, must be studied. Wolff maintains that this division has to be completed, for it does not tell us how these beings are related to each other as objects of philosophy. After having explained further divisions within philosophy, such as the distinction between ethics and politics, Wolff conceives of ontology or frst philosophy, defned as the science of being in general, as the part of metaphysics that treats the properties common to all beings, such as the notions of essence and perfection. I do not intend to analyze this science here,8 but rather to underline a relevant point for our discussion: Wolff frst introduces ontology not in the context of his division of metaphysics, even though it will become a part of this division subsequently, but in the context of his general conception of philosophy. He writes with regard to the notions treated in ontology: Such general notions are the notions of essence, existence, attributes, modes, necessity, contingency, place, time perfection, order, simplicity, composition, etc. They are not explained properly in either psychology or physics because both of these sciences, as well as the other parts of philosophy, use these general notions and the principles derived from them. (DP § 73) Furthermore, Wolff affrms that we need ontology because it enables us to proceed by means of the demonstrative method: the ars demonstrandi depends on the principles established in ontology to demonstrate other propositions. However, he does not tell us here exactly how these ontological principles must themselves be demonstrated and to what extent these demonstrations can be completely a priori or must rely, in some ways, on experience. Wolff asserts that physics is concerned with two main kinds of bodies: on the one hand, bodies from which the world is composed (corpora totalia), and, on the other hand, bodies that are contained in the former, namely terrestrial, vegetal, and animal bodies (corpora partialia). Each of these kinds is studied in specifc disciplines such as phytology, physiology, and physical pathology. They all draw their principles from a science that Wolff calls general physics:

40

Christian Leduc The part of physics that deals with the general affections of bodies and with the affections common to many species is called general physics. Hence general physics is defned as the science of those things that pertain either to all bodies or the various species of bodies. (DP § 76)

While the Discursus does not contain further details on this discipline, Wolff certainly had in mind his German Physics, which was published in 1723. In the latter work, he frst discusses the nature and changes of bodies as such and then turns to the nature of celestial and terrestrial bodies. This work is relevant here, because it relies not only on demonstrations elaborated in the cosmology included in the German Metaphysics of 1719 but also on his so-called Experimentalphysik of 1721.9 In the frst section of the German Physics, most corporeal properties are deduced from cosmological principles, but many are also arrived at through experimentation. For instance, in order to demonstrate that matter is infnitely divisible, Wolff relies on two arguments. According to the frst, the division of matter should be carried out by the intellect rather than the imagination. This means that the infnite divisibility of matter can be deduced from the very idea of matter. The second argument, by contrast, is based on observations, made with the microscope, which reveal that what appeared to be indivisible is divisible after all (GPh § 5). I will analyze other arguments later, but this one suffces for the moment to see how general physics can beneft from both rational demonstration and empirical observation. The idea that general physics relies on both metaphysics and experimentation is confrmed in the Discursus. In this work, Wolff makes a further distinction within the physical sciences, namely, experimental and dogmatic physics. According to him, experimental physics must precede dogmatic physics, since many demonstrations concerning the structure of matter and the laws of motion rely on experimental proofs: With the introduction of experimental physics, the term ‘physics’ becomes a general name. In order to distinguish the science which we previously called physics from experimental physics, the former discipline will now be designated as dogmatic physics. (DP § 108) Based on these considerations, it seems evident that all parts of physics require experimental principles from which more general propositions could be demonstrated. However, the passages discussed so far fail to provide a satisfactory answer to our very frst question. The German Physics obviously relies on experimental principles, but we know that it also requires metaphysical truths, in particular the cosmological ones treated in the chapter on the world of the German Metaphysics and the Cosmologia. The question therefore remains: does cosmology,

Experience in Wolff’s General Cosmology 41 understood as part of metaphysics, rely solely on a priori principles that are established in ontology or does it also require an empirical foundation? In order to answer this question, we need to complete our analysis of the Discursus.

2 Wolff’s Defnition of Cosmology in the Discursus As was noted above, Wolff’s Discursus considers physics to deal with two kinds of bodies, namely, corpora totalia and partialia. Particular kinds of bodies are studied in disciplines such as phytology and physiology. The branch of physics that deals with total bodies, by contrast, is what he calls cosmology. In other words, cosmology is the science of the actual world insofar as it contains total bodies. Its task is to understand the motion of celestial bodies, which corresponds to what Wolff calls celestial physics or astronomy.10 Here as well, Wolff has in mind previous works such as the Anfangsgründe aller mathematischen Wissenschaften and the German Physics. Indeed, a large part of the latter treatise deals with celestial bodies and the order of the cosmic system. As with the other parts of physics, it appears that cosmology must be established not only with the help of antecedent metaphysical principles but also with that of experimental results (DP § 109). Like general physics, cosmology, in this specifc sense, is based on both sources of knowledge. Wolff seems to follow Kepler’s model, according to which observations are structured both mathematically and philosophically.11 From these general divisions of philosophy, Wolff then describes cosmology in its metaphysical sense and explains the task of general cosmology as follows: There is also a general understanding of the world, which explains those things that are common to the existing world and to any other possible world. The part of philosophy that develops these general and abstract notions I call transcendental or general cosmology. Hence general cosmology is defned as the science of the world in general. General cosmology has in the past been unknown to philosophers, even though they have occasionally treated the things that pertain to it. But I have decided to establish this science because psychology, natural theology, and physics derive principles from it. Moreover, the things which pertain to general cosmology are not properly treated anywhere else. (DP § 78) Many interesting points are mentioned in this excerpt. First, Wolff notes that general cosmology explains those features of the world that any world must possess. On his account, for instance, any world is a unity made up of interconnected beings that are fnite, coexistent, and successive.12 Second, general cosmology is called transcendental because

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it treats the most abstract and general properties of the world by drawing on the principles of ontology.13 I will come back to the relationship between possible and actual worlds, but let us simply remember that the elaboration of cosmology is based, according to these passages, on ontology and therefore has a broader scope than physics. Third, Wolff is aware that the way in which he demarcates general cosmology is original. Obviously, earlier accounts of the world as such by Descartes, Leibniz, and Newton, among many others, were carried out in the context of either natural philosophy or general metaphysics. Yet Wolff’s conception of general cosmology as a distinct metaphysical realm is thus a new designation, constituting a part of metaphysics and possessing a relationship with ontology that is unprecedented. The prolegomena to the Cosmologia repeats more or less the same ideas. General cosmology is defned as “the science of the world or universe in general.” However, Wolff in this context is clearer about its dependence on the results obtained in ontology: [T]he theory of being in general is applied in general cosmology to the world or universe in general, and the general theory of compound being is delivered in frst philosophy, and to such an extent that the notions of general cosmology must be demonstrated from the principles of frst philosophy.14 As was previously mentioned, Wolff considers general cosmology to be one of the three metaphysicae speciales since it demonstrates abstract properties of corporeal beings on the basis of ontological principles. Like any other metaphysical discipline, conversely, general cosmology serves as the foundation of sciences that provide explanations of the physical world, including astronomy qua study of planetary motion (DP § 94). Before examining the Latin cosmology in more detail, however, the next section returns to the German corpus.

3 Cosmology in the German Metaphysics As was mentioned above, Wolff’s frst analysis of nature as such can be found in the fourth chapter of the German Metaphysics. While many elements of this chapter recur in a more systematic way in the Ontologia and the Cosmologia, there appear to be two main differences. First, the German cosmology takes recourse to experience in a more substantial way: many proofs are established on the basis of observation and experimentation, and in numerous sections Wolff adduces everyday experience or scientifc experiments to vindicate his views. Second, the chapter is concerned with the physical world such as it is known through actual perceptions. Wolff did not necessarily believe that the treated cosmological

Experience in Wolff’s General Cosmology 43 principles were applicable to all possible worlds. In my view, accordingly, the German cosmology has much more in common with the discipline called physics in the Discursus, on both its experimental and dogmatic senses, than with the general cosmology elaborated in the Cosmologia, even though it anticipates many aspects of the latter. To support this interpretation, I would like to focus on two examples that are particularly signifcant: the principle of inertia and the idea that physical change always occurs through mechanical impulse. Both positions are justifed with the help of empirical procedures, although Wolff also draws on the principle of suffcient reason. Let us begin with the frst case. As was to be expected, Wolff holds that a metaphysics of nature seeks to determine those properties of corporeal beings that are necessarily presupposed in physics, including extension, force, motion, and inertia. At the time, philosophers tried to demonstrate the law of inertia by means of two different methodological procedures: either by deriving it from the other properties of matter, such as extension or passivity, or by drawing on what experience tells us about bodies. In his Specimen dynamicum, for instance, Leibniz accounts for the force of inertia on the basis of an a priori demonstration that involves the distinction between active and passive forces. Resistance to change, or inertia, is explained analogically in comparison with active primitive force, which is, for its part, caused by substantial forms or substances.15 One would expect Wolff to demonstrate inertia by means of the deductive procedure as well. Admittedly, both the German Metaphysics and the Cosmologia contain a metaphysical explanation of inertia that is inspired by Leibniz: since there is no suffcient reason why a body should change its state of motion or rest by itself, Wolff asserts, it must be endowed with resistance or inertial force.16 However, the German Metaphysics gives an additional explanation, one that is absent from the Cosmologia: In such a way, each body persists either in its rest or in its motion, and keeps in its motion the same direction, until it is put in another state through another body. We all fnd this also in experience, and from which the rules of motion are examined, just as an unchangeable law of nature is accepted.17 Thus, Wolff apparently felt the need to complement the argument based on the principle of suffcient reason with empirical evidence. Actually, it might even be argued that the very validation of the law of inertia has an empirical foundation. While the principle of suffcient reason motivates the necessity of inertia, its actual confrmation has to be provided by experience: this or that body is endowed with inertia because we perceive that it maintains the same place or velocity as long as another body does not change it.

44 Christian Leduc Interestingly, at the end of the section Wolff refers in a footnote to Newton’s scientifc explanation of the law of inertia in the Principia mathematica. This point is worth highlighting because we might have expected Leibniz to have been mentioned. In Leibniz’s doctrine, inertial force or resistance is based on corporeal passive force, and not on extension alone, as Cartesians would hold.18 The reference to Newton’s Principia is another reason to maintain that Wolff, at this point, conceived of cosmology as a discipline based not only on metaphysical principles but also on empirical perception and experimental physics. Wolff adopts a similar approach in his explanation of other laws and properties of matter. An illuminating example of the weight he grants to scientifc experimentation is his description of what today is called Boyle-Mariotte’s law of the effect of pressure on the volume of a gas. It is in virtue of Mariotte’s experiments that Wolff develops his proofs for this law concerning gaseous bodies.19 However, even if Wolff quotes Newton’s physics from time to time, his conception of matter and motion is mostly infuenced by Descartes and Leibniz, most notably by their view that all change in the corporeal world is produced by mechanical processes. Like his predecessors, Wolff excludes any kind of non-mechanical interaction, including interaction based on occult principles and Newtonian attraction at a distance. 20 As is well known, Descartes and Leibniz held that, although everything in nature can be explained in mechanical terms, mechanistic laws themselves do not rely on mathematical principles alone but must be founded on metaphysical principles as well. As Leibniz puts it, “all corporeal phenomena can be traced back to mechanical effcient causes, but those mechanical laws as a whole must be understood as themselves deriving from higher reasons.”21 Following Leibniz, Wolff frst employs the principle of suffcient reason to frame the problem of mechanism. This principle requires that one fnd a reason for changes in fgure and motion. Yet whereas the principle of suffcient reason tells us that we need to explain these modifcations, it does not itself provide that explanation. In order to account for changes in fgure and motion, Wolff appeals to experience. We simply perceive that an increase or decrease of velocity is caused by mechanical impact: We fnd in experience that change in the speed of a body can only occur through impulse, namely, if there is body in motion that pushes another body, which is moving faster than the former, then its speed will be higher; on the contrary, if it pushes another body that either stands still, or is moving slower, then its speed will be reduced. (GM § 664) Wolff also refers to more experimental methods to describe impulse. He notes, for instance, that we learn from experience that, when a soft body

Experience in Wolff’s General Cosmology 45 possesses a suffcient degree of force and interacts with a hard surface, its fgure is compressed. This elasticity is the reason why bodies bounce back.22 These passages show that Wolff regarded experiments, and even sensible perception, not merely as complementary sources of knowledge but as essential means to explain fundamental aspects of the physical world. I admit, however, that Wolff probably considered the universal validity of such explanations to be based on the principle of suffcient reason. Whereas it follows from this principle that any change in nature occurs mechanically, this view must be justifed by our actual experience of mechanical causes. I take the previous analyses to have demonstrated the following two points. First, it is clear that the origin of cosmology in the Wolffan corpus can be traced back to the German Metaphysics. Even if the discipline is designated as such only eight years later, in the Discursus, the content and structure of the discipline treated in Chapter 4 of the German work possess the main characteristics of what will later be called cosmology. Second, the German cosmology, as I have pointed out, nonetheless possesses distinct characteristics. It not only aims at describing corporeal properties and laws that concern the actual world, but does so by giving much weight to empirical and experimental knowledge. In particular, in the case of Wolff’s explanation of mechanism, we have seen, experience even functions as the main source of proper scientifc knowledge.

4 Experimental and Scientifc Cosmologies In this fnal section, I would like to examine the relationship between experience and cosmological truths such as it is conceived in the Cosmologia generalis in order to determine in which respects this work differs from the account of the world in the German Metaphysics. Considering the fact that general cosmology is located between ontology and physics, we now fnd ourselves at the heart of the matter. According to Wolff’s Latin works, general cosmology derives its fundamental principles from ontology. Since it establishes the principles underlying our knowledge of any possible world, including the actual one, it is antecedent to physics. The Discursus is clear on this point: If everything is to be demonstrated accurately in physics, then principles must be borrowed from metaphysics. Physics explains those things, which are possible through bodies. If these things are to be treated demonstratively, then the notions of body, matter, nature, motion, the elements, and other such general notions must be known. For such notions contain the reason of many things. Now these notions are explained in general cosmology and in ontology. Therefore, if all things are to be demonstrated accurately in physics, principles must be borrowed from general cosmology and ontology. (DP § 94)

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Wolff’s position in the Cosmologia is very similar. General cosmology establishes the general notions and attributes according to which natural philosophers operate (CG § 1). General cosmology explains the properties and laws of matter, force, and motion that are required in both dogmatic and experimental physics. For its part, physics accounts for the proper quantities of force and motion in actual and singular cases. The inverse relationship demands more clarifcation however. Does Wolff’s Cosmologia consider principles established in experimental physics to contribute to the demonstration of cosmological principles, as is the case in the German Metaphysics? The Wolffan notion of a marriage between reason and experience implies that a posteriori cognition must complement a priori principles. Let us recall an important passage from the Discursus in which historical or empirical knowledge is said to provide the frst elements of cognition that philosophical reasoning requires: Historical knowledge provides the foundation for philosophical knowledge insofar as experience establishes those things from which the reason can be given for other things which are and occur, or can occur. Things that are established by experience are known by historical knowledge. And if from this you discover the reason of the other things which are and occur, you have built up philosophical knowledge. Therefore historical knowledge is the foundation of philosophical knowledge. (DP § 10) Furthermore, the Discursus gives an example that seems to support the interpretation according to which general cosmology, like any other kind of knowledge, is based on experience. As seen, Wolff notes here that experimentation teaches us that air is elastic and endowed with gravitation. This knowledge is historical insofar as it consists of factual descriptions but does not account for the causes of elasticity and gravitation. It merely allows us to describe some phenomena, such as the water surge in pumps or its jet in man-made fountains. However, we need philosophical reasoning to address the causes of these phenomena. In sum, Wolff holds that the philosophical search for the cause and reason of things presupposes empirical and particular knowledge about these things: historical cognition is knowledge of a fact, while philosophical cognition accounts for the reason behind such a fact (DP § 7). However, both in the Discursus and in the Ontologia, Wolff stresses that ontology must proceed demonstratively. On this account, both physics and general cosmology belong to a lower axiomatic level of demonstration (PPO § 4). Yet it is more than probable that the Latin cosmology is exclusively based on ontological truths and principles. My interpretation is the following: although the methodology Wolff expounds in the Discursus seems to require him to proceed from

Experience in Wolff’s General Cosmology 47 historical cognition to philosophical reasoning in all cases, it seems that he neglects this order in the Cosmologia. The main reason is that he in this context seeks to fulfll another essential methodological requirement for philosophical reasoning, namely, to demonstrate principles on the basis of well-established defnitions in a quasi-mathematical manner (DP § 119). I would thus suggest that the methodological aspects are here essential to understand what seems to be ambivalent or even contradictory in Wolff’s approach: whereas the German cosmology seems to favor the analytic method of discovery (methodus inventionis), which requires both historical and philosophical knowledge, the Latin cosmology rather seems to adopt a synthetic method of exposition (methodus doctrinae) to deduce cosmological principles, that is, a method that is based on an axiomatic model. 23 In the latter case, therefore, experience plays a role in the discovery of cosmological principles but is left aside when it comes to exposing these principles in a demonstrative way. Yet Wolff in the Cosmologia does not completely reject the possibility of discovering cosmological principles by empirical means. The prolegomena to this work contains the most important assertions in this regard. Wolff here emphasizes the mutual dependency between the transcendental part of cosmology, which studies the properties of all possible worlds, and the part devoted to the principles that govern the actual world: Since the world that exists is accessible through our observations and since we can abstract from it the general determinations without which no world can be conceived, what must be demonstrated of the world in general cosmology from the principles of frst philosophy is confrmed by observations. (CG § 2) In this passage, general cosmology is said to demonstrate the general determinations of the world by relying on ontological principles, such as the principles of unity and interconnection. However, the principles of general cosmology are confrmed in the actual world. Experiments and observations would thus serve to show that the general properties deduced from ontological principles are indeed real ones. Wolff clarifes this by means of an example: he claims that ontology defnes the world as a compound order and that this defnition corresponds to the visible world (CG §§ 66–72). The multiplicity of material parts and motions are perceived through observations, confrming the general idea that a world is composite (CG §§ 62, 65). This suggests that Wolff considered experience to play a role in general cosmology in that it allows us to move from our knowledge of properties of the actual world to demonstrative knowledge of those properties that pertain to all possible worlds. However, Wolff is not very clear on what this recourse to experience consists in. He does not indicate, for example, whether general

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cosmology must take into account the results of common observation or those of experimental physics. The following passage from the prolegomena offers some indications in this regard: Thus there exist two cosmologies: one scientifc, the other experimental. General cosmology is scientifc in that it demonstrates the general theory of the world from the principles of ontology. Experimental cosmology, by contrast, abstracts from observations the theory that is or ought to be stabilized in scientifc cosmology. (CG § 4) Clearly, Wolff associates general cosmology with the scientifc part of cosmology. As was seen above, this discipline provides a theory of the world as such on the basis of principles treated in ontology. The passage suggests that, for Wolff, experimental cosmology is a discipline that applies these principles to observable phenomena and, thus, confrms the results of general cosmology with the help of a posteriori perceptions. Admittedly, in the Cosmologia, Wolff focuses on the scientifc method and does not really employ empirical observations to establish or confrm cosmological principles. This can be clarifed by comparing once again his accounts of mechanism and inertia in the German Metaphysics to the treatment of these issues in the Cosmologia. In the latter work, Wolff mobilizes the principles of the Ontologia in order to demonstrate that the changes in nature are mechanical and that action at a distance is impossible (CG §§ 320–23). As Leibniz had done before him, Wolff holds that mechanical and mathematical principles ultimately derive from metaphysical ones. In the Cosmologia, he considers the principle of suffcient reason and its main ontological consequences, such as the foundation of motion in active primitive force, to suffciently account for the mechanistic framework of physics. Thus, we can note an important difference between the German and Latin works: while the former proceeds from the principle of suffcient reason to the empirical description of mechanical causes, the latter remains at the metaphysical level of explanation in order to account for a mechanistic conception of nature. In the latter case, the principle of suffcient reason serves the purpose of deducing other principles, including force, relative motion, and continuity, so as to justify mechanism in the explanation of change of fgure and motion. The example of inertia is also very telling, since Wolff provides two kinds of explanation of the phenomenon. In the Cosmologia, the inertial force of bodies is said to be grounded on ontological principles, in particular the principle of suffcient reason: since there is no suffcient reason for a body to change its actual state, it will remain in this state until an external force changes it. 24 This procedure is clearly demonstrative. By contrast, as was previously mentioned, the German Metaphysics draws on experiments to establish that inertia actually exists (GM § 657). Mariotte’s experiment is mobilized: he showed that inertial force

Experience in Wolff’s General Cosmology 49 can be tested when one measures the quantity of pressure in a gas. This increase of pressure comes from the inertial force of matter: the more a body possesses inertial force, the more it increases its pressure. Wolff summarizes this point as follows: However, because a body that is pushed by another one pushes it back with the help of its force of resistance, according to which it resists motion, it is clear that the quantity of its force of resistance is determined by the quantity of repulsion. (GM § 657) On the basis of experimental induction, we know that material bodies possess an inertial force, that is, are capable of resisting pressure. Wolff employs a similar procedure to show that Newton’s third law of motion requires the law of inertia (GM §§ 669–71). Thus, even if the metaphysical principle of suffcient reason is a fundamental tool for conceiving of such laws, experimentation is obviously an important source of knowledge. The following paragraph must however prevent us, once again, from concluding that the Cosmologia completely disregards, at least in principle, experimental knowledge. Wolff argues here that the relationship between scientifc and experimental cosmology goes both ways: Since experimental cosmology is drawn on observations that are demonstrated in scientifc cosmology, the experimental cosmology presupposes the scientifc one. However, because it is not impossible to provide in the scientifc cosmology what was drawn from observations or observed phenomena, experimental cosmology improves knowledge before developing the scientifc one and can be associated with it. (CG § 5) Our main question receives a surprising answer here: in general, Wolff holds that experimental cosmology presupposes scientifc cosmology, that is, a discipline that essentially proceeds by means of demonstrations. Clearly, the method employed in the Cosmologia is more straightforwardly a priori, for the work almost entirely relies on the content of the Ontologia. But since one can learn many truths about nature from observation and experimentation, Wolff claims that we can improve general cosmology by drawing on a posteriori knowledge and combine the results of both disciplines. This suggests that he considered scientifc cosmology to be prior to the experimental one as regards the exposition of the doctrines but not necessarily as regards their discovery. What is more: Wolff suggests that the entirety of general cosmology might in principle be derived a posteriori, that is, from observation and experimentation. In other words, he seems to hold that one might proceed either by moving from ontology to general cosmology and fnally to physics or by moving from the latter to general cosmology.

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In my view, this empirical direction is more prominent in Wolff’s German Metaphysics, even though the principles treated here rest on ontological principles that are also required. In contrast, the Latin cosmology is more straightforwardly a priori, for it almost entirely relies on the content of the Ontologia; however, we can note traces of the empirical approach in the Cosmologia as well.25 One last question: should one of the methods be preferred over the other? Wolff does not seem to address this point in detail. The paragraph of the Logica cited above (LL § 885), concerning the analytic and synthetic methods more generally, indicates that mathematicians have always adopted both the methodus inventionis and the methodus doctrinae: whereas the former is required to analyze the truth, the latter is required to recompose it. I believe we should interpret Wolff’s distinction between two kinds of cosmologies in a similar way. This is for instance the way Wolff treats the relationship between dogmatic and experimental physics in the Discursus. Approaches in physics need not be given an order of priority, as long as propositions can be demonstrated: Indeed, the treasury of nature is so full that matter for discussion will not be lacking in dogmatic physics. When we agree that a thesis is true, it makes no difference whether we have learned it in experimental or in dogmatic physics. (DP § 110) This means that both experimental and demonstrative methods can be used to prove the truth of propositions and that the way in which this truth is obtained is of secondary importance. These methods must of course respect precise rules of demonstration, but the question as to whether we should proceed by induction or, say, take a priori defnitions as our starting point, does not seem to be entirely settled by Wolff. Accordingly, the relationship between experimental and scientifc cosmology could truly be a marriage between reason and experience, since we can draw from both sources, although they pertain to distinct objects, namely, the actual world and the essence of all possible worlds, respectively.

5 Conclusion In this chapter, I have tried to support the three following claims concerning experience and cosmology in Wolff’s philosophy. First, I have argued that Wolff admits of two main ways of demonstrating cosmological principles. The frst way, resulting in a scientifc cosmology, follows a method of exposition and is primarily based on abstract ontological truths. This way fts with what is said in the Discursus about the priority of ontology over special metaphysics, including general cosmology. It relies on the principle of suffcient reason and the results of ontology

Experience in Wolff’s General Cosmology 51 to demonstrate the properties of matter, such as indivisibility or fuidity, and the laws of motion, such as inertia or mechanism. The second way of reasoning relies on experience and results in an experimental cosmology. In this case, the actual properties and laws of matter are explained by combining reason and experience. I have suggested that the frst approach consists in what Wolff calls the synthetic method of composition, whereas the second approach consists in an analytic method of discovering or inventing. Second, the German cosmology integrates the latter approach because many of its proofs originate from joining together metaphysical principles and empirical evidences. One of the main aspects of this is that the German Metaphysics is explicitly devoted to accounting for the actual world that can be observed empirically. Ontological truths are necessary for structuring the search for causes, but many demonstrations must be completed with empirical or historical knowledge. Third, I have argued that the Latin cosmology is essentially based on the former procedure and could thus be qualifed as a scientifc cosmology. The role of experience has almost completely disappeared in favor of demonstrations based on ontological principles. Contrary to the German cosmology, Wolff is concerned here with the abstract properties of any possible world, not just those of the actual one, and seeks to prove them by entirely relying on the principles of ontology. At the same time, the prolegomena to the Cosmologia mentions the possibility of explaining the whole content of cosmology with the help of the experimental knowledge. In my view, this assertion refers to the approach adopted in the German Metaphysics, even if Wolff now favors an a priori and abstract way of demonstration. In sum, experience does play a role in Wolffan cosmology, but the weight it is given depends on the methodological context, and it seems evident that the Latin cosmology departs from the more empirical approach that prevails in the German cosmology.

Notes 1 See Wolff (1729a: §9, 345). 2 On the difference between Wolff and Kant in this regard, see École (1979: 45–61), Paccioni (2003: 307–22), and Anderson (2005: 22–74). 3 See Albrecht (1982: 1–24) and Vanzo (2015: 225–55). 4 Vanzo (2015: 228). 5 Wolff, PE § 497. On this aspect, see Dyck (2014: 19–42). 6 Wolff, DP § 99. Baumgarten’s Metaphysica, for instance, follows this order of exposition and thus devotes a whole section to cosmology (see M §§ 351ff.). 7 On this topic, see Vollrath (1962: 258–84) and Leduc (2018: 39–44). 8 See École (1980). Jean École’s works remain the most important source for these questions. 9 The full title of this work is Allerhand nüztliche Versuche dadurch zu genauer Erkänntnis der Natur and Kunst der Weg gebahnt wird.

52 Christian Leduc 10 See Wolff (1999: §1, 1145). This meaning of the term ‘cosmology’ was used before Wolff, notably by Weigel (1680). 11 Wolff, DP § 77. Wolff here mentions the Astronomia nova that was published by Kepler in 1609. 12 Cf. Wolff, CG §§ 48 and 60. 13 Cf. Wolff, CG § 1. The occurrence of the term ‘transcendental’ in this pre-Kantian context is of course interesting for understanding the evolution of the term. On this point, see Hinske (1968: 86–13), Angelelli (1975: 116–20), and Tommasi (2003: 53–66). 14 Wolff, CG § 2. Translations from the Cosmologia and the German Metaphysics are my own. 15 See Leibniz, Specimen, GM VI, 236–37. 16 Wolff, GM §§ 608–9; cf. CG §§ 130–32. 17 Wolff, GM § 610. 18 Leibniz repeats this argument on several occasions in his published works, not only in the Specimen, but also in De ipsa natura (see Leibniz, GP VI, 510–11). In the Cosmologia, Wolff is closer to Leibniz’s position in that he argues that inertia is not determined by extension, as the Cartesians supposed, but is added to extension on the basis of the passive force (CG § 131). 19 Wolff, GM § 656. See Mariotte (1673). 20 Wolff’s commitment to mechanism is indeed justifed by his rejection of action at a distance (see CG §§ 322–23). 21 Leibniz, Specimen, GM VI, 242. Leibniz mentions this thesis on many other occasions; see, for example, Essais de théodicée, GP VI, 321; Principes de la nature et de la grâce, GP VI, 603. 22 Wolff, GM § 665. In this section, Wolff refers once again to Mariotte in order to explain the conservation in speed after the body rebounds (see Mariotte 1673: 73). 23 Wolff, PR § 885. This methodological distinction does not concern cosmological reasoning specifcally, but I believe it is relevant to understand the different procedures in the German and Latin cosmologies. 24 Wolff, CG §§ 129–31; cf. PPO § 727. 25 Wolff mentions in this work one more reason why a posteriori procedures could be required in general cosmology, namely, the fact that a straightforwardly demonstrative approach is not always suffcient to attain the truth. Wolff gives the example of astronomy or celestial physics, some properties of which are not directly perceived. In these situations, the ars inveniendi must be completed by employing hypothetical principles. Wolff is aware that celestial physics could not operate without hypotheses, in particular concerning the planetary motion and the order of the solar system. This seems to be an additional reason for proving the validity of cosmological principles drawn from experience: when a priori and scientifc demonstrations are not available, the hypothetical method of experiencing can be very helpful (see CG § 5). The Discursus offers a general conception of hypotheses that include both experimental and metaphysical conjectures (DP §§ 126–29). On this point, see Leduc (2017: 77–97).

Bibliography Primary Sources Baumgarten, Alexander Gottlieb (1743), Metaphysica, Halle: Hemmerde; 1st edn. 1739 / Metaphysics, transl. and ed. by C.D. Fugate and J. Hymers, London: Bloomsbury 2003 (M).

Experience in Wolff’s General Cosmology 53 Leibniz, Gottfried Wilhelm (1965a), De ipsa natura, in Die philosophischen Schriften, vol. 6, ed. by C.I. Gerhardt (GM VI), Hildesheim: Olms. ——— (1965b), Essais de théodicée, in Die philosophischen Schriften, vol. 6, ed. by C.I. Gerhardt (GP VI), Hildesheim: Olms. ——— (1965c), Principes de la nature et de la grâce, in Die philosophischen Schriften, vol. 7, ed. by C.I. Gerhardt (GP VII), Hildesheim: Olms. ——— (1971), Specimen dynamicum, in Mathematische Schriften, vol. 6, ed. by C.I. Gerhardt, (GM VI), Hildesheim: Olms. Mariotte, Edme (1673), Traité de la percussion ou choc des corps, Paris: Michallet. Weigel, Erhard (1680), Cosmologia Nucleum Astronomiae et Geographiae, Jena: Meyer. Wolff, Christian (1720), Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt, Halle: Renger; repr. Gesammelte Werke, I.2, Hildesheim: Olms 1983 (GM). ——— (1721–23), Allerhand nüztliche Versuche dadurch zu genauer Erkänntnis der Natur and Kunst der Weg gebahnt wird, Halle: Renger; repr. in Gesammelte Werke, I.20.1–3, Hildesheim: Olms 1982. ——— (1723), Vernünfftige Gedancken von den Würckungen der Natur, Halle: Renger; repr. in Gesammelte Werke, I.6, Hildesheim: Olms 1981 (GPh). ——— (1729a), ‘De Notionibus directricibus & genuino usu philosophiae primae’, in Horae subsecivae Marburgenses, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II.34.1 (Winter Trimester 1729), Hildesheim: Olms, 310–50. ——— (1729b), Philosophia prima sive Ontologia, Frankfurt/Leipzig: Renger 1729; repr. in Gesammelte Werke, II.3, Hildesheim: Olms 1962 (PPO). ——— (1731), Cosmologia generalis, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II.4, Hildesheim: Olms 1964 (CG). ——— (1732), Psychologia empirica, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II.3, Hildesheim: Olms 1968 (PE). ——— (1734), Psychologia rationalis, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II.6, Hildesheim: Olms 1994 (PR). ——— (1963), Discursus praeliminaris de philosophia in genere / Einleitende Abhandlung über Philosophie im Allgemeinen, ed. by G. Gawlick and L. Kreimendahl, Stuttgart-Bad Cannstatt: Frommann-Holzboog / Preliminary Discourse on Philosophy in General, transl. by Richard J. Blackwell, Indianapolis/New York: Bobbs-Merrill 1996 (DP). ——— (1999), Anfangsgründe aller mathematischen Wissenschaften, III, repr. in Gesammelte Werke, I.14, Hildesheim: Olms (1st edn. Halle: Renger 1710). Secondary Sources Albrecht, Michael (1982), ‘Kants Kritik der historischen Erkenntnis: ein Bekenntnis zu Wolff?’, Studia Leibnitiana, 14/1, 1–24. Anderson, Lanier R. (2005), ‘The Wolffan Paradigm and Its Discontent: Kant’s Containment Defnition of Analyticity in Historical Context’, Archiv für Geschichte der Philosophie, 87/1, 22–74. Angelelli, Ignacio (1975), ‘On the Origins of Kant’s Transcendental’, KantStudien, 66, 116–20. Dyck, Corey (2014), Kant and Rational Psychology, Oxford: Oxford University Press.

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École, Jean (1979), ‘En quels sens peut-on dire que Wolff est rationaliste?’, Studia Leibnitiana, 11/1, 45–61. ——— (1980), La métaphysique de Christian Wolff, Hildesheim: Olms. Hinske, Norbert (1968), ‘Die historischen Vorlagen der kantischen Transzendantalphilosophie’, Archiv für Begriffsgeschichte, 12, 86–113. Leduc, Christian (2017), ‘Wolff on Hypothesis’, in A. Pelletier (ed.), Christian Wolff’s German Logic: Sources, Signifcance and Reception, Hildesheim: Olms, 77–97. ——— (2018), ‘Sources of Wolff’s Philosophy: Scholastics/Leibniz’, in R. Theis and A. Aichele (eds.), Handbuch Christian Wolff, Wiesbaden: Springer, 35–54. Paccioni, Jean-Paul (2003), ‘Wolff, l’expérience et la raison non pure’, Revue philosophique de la France et de l’étranger, 193/3, 307–22. Tommasi, Francesco V. (2003), ‘Kant di fronte alla tradizione del transcendentale: Stato della ricerca e prospettive alla luce du un nuovo particolare’, Studi Kantiani, 16, 53–66. Vanzo, Alberto (2015), ‘Christian Wolff and Experimental Philosophy’, Oxford Studies in Early Modern Philosophy, 7, 225–55. Vollrath, Ernst (1962), ‘Die Gliederung der Metaphysik in eine Metaphysica generalis und eine Metaphysica specialis’, Zeitschrift für philosophische Forschung, 16/2, 258–84.

3

Aesthetica Experimentalis Baumgarten and the Aesthetic Dimension of Experience* Alessandro Nannini

1 Introduction At the beginning of the frst volume of his Aesthetica (1750), Alexander Gottlieb Baumgarten famously defnes aesthetics as the science of sensible knowledge (scientia cognitionis sensitivae) (Aesth § 1).1 Etymologically linked with the term ‘aisthesis’ (sensation), aesthetics is accordingly set to deal with all that pertains to sensibility. This emphasis on sensibility is not unrelated to what Zelle has called the “empirical thrust in the sciences of the eighteenth century.”2 As Ludger Schwarte has claimed in a recent essay: Within the culture of the experiment, the inclusion of the senses in a process of experimental knowledge production works in two directions—as an empirical research of facts, towards the object of inquiry, which necessitates, in view of the experimenting subject, a formation of the body, so that the senses can detect and can be trusted. This is where the aesthetic subject was first produced.3 There is no doubt that the senses played a prominent role in seventeenthcentury experimental practices. In his Exercitatio anatomica de motu cordis et sanguinis in animalibus (Anatomical Studies on the Motion of the Heart and Blood, 1628), William Harvey explains that scientists who carry out autopsies in experiments (experimenta ocularia) importantly rely on the testimony of their own eyes: Whoever wishes to know what is in question (whether it is perceptible, or not) must either see for himself or be credited with belief in the experts, and he will be unable to learn or be taught with greater certainty by any other means.4 Along with sight, touch was regarded as a crucial means to prove the existence of body parts. Wepfer, for example, claims with regard to his anatomical observations that the existence of a visible and tangible part in the human body can only be proved through the eyes and the dexterous

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hand of the observer.5 Even taste was considered useful in experimental practice. In the attempt to better understand the causes of diabetes, for instance, the English physician Thomas Willis drank some urine of a patient, stating that it “was wonderfully sweet as if it were imbued with Honey or Sugar.”6 Scientists who viewed the senses as essential cognitive instruments importantly contributed to setting up the loose framework out of which the discipline of aesthetics arose. It is less clear, however, how this experimental tradition actually infuenced the origin of aesthetics as a science in its own right. Since Alexander Gottlieb Baumgarten (1714–1762) was the frst to coin the word ‘aesthetics’ and to regard this discipline as a science, the present chapter will mainly deal with his conception. More specifcally, it is the aim of this essay to analyze the impact of the philosophical discourse about experience and experimentalism on Baumgarten’s aesthetics as well as the reasons why Baumgarten, in turn, considered aesthetics to be essential to that very discourse. To do so, I will begin by briefy sketching Baumgarten’s position on aesthetics in general. I will then turn to his conception of experience in the context of his age, with special regard to the two felds that most emphasized the relevance of experimentalism: natural science and theology. Delving into the mutual ties between these two disciplines in the frst half of the German eighteenth century, I will argue that both hinge on a notion of experience based on sensuous knowledge, obtained through the use of the outer senses and the inner sense, respectively. On the one hand, I intend to demonstrate that Baumgarten tried to provide the experimental practices of his contemporaries with a unique epistemological ground, namely, the aesthetic art of experience. On the other hand, I will argue that experimental culture became key to achieving the ultimate goal of Baumgarten’s aesthetics, which is beauty. Thus, while Baumgarten’s aesthetics intends to provide experimentalism with a philosophical foundation, I will conclude, this very experimentalism lies, in turn, at the heart of his own project.

2 Baumgarten’s Aesthetics Alexander Gottlieb Baumgarten was born in Berlin in 1714 as the son of the Pietist military chaplain Jakob Baumgarten and Rosina Elisabeth Wiedemann. After the early death of his parents, he went to study at Halle’s orphanage, the Waisenhaus, founded by the Pietist August Hermann Francke. Without neglecting theology, Baumgarten graduated in philosophy at the University of Halle in 1735 and obtained the venia legendi in the same year with the disputation Meditationes philosophicae de nonnullis ad poema pertinentibus (Philosophical Refections on Several Issues Concerning Poetry). It is at the end of this academic writing that the word ‘aesthetics’ is recorded for the frst time ever. Following

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a King’s order, Baumgarten was appointed to the chair of philosophy at Frankfurt on the Oder in 1740, where he remained until his death in 1762. At this university, he began to lecture on aesthetics (1742/1743) and published the frst volume of his often-cited Aesthetica in 1750 (the second volume was released, unfnished, in 1758). While Baumgarten regarded aesthetics frst and foremost as the “science of sensible knowledge,” he also defned it as a theory of the liberal arts (theoria liberalium artium), a lower gnoseology (gnoseologia inferior), the art of thinking beautifully (ars pulcre cogitandi), and the art of the analogue of reason (ars analogi rationis) (Aesth § 1). In this sense, aesthetics is considered to be parallel to logic: while logic is committed to higher gnoseology, and thereby to the higher cognitive powers of the mind, aesthetics takes on the challenge of developing an ‘organon’ for the lower cognitive powers and sets beauty in thinking as its ultimate goal.7 According to Baumgarten’s project, both practical exercises aimed at strengthening the lower faculties and disciplinary learning crucially contribute to this end.8 Since Baumgarten’s unfnished Aesthetica mainly deals with the various kinds of beauty, that is, with the several ways to achieve the perfection of sensible knowledge,9 his hints concerning further aspects of aesthetics, scattered in other writings of his, have received less scholarly attention. This is due not least to the transformation the discipline underwent after Baumgarten’s death. Indeed, while aesthetics has obtained wide currency as a philosophical discipline, especially in the German-speaking world, its focus soon shifted from the theory of sensibility as conceived by Baumgarten to the theory of the fne arts and art tout court. Culminating in Hegel’s work, this tendency was not called into question until the second half of the twentieth century, when the issue of aisthesis, in its multiple layers, gained new momentum. This notwithstanding, the genesis of this more original meaning of aesthetics and the relevance of experience within this discipline has not yet received the consideration it deserves.

3 Baumgarten’s Aesthetic Conception of Experience At the beginning of the eighteenth century, the concept of experience was often connected with casuistry and moral prudence.10 According to August Friedrich Müller’s commentary on the German translation of Gracián’s Oráculo Manual (Manual Oracle), for example, experience is a kind of knowledge that is acquired over the course of time by observing particular cases and that can have a practical effect on one’s future actions.11 By defning experience as “clear knowledge by means of sense” in § 544 of the second edition of his Metaphysica (1743), Baumgarten clearly departs from this heritage. He rather aligns himself with the position of

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Wolff, who held that experience was the knowledge we acquire when we pay attention to our own perceptions.12 However, while Baumgarten discusses this theme in the section on the senses, Wolff dealt with the issue of experience in the section of his Psychologia empirica devoted to the higher part of the cognitive faculty (PE § 456), thus suggesting that experience involves the intellect.13 Baumgarten’s accentuation of the sensuousness of experience is even more evident in his Acroasis logica, which clearly conceives of experience as a type of knowledge that hinges on an “immediately acquired sensation” (AL § 163).14 Similarly to Wolff, though in a clearer way, Baumgarten also distinguishes between two types of experience, namely, observations and experiments.15 Unlike observations, experiments rest on the active manipulation of the observable data (AL § 329). The most innovative side of Baumgarten’s analysis concerns the double perspective from which he considers the epistemic achievements of experience. On the one hand, following in the wake of Wolff, he seeks to develop an ars observandi and experimentandi (Erfahrungs- und Versuchkunst).16 Thus, in the chapter of his Acroasis logica devoted to empirical logic, Baumgarten accounts for the way in which distinct concepts, defnitions, and judgments can be obtained from both observations and experiments (AL, ch. 5).17 On the other hand, Baumgarten pays more attention to the sensuous basis of experience, thus extending the discussion to the terrain of aesthetics. As he recalls in the second issue (1741) of his Philosophische Brieffe von Aletheophilus (Philosophical Letters of Aletheophilus), it is not suffcient to demand, as Wolff had done, that one pay attention to what we experience and to caution against the risk of attributing to sensations, thus to experience, representations that one has not perceived through the senses.18 Without a proper investigation of sensations themselves, he points out, it remains unclear how this requirement must be met in individual cases. For this reason, Baumgarten undertakes to promote, along with an ars observandi et experimentandi, an ars sentiendi.19 This art, which he also called an aesthetic art of experience (Aesthetische Erfahrungs-Kunst) or aesthetic empirics (Aesthetische Empirik), is concerned with gathering and improving experience regardless of the possibility of obtaining distinct concepts. 20 More specifcally, aesthetic empirics aims to teach scientists how to use their senses more effcaciously and prevent possible deceptions. Moreover, it deals with the perfection and proper use of instruments that sharpen the senses—the so-called weapons of the senses—ranging from telescopes to artifcial ears (PBA 8). 21 Aesthetic empirics, however, deals not only with the improvement of the use of the senses but also with the laws of sensation on which this use is grounded. As emerges from the aforementioned issue of his Philosophische Brieffe von Aletheophilus, Baumgarten is fully aware that he is

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not the frst one to think of such laws, referring both to philosophers like “the great Bacon” and “the deep Malebranche” and to works of important experimental scientists such as Robert Boyle’s On the Unsuccessfulness of Experiments (1669) and Pieter van Musschenbroek’s Oratio de methodo instituendi experimenta physica (Discourse on the Method for Performing Experiments in Physics, 1731).22 Given this background, it is clear that Baumgarten, who taught both aesthetica and physica during his career, considered the methodology of the experimental sciences to be of great signifcance for aesthetic empirics.23 Baumgarten’s discussion of the sensuous root of the laws of experience could also have drawn inspiration from his own academic milieu. 24 Particularly interesting is the account delivered by Michael Christoph Hanov in the frst volume of his Entwurf der Erfndungs-Kunst (A Sketch of the Art of Invention, 1739). 25 As regards external experience, which is obtained through sensory organs, Hanov distinguishes the laws belonging to the experientia vulgaris from those belonging to the experientia rarioris (EEK §§ 65–66). In the former case, such laws demand, for example, that one pay attention to whether a certain bodily characteristic can be known through a certain sense and whether this process is soundly and correctly carried out (EEK § 65). In the latter case, one also needs to rely on reasonable and honest witnesses and to observe a given phenomenon from different points of view in order to tell apart appearance from reality (EEK § 66). If scientists have to deal with elements that are inaccessible through the bare senses, it is crucial that they properly know their instruments and use them with caution (EEK §§ 67–68). Finally, Hanov mentions the laws that enable one to appeal to the experience of others, since not everything can be perceived by one’s own senses. In this case, it is important to establish whether or not the experience at issue is repeatable under other circumstances and whether the report is verisimilar in terms of both its consistency and the authority of the writer (EEK § 69). As for experiments, whereby we perceive things which do not happen without our intervention (EEK § 70), Hanov cites some general precautions we need to take. In particular, it is essential to be knowledgeable about the most signifcant trials of the best practitioners as well as to repeat them with the utmost care in view of both the details and the order of actions they imply (EEK §§ 75–77). Only in this way is it possible to rationally modify others’ attempts, so as to gradually learn how to conduct experiments of which we do not have examples either in others or in nature (EEK § 78–79). Although Baumgarten must have been quite familiar with the issues Hanov treats, his intention is to go beyond his predecessors. For whereas previous philosophers and scientists identifed laws of merely sensuous experience (bloß sinnliche Erfahrung), Baumgarten claims that the aesthetic empirics elaborated in the Metaphysica seeks to offer a

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more systematic account of the rules by which experience is governed. Summing up the main points of his discussion, Baumgarten states that external sensation is facilitated when 1) it belongs to a well-prepared organ; 2) when the body that is brought near to excite motion appropriately in the organ is most suited to the sphere of sensation or, more specifcally, 3) is as suited as possible to the point of sensation (punctum sensationis), both in terms of 4) quality and 5) quantity; and this not only if 6) stronger heterogeneous sensations are impeded, but also indeed if 7) all the somewhat weaker yet more numerous sensations are impeded, or rather 8) when other completely heterogeneous perceptions are impeded as well. (M § 543) The appropriate motion of the senses thus relies on two conditions: the presence of the object in the sphere of sensation and the acuteness of the senses.26 Moreover, as Baumgarten points out, one should try to prevent other possible sensations from interfering, which comes down to the methodological rule that scientists conduct experiments in a quiet and undisturbed situation. 27 By enabling one to exploit at best the performances of the senses, aesthetic empirics also commits itself to averting the deceptions of the senses (fallaciae sensuum). 28 Baumgarten claims that these deceptions “are false representations that depend on the senses, and these are either themselves sensations, or the reasoning for which sensation is a premise, or perceptions held to be sensations through the fault of subreption” (M § 545). Since external sensations pertain to actual states of this world, they cannot deceive (M § 546). If, for instance, we see from a distance a quadrangular tower as round, the senses are not to be held accountable for the mistake, but rather the judgment we too precipitately draw from the sensation. Our experience, however, can give rise to deception not only if our judgment is too hasty but also if it is considered to be the only touchstone for the existence or the non-existence of something. Thus, it will be very dangerous to take as major premise of an inference the statement: “Whatever I do not experience or sense clearly does not exist.” Indeed, by calling this fallacy the “prejudice of Thomas” (M § 548), Baumgarten suggests that it was precisely this premise that led the apostle Thomas to mistrust his fellow apostles’ tale about Jesus’s resurrection.29 As Baumgarten fnally points out, deceptions can also arise from illusions, that is, from devices intended to fool the senses. To overcome such illusions, Baumgarten recommends his readers to get rid of the prejudices and guard against the fault of subreption: “Before a person free from all prejudices and errors of subreption, every illusion will be ineffcacious” (M § 547).30 While Baumgarten does not follow up on these themes in his Aesthetica, some of these principles are detailed by Georg Friedrich Meier, his

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most famous pupil. In his Anfangsgründe aller schönen Wissenschaften (First Principles of All Fine Sciences, 1748–1750), Meier intends to investigate more closely the rules to be followed in order to carry out observations and experiments “in an aesthetic manner” (auf eine ästhetische Art), that is, in accordance with the principles of the senses (ASW 215). Consequently, Meier advises experimental scientists, for example, to appeal to the highest number of senses possible so as to render their experience more correct (ASW 216). Further, he recommends that one prepare in advance, on the basis of one’s own cognitions and others’ reports, a series of questions guiding the observation or the experiment, and that one take into account the conditions of time, place, etc., under which a certain experience occurs (ASW 216–20). From the more than forty pages devoted to this issue (ASW 213–56), the thesis emerges that only on the basis of the aesthetic care for the senses is it possible, with Bacon’s words, to extort nature’s secrets.31 While the methodology of experimental physics provides aesthetics with some laws of experience, aesthetics thus aims to become, in turn, the instrumental science for experimental physics.32

4 Experience and Experiments in Theology For Baumgarten, however, experience relies not only on external sensations but also on internal sensations. As he explains in his Metaphysica, external sensations are caused by the external senses, which represent the current state of one’s body by virtue of the fve sensory organs or aistheteria (M §§ 535–56). Internal sensations, on the contrary, depend on one’s inner sense, which represents the current state of one’s soul (M § 535).33 In the aforementioned passage of the Philosophische Brieffe von Aletheophilus on the tasks of aesthetic empirics, Baumgarten is well aware of the problems related to internal sensations. Although we all have internal sensations, Baumgarten declares, they are weaker in some and stronger in others, not to mention the fact that our assessment of them is often mistaken. In this case too, therefore, aesthetic empirics should promote the veracity of one’s internal sensations and, hence, internal experiences, as well as prevent possible subreptions. While Baumgarten is not very precise about strategies to do so, a quick glance at the intellectual context in which Baumgarten worked makes it possible to better understand how aesthetic empirics could be benefcial in this case as well. In his Entwurf der Erfndungs-Kunst (1739), Hanov had already recommended some rules to handle ambiguous cases of internal experience. To verify whether the soul is capable of producing a certain internal experience, for example, he suggests that one scrupulously examine the order in which the experience has happened, so as to detect possible incongruencies (EEK § 50), in particular if the experience

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at issue is not usual (EEK § 51). Yet the sensation through which we experience something can arise not only from the soul itself but also from a supernatural force. When the Apostles clearly felt on Pentecost day that they were able to speak languages they had never learnt, they had a supernatural experience. A specifc case of supernatural experience is spiritual experience, which, Hanov claims, arises from the habitual effects of the Holy Spirit on the soul through the mediation of the Word of God (EEK § 49). The importance of theology in the treatment of internal experience need not come as a surprise. Despite the principle of sola Scriptura, theological experimentalism had deep roots in Protestantism. 34 Luther himself had already stressed the relevance of a cognitio experimentalis in faith.35 Pietism, the Lutheran tradition in which Baumgarten was raised, conceived of aisthesis (sensation)—or, according to Luther’s translation, Erfahrung (experience)36 —as the spiritual precondition of a correct exegesis of Scripture.37 Gottfried Arnold, the author of a Theologia experimentalis (1714), even considered experience the very cornerstone of the believer’s relationship to God.38 Wolff himself entertained the idea of an experimental theology and proposed to model it on experimental philosophy: Just as in experimental philosophy, which nowadays is not unknown to anybody who has incidentally touched upon natural philosophy or physics, we teach how theories are submitted to experiments so that truth can be more certain, so too can we teach how to experience the truth of Christian doctrines in ourselves and others, but in particular in ourselves.39 In his Meditationes philosophicae de methodo mathematica (Philosophical Refections on Mathematical Method, 1734), the Wolffan philosopher Gottlieb Friedrich Hagen went as far as to acknowledge the signifcance in theology not just of experience but of outright experiments. While experiments in the natural sciences are tentamina intended to extort nature’s secrets, he argues, in the case of theology they are tentationes intended to test the faith of the believer.40 This emphasis on experiments did not take long to bring to the fore the epistemological stakes linked with the issue. Thus, Hanov’s Entwurf der Erfndungs-Kunst (1739) extends earlier attempts to identify the laws of experience to supernatural experience itself so as to guarantee the genuineness of the latter. On his account, a supernatural experience cannot be attained through the (natural) senses and imagination, is necessary for the achievement of the highest felicity, must comply with all divine properties, and not contradict any other truth. Moreover, while such an experience may defy the usual laws of the soul, it cannot be invented at leisure and might well occur against our will (EEK § 57).

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As regards spiritual experience, Hanov further specifes that one must be certain of the truth, divinity, necessity, sanctity, and importance of the revealed truths, as well as feel the constant urge to live according to their prescriptions. Those who do not comply with these two rules, Hanov concludes, cannot have a spiritual experience, but most likely fall victim to a mere fancy (EEK § 58), that is, to the fault of subreption. What this risk concretely means in the theological domain is exemplarily shown by Israel Gottlieb Canz, a Wolffan philosopher appreciated by Baumgarten. In his Philosophiae wolffanae […] consensus cum theologia (The Concordance between Wolffan Philosophy and Theology, 1737), Canz claims that those who blindly trust spiritual sensations tend to be more exposed to the risk of deceptions and mistakes.41 These “spiritual empirics,” Canz argues, are led by what they consider to be an inexplicable divine drive to place their trust in God and to manifest candor toward all humans. For this reason, these believers feature three prominent characteristics: frst of all, they offer themselves to God without being able to account for the reasons of their obedience; second, they, similarly to children, often believe they sense what they actually only imagine; and third, they can be easily misled by a fttingly disguised evil spirit. Consequently, he recommends that believers join sensations with refection on the operations carried out by the Holy Spirit in the soul of the pious as well as on scriptural teachings, thus acquiring the well-trained senses, or aistheteria gegymnasmena, that are mentioned by Paul in his Epistle to the Hebrews (5:14).42 Despite the different context, the need for well-trained senses in the case of spirituality seems to parallel the recommendations put forward in Baumgarten’s aesthetic empirics. Not by chance, while Baumgarten does not linger much on internal experience in general, he does deal with spiritual experience and its possible misuses. At a crucial point in his Praelectiones theologiae dogmaticae (Lectures on Dogmatic Theology, post. 1773), Baumgarten notes that experience, or intuitive judgment, is the frst infallible internal argument in favor of the divine inspiration of Holy Scripture.43 In an intuitive judgment, Baumgarten explains in his Acroasis logica, one takes the sensed thing as the subject and that which one feels by paying attention or refecting on it as the predicate (AL  §  320). The judgment is intuitive if one can obtain complete certainty about it by means of experience (AL § 315). In the case of Holy Scripture, the doctrine contained in this book is the sensed thing, whereas its irreducibility to any fnite spirit is what one feels by reading and pondering its contents. We can infer from this feeling that the work must have been written by divinely inspired men.44 Spiritual experience is thus key to obtaining the utmost certainty about the transcendent origin of the holy texts.45 In a similar vein, Baumgarten argues in his thoughts about Jesus’ sayings that what has been handed down in Scripture has to be experienced

64 Alessandro Nannini frsthand in order to be truly effcacious.46 He illustrates this by referring to Andrew’s encounter with Jesus: while Andrew used to believe in Jesus because of John’s testimony, after the frst meeting with the master he could claim by his own experience: “We have found the Messiah.”47 Such an experience can be external, as in the case of the apostle Thomas, who acknowledged the divinity of the resurrected Jesus only after seeing him, but also and above all internal.48 For Baumgarten, it is only by joining this experimental aspect to faith that it is possible to avert the excesses of historical faith, which does not touch the heart, as well as of spiritualism, which bypasses the mediation of Scripture.49 Despite their importance, therefore, internal experiences of the divine must never lead to fanatic enthusiasm (EP § 44). Enthusiasm, Baumgarten explains in his Ethica philosophica (1740), is the “habit of incurring the fault of subreption in divine matters” (EP § 39). In the issue of his Philosophische Brieffe von Aletheophilus devoted to the Herrnhuters, Baumgarten illustrates this aspect with the example of Catholics who mistake an alleged crying icon of the Virgin Mary for a wonder (PBA 84). Baumgarten distinguishes three degrees of this error: those who have such vivid mental images that they take them for truly perceived sensations are called fantasists (PBA 81). If they consider these imagined sensations to have a supernatural cause, they are called enthusiasts (PBA 81).50 If enthusiasts view themselves as directly inspired by God and violate public order, they are called fanatics (Schwärmer).51 Only the ability to tell apart sensations from products of the imagination, Baumgarten argues, can avoid this fault as well as its noxious consequences. Such an ability is not easy to acquire, however, especially if the imagined thing is desirable and the people involved do not have much insight into natural phenomena. Indeed, uneducated people tend to attribute to God what happens according to laws of nature unknown to them, thus falling victim to the prejudice of Thomas: whatever they do not experience or sense clearly is regarded as impossible and therefore attributed to a miracle (PBA 84).52 From this analysis, it is clear that the hygiene and training of the internal sense was considered to play an important role in the preparation for true spiritual experience and, more indirectly, the peaceful coexistence of people. Although Baumgarten does not explicitly mention aesthetic empirics in this issue of his Aletheophilus, the extension of its relevance from scientifc practices to the theological domain seems to be very consequential. This conclusion is not unexpected if we take into account the ties between experimentalism in the natural sciences and theology in Germany during the 1720s and 1730s.53 Indeed, physical (external) and spiritual (internal) experience were increasingly treated as two different species of experience understood as knowledge arising from the senses (Buddeus)54 or the “observation of things through the senses” (Syrbius).55

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If we consider aesthetic empirics against the backdrop of these accounts, it is possible to better understand the stakes of Baumgarten’s project. In fact, to the extent that aesthetic empirics aims at improving the knowledge that can be obtained by both the external and internal senses, Baumgarten meant it to provide an encompassing epistemological foundation for the entire experimental practice of the time. To put it bluntly, if experience is grounded on the senses, then the theory of experience, regardless of its feld of application, has to rely on aesthetic principles.

5 Aesthetics as an Experimental Discipline Aesthetic empirics, however, is not the only way in which Baumgarten connects aesthetics and experimentalism. While in aesthetic empirics it is aesthetics that grounds experimentalism, experimentalism itself can be said to ground aesthetics in turn.56 From this point of view, aestheticians do not limit themselves to dealing with experiments carried out in other disciplines, be they physics or theology, but have to conduct experiments themselves in order to achieve the highest goal of aesthetics, that is, beauty. Baumgarten discusses aesthetic experiments in the fnal paragraphs of the chapter of his Aesthetica devoted to aesthetic exercises. The point at issue concerns in particular psychological dynamics. In his German Logic, Wolff had devoted a chapter to the question as to how it is possible to investigate one’s own and others’ psychological powers (Kräfte), with special regard to determining whether they suffce to know a particular truth (GL, ch. 8).57 Baumgarten too wrote a chapter on this topic in his Acroasis logica, explicitly using the term ‘dynamica’ in the title (AL, ch. 8). On this basis, Baumgarten felt entitled to extend the task of determining the capacity of psychological powers to lower gnoseology: “Beautiful minds must seek to know their own and others’ powers in beautiful thinking; this means they have to study the dynamics of aesthetics” (Koll § 60). It is precisely in order to study the dynamics of aesthetics that aesthetic experiments become essential. Baumgarten’s proximate source in this regard may well have been the Wolffan Hagen, not yet considered by commentators in this respect, who had attempted to measure the powers of the soul (dynametria) by carrying out certain psychological experiments (Aesth § 60).58 In order to compare and determine the capacities of two boys to learn history, for instance, Hagen puts forward the following experiment: the researcher narrates to them a certain event until they have learned it. The lesser the need to reiterate the event, the better their learning speed and, hence, their intellectual power.59 For his part, Baumgarten narrows down the focus of such experiments to aesthetic ones. In particular, the discipline he calls ‘dynamic aesthetics’ aims to test one’s psychological powers so

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as to verify whether or not they are able to achieve a certain beauty.60 Baumgarten illustrates his thesis with the following example: One has to decide: will I be able to write a heroic ode about the military profession in our lands? When I determine this case, I can judge about my powers, and perhaps I will fnd out that, according to my powers, I can write a letter about the military profession in our lands, but not a heroic ode. (Koll § 60) The only way to fnd out if one is endowed with the necessary mental powers is to put them to the test by means of a tentamen or periculum, that is, an experiment. The result obtained by means of this exercise will enable beautiful minds to discover if their forces are adequate to the pursued end. As his use of the term ‘dynamics’ suggests, Baumgarten here relies on Leibniz.61 The latter had famously claimed that the living force can be measured by the magnitude of the effect that it produces when it is consumed (the so-called violent effect).62 In adapting this thesis to his aesthetics, Baumgarten claims that the beauty of knowledge is the effect brought about by the living forces of those who think beautifully (Aesth §§ 27, 60). In this way, the outcome of an aesthetic experiment can be conceived of as the effect of the psychological causes involved in the experiment, which are thereby assessed. In a sense, Baumgarten’s perspective here is similar to that of the natural philosopher. The latter experimentally investigates whether or not the potential energy in a given body, for example, an object placed at a certain height, is suffcient, once actualized, to do a certain work under given circumstances. Analogously, beautiful minds have to experimentally investigate whether or not their mental powers are suffcient, once actualized, to produce a certain degree of beauty in a given domain of beautiful thinking and under given circumstances. While the analysis of the mental powers as well as of beauty are treated in aesthetics as a scientia cognitionis sensitivae (that is, in Baumgarten’s treatise Aesthetica), the attempt to concretely produce beauty belongs to aesthetics as an ars pulcre cogitandi, that is, to aesthetics as a lived practice. In this regard, aesthetic experiments can be said to provide the link between aesthetics in its theoretical dimension and aesthetics in its practical dimension or, to take up a distinction usually applied to physics, between aesthetica speculativa and aesthetica experimentalis.63 Given these considerations, it is clear that Baumgarten considered aesthetic experiments to serve as preliminary steps toward the performance of beautiful thinking, in particular when the aestheticus has to deal with a kind of beauty or a subject with which he is not familiar. If the

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experiment succeeds, then the beautiful mind, aware of the suffciency of the required psychological forces, can embark on that kind of performance with higher commitment and expectations. If it does not succeed, however, this does not necessarily point to a defciency of the beautiful mind, since the failure of aesthetic experiments can also be due to the lack of preparatory exercises, the lack of inclination for a specifc genre of beauty, or the interference of external contingencies. Thus, Baumgarten notes, the fact that Ovid’s and Horace’s experiments with epic poetry failed does not call into question their reputation as beautiful minds.64 Yet aesthetic experiments are not just a means that beautiful minds employ in order to try their hand at a certain beautiful cognition: they also play a crucial role in the preparation for beautiful thinking in general. In Baumgarten’s Aesthetica, the sample that allows a given person to test his or her own power of thinking beautifully is called autoschediasma, which means improvisation.65 Albeit without quoting him, Baumgarten most likely draws this notion from a passage of Aristotle’s Poetics (1448b, 23), where the latter considers autoschediasmata to be the origin of poetry. Shifting Aristotle’s notion from poetry to aesthetics, Baumgarten suggests that aesthetic experiments, qua improvisations, lie at the very origin of beautiful thinking. As Baumgarten puts it: This kind [of exercises] includes all those examples of beautiful knowledge of humankind which predate the discovery of the erudite arts, as well as those frst stirrings, typical of any nature particularly inclined to beauty, which precede any art, like when, for example, Ovid remembers about himself: “Whatever I tried to do, it was in verses.” (Aesth § 52) As is clear from this passage, Baumgarten considers improvisations, often performed without a clear vision of the goal to be achieved, as the frst instances of beautiful thinking carried out collectively as well as individually. This is to say that both humankind and single individuals gradually learn to think beautifully only through more or less successful aesthetic experiments. In this sense, aesthetic experiments turn out to be an inescapable precondition not only for single aesthetic performances but also for the historical rise of beautiful thinking as such (Aesth § 14).

6 Conclusion In this chapter, I have outlined the ways in which Baumgarten relates aesthetics and experimentalism. Against the background of the concept of experience in early eighteenth-century Germany, I have discussed the signifcance Baumgarten grants to experience in the science of sensible

68 Alessandro Nannini knowledge he had just invented. By conceiving a specifc branch of aesthetics (aesthetic empirics) aimed at both theoretically studying and practically perfecting all that pertains to the knowledge of the senses, I have argued, Baumgarten intends to provide the diverse domain of experimentalism, ranging from natural science to theology, with a unifed epistemological framework. Yet while aesthetics is pivotal to experimentalism as regards the justifcation and improvement of sensuous knowledge, experimentalism too is crucial to aesthetics in the achievement of its ultimate goal, namely beauty, insofar as the production of beauty requires that the forces of the beautiful mind be duly tested. While Baumgarten earmarks a special domain of the newly born aesthetics for the theory of experience qua knowledge obtained by the senses, experience and experiments, in turn, lie at the very core of his project at large. Thus, well before Gustav Theodor Fechner’s Vorschule der Aesthetik,66 Baumgarten paved the way for the conception of aesthetics as aesthetica experimentalis.

Notes * I owe greatly to the editors of this volume, Karin de Boer and Tinca PruneaBretonnet, for their invaluable advice and support. My warmest thanks go to Clemens Schwaiger, Salvatore Tedesco, and Stefan Borchers for their attentive reading and helpful suggestions. This essay is published within the research project PN-III-P4-ID-PCE-2020-2579 (funded by UEFISCDI). 1 Baumgarten employs the Latin adjective sensuale to designate the knowledge obtained by the senses and the adjective sensitivum to designate sensibility in a broader sense, including the senses, imagination, memory, wit, etc. To translate the frst term, I will use the term ‘sensuous’; to translate the second term, I will use the term ‘sensible.’ 2 Zelle (2013: 104). 3 Schwarte (2009: 18–19). On this problem, see also Feger (1993). 4 Harvey (1963: 166). 5 See Wepfer (1658: 36). 6 See Willis (1679: 79). 7 On the determination of beauty, namely of the perfection of sensible knowledge, as the goal of aesthetics, see Baumgarten, Aesth § 14. The liberal arts (not yet the fne arts) fnd in this epistemic domain their common ground. For more detail, see Nannini (2021). 8 For more detail, see Nannini (2015). 9 For more detail, see Nannini (2020). 10 See in general Holzhey (1995) and Schneiders (1978). 11 See Gracián (1715: 44–46, 72, 464–66). See Walch (1726: col. 785–86). As Zelle remarks, Walch’s Philosophisches Lexicon mentions the link of experience with the senses only from the fourth edition of 1775. See Zelle (2001: 173). 12 Wolff, GM § 372: “We therefore have two ways whereby we attain the knowledge of truth, namely experience and reason. The former is grounded in the senses, the latter in reason”; see also Wolff, PPU 300, scholium. As we will see at the end of § 3, the link between experience and knowledge of the senses also emerges in authors like Buddeus and Syrbius, who are

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closer to Thomasius. See also Wolff, GL, ch. 4, § 1; LL § 664. Wolff makes clear that we have experience of singular things only (LL § 665). On Wolff’s conception of experience, see, apart from the relevant essays in this volume, Holzhey (1970), Buschmann (1991), Pimpinella (2002), Cataldi Madonna (2007), and De Felice (2017). See Schwaiger (2011: 58–64) for a useful analysis of Wolff’s development in this regard. See Schwaiger (2011: 65–66). See Baumgarten, Aesth § 482. Schwaiger (2011: 65) points out the importance of Reusch in this transformation. According to Baumgarten, experience in a broader sense includes the collection of cognitions in which some elements of sensation are involved. For a comparison to Wolff in this regard, see Pimpinella (2002: 96–97). Against the possible confusion between sensation and experience, see Chladenius (1749). Chladenius conceived of experience as a general proposition stemming from one or more similar sensations. See for example Wolff, PE § 456. See Pimpinella (2002: 112). Poser (1984: col. 1073) attributes to Wolff the merit of introducing the issue of observation in Germany. Actually, however, the link between experience and observation was already drawn by Buddeus, who viewed “experientia & observatio” and the reading of books as the two sources of cognitio historica (Buddeus 1703: 158–59). For another early source on this topic, see Cyprian and Brockhausen (1693: ch. 4). On the link between cognitio historica and empirics, see Seifert (1976). See Wolff, PE §§ 457, 459 and GM §§ 329–30. For an interpretation, see Pimpinella (2002: 112–17). According to Wolff, since the relationship between mind and body, whatever it may be, cannot be determined by way of experience, the thesis that an arm moves under the command of the mind cannot be confrmed or denied by experience, and whoever claims the opposite incurs the fault of subreption. See Wolff (1718: 148–49); GM § 529. For a detailed comment, see Birken-Bertsch (2006: 41ff., in particular 58–61); see also the editorial note in Baumgarten, M 208. Baumgarten had addressed the necessity of an ars sentiendi in his lectures since 1739–40. See Baumgarten (1769, § 26) and PG § 14. See Baumgarten, EP §§ 203–4; M § 544 and PBA 7–8. On the weapons of the senses, see also Baumgarten, AL § 37. For Wolff’s background, see Wolff, GL, ch. 1, § 22). Dealing with this issue is necessary, Baumgarten argues, because experimental physics rightly limits itself to assuming the existence of these instruments and their proper use. See also Baumgarten, PG § 26. The necessity to improve the use of the senses by means of specifc devices in the experimental practice was already discussed in the theoretical debate about experimentalism. In his Micrographia, for example, Robert Hooke traced back the faults of the senses to a lack of proportion between the object and the sensory organ. To remedy this, Hooke recommended, among other things, “the adding of artifcial Organs to the natural […]. By the means of Telescopes, there is nothing so far distant but may be represented to our view; and by the help of Microscopes, there is nothing so small, as to escape our inquiry.” (Hooke 1665: Preface). For a contextualization, see Corneanu (2012: 1–2). Campe remarks that the preparatory exercises for experimental practice demand the widening of the ancient rhetorical concept of techné, so as to also include technique in a modern sense, see Campe (2016: 160–70). While Boyle emphasized the importance of the chosen materials and of accidental contingencies for the success or failure of experiments, Musschenbroek explicitly pinpointed the importance of the correct use of the sensory

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23 24 25

26

27 28 29

30 31 32

33

34 35 36 37 38

organs in experiments as well as the proper functioning of the necessary mechanical instruments. For the presentation of his physics course, see Baumgarten (1743: § 9). Baumgarten prefers the phrase ‘physica empirica’ to ‘physica experimentalis.’ See already Von Rohr (1726: ch. 8). Wolff himself devoted a short article to the laws of experience; see Wolff (1708). See Hanov, EEK, chs. 4–5. Hanov defnes experience in general as the knowledge obtained through attention to our sensations, a defnition in line with the Wolffan teaching. Apart from this broader sense, Hanov uses the term ‘experience’ in a stricter sense as well, namely, to refer to observation as opposed to experiment. Accordingly, ars observandi is the same as Erfahrungs-Kunst (EEK § 42). The sphere of sensation is the place in which bodies “can still appropriately move a sense organ such that they are clearly sensed” (M § 537). Baumgarten notes in the same paragraph that the point of sensation is “the most appropriate place in the sphere of sensation.” As noted by Pimpinella (1996: 491), these two conditions restate in new terms Wolff’s distinction between the material and formal conditions of sensation. See for example Musschenbroek (1731: XXI). In his Psychologia rationalis, Wolff already stresses the importance of avoiding ‘fallaciae sensuum’ as a premise of science (PR § 124). Other major premises of possible deceptions of the senses that Baumgarten mentions are “whatever is (partially) the same as another representation is that very same perception” and “one of those things that coexist or mutually succeed each other really infuences the other” (M § 548). See Schwaiger (2011: 66–67) and Holzhey (1970). Hanov too warned against the faults of the senses in the chapter on Erfahrungs-Kunst (EEK § 64). Meier repeats twice the phrase, indebted to Baconianism, “die Natur zwingen” (ASW 214). Bacon is mentioned favorably over the course of the whole discussion (see in particular ASW § 366). On Baumgarten’s aesthetics as the instrumental science for physics, see Peres (2016a: 99ff.), who also emphasizes the relevance, apart from the senses, of other lower powers of the mind for physics. On Baumgarten’s aesthetics as ‘Erfahrung-Instrument,’ see Wübben (2007: 120ff.). Since the inner sense is involved in any psychological working, Baumgarten calls it conscientia strictius dicta (M § 535). See Pimpinella (1996: 474) and Hernández Marcos (2014). For the importance of the cultivation of inner sense in aesthetics, see Rydberg (2017: ch. 4). Although Wolff had not developed the issue of the internal sense in a systematic way, he states in his German Metaphysics that experience can also make reference to the internal workings of the soul (GM § 325). Insofar as a sensation is always a representation present in the soul, as Hanov had already clarifed, external experience cannot exist without a concurrent internal experience (EEK § 48). For a commentary, see Keding (2001: 29 and 81ff.). See for example Luther (1930: 738). For the equation of the two terms in the wake of Luther, see Lange (1710: 18). See for example Francke (1723: 238). According to Francke, such an experience is a prerogative of the reborn, insofar as they share the affects animating the holy writers. On this, see Grote (2008). See Arnold (1714). For more specifcations and other bibliographical entries on this theme, see Keding (2001), who points out the centrality of the category of experience in seventeenth-century Lutheranism and Pietism in particular (28ff.). The third International Congress for Pietism Studies

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42 43 44 45 46 47 48 49

50 51

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(Halle/Saale 2009) was devoted to this issue; on this, see Soboth and Sträter (2012). Wolff (1735: 45). Wolff here specifes that experimental philosophy provides an example to experimental theology as to the way it explains and applies the rules of experimentation to speculative data. See Hagen (1734a: 133–35) for the double dimension of experience and experiment in theologicis. See Canz (1737: 797–801). While Leibniz states in his Monadology (§ 28) that we all are empirics in three quarters of our actions, Wolff defned as “empirics” those who let their actions be governed by experience (PE § 502). On the necessity to mistrust bare sensations in religion, see Leibniz (1692: 4ff.). Canz (1737: 801). Baumgarten (1773: §§ 105–6). Baumgarten (1773: § 105) Baumgarten (1773: § 106). See Baumgarten (1796: 32). John, 1:40–41. Baumgarten (1796: 32). On the issue of faith in Baumgarten as well as on the relevant bibliographical references, see Nannini (2019). Baumgarten (1796: 21). In notes taken by Johann Gottfried Beneke of Baumgarten’s lectures on dogmatic theology, as yet unpublished, the link between spiritual experience and its scriptural content is frmly stated. See Baumgarten (1748: § 56, small scholion beside the main text of the paragraph); the four-volume work is held in the Staatsbibliothek in Berlin (Ms. theol. lat. oct. 48–51). The frst volume is dated March 1748. The theme of enthusiasm has another meaning in aesthetics as well, namely, one drawn from the theology of ancient pagans (see Baumgarten, Koll § 78). Baumgarten, PBA 82, cf. EP § 39. The term ‘fanaticismus’ is rendered in German as Geisttreiberey and Schwärmerey. The German translations are added in the third, posthumous, edition of the Ethica philosophica (EP  III,  §  39). In the frst edition of his Metaphysica, Baumgarten already distinguishes fantasists, here equated with visionaries and fanatics and regarded as “those who, while awake, customarily take certain imaginations for sensations,” from “those who absolutely confuse them with sensations,” which are defned as delirious (M § 594). Already in his Ethica philosophica, Baumgarten acknowledges the danger of this prejudice for the experientiae divinorum, warning against the risk of taking sensations for mental images or mental images for sensations (EP § 63). Another religious application of the prejudice of Thomas can be found in a private letter by Baumgarten to his pupil Kettel dated January 1761. In it, Baumgarten claims that the experience of rebirth for a Christian believer cannot be forgotten, although the levels of joy and the ways of soothing the soul are not the same for all. In this sense, it is not possible to conclude that if one has experienced this moment in a certain way, the others too have to experience it in the same way, and that if one has not experienced it in that way, the others lie; see Kettel and Deutsch (1762: 25). The connection with Thomas emerges for the frst time in the aforementioned passage of the Philosophische Brieffe von Aletheophilus (PBA 84) and will be then mentioned in the Metaphysica starting from the second edition (1743). On this, see Schwaiger (2011: 67–68). As is shown by Harrison (2011), this link is remarkable in the British milieu. Jonathan Edwards, for example, claimed in 1746: “This is properly Christian experience, wherein the saints have opportunity to see, by actual

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Alessandro Nannini experience and trial, whether they have a heart to do the will of God, and to forsake other things for Christ, or no. As that is called experimental philosophy, which brings opinions and notions to the test of fact; so is that properly called experimental religion, which brings religious affections and intentions to the like test.” See Edwards (1998: 333). See Buddeus (1732: 195–98). According to Buddeus, spiritual experience is included in theological experience, along with ecclesiastical experience. In turn, spiritual experience includes those acts of grace that all reborn Christians feel and experience, even if not all in the same way; on the contrary, in extraordinary experience the Holy Spirit brings about a sudden effect in the human mind. Syrbius, IP 91. Syrbius defnes experience as the “observation of things through the senses” (observatio rerum per sensus). On his account, external experience is concerned with individual things existing or happening beyond our mind, while internal experience discloses things that happen in our mind and stem either from the mind itself or from a spiritual principle. Syrbius discusses external and internal experience in much the same way as Hanov, who deals with external and spiritual experience in the course of the same chapter of his aforementioned book at the end of the 1730s (EEK, ch. 4). According to Baumgarten, aesthetic empirics is aimed at the perfection of the senses alone, while the production of beauty, that is, the perfecting of sensible knowledge, requires the use of all the sensible faculties of the soul, and, to a lesser extent, of the higher faculties as well (Aesth §§ 28–46). According to Pimpinella (2002: 118), the cultivation of perfect sensible knowledge is crucial to the elaboration of the individual experience in a broad sense in Baumgarten’s perspective. In Wolff’s Latin Logic, the section entitled “De usu logicae in aestimandis viribus ad rerum cognitionem requisitis” is divided into three chapters, dealing with the estimation of the powers in the discovery and judgment of a true cognition (LL §§ 1135–63), in the writing, judging, and reading of books (LL §§ 1164–86), and in convincing, controverting, disputing, and teaching (LL §§ 1187–1210). See Hagen (1733: § 27). See Hagen (1734b: 4–5). The issue of dynamometry runs through Baumgarten’s discussion of the different kinds of beauty. For example, Baumgarten claims that the best wits possess a “natural dynamometry,” namely the capacity to weigh up the proportion between cause and effect in the aesthetic matter proposed to their audience by means of their sensible wit. See Aesth §§ 457ff., Koll §§ 457ff. See also Aesth §§ 493–95, 645, 678, 818, 846 and Koll §§ 493–95. See Peres (2016b: 111–12). See Leibniz (1860: 218). The frst version of Leibniz’s essay dates back to 1692. On the importance of this background for Baumgarten’s aesthetics, see Torra-Mattenklott (2002: 197ff.) and Schwaiger (2016: § 5). From this point of view, Baumgarten seems to extend to aesthetics itself Wolff’s attempt to apply experimentalism to all branches of philosophy. See Baumgarten, Aesth §§ 60–61 and Koll §§ 60–61. The relevance of external contingencies for the failure of scientifc experiments was already emphasized by Boyle (see above). See Baumgarten, Aesth § 60; see also Frey (2016). See Fechner (1876).

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Soboth, Christian and Sträter, Udo (eds.) (2012), ‘Aus Gottes Wort und eigener Erfahrung gezeiget’. Erfahrung—Glauben, Erkennen und Handeln im Pietismus, 2 vols., Halle: Verlag der Franckeschen Stiftungen. Torra-Mattenklott, Caroline (2002), Metaphorologie der Rührung. Ästhetische Theorie und Mechanik im 18. Jahrhundert, München: Fink. Wübben, Yvonne (2007), Gespenster und Gelehrte. Die ästhetische Lehrprosa G. F. Meiers (1718–1777), Tübingen: Niemeyer. Zelle, Carsten (2001), ‘Experimentalseelenlehre und Erfahrungsseelenkunde. Zur Unterscheidung von Erfahrung, Beobachtung und Experiment bei Johann Gottlob Krüger und Karl Philipp Moritz’, in C. Zelle (ed.), “Vernünftige Ärzte”. Hallesche Psychomediziner und die Anfänge der Anthropologie in der deutschsprachigen Frühaufklärung, Tübingen: Niemeyer, 173–85. ——— (2013), ‘Ästhetische Anthropoiesis. Leibniz’ Erkenntnisstufen und der Ursprung der Ästhetik’, in A. Košenina and W. Li (eds.), Leibniz und die Aufklärungskultur, Hannover: Wehrhahn, 93–117.

Part II

Eclecticism and Popularphilosophie

4

The Thomasian Context Crusius on Experience Stefan Heßbrüggen-Walter

Christian August Crusius (1715–1775) was a follower of the Leipzig jurist and philosopher Christian Thomasius (1655–1728), a central fgure in the early German Enlightenment who argued against torture and the criminalization of heresy and magic.1 Favoring an eclectic approach to philosophy, Thomasius and his disciples searched for truths in various philosophical schools and traditions. At the same time, they emphasized epistemic autonomy (Selbstdenken) over undue reliance on authority. 2 Some of them, including the Jena professors Johann Franz Budde (1667–1729) and Johann Jakob Syrbius (1674–1734), aligned themselves with the Protestant movement of Pietism.3 Crusius’s teacher Adolph Friedrich Hofmann (1703–1741) had studied with Andreas Rüdiger (1673–1731), who himself had been a student of Thomasius.4 By the time Crusius started to teach and publish, in 1740, the increasing success of Wolffanism threatened to eclipse the philosophical endeavors of Thomasius’s followers. Crusius was the exception to the rule.5 He summarized and systematized the more rhapsodic teachings of his predecessors in a way that made them accessible to a broader audience.6 During the 1740s, his works came to represent the most comprehensive philosophical alternative to Wolff’s philosophical system.7 As we will see, the concept of experience played a prominent role in this project. Rüdiger, Hofmann, and Crusius all taught at the University of Leipzig. While Thomasius had discarded metaphysics as empty speculation, Rüdiger conceded that the discipline can play a heuristic role in some cases. Yet he denied that metaphysical insights can be used as foundations of moral or natural philosophy.8 Hofmann, for his part, mainly published works on logical topics. He advanced the debate on the relationship between philosophical and mathematical methods of argumentation and emphasized the validity of subjective reasons in logic.9 Crusius completed the rehabilitation of metaphysics within Thomasian philosophy in his 1745 Entwurf der nothwendigen Vernunft-Wahrheiten (Outline of the Necessary Truths of Reason). The historical relevance of Thomasian thinking has been disputed.10 But as far as the topic of experience is concerned, I hold that the

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Thomasians went beyond the teachings of philosophers like Bacon or Locke. The most salient feature of early eighteenth-century German theories of experience in comparison to their British counterparts is their effort to determine what is meant by the very concept of experience. This discussion mostly came up in relation to the question concerning the role of logic in the production of knowledge. All Thomasians under examination here, starting with Rüdiger, understood experience as a mental state that is distinguished from perception and sensation. However, before 1713, when Wolff’s German Logic was published, we only fnd scattered remarks on how to understand the concept. Later discussions of the concept are more comprehensive. Rüdiger, Syrbius, and Budde considered experience to consist in a ‘plurality’ of sensations of an object, i.e., in repeated sensations of the same object. By contrast, Hofmann and Crusius held that experiences are states that can be expressed in a proposition, a change in perspective that was occasioned by Hofmann’s critique of Wolff’s understanding of truth in the latter’s Philosophia rationalis sive Logica.11 Thomasians also worried about the exact relationship between experience and reason. We will see that Wolff tended to keep both dimensions strictly separate. While Rüdiger agreed with Wolff in this regard, others, most notably Syrbius and Müller, believed that the concept of ‘relative experience’ could bridge the gap between, on the one hand, experience and sensations and, on the other, higher-order cognitive functions such as judging and reasoning. By contrast, Crusius’s teacher Hofmann criticized this view and held, for instance, that causal judgments could not be based on experience. Crusius tried to forge a compromise between both views. A third area of internal disagreement among the Thomasians concerned the role of inner experience. Whereas Budde and Syrbius acknowledged the possibility of direct experience of the supernatural, Crusius and his teachers either denied this possibility or simply remained silent on it. However, I hope to show that inner experience is of central importance to Crusius’s metaphysical method. As I will demonstrate in this chapter, Crusius’s analysis of the concept of experience mostly follows his teachers Rüdiger and Hofmann against the Pietist camp. It would therefore be misleading to qualify his understanding of the concept as an important innovation in its own right.12 While he did introduce some minor modifcations, his main achievement is the systematization and clarifcation of views that can already be found in the works of his teachers.

1 The Thomasian Conception of Experience Thomasius’s predecessors and contemporaries took a lively interest in the notion of experience. Already in the Opera omnia of Johann Clauberg,

Crusius on Experience 83 an important German Cartesian, the relevance of experiment and observation for natural philosophy is unambiguously affrmed.13 Explicitly referring to Bacon, Thomasius’s Leipzig colleague Cyprian distinguished experience from sense perception and conceived of the former as a separate source of the knowledge to be obtained in natural philosophy.14 According to Cyprian, experience, in contrast to sense perception, is concerned with scientifc practice (usus). Experience is a skill that depends on ‘indefatigable attentiveness’ (diligentia indefessa) and acute judgment (judicium acutum). This is why it cannot be taught by others: we must acquire it on our own.15 Thomasius himself had not much to contribute to this discussion.16 In his Einleitung zu der Vernunftlehre (1691), he briefy mentions two functions of experience: experience can help to obtain what he calls ‘probable concepts’ and to fnd new truths. Probable concepts are based on incomplete inductions. These inductions, in turn, depend on “good or long experience,” i.e., a plurality of sensations that is qualitatively and quantitatively suffcient: The ‘probable concept’ is actually formed through an induction based on many individuals and is generated from several sensations. This is why it cannot come into being without good or long experience.17 Experience can also have a heuristic function, because it allows scientists to fnd new truths, so that we should not rely only on the knowledge of others when schooling our cognitive abilities. Thomasius urges his readers to no longer rely on the help of other people and put away the books from which until now you used to collect new truths. […] Encounter more and more indisputable and unknown truths about nature, using your external senses.18 The frst edition of Andreas Rüdiger’s De sensu veri et falsi (1709) contains the frst comprehensive discussion of experience as a plurality of similar sensations.19 Thus, we have an experience of x if we have repeatedly observed that x is the case and can therefore infer that x will also be the case in the future. 20 Rüdiger criticizes Locke’s view that we can draw on experience to justify all kinds of probable statements if there is a preponderance of evidence for affrming or negating them. 21 There may be cases—Rüdiger cites Copernicus’s De Revolutionibus—in which the weight of evidence is equal on both sides. Copernicus’s readers could explain the visible movement of stars and planets by relying on either the Copernican or the Ptolemaic system. Since the empirical evidence available to heliocentrism and geocentrism was exactly the same, the choice

84 Stefan Heßbrüggen-Walter between both hypotheses could not be based on experience. 22 Rüdiger infers from this that experience is relevant only to those probable statements that are based on the senses alone. 23 After the publication of Wolff’s German Logic, in 1713, various Thomasian authors began to see experience and its role in cognition and action in a more positive light. Wolff’s logic defnes experience as a cognition that is based on attention to our sensations (GL, ch. 4, § 1). Yet Wolff uses the term ‘experience’ not only to refer to a mental state, e.g. my conscious perception that a candle has been lighted, but also to refer to a species of propositions, namely, propositions that are concerned with particulars like ‘this candle has been lighted’ (GL, ch. 4, § 2). By contrast, Thomasians such as Syrbius, the later Rüdiger, and Budde largely identifed experience with a plurality of similar sensations.24 They did not take up Wolff’s suggestion that the element that distinguishes experience from mere perception is attention. Neither did they interpret experience as a species of propositions. This changes only after the publication of Wolff’s Philosophia rationalis sive Logica in 1728. 25 The frst Thomasian who conceived of experiences as propositions was Crusius’s teacher Hofmann. In order to understand his motivation for turning away from a purely sensation-based view of experience, we must frst turn to Hofmann’s criticism of the theory of logical truth Wolff puts forward in his Philosophia rationalis sive Logica. According to this theory, a proposition is logically true if it is possible to ‘determine’ a predicate through the concept (notio) of the subject. 26 Wolff realizes that this defnition poses a problem for propositions about contingent properties such as ‘the stone heats’ (or ‘this author is balding’). Predicates that pertain to such properties cannot be part of the defnition of the subject term, because the defnition can include only essential, i.e., necessary properties: If a predicate does not always belong to a subject and if one therefore cannot always attribute it [to the subject] based on the defnition, then it is without doubt not suffciently determined by the defnition. (LL § 228) Given the principle of suffcient reason, Wolff maintains that there must be another kind of reason, or ground, that entitles us to attribute a contingent property to a thing. Such a reason must determine the state of the subject of the proposition in such a way that the predicate is applicable to it. A stone can heat something only when it is itself hot—it cannot heat something qua being a stone. This author is balding, but he is not balding qua being this author. In order to attribute the predicate ‘heats’ to the subject ‘stone’ in a true proposition, we need to take into account an additional determination of the stone, namely its ‘being hot.’ In the same way, there must be an additional reason not contained in

Crusius on Experience 85 the defnition of this author that is responsible for his receding hairline. Thus, for Wolff a proposition is true if the predicate is suffciently determined either through the defnition of the subject term or through a reason derived from a perception of the thing to which the predicate is attributed (LL § 228). In Gedancken über Hn. Christian Wolffens … Logic oder sogenannte Philosophiam rationalem (Thoughts on Mr. Christian Wolff’s … Logic or So-Called Rational Philosophy, 1729), Hofmann takes issue with this position. He holds that the defnition of the subject must explain why the predicate can be applied to it even if the predicate itself is not contained in this defnition. To use Wolff’s example, even if the predicate ‘being hot’ is not contained in the defnition of a stone, the defnition itself must provide us with reasons to assume that a stone can heat something. 27 If this is impossible, we are not allowed to take the proposition to be true. 28 Hofmann clarifes his position by referring to the fact that while some animals are killed by lightning, others are not, a fact that contemporary science could not explain. If it is impossible to identify the reason that determines whether a living body dies or stays alive, Hofmann reasons, then Wolff’s defnition of truth commits him to the conclusion that propositions concerning facts such as these cannot be true.29 But if we perceive that an individual animal dies due to lightning, we want to assert this as true here and now. He grants that one may attempt to save Wolff’s defnition by pointing out that further investigation may well provide us with the determining reason of the empirical proposition. But further investigations might also show that there is no such reason, in which case we should evaluate the respective proposition, e. g. ‘This individual animal has died from lightning’ as false.30 This outcome would, of course, be quite counterintuitive, because the argument is based on the premise that we have perceived the death of the individual animal in question. Accordingly, Hofmann develops a taxonomy of propositions that takes into account differences that Wolff had unduly neglected. He begins by distinguishing truths based on inferences from propositions that are ‘immediately’ true. Immediately true propositions fall into two classes. The frst class, consisting of ‘immediate essential propositions,’ comply with Wolff’s criterion of logical truth, because in them the nexus between subject and predicate is based on our knowledge of the essence of the former.31 The second class is that of ‘immediate existential propositions’ or ‘experiential propositions’ (Erfahrungs-Saz) (VL, Vorbericht, § 15). If both subject and predicate as well as their nexus are experiential, the proposition is a ‘common experience.’ If the use of the copula is experiential, but it connects abstract concepts, the proposition is a ‘refective experience’ (VL, Vorbericht, § 15).32 The truth of this class of propositions depends on experiences that justify the truth or falsity of

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propositions even if the underlying concepts have not been suffciently analyzed, as Wolff would have to contend. This is why Hofmann can maintain that some propositions may be true for conceptual reasons, while others owe their truth to perceptions. Only immediate essential propositions fall under Wolff’s criterion of logical truth, while the truth of experiential propositions depends obviously only on appropriate experiences: if this individual animal has been killed by lightning, we can assert this here and now without worrying whether or not we have understood the concept of an animal or that of lightning with suffcient distinctness. Hofmann had suggested that immediate propositions are in no need of proof at all, because their truth does not depend on inferences. In Weg zur Gewißheit und Zuverläßigkeit der menschlichen Erkenntnis (Path to the Certainty and Reliability of Human Knowledge, 1747), Crusius defnes this class of propositions in a slightly different way. On his account, the truth of immediate propositions cannot be obtained completely independently of inferences but rather requires a single proof: Moreover, [we] have to take into account the difference that […] the truth of other propositions is proven in logic once and for all. Experiences and immediate propositions or axioms belong to the latter class. (Weg § 40) Crusius follows Hofmann by distinguishing two species of immediate propositions: experiences and ‘axioms’ (which Hofmann had called ‘immediate essential propositions’). For Crusius, experiences are propositions the truth of which can be determined through a single logical proof that establishes that sensation is veridical and always has an object (Weg §§ 434ff.). In the case of axioms, however, Crusius’s criterion is ‘subjective’: we cannot help but to think subject and predicate together, as we do, for example, in the proposition ‘every line is identical with itself’ (Weg § 42).33 In the case of experiences, by contrast, it is not necessary to think subject and predicate together: we can grasp the concept of the subject independently from the predicate. I merely must perceive that subject and predicate are linked through the copula: An experience is a proposition in which the conjunction of the subject and the predicate is immediately perceived through sensation. (Weg § 41, my emphasis) If the concepts linked in a proposition are themselves sensible, the resulting experience is called a ‘common’ experience. If the linked concepts are abstract and only the conjunction of both concepts is sensed, we speak of ‘refective experience.’34 While experiences are propositions, we

Crusius on Experience 87 must keep in mind that they are produced by a mental activity. Crusius calls this activity ‘acquisition’ (Einziehung). We must keep both aspects separate.35 In sum, Crusius followed the view of his teacher Hofmann that experiences are a species of propositions but added two aspects. He held, frst, that propositions count as experiences as soon as the use of the copula is justifed empirically and, second, that the conjunction of two abstract concepts can itself be experienced even if the concepts are not themselves based on experience.

2 The Scope of Experience: Experience and Reasoning Prima facie, Thomasius and Wolff agree that knowledge depends on both experience and our ability to reason well. Thomasius demands explicitly that experience and reason cooperate. For him, the ability to reason well encompasses not only reason (Vernunft) but also refection (Nachdenken), inference (ratiocinatio), and contemplation (meditatio).36 Wolff as well maintains that experience provides the foundation for knowledge and the material for inferences that lead to scientifc knowledge.37 However, the agreement between both is not complete. Thomasius assumes that the power of experience is limited: it cannot provide insight into natural causes. He argues that natural philosophers mostly agree with regard to the experiences they rely upon but nevertheless cannot agree on general theories. This is because experiences concern particulars only, while theories must be based on proofs that are universally valid.38 Wolff disagrees: on his account, experience does play a role in the cognition of causes. In his German Logic he uses an example to clarify the problem: the question whether or not the proposition ‘air has weight’ is true can only be answered by appealing to experience. Wolff argues that the truth of this proposition must be substantiated or explicated by providing the opportunity to make corresponding perceptions, in other words, by carrying out an experiment. He describes such an experimental explication in some detail: we must balance the weight of a large glass sphere on a scale, pump air out of it, and weigh it again. If the scale moves, the proposition stating this fact counts as an experience, while the proposition ‘air has weight’ is, strictly speaking, based on an inference.39 In other words, experiences are propositions about particulars. If we want to ground claims to knowledge on experiences, we must be able to point to particular cases that can substantiate our claims (GL, ch.  4, § 2). Sometimes an explication along such lines is not required, because the link between the proposition and the perceptions we need to substantiate it is obvious. We can claim without further explanation that spilling water on a table makes the table wet. If anyone should

88 Stefan Heßbrüggen-Walter question this claim, this person could be expected to conduct the relevant experiment—spilling water on a table and examine whether or not it is wet (GL, ch. 4, § 3). So Wolff believes that we must distinguish what we could call ‘obvious experiences’ from non-obvious ones. And if experiences are non-obvious, we must rely on inferences to provide explanations of them. So if there is disagreement about purported experiences, it is based on mistaking non-obvious experiences for obvious ones (GL, ch. 4, § 4). If opponents lay out the explanation for a nonobvious experience in detail, any disagreement about the experience could be resolved. Some Thomasians refused to follow Wolff and held that in some cases having the experience alone is suffcient for the cognition of the cause of the observed phenomenon. They contrast these so-called relative experiences with ‘absolute’ or ‘vulgar’ experiences that are based on immediate perceptions alone. ‘Relative experiences’ contain insights into causes, effects, or other properties.40 Others, including Rüdiger, accepted Wolff’s claim that experience provides only ‘vulgar’ knowledge that must be refned by using our rational capacities.41 In the 1717 edition of his Institutiones eruditionis, Rüdiger elaborates this point: on his account, it is impossible to fnd the defnition of an individual. Since erudition is concerned with what is defnable, the sphere of what we can experience and the sphere of what we can know by means of erudition are disjunct.42 Erudite knowledge, and only erudite knowledge, is philosophical: it provides insight into essences and, to a limited extent, into the causal structure of nature.43 Hofmann is more radical. Claims of a causal nexus imply a counterfactual conditional: if the effect were absent, the cause would be absent too. This conditional, however, cannot be verifed through experience but must be based on an inference. Therefore the concept of ‘relative’ experience is an illusion.44 Following Wolff in this regard, Crusius holds that we can classify some propositions as experiences, even if they are, strictly speaking, based on inferences, and contrast them with propositions that are based on perceptions alone. He calls the former class ‘mixed’ experiences and the latter class ‘pure’ experiences: We commonly accept those propositions as experiences in which experience is connected with an inference that is obvious and need not be specifed separately. One can call these propositions mixed experiences and the others pure experiences. For example, that it will be day as soon as the sun is visible on the horizon is a pure experience. That the sun causes the day, by contrast, is a mixed experience. For experience, strictly speaking, does not teach causal connections, but only that a thing presents itself in a certain way and that certain things present themselves together or successively.45 (Weg § 41)

Crusius on Experience 89 The proposition ‘the sun causes the day’ is a mixed experience, because in a strict sense we only experience the correlation between sunrise and the beginning of the day. Thus, Crusius agrees with Thomasius, Rüdiger, and Hofmann that causal connections cannot be perceived.

3 Inner Experience and Its Application in Metaphysics As was mentioned above, some Thomasians were closely aligned with the religious movement of Pietism. A key topic in this movement was the possibility of the mystic union with the Divine.46 In order to account for the possibility of this ‘rebirth,’ the Pietist philosopher Joachim Lange postulated a superior lumen supernaturale as a complement to our natural epistemic capabilities, the so-called lumen naturale.47 Yet since our awareness of the Divine is awareness of a particular being and is not mediated by concepts, it must be counted as an experience. This explains why Syrbius defnes inner experience as the observation of what takes place in our souls, including observations of phenomena that are caused by some other ‘spiritual principle’ (whether God, the devil, or other incorporeal substances).48 Budde likewise entertains the idea that there can be a direct effect of another spiritual substance on our mental life.49 However, the claim that supernatural interventions in our own mind are possible poses the problem of how to verify that a particular experience is in fact caused by God rather than by another spiritual substance, a demon or even the Devil himself. This problem is especially urgent for Syrbius, because he also maintains that there are ‘relative experiences,’ that is, experiences that include an awareness of their causes. But in the case of inner experience, such ascriptions can be fallible: purportedly divine inspirations may be hallucinations or suggestions of evil spirits. Syrbius only mentions this problem and leaves its resolution to theologians.50 For Budde, the direct experience of interventions caused by God or another spiritual substance is only one class of what he calls ‘theological experience,’ namely, ‘the extraordinary’ spiritual experience that depends on direct interaction with the respective substance, e.g., the Holy Spirit. Other varieties are ‘ordinary’ spiritual experience, based on Scripture and the sacraments, and ‘ecclesiastical experience,’ which concerns the fate of the church.51 Unlike Syrbius and Budde, Crusius nowhere discusses inner experience in relation to theological matters. He does, however, acknowledge the possibility of inner experience in his logic (Weg § 41). Moreover, this possibility plays an important role in his Entwurf der nothwendigen Vernunft-Wahrheiten, but only in relation to what we can perceive of our own thoughts. It is worth noting that in this context Crusius does not clearly distinguish experience and sensation but uses both terms interchangeably.

90 Stefan Heßbrüggen-Walter We should also remind ourselves that in one version of his textbooks Crusius’s teacher Rüdiger had qualifed inner experience as the foundation of all erudition.52 The primary function of inner sensation and experience in Crusius’s ‘meta-philosophy’ is to contribute to the justifcation of philosophical insights. According to Crusius, all knowledge must be grounded in experience. In the case of philosophical knowledge, it is inner experience that provides such a foundation. Crusius explains in general terms how experience can ground knowledge at the beginning of the Entwurf: From this it becomes clear how and why ultimately sensation is always the mark of reality in our understanding. For sensation is just that state of our understanding in which we are forced to think something immediately as existing, without having to cognize it frst through inferences.53 (Entwurf § 16) This general characteristic of sensation applies also to inner sensation and experience: if we observe an inescapable compulsion to connect certain concepts in a proposition, then this compulsion is in itself a justifcation of the resulting proposition. This is a recurring pattern in Crusius’s philosophy.54 Thus, he claims that inner experience shows us that, as soon as we think something as existing, we are forced to think that it exists in a place.55 Inner experience also justifes causal axioms, according to which it is impossible to think the subject without thinking the predicate: A causal axiom refers to a kind of sentence in which the predicate is an immediate consequence of the subject and in which one senses internally that the subject cannot be thought, without conceding to it this immediate consequence. (Entwurf § 72) Similarly, Crusius claims that inner sensation forces us to acknowledge that the intellect and the will are distinct faculties, a fundamental tenet of Thomasian psychology (Entwurf § 429). It may even be argued that inner sensation is for Crusius the foundation of all consciousness, since he calls it “the power of consciousness” and claims that “we sense through it […] that we think” (Weg § 65).56

4 Conclusion As we have seen, Thomasians defended two different accounts of experience, considering it either to be based on sensations (Rüdiger, Syrbius, Budde) or to be a type of proposition (Hofmann, Crusius). To this, Crusius added the crucial distinction between acts of experience and their

Crusius on Experience 91 content. Moreover, with regard to the relationship between experience and reasoning, Crusius tried to fnd a middle ground: he did not deny that we may be able to have what he calls ‘mixed experiences,’ or experiences that rest on inferences, but he insisted that in scholarly discourse such inferences must be made explicit. Both Hofmann and Crusius believed that experiences are ‘immediate propositions’ that are not true as the result of an inference. Hofmann divides immediate propositions according to whether or not the predicate is contained in the defnition or essence of the subject term. If this is the case, the resulting proposition is an ‘immediate essential proposition.’ The corresponding class of propositions in Crusius’s account is called ‘axiom.’ In the case of axioms, we are necessitated to think the predicate when thinking the subject term: we cannot help to think about a proximate effect when we think of a cause. If we can think the subject term without the predicate, the resulting proposition is an ‘immediate existential proposition’ or ‘experiential proposition’ (Erfahrungs-Saz). However, the claim that a particular proposition is in fact an axiom is itself an experiential proposition: we must observe the subjective necessity to think both terms together in inner sensation or experience. This is also true for axioms in philosophy: we need inner experience and sensation in order to justify philosophical principles. If we observe that we are necessitated to think a principle, the principle is thereby true. As far as his account of experience is concerned, Crusius may have been a less innovative thinker than his most enthusiastic readers have argued. At the same time, he integrated various aspects of the concept into a coherent theory. This alone is no small achievement and should be reason enough to investigate his infuence on later theories of experience in German eighteenth-century philosophy in more detail.

Notes 1 2 3 4 5 6 7 8 9 10

See Holzhey and Zurbuchen (2001: 1171). See Schneiders (2014: 63–64). See Rüping (2001: 1205). See Albrecht (2014: 207). See Schneiders (2014: 64–65). See Albrecht (2014: 211). See Beck (1969: 394) and Albrecht (2014: 210). See Leinsle (2014b: 86–87). See Theis (2014: 97). See Kuehn (1987: 254), who refers to Zart (1881: 40–72). However, Zart is only concerned with the general epistemology of the Thomasians and ignores their detailed analyses of the concept of experience and its uses in ‘practical logic.’ 11 The disagreement about whether experience should be understood as primarily perceptual or primarily propositional is an echo of the early modern scholastic debate between Scotists and Thomists. Scotists opted for an

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14 15 16 17 18 19 20 21

22 23

24

25 26

27

Stefan Heßbrüggen-Walter understanding of experience as the repeated perception of an object, while Thomists held that it must be understood propositionally. On this, see Heßbrüggen-Walter (2013: 136–39). See Holzhey (1970: 101) and Heimsoeth (1956: 129). See Clauberg (1691: 1214). Clauberg refers the reader for a more comprehensive analysis to De Raey’s Clavis philosophiae naturalis AristotelicoCartesiana. According to De Raey, experience provides the ‘material’ (materia) of natural philosophy but does not lead to knowledge of causes, basic concepts, or frst principles. It rather serves to illustrate or confrm these concepts (41f). On De Raey, see Nyden (2013: 235). Cyprian (1693: ch. 4, § 1). Cyprian (1693: ch. 4, § 2). For an overview of Thomasius’s stance on experience and experiment, see Widmaier (1989: 109–13) and Vollhardt (2012: 8–10). Thomasius (1691: ch. 10, § 65). All translations are mine. Thomasius (1691: ch. 12, §§ 36–37). Rüdiger, SVF, III, ch. 1, § 8. Rüdiger, SVF, III, ch. 1, § 16. Rüdiger, SVF, III, ch. 1, § 7. Rüdiger does not provide an exact citation, but he apparently refers to Locke, Essay, IV.xv.4–5. Scholz (2015: 156) mentions only Thomasius and Gundling as early readers of Locke. Rüdiger must be added to this list. Rüdiger, SVF, III, ch. 1, § 8. Rüdiger distinguishes theoretical and practical probability, arguing that the former is concerned with wisdom and the latter with prudence. On his account, theoretical probability is concerned with what is not immediately obvious to us in perception and therefore requires the aid of memory and experience. If something is not completely obvious to us in demonstration, we base the probable statement on the faculty to judge (iudicium). See Rüdiger, SVF, III, ch. 1, § 15. Syrbius, IP, I, ch. 9, § 3. Syrbius identifes experience with observation and contrasts both with experiments. Both universal and particular truths are said to originate in experience (I, ch. 9, § 8); cf. Syrbius (1726: I, ch. 5, § 39). Experience is useful because it helps to investigate unknown facts, serves to communicate our fndings to others, and provides the foundation of proofs (Syrbius, IP, I, ch. 9, § 8). Rüdiger revised his 1709 view and came to identify experience and sensation. Nevertheless, experience is said to function as a touchstone (lapis lydius) of knowledge; see Rüdiger (1722: I, ch. 12, § 2). This formulation can also be found in the revised edition of Wolff’s German Metaphysics (GM § 727), where he claims that experience of ourselves must serve as a touchstone for rational psychology. In the 1720 edition this passage is not yet present. In 1729, Rüdiger presumes that experience is a multitude of sensations only in outer sense. Perceptions in inner sense lead to a different state, namely, erudition. See Rüdiger (1729: § 41). Scholz (2015: 152) does not take into account this difference between Thomasians and Wolff. See Wolff, LL § 513: “Truth is the determinability of the predicate through the notion of the subject.” In universal propositions such as ‘All bodies are extended’ this determinability is obvious, because the predicate is contained in the defnition of the subject. See Hofmann, Gedancken § 23: “This means that a proposition is true when it can be proven a priori from the idea of the subject why the predicate agrees with the subject.”

Crusius on Experience 93 28 See Hofmann, Gedancken § 23: “If I contemplate a proposition with a predicate that cannot be proven from the [notion of the] subject, the proposition is not true.” 29 See Hofmann, Gedancken § 23: “Thus it is, for example, not true that some lightning can consume animal bodies [while] another does not; for it is not true under this condition that we cannot demonstrate the difference of the same lightning and the nature of infammable bodies which are the cause of this effect.” 30 See Hofmann, Gedancken § 23: “If you say that it could be understood over time by those who do not understand it now, because it may be possible that we identify the missing determinations in which the reason of the predicate may be hidden, I say: It could also be the case that the predicate cannot be proven a priori from this subject at all and that hence such determinations are completely impossible, because the proposition may be totally false and impossible. Therefore it remains undetermined whether or not such experiences are truths.” 31 See Hofmann, VL, Vorbericht, § 14: “If the truth of a proposition can be clarifed with regard to all of its parts, […] this happens either through inferences or through immediate experience. In the former case it is called an inferred proposition; […] in the latter it is either an immediate existential proposition that affrms or denies a mere existence that is perceived or not perceived through immediate experience […] or it is an immediate essential proposition in which the predicate is immediately known from the nature of the subject, because it is immediately connected to the idea of the subject without mediation through another idea.” 32 Hofmann’s example of a ‘refective experience’ is the proposition ‘some misers take many risks.’ 33 Another example is the axiom of causality: “An axiom is […] an axiom of causality, if with regard to a suffcient cause one asserts the proximate effect without which it cannot be thought” (Crusius, Weg § 42). We will see below that, for Crusius, the axiomatic character of a given proposition is itself known through inner sensation. 34 See Crusius, Weg § 41: “Moreover, it [i.e., experience] is either a common experience when the subject and the predicate themselves are sensible, not just the connection between subject and predicate. Or it is a refecting experience, when only the connection between subject and predicate is sensed while the subject and the predicate themselves are something abstract, e.g. when, having one idea, we remember those we perceived simultaneously.” 35 See Crusius, Weg § 461: “The word ‘experience’ is partly used for a certain kind of propositions, partly for the act or the acquisition (Einziehung) of experience by which we get to the former. We must look at each [sc. aspect] separately.” Holzhey (1970: 98) regards this as an important clarifcation of the concept. 36 Thomasius (1699: ch. 1, § 9). 37 See Cataldi Madonna (2018: 107–8). 38 See Thomasius (1699: ch. 1, § 14): “No sensibility or experience can be used in order to demonstrate the causes of movement and effects of natural things; partly, because individual things prove nothing universal, the proof is taken from individual things to which the general principles and doctrines must be applied; partly, because scholars who are completely opposed to each other with regard to the examination of the causes of natural things, still agree with regard to most experiments and do not argue over them. And they cannot, because no prudent man is prone to deny those things about which he is assured by the senses.”

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39 See Wolff, GL, ch. 4, § 4. 40 See Syrbius, IP, I, ch. 9, § 4, but also Müller (1733: ch. 5, § 21). Müller was another student of Rüdiger. Syrbius is committed to this, because he believes that experience can also ground universal truths. See note 24 above. 41 See Rüdiger (1716: I, ch. 1, § 83). 42 See Rüdiger (1717: 58): “Everything that is neither below nor above erudition can be defned. Infnite things are above erudition, sensual and common things are below it.” 43 See Rüdiger (1717: 52–53). 44 See Hofmann (1737: I, ch. 12, § 688): “For the same reason it follows that those propositions that assert a causal nexus or another essential relation cannot be mere experiential propositions. For if someone predicates a causal nexus or another essential relation with regard to two things, he does not merely claim that two things are related to each other with regard to existence. But [he also claims] that one thing would not exist if the other one did not exist. Hence he not only affrms, but also negates something. But he cannot sense this negating proposition, but must necessarily infer it.” 45 Holzhey (1970: 99) states that the distinction between pure and mixed experiences cannot be found either in Wolff or in Locke. Fugate (2014: 140) claims the same with regard to Wolff. Both are correct, insofar as Wolff does not use the same terminology. But the distinction itself is Wolff’s: as was seen above, experiences that are non-obvious must be explicated, whereas obvious ones do not require an explication. Fugate (2014: 138) considers this statement to claim that mixed experiences must involve “higher and more general material principles.” Crusius’s formulation certainly does not preclude this possibility but does not demand such a link to higher principles either. The only thing that distinguishes pure from mixed experiences is that the former do not contain implicit inferences. Whether or not the mixed experience ‘the sun causes the day’ is in need of such higher principles is an open question. 46 In 1715, the Pietist theologian Gottfried Arnold published a book with the title Theologia experimentalis. On its background in seventeenth- and eighteenth-century Lutheran theology, see Keding (2001: 19–32). On Thomasius’s relation to Pietism, see Ahnert (2005). 47 See Lange (1718: III, ch. 3, §§ 1, 4). 48 See Syrbius, IP, I, ch. 9, § 3. 49 See Budde (1732: I, ch. 4 § 2, 196). 50 See Syrbius, IP, I, ch. 9, § 14. 51 Budde (1732: I, ch. 4, § 2). 52 See note 24 above. 53 On this, see Heimsoeth (1956: 161). 54 Heimsoeth (1956: 162–63) objects that Crusius illegitimately confounds two different forms of what he calls ‘evidence,’ namely experiential evidence and evidence on the rational level. This confusion increases the risk to introduce erroneous principles. A Kantian might also object that the mere necessity to think of states as successive is no suffcient indication of a causal relation. Still, Crusius’s view had its followers. Tetens, for instance, claims: “We have no other idea of objective causality than this subjective causality in the understanding” (PV 327). On the relationship between the German tradition and Hume in this regard, see Kuehn (1989: 371). 55 See Crusius, Entwurf § 50: “Now inner experience will teach everyone that it is impossible for him to think something as existing without thinking that it is somewhere; to say that it exists, and that it still is nowhere.” For a

Crusius on Experience 95 critical discussion of this point, see Heimsoeth (1956: 180). Kant criticizes this axiom in his 1770 dissertation. On this, see Heßbrüggen-Walter (2014: 26, 38). 56 On this, see Indregard (2018: 177).

Bibliography Primary Sources Arnold, Gottfried (1715), Theologia experimentalis, das ist: Geistliche Erfahrungs-Lehre oder Erkäntniß und Erfahrung von denen vornehmsten Stücken des lebendigen Christenthums, Frankfurt: Zunner & Jung. Budde, Johann Friedrich (1706), Elementa philosophiae instrumentalis, Halle: Orphanotropheum. ——— (1732), Observationes in elementa philosophiae instrumentalis, Halle: Orphanotropheum. Clauberg, Johann (1691), Opera omnia philosophica, Amsterdam: Ianssonio-Waesbergius. Crusius, Christian August (1745), Entwurf der nothwendigen VernunftWahrheiten, Leipzig: Gleditsch (Entwurf). ——— (1747), Weg zur Gewißheit und Zuverläßigkeit der menschlichen Erkenntnis, Leipzig: Gleditsch (Weg). ——— (1774), Anleitung über natürliche Begebenheiten ordentlich und vorsichtig nachzudenken, 2nd ed., Leipzig: Gleditsch. Cyprian, Johann (1693), De mediis investigandi veritates rerum naturalium, Leipzig: Richter. De Raey, Johannes (1654), Clavis philosophiae naturalis, seu, Introductio ad naturae contemplationem, Aristotelico-Cartesiana, Lyon: Elsevier. Hofmann, Adolph Friedrich (1729), Gedancken über Hn. Christian Wolffens… Logic oder sogenannte Philosophiam rationalem, Leipzig: Heinsius (Gedancken). ——— (1737), Vernunftlehre, Leipzig: Hofmann (VL). Lange, Joachim (1718), Medicina mentis, 4th edn., Halle: Orphanotropheum. Locke, John (1975), An Essay Concerning Human Understanding, ed. by P.H. Nidditch, Oxford: Clarendon Press (Essay). Müller, August Friedrich (1733), Einleitung in die philosophischen Wissenschaften, vol. 1, 2nd edn., Leipzig: Breitkopf. Rüdiger, Andreas (1706), Philosophia synthetica, Halle: apud autorem. ——— (1709), De sensu veri et falsi, Halle: Gruner (SVF). ——— (1716), Physica divina, Frankfurt: Andrea. ——— (1717), Institutiones eruditionis, seu philosophia synthetica, Frankfurt: Gleditsch & Weidmann. ——— (1722), De sensu veri et falsi, 2nd edn., Leipzig: Coernerus. ——— (1729), Philosophia pragmatica, Leipzig: Heinsius. Syrbius, Johann Jacob (1717), Institutiones philosophiae rationalis eclecticae, Jena: Bielcke (IP). ——— (1726), Institutiones philosophiae primae novae et eclecticae, 2nd edn., Jena: Meyer.

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Tetens, Johann Nicolaus (1777), Philosophische Versuche über die menschliche Natur und ihre Entwickelung, Leipzig: Weidmann und Reich (PV). Thomasius, Christian (1691), Einleitung zu der Vernunfft-Lehre, Halle: Salfeld. ——— (1699), Versuch vom Wesen des Geistes, Halle: Salfeld. Wolff, Christian (1713), Vernünfftige Gedancken von den Kräfften des menschlichen Verstandes, Halle: Renger (GL). ——— (1720), Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt, Halle: Renger; 3rd edn. 1725 (GM). ——— (1724), Anmerckungen über die vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt, Frankfurt: Andreä. ——— (1728), Philosophia rationalis sive Logica, Frankfurt: Renger (LL).

Secondary Sources Ahnert, Thomas (2005), ‘Enthusiasm and Enlightenment: Faith and Philosophy in the Thought of Christian Thomasius’, Modern Intellectual History, 2/2, 153–77. Albrecht, Michael (2014), ‘Christian August Crusius’, in H. Holzhey and V. Mudroch (eds.), Die Philosophie des 18. Jahrhunderts, vol. 5, Basel: Schwabe, 206–12. Beck, Lewis White (1969), Early German Philosophy: Kant and His Predecessors, Cambridge, MA: The Belknap Press of Harvard University Press. Cataldi Madonna, Luigi (2018), ‘Logik’, in R. Theis and A. Aichele (eds.), Handbuch Christian Wolff, Wiesbaden: Springer, 93–114. Fugate, Courtney (2014), The Teleology of Reason: A Study of the Structure of Kant’s Critical Philosophy, Berlin/Boston: De Gruyter. Heimsoeth, Heinz (1956), ‘Metaphysik und Kritik bei Chr. A. Crusius: Ein Beitrag zur ontologischen Vorgeschichte der Kritik der reinen Vernunft im 18. Jahrhundert’, in H. Heimsoeth, Studien zur Philosophie Immanuel Kants: Metaphysische Ursprünge und Ontologische Grundlagen, Köln: Kölner Universitätsverlag, 125–88. Heßbrüggen-Walter, Stefan (2013), ‘Scientifc Knowledge and the Metaphysics of Experience: the Debate in Early Modern Aristotelianism’, Studia Neoaristotelica, 10/2, 134–56. ——— (2014), ‘Putting Our Soul in Place’, Kant Yearbook, 6/1, 23–42. Holzhey, Helmut (1970), Kants Erfahrungsbegriff: Quellengeschichtliche und bedeutungsanalytische Untersuchungen, Basel: Schwabe. ——— and Zurbuchen, Simone (2001), ‘Christian Thomasius’, in H. Holzhey and V. Mudroch (eds.), Die Philosophie des 17. Jahrhunderts, vol. 4, Basel: Schwabe, 1165–202. Indregard, Jonas Jervell (2018), ‘Consciousness as Inner Sensation: Crusius and Kant’, Ergo, 5/7, http://dx.doi.org/10.3998/ergo.12405314.0005.007, last visit: 2019-03-12. Keding, Volker (2001), Theologia experimentalis: die Erfahrungstheologie beim späten Gottfried Arnold, Münster: Lit-Verlag. Kuehn, Manfred (1987), Scottish Common Sense in Germany, 1768–1800: A Contribution to the History of Critical Philosophy, Kingston and Montreal: McGill-Queen’s University Press.

Crusius on Experience 97 ——— (1989), ‘Hume and Tetens’, Hume Studies, 15/2, 365–76. ——— (1995), ‘The German Aufklärung and British Philosophy’, in S. Brown (ed.), British Empiricism and the Enlightenment, Boca Raton: Routledge, 309–31. Leinsle, Ulrich G. (2014a), ‘Johann Jakob Syrbius’, in H. Holzhey and V. Mudroch (eds.), Die Philosophie des 18. Jahrhunderts, vol. 5, Basel: Schwabe, 76–79. ——— (2014b), ‘Andreas Rüdiger’, in H. Holzhey and V. Mudroch (eds.), Die Philosophie des 18. Jahrhunderts, vol. 5, Basel: Schwabe, 83–88. Nyden, Tammy (2013), ‘De Volder’s Cartesian Physics and Experimental Pedagogy’, in M. Dobre and T. Nyden (eds.), Cartesian Empiricisms, Dordrecht: Springer, 227–50. Rüping, Hinrich (2001), ‘Budde und die Naturrechtslehre der ThomasiusSchule’, in Helmut Holzhey, Vilem Mudroch (eds.), Die Philosophie des 17. Jahrhunderts, vol. 4, Basel: Schwabe, 1203–15. Schneiders, Werner (2014), ‘Der Thomasianismus—Einleitung’, in H. Holzhey and V. Mudroch (eds.), Die Philosophie des 18. Jahrhunderts, vol. 5, Basel: Schwabe, 63–68. Scholz, Oliver (2015), ‘Erfahrung’, in H. Thoma (ed.), Handbuch Europäische Aufklärung: Begriffe—Konzepte—Wirkung, Stuttgart/Weimar: Metzler, 150–60. Theis, Robert (2014), ‘Adolph Friedrich Hoffmann’, in H. Holzhey and V. Mudroch (eds.), Die Philosophie des 18. Jahrhunderts, vol. 5, Basel: Schwabe, 93–98. Vollhardt, Friedrich (2012), ‘“Die Fünsterniß ist nunmehro vorbey”. Begründung und Selbstverständnis der Aufklärung im Werk von Christian Thomasius’, in F. Vollhardt (ed.), Christian Thomasius (1655–1728): Neue Forschungen im Kontext der Frühaufklärung, Berlin/New York: De Gruyter, 3–13. Widmaier, Rita (1989), ‘Alter und neuer Empirismus. Zur Erfahrungslehre von Locke und Thomasius’, in W. Schneiders (ed.), Christian Thomasius: 1655–1728; Interpretationen zu Werk und Wirkung, Hamburg: Meiner, 95–114. Zart, Gustav (1881), Einfuss der englischen Philosophie seit Bacon auf die deutsche Philosophie des 18. Jahrhunderts, Berlin: Dümmlers Verlagsbuchhandlung.

5

Experience and Inner Sense Feder–Lossius–Kant Udo Thiel

Is there inner as well as outer experience, and if so, what exactly is inner experience, and what is its source? Is there something analogous to the outer senses that provides us with material for ‘inner experience’? Is there such a thing, then, as an inner sense? If so, what exactly is its relationship to the outer senses, to empirical cognition, and indeed to cognition as such? While most eighteenth-century philosophers seem to have taken the existence of an inner sense for granted, there were various views and arguments concerning its nature and its role in the cognition of one’s own self and cognition in general.1 Our focus in this chapter is on a certain development of thought on these questions, concentrating on three of the most important Enlightenment thinkers in this regard, namely Johann Georg Heinrich Feder, Johann Christian Lossius, and Immanuel Kant.

1 Inner Sense and Inner Experience The view that we are able to experience not only external objects or their properties but also our own minds or mental states goes back as far as antiquity. As regards modern philosophy, however, John Locke provided the starting point of subsequent discussions on this theme. At the outset of Book II of his Essay Concerning Human Understanding, Locke famously argues that “all the materials of Reason and Knowledge” are derived “From Experience” (Essay II.i.2). Locke’s technical term for these ‘materials’ or mental contents in general is ‘ideas.’ He hastens to add, signifcantly, that experience is twofold: Our Observation employ’d either about external, sensible Objects; or about the internal Operations of our Minds, perceived and refected on by our selves, is that, which supplies our Understandings with all the materials of thinking. These two are the Fountains of Knowledge, from whence all the Ideas we have, or can naturally have, do spring. (Essay II.i.2) Our senses, Locke writes, are “conversant about particular sensible objects,” and they convey to the mind ideas of “sensible qualities,” of

Experience and Inner Sense 99 cold, soft, hard, yellow, white, and so on. Locke terms this source of ideas ‘sensation.’ The other experiential source of ideas he calls ‘internal sense’ or ‘refection.’ As he puts it: This Source of Ideas, every man has wholly in himself; and though it be not Sense, as having nothing to do with external Objects, yet it is very like it, and might properly enough be called internal Sense. But as I call the other Sensation, so I call this Refection, the Ideas it affords being such only, as the Mind gets by refecting on its own Operations within it self. (Essay II.i.4) Locke notes that the term ‘operations’ here is to be understood in a very broad sense. It refers not only to “Actions of the Mind about its Ideas” but also to “some sort of Passions arising sometimes from them, such as is the satisfaction or uneasiness arising from any thought” (Essay II.i.4). According to Locke, outer sense has a certain temporal priority over inner sense or refection. We begin to think, or “to have any Ideas,” he writes, when we frst have “any Sensation” (Essay II.i.23). Subsequently, “the Mind comes to refect on its own Operations, about the Ideas got by Sensation, and thereby stores itself with a new set of Ideas, which I call Ideas of Refection” (Essay II.i.24). Accordingly, Locke says “’tis pretty late,” before we get “Ideas of the Operations” of our own minds, “and some have not any very clear, or perfect Ideas of the greatest part of them all their lives” (Essay II.i.8). Similarly, even Immanuel Kant held that, at least as far as the genetic issue is concerned, outer sense is prior to inner sense in that it provides the material for all representations. As he puts it in the Critique of Pure Reason, it is “the existence of things outside us […] from which we […] get the whole matter for our cognitions, even for our inner sense” (Bxxxix). Therefore, he holds that “outer experience is really immediate and that only by means of it inner experience is possible” (B276–77). In the passages cited above, Locke seems to conceive of sensation and refection as outer and inner experience, respectively. He does not claim, however, that outer and inner sense by themselves provide us with empirical cognition or beliefs about the world or the mind. They merely provide us with ideas, or the “materials of thinking,” about these matters. Knowledge, Locke insists, “all consists in Propositions” (Essay, II.xxxiii.19). Thus, Locke assumes an important distinction between, on the one hand, experience as a “source of ideas” and, on the other hand, experience as empirical cognition about the self and the world. German Enlightenment thinkers likewise appealed to this distinction, be it implicitly or explicitly. Kant in particular emphasized that experience, be it inner or outer, is propositional and involves the use of concepts. Thus, he notes in the Anthropology that inner and outer sense do not themselves constitute experience because “experience is empirical cognition, but cognition (since it rests on judgments) requires refection

100 Udo Thiel (refexio), and consequently […] concepts and thought in general (as distinct from intuition).”2 Inner sense, then, is not inner experience (empirical cognition) of oneself because it merely “contains a manifold of determinations that make an inner experience possible.”3 Therefore, we need to distinguish between the “perception of the inner sense and the empirical cognition of oneself (inner experience) grounded thereon” (Anthr, 7: 397). It is plain, however, that both Locke and Kant (as well as other Enlightenment thinkers) believe that inner sense is the basis of inner experience or cognition insofar as it provides material for empirical beliefs about our own minds. As Kant puts it in the passage quoted above, inner sense is that which makes “inner experience possible.” Other Enlightenment thinkers believed, moreover, that inner sense is a source of cognition not only of ourselves as individuals but also of the nature of the human mind in general. Some, including the pre-critical Kant, as we shall see, were tempted to ascribe to inner sense an even more fundamental role, namely, that of grounding experience and cognition in general.

2 Feder on Inner Sense and the Fundamental Faculty of Selbstgefühl While Locke was not the frst in early modern British philosophy to draw a distinction between inner and outer sense, he was the frst to assign it a distinctive systematic role in his account of the origins, extent, and nature of human knowledge. His distinction became the main reference point for discussions of experience and experiential beliefs about the world and the self in eighteenth-century Germany. Perhaps the most infuential account of inner sense in German eighteenth-century thought is the one provided by Johann Georg Heinrich Feder. Feder, a well-known and highly respected philosopher at the time, had become a professor of philosophy at the University of Göttingen in 1768. The fact that he devoted his inaugural lecture at Göttingen, De sensu interno, to the notion of inner sense indicates the signifcance of this notion to his thought.4 In 1769 Feder published a very successful textbook, titled Logik und Metaphysik, that became widely used and extremely infuential: its seventh edition was published in 1790. Although strongly infuenced by British philosophy and by Lockean thought in particular, Feder was not a straightforward empiricist. Instead of following one particular tradition, he rather attempted to develop his own philosophy by way of critically examining other systems and retaining what is valuable from each. In the last analysis, Feder sought a balance between empiricism and a traditional Wolffan approach. Both before and after the publication of the Critique of Pure Reason, Feder wrote favorably about some of Kant’s pre-critical writings, especially Dreams of a Spirit-Seer and Observations on the Beautiful and

Experience and Inner Sense 101 the Sublime. However, when Feder in the 1780s became involved in the debate about Kant’s transcendental philosophy, he took sides with the anti-Kantians. Most famously, he edited and published Christian Garve’s critical review (1782) of the Critique of Pure Reason, which drew a ferce and devastating response from Kant. Like other philosophers at the time, Feder does not clearly distinguish terminologically between inner and outer sense on the one hand and inner and outer experience on the other hand. He does, however, distinguish between sensations (Empfndungen) and judgments of sensation (Empfndungsurteile).5 But what is inner sense, according to Feder? To begin with, he describes inner sense negatively through its opposition (frst) to the outer senses, and (second) through its opposition to the understanding: inner sense does not relate, at least not directly, to external objects, and it is not a capacity of thought or refexion. Feder sums up these frst two aspects of inner sense in the following passage: One can learn what is to be understood by inner sense and inner sensations partly from the fact that this way of cognizing is opposed both to outer sensation and to the so-called higher cognition, which is based on reason and general concepts, and the distinctness that is characteristic of it, and partly from the special kinds of inner sensation and the capacities of inner sense that relate to them.6 Rephrasing these points in a positive way, Feder considers inner sense, frst, to be concerned only with the mind and its states and, second, to be characterized by immediacy. He states that the “general explanation of inner sense” consists in accounting for it as “the capacity of the soul” to become “immediately aware of its states and the relations of its ideas.”7 In a later edition of Logik und Metaphysik, Feder defnes inner sense as “the faculty of the soul indistinctly to cognize its state and the relations of its ideas from the impression that the latter jointly produce.”8 The ‘indistinct’ nature of inner sense is due, obviously, to the fact that the latter’s relating to mental states is sensible and non-conceptual. Feder further characterizes inner sense by distinguishing it from memory. Contrary to the latter, inner sense is exclusively concerned with the present or immediate past. It is, he writes, “the faculty of perceiving that which occurs most intimately, such as it is represented at present” (GLM 18–19, my emphasis).9 In sum, then, Feder considers inner sense (1) to pertain to mental events, states, or processes alone; (2) to concern one’s own mind only, not other minds, at least not directly; (3) to relate to mental states that are either current or belong to one’s immediate past; and (4) to be characterized by immediacy. As was seen above, Feder mentions “special kinds of inner sensation” (besondern Arten der innern Empfndung) and several “capacities of inner sense” (Fähigkeiten des inner Sinns).10 This suggests, clearly, that

102 Udo Thiel he regards inner sense as a sum total of several distinct mental capacities. Indeed, Feder distinguishes four types of inner sensation and their corresponding capacities. These are “the feeling of self [Selbstgefühl], the feeling of the true, the feeling of the beautiful, and the feeling of the morally good.”11 The true, the beautiful, and the morally good are, of course, traditional metaphysical notions that were used by Renaissance Platonists in their attempts to explain and adapt Plato’s thought. In the seventeenth and early eighteenth centuries, the Cambridge Platonists took up these ideas.12 Feder departs from this tradition, however, by ‘internalizing’ the metaphysical ideas of the true, the beautiful, and the morally good: they become objects of three distinct kinds of feeling, which together characterize inner sense. These feelings share common ground in that they are, or seem to be, produced by “representations that develop from within” (GLM 19).13 They differ from one another with respect to their objects. Thus, the feeling of the true, Feder writes, is the “capacity to perceive truth or falsehood immediately, without reasoning, and therefore often merely indistinctly.”14 The feeling of the beautiful is the capacity to notice without refection the “beauty (that is present in our representations).”15 Finally, the feeling of the morally good is the capacity “to notice immediately […] what is right or wrong.”16 Apart from a lengthy (and critical) treatise on the notion of a moral sense, Feder does not elaborate on these three feelings. The kind of inner sense that Feder considers to be the most important and fundamental, however, is the feeling of self (Selbstgefühl). That Feder does assign to the feeling of self a special role is indicated even by the passage quoted above, where Selbstgefühl is clearly set apart from the triad of the true, the beautiful, and the good. But what kind of feeling or inner sensation is Selbstgefühl? Feder seems to have taken up the notion from Johann Bernhard Basedow’s Philalethie of 1764, a work to which he appeals explicitly in his De sensu interno (DSI 25).17 Basedow writes: We have looked at two of our ways of thinking or subsidiary powers of our understanding, namely outer sense, which shall retain the name sense in my presentation, and inner sense, which I shall call feeling of self (Selbstgefühl). (Phil § 10) Basedow introduces the term ‘Selbstgefühl’ in order to replace that of ‘inner sense.’ While, for him, the two terms are synonymous, he argues that the term ‘inner sense’ is misleading because it conveys the idea of an analogy between inner and outer perception. He holds that outer sense and Selbstgefühl differ much more from each other than do the various types of outer sense, say, hearing and vision (Phil § 10). Although Feder takes up the notion of Selbstgefühl from Basedow, he does not, as we saw, simply equate Selbstgefühl with inner sense.18

Experience and Inner Sense 103 Rather, for Feder, Selbstgefühl is a special kind of inner sense. Moreover, Feder considers Selbstgefühl to relate to more than one kind of object. It relates not only to “one’s inner states and properties” but also to the existence of one’s own self as the subject of those states and properties (DSI 25).19 On Feder’s account, then, the feeling of self involves an immediate or ‘pre-refective’ awareness of one’s own existence. He seems to hold that each sensation brings about the feeling or the consciousness that it is me who has this sensation. By dint of this Selbstgefühl, he writes, “every sensation or representation that we receive contains at the same time the consciousness that we have this sensation or representation.”20 According to this passage at least, it seems that Selbstgefühl, as an awareness of one’s own subject of thought, is dependent on Selbstgefühl as an immediate relating to one’s “sensations, representations, thoughts, desires” (GLM 9). Clearly, such an awareness of one’s own existence and states is needed in order to have the particular feelings of the true, the morally good, and the beautiful mentioned above. Selbstgefühl is said to differ from the other three kinds of inner sense in that it relates to “all inner states of activity, receptivity, of thinking, willing and feeling” (GLM 19). This relating, as well as the feeling of one’s own existence, is needed in order to have the particular feelings of the true, the beautiful, and the morally good. Clearly, then, Feder’s view that inner sense comprises several mental capacities differs from Locke’s view of refection or internal sense as a mere source of ideas. Rather, Feder considers Selbstgefühl to play an essential role in empirical cognition or experience in general. In order to clarify this, we need to consider what he calls “the distinct thought of the self.”21

3 Feder on Selbstgefühl and “the distinct thought of the self” Following Basedow, Feder next distinguishes between the immediate relating to the self via Selbstgefühl on the one hand and a conceptually mediated relating to the self on the other hand. 22 As was noted above, he distinguishes inner sense (and thereby Selbstgefühl) from the intellect or the understanding. The latter includes the capacity to refect, or, as he has it, the capacity to distinguish and compare representations.23 Feder emphasizes the difference between “that which can be called the actual feeling or intuition of the present in relation to an assumed object and that which is being added through other acts of the faculty of representing” (GLM 19). More specifcally, he distinguishes between Selbstgefühl and a type of self-relation that involves conceptuality and mental acts of abstraction. 24 According to Feder, “the distinct thought of the self” or “the notion” that the self has of itself is the result of such mental activity. Selbstgefühl, for Feder, is presupposed by this mental activity

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and constitutes the ultimate basis of the distinct thought of the self. Feder writes: A large part of our concepts stems from the sensations that we have through inner sense. From this source the soul draws the notion of itself, the distinct thought of the self and of its properties. 25 Thus, Selbstgefühl, for Feder, is the ultimate source of a conceptually mediated representation of the self. Understood as the consciousness of one’s inner states, it is the reason why we are able to ascribe a soul to ourselves at all: “We ascribe a soul to ourselves because we are conscious that we have sensations, representations, thoughts, desires” (GLM 9). Since, moreover, Selbstgefühl and refection make us acquainted with basic features of the soul, they also provide us with the means to develop a general doctrine of the soul: It is certain that we would not know anything of thinking substances and their properties if Selbstgefühl and refection on the latter did not acquaint us with something about the nature of our soul. Herein, then, lies the origin of all our pneumatological concepts. 26 Here and elsewhere, Feder refers to the subject of our representations simply as ‘the soul.’ What is this soul, however? In places Feder suggests that it is just the indeterminate “subject of our consciousness”27 or that part of us “in which we are conscious of the present and the past, of pleasure and pain” (GLM 21). Obviously, this tells us nothing about the nature of the subject called ‘the soul.’ According to Feder, we cannot know with absolute certainty what the nature of the self is. However, he does consider it highly probable that the subject of consciousness, or the soul, is (1) a substance and (2) an immaterial substance. Even though these beliefs are not the content of Selbstgefühl itself, Feder claims that they originate in the latter. As regards (1), Feder holds that the understanding forces us to go beyond the “concepts of properties, states, and relations” and add the concept of substance. 28 He makes use of an old argument, also present in Locke, according to which properties and states require a something to which these properties and states belong. 29 Of course, one could argue against Feder that even if it is true that conceiving of properties and states requires that we posit a subject, it does not follow that the latter must be a substance. Further, as regards (2), even if we were to agree with Feder that the subject of states and properties must be a substance, the nature or essence of this substance would still be an open question. In this regard, however, Feder maintains that “Locke’s well known skepticism on this matter really goes too far.”30 He claims that although we may not be

Experience and Inner Sense 105 able to know the inner nature of the soul, Selbstgefühl itself points to its most fundamental feature, namely, its simplicity and immateriality. 31 Feder concedes that there is room for doubt about this matter and that certainty cannot be obtained in this area.32 Yet he insists that it is “more probable” that the soul is simple than that it is not simple. According to Feder, then, in spite of all remaining doubts, the “distinct thought of the self” that is developed from our feeling of self is the thought of a subject that is simple and immaterial.33 In this way, then, inner sense, understood as Selbstgefühl, is not only the source of our beliefs about the existence and properties of our own self but also of universal knowledge claims about thinking substances in general. The “general concept of thinking substances,” Feder notes, is based on the “natural inference” that other substances that are similar to us “in their external properties and actions” must also have “similar powers in themselves” and, hence, must be thinking substances as well. By employing various acts of abstraction, we may even arrive at a transcendent concept of a thinking substance or spirit.34 Thus, Selbstgefühl, for Feder, constitutes the basis of a special part of metaphysics, namely ‘pneumatology’ or ‘the doctrine of spirits.’35 Elsewhere, Feder claims that inner sense constitutes the basis not just of pneumatology but even of metaphysics as a whole. He suggests that the various parts of philosophy can be distinguished, “with respect to its object,” on the basis of the distinction between inner sense and the outer senses. Insofar as philosophy is concerned with things “that can be perceived by the outer senses,” it is a “general doctrine of nature and a special doctrine of man (anthropology).” By contrast, insofar as philosophy is concerned with things “that are represented through inner consciousness and through inferences from general principles (Gründe),” it is metaphysics (GLM 2). Practical philosophy, too, is said to be based on inner experience, for here one must “above all observe oneself.”36 Thus, inner sense, Selbstgefühl as understood by Feder, and inner experience are assigned a central systematic function for philosophy. Although there was no ‘school’ based on Feder’s philosophy, he had several pupils and followers. Gottlob August Tittel, for example, published a systematic outline of Feder’s philosophy as a whole.37 Feder’s impact went well beyond the production of such summaries, however. Johann Nikolaus Tetens, a philosopher highly respected by Kant, used Feder’s Logik und Metaphysik as a textbook for his lectures from 1769 to 1776, that is, until the publication of his own Philosophische Untersuchungen in 1777.38 Moreover, Feder’s introduction of the notion of Selbstgefühl as a special kind of inner sense proved to be immensely infuential in late-eighteenth-century German philosophy. This is evident from the writings of Tetens, Meiners, Hißmann, Platner, and several other thinkers of the time.39 We shall focus on a particular development of the notion of Selbstgefühl in this context.

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4 Selbstgefühl as “preceding all experience”: Lossius Johann Christian Lossius became a professor of philosophy at the University of Erfurt in 1770. His main work in philosophy, published in 1774, is Physische Ursachen des Wahren. Appealing to then current physiological hypotheses introduced to explain mental processes, he here advances an empiricist account of mind and cognition. Lossius praises “the excellent Feder” and rejects, unsurprisingly, the metaphysics represented by Leibniz and Wolff (PU 59). As the title of his book suggests, Lossius focuses on the ‘physical causes’ of the workings of the mind. In particular, he seeks to explain the latter in terms of ‘fbre systems.’ His philosophy is not materialist in a metaphysical sense, however, since he does not attempt to establish what the nature of the thinking substance is. Rather, Lossius’s position has rightly been described as a form of eclecticism.40 Unlike Feder, Lossius did not become a major player in the debates about Kant’s critical project.41 Lossius says that the faculty through which the soul can become conscious of its inner modifcations is called inner sense, and he states, very probably with Feder in mind, that inner sense has been divided into “the feeling of self [Selbstgefühl], the feeling of the true, the beautiful and the morally good.” Unlike Feder, however, he does not think of Selbstgefühl as a kind of inner sense but distinguishes differently between Selbsgefühl and inner sense (PU 140). Lossius’s distinction relates to what we saw are the two basic ‘objects’ of Selbstgefühl as Feder understands it. Lossius distinguishes between (1) the consciousness of one’s own self as the subject of perceptions (Lossius’s Selbstgefühl), and (2) the consciousness of perceptions (Lossius’s inner sense).42 Inner sense, for Lossius, is the faculty of the soul through which it can become aware of its inner modifcations. He argues that inner sense presupposes outer sense (PU 140) and requires a body. According to Lossius, without being connected to a body, the mind could not be the object of its own observation, as it would not be able to acquire materials for observation and thought (PU 17). By contrast, Selbstgefühl in Lossius’s account does not so much concern thoughts and feelings, but the self as the subject of its thoughts and feelings. Selbstgefühl, Lossius holds, is the feeling we have of our own existence at any one point of time (PU 160). He further distinguishes between Selbstgefühl and what he calls the feeling of one’s own personality. The latter concerns the manner of one’s own existence, that is to say, one’s character and the memory of those relations and modifcations that one has ascribed to oneself in the past.43 Lossius does not elaborate on the distinction, however. Indeed, he concedes that he is not certain how exactly the distinction between these two feelings should be drawn.44 Nevertheless, his distinctions between various forms of relating to one’s own self can be summarized in the diagram below.

Experience and Inner Sense 107 Consciousness

of Perceptions

of the Subject of Perceptions

(Inner Sense) Selbstgefühl

Feeling of Personality

As was noted above, Lossius considers inner sense, or the soul’s consciousness of its own modifcations, to depend on outer sensations. Like most philosophers with an empiricist bent, accordingly, he suggests that we could not have inner experience without outer experience. Lossius does not think, however, that Selbstgefühl, or the feeling of one’s own existence, requires outer sensations or, indeed, experience of any kind. And while his book aims to search for ‘physical causes’ of truth, he explicitly states that Selbstgefühl is an exception in that it cannot be explained in terms of a “play of fbres” in the brain (PU 163–64). As he puts it, it “does not require any experiential idea apart from the consciousness of our own existence” (PU 161). In this respect, Lossius differs from Feder in a signifcant way. According to Feder, we cannot have the feeling of our own existence without being conscious of perceptions. Lossius, by contrast, believes that we would have Selbstgefühl even if we had no other inner or outer experience.45 He also states explicitly that the feeling of one’s own existence is immediate and that one must accept it as true without any proof or argument.46 Moreover, Lossius conceives of Selbstgefühl as a foundational capacity in the sense that it precedes all experience: For Selbstgefühl cannot be explained by any kind of oscillation of a fbre, nor is it stimulated by any kind of external sensation […]. Selbstgefühl, as far as I can see, cannot be understood by any kind of interplay of these fbres, but is a simple consciousness of itself, and precedes all experience, and is as inherently part of the soul as fying is to a bird or as gravity is to a stone. (PU 163–64, my emphasis) Lossius further maintains that Selbstgefühl reveals the unitary nature of our own self (PU 161). Through my Selbstgefühl, he notes, “I feel that the thing that thinks its own self in me and feels its existence is not multiplied or divided, but is in the strict sense exactly one.”47 Similarly, we know through Selbstgefühl that the self is not a bodily being (PU 161). Unlike Feder, then, Lossius asserts that our Selbstgefühl allows us to obtain cognitions of essential aspects of the nature of the self. However, these claims are clearly at odds with his thesis that Selbstgefühl reveals the existence of the self but not the specifc manner of this existence.

108 Udo Thiel Lossius attempts to explain, however, how Selbstgefühl can provide us with knowledge of the non-corporeal nature of the self. He argues that the connection of Selbstgefühl with the very idea that we are subject to constant change and with the consciousness of our past convinces us that the self, or that substance in us that is conscious of these changes, must be essentially distinct from the body.48 Thus, in spite of his stated concern with the ‘physical causes’ of mental phenomena, Lossius is a far way off from materialism. However, Lossius’s account leaves a number of questions unanswered. First, Lossius does not address the question of whether his conception of self-consciousness as an original feeling is compatible with his claim that all inner feelings depend on outer experience. More importantly, it is unclear in which sense the consciousness that “precedes all experience” can itself be a feeling, which would seem to draw it into the experiential sphere. In other words: if it is required by experience, how can it be experiential itself? Notwithstanding these problems in Lossius’s account, it is signifcant that he assigns Selbstgefühl a more fundamental epistemological role than Feder. Moreover, his notion of a feeling of self that precedes experience is, of course, reminiscent of Kant’s ideas about self-consciousness or apperception, to which I now turn.

5 Kant: From Inner Sense as “a fundamental faculty” to Apperception We saw above that, for Kant, inner experience, understood as empirical cognition, involves the use of concepts and, therefore, that inner sense on its own does not constitute inner experience. Inner sense merely provides the representational material for empirical cognition of oneself. In some of his early writings, however, Kant ascribes to inner sense a role that is more fundamental than that of providing material for a particular kind of cognition (inner experience) and that relates to cognition as such.49 Thus, in an important ‘Concluding Refection’ to his short piece on The False Subtlety of the Four Syllogistic Figures of 1762, Kant refects on the capacity to distinguish between ideas, or representations, and explains that this involves our “capacity to judge.” Kant emphasizes that there are two ways of distinguishing representations. He argues that “it is one thing to differentiate things from each other, and quite another thing to recognize the difference between them. The latter […] cannot occur in the case of animals, which are not endowed with reason” (FS, 2:59). Kant elaborates on this by drawing a distinction between a logical and physical way of distinguishing: Differentiating logically means recognizing that a thing A is not B; it is always a negative judgement. Physically differentiating means

Experience and Inner Sense 109 being driven to different actions by different representations. The dog differentiates the roast from the loaf, and it does so because the way in which it is affected by the roast is different from the way it is affected by the loaf […], and the sensations caused by the roast are a ground of desire in the dog which differs from the desire caused by the loaf, according to the natural connection which exists between its drives and its representations. (FS, 2:60) Since ‘differentiating logically’ involves recognition, it presupposes the capacity to combine concepts in judgments. As Kant argues earlier in the piece, both understanding and reason consist in the capacity to judge: It is […] obvious that understanding and reason, that is to say, the faculty of cognising distinctly and the faculty of syllogistic reasoning, are not different fundamental faculties (Grundfähigkeiten). Both consist in the capacity to judge. (FS, 2:59) Accordingly, Kant argues that “the higher faculty of cognition rests absolutely and simply on ‘the capacity to judge’” (FS, 2:59). Pushing his investigation further, he asks what “the mysterious power is” that, in turn, “makes judging possible.” He does not claim to have a defnite answer at this point but suggests that this searched-for power is “nothing other than the faculty of inner sense, that is to say the faculty of making one’s own representations the objects of one’s thought.” As “this faculty cannot be derived from some other faculty,” he notes, “it is in the strict sense of the term, a fundamental faculty” which “can only belong to rational beings.” The “entire higher faculty of cognition,” Kant concludes, “is based” on this fundamental faculty of inner sense (FS, 2:60, my emphasis).50 Both Feder and Lossius were familiar with Kant’s False Subtlety piece of 1762.51 However, they do not seem to have taken up the notion of inner sense that Kant invokes there. Kant, in turn, does not make use of the notion of Selbstgefühl or similar notions such as that of apperception in his writings from the early 1760s. Indeed, the term ‘Selbstgefühl’ does not seem to have been in philosophical use prior to its introduction by Basedow in 1764. ‘Apperception,’ however, a term coined by Leibniz, was common well before the 1760s through the work of Christian Wolff and the debates about his philosophy.52 However, Kant does not make use of the term ‘apperception’ before the 1770s. Indeed, it is only after 1770 that self-consciousness begins to play a central role in Kant’s thought.53 There seems to be no evidence that Kant was familiar with Lossius’s Physische Ursachen des Wahren in the 1770s. He clearly knew Feder’s work, however, and even seems to have used Feder’s Logik and Metaphysik as a textbook for his lectures in 1770–1771.54 In any case, we are not asserting any direct ‘infuence’ of Feder and Lossius

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on Kant’s development of the notion of apperception. It is plain, however, that Kant during the 1770s further developed the idea of a fundamental faculty (called ‘inner sense’ in the early 1760s) by introducing the idea of a fundamental self-consciousness that “precedes all experience,” as Lossius had put it. Kant will argue that such fundamental selfconsciousness or apperception, as he comes to call it, cannot be ascribed to inner sense, which he will characterize by receptivity. Kant comes to realize that we must distinguish between inner sense and apperception or self-consciousness.55 While Kant’s account differs in many ways from the distinctions we fnd in Feder and Lossius, it is plain that there is a sense in which Lossius’s account of inner sense and of a Selbstgefühl that “precedes all experience” anticipates Kant’s notion that we need to distinguish between inner sense and apperception. In his writings from the critical period, Kant no longer considers inner sense a fundamental faculty. Thus, in the Anthropology he refers to inner sense as the mere consciousness “of what he [the human being] undergoes in so far as he is affected by the play of his own thoughts. It rests on inner intuition and, consequently, on the relations of ideas in time.”56 In the Critique of Pure Reason, Kant sometimes equates inner sense with empirical apperception. Since empirical apperception or inner sense concerns the actual awareness of particular mental states, it “is by itself dispersed” and cannot be precisely the same at different points of time. It is, as Kant puts it, “without relation to the identity of the subject” (B133). As a consciousness accompanying different perceptions, empirical apperception is “forever variable” (A107). In general, Kant in the Critique distinguishes sharply between sensibility (including inner and outer sense) and the understanding or the intellect. Whereas the former is characterized by receptivity, the latter is characterized by spontaneity. It follows, obviously, that inner sense can no longer fulfll the function of a fundamental faculty on which the “capacity to judge” depends. Arguing that the “identity of the subject” that is required for thinking (or for combining representations) cannot be provided by inner sense, Kant introduces a kind of self-consciousness that he calls “pure apperception.” Pure apperception can fulfll the searched-for function because it belongs not to sensibility but to the faculty of thought or the understanding. Thus, Kant develops the notion of a fundamental faculty that he identifed as inner sense in the pre-critical False Subtlety piece into the notion of pure and, indeed, transcendental apperception or selfconsciousness. Pure apperception is now considered the “highest point to which one must affx all use of the understanding” (B134) and a “pure intellectual faculty” (B423). In the frst edition of the Critique of Pure Reason, Kant even describes pure apperception as “the radical faculty of all our cognition” (A114), an expression that seems to correspond to that of a “fundamental faculty” used in the 1760s.

Experience and Inner Sense 111 While Kant’s new notion of apperception is non-experiential, it is also non-metaphysical, as no knowledge of the nature of the self can be derived from pure apperception. In this regard, Kant argues that “it is not possible at all through this simple self-consciousness to determine the way I exist, whether as substance or as accident” (B420). However, Kant claims about pure apperception or “intellectual consciousness” what Lossius had claimed about Selbstgefühl, namely, that it “does to be sure precede” (Bxl) any actual thought and is in this sense original. While Kant’s conception of pure apperception clearly differs from Feder’s and Lossius’s conceptions of Selbstgefühl, it also retains aspects of their accounts. Thus, Kant in the Prolegomena notes that “the representation of apperception, the I, […] is nothing more than a feeling of an existence.”57 This idea seems to correspond to Lossius’s understanding of Selbstgefühl. We saw that Lossius’s theory raises the question of how his Selbstgefühl can “precede all experience” when it is itself, qua feeling, obviously experiential. Similarly, one could ask how pure apperception, said to precede all experience, can at the same time be a feeling, that is, something experiential. There is considerable scholarly debate about this particular issue, the pros and cons of which cannot be rehearsed here.58 In my view, Kant is able (unlike Lossius) to accommodate both aspects of apperception. Pure apperception, Kant writes, is “that self-consciousness which […] produces the representation ‘I think’” (B132). Since this self-consciousness is an “act of spontaneity,” it “cannot be regarded as belonging to sensibility” (B132). Therefore, as noted, pure apperception needs to be distinguished from empirical apperception or inner sense. While we cannot know anything about the nature of our own being through pure apperception, Kant argues that we are aware of our own existence through the representation or judgment ‘I think.’ Kant states: “The I think expresses the act of determining my existence. The existence is thereby already given” (B157n). When I perform the act ‘I think,’ I am thereby aware of my own existence. It is important, then, to note that Kant distinguishes between the pure I of apperception and the act of stating ‘I think.’ Whereas the former is “purely intellectual, because it belongs to thinking in general,” the latter concerns the “application […] of the pure intellectual faculty” of apperception and is empirical (B423n). In formulating the proposition ‘I think,’ Kant writes, I make a statement about myself that “contains within itself the proposition ‘I exist’” (B422n, cf. B420). In this regard, it “expresses an indeterminate empirical intuition” (B422n, my emphasis). In the proposition ‘I think,’ the I is given only “as something that in fact exists and is indicated as an existing thing” (B423n). To acquire cognition of the manner of my existence, I would require additional inner intuitions (through inner sense), “since for the cognition of ourselves […] a determinate sort of intuition, through which this manifold is given, is also required” (B157, second emphasis mine). Regardless of how we may acquire cognition of

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the manner of our existence, however, Kant can consistently consider apperception to be both pure and a feeling, for apperception as a “feeling of existence” corresponds to what he calls the “indeterminate empirical intuition” that is expressed by the ‘I think.’

6 Conclusion Kant’s critical account of apperception, then, is aligned with both his own pre-critical notion of inner sense as a fundamental faculty that grounds both reason and understanding and the notion of Selbstgefühl put forward by Feder and, especially, Lossius. According to Feder, the consciousness of perceptions and the consciousness of existence belong together and are different aspects of Selbstgefühl. For Feder, the latter cannot be had without the former. Unlike Feder, Lossius separates Selbstgefühl as the feeling of one’s own existence from the consciousness of perceptions (inner sense), arguing that it plays an independent and fundamental role and precedes all experience. Kant retains the notion of a fundamental faculty that grounds thought in his critical philosophy, but he no longer believes, as he did in the early 1760s, that inner sense could be this faculty. The self of inner sense is now considered to be merely the “psychological self.”59 To refer to the idea of a fundamental or radical faculty that grounds thought, he develops the notion of pure apperception, taking up Lossius’s idea of a relating to the self that is independent of other forms of consciousness and that “precedes all experience.” Insofar as it is pure or a priori, Kant’s apperception differs from Feder’s or Lossius’s Selbstgefühl. Insofar as apperception “produces the I think” and as the ‘I think’ expresses “an indeterminate empirical intuition,” however, it retains at the same time the notion of a “feeling of existence” that played such a crucial role in the works of thinkers such as Feder and Lossius.

Notes 1 Heller-Roazen (2007) provides a very informative historical overview of the doctrine of inner sense from antiquity to the present. However, he does not deal with German eighteenth-century thought on the issue in any detail. 2 Kant, Anthr, 7:141. He notes that “an empirical intuition which, through refection and the concept of understanding arising from it, becomes inner experience” (7:142). On Kant’s account of inner experience as propositional, see Mohr (1991: 28–30). 3 Kant, Anthr, 7:134n. Kant here refers to the self considered in (empirical) psychology as “the ‘I’ as object of perception, therefore of inner sense, which contains a manifold of determinations that make an inner experience possible.” 4 For a detailed account of Feder’s notion of inner sense in his writings from the late 1760s to the 1780s and 1790s, see Thiel (2018a: 55–86). 5 See, for example, Feder, LM (1790) 80–83.

Experience and Inner Sense 113 6 See Feder, LM (1771) 31; LM (1783) 30; LM (1790) 28–29. 7 Feder, LM (1771) 32. 8 Feder, LM (1790) 29–30, my emphasis. He writes elsewhere that “inner sense consists of those capacities of the soul through which it feels itself, what passes in it, and the relations of its ideas” (LM (1790) 116). 9 Elsewhere, Feder writes: “Inner sensations are called the perceptions of the present state of our inner being which is totally hidden from the outer senses” (UMG 18). 10 Feder, LM (1771) 31. 11 Feder, LM (1771) 31–32; LM (1783) 30; LM (1790) 29. See also LM (1769) 116, 225; DSI 25. 12 For an overview of the development of this triad from antiquity to the present, see Kurz (2015: 22–25). Kurz does not discuss the doctrine of inner sense and how the triad was adopted and modifed in this context. 13 See also LM (1771) 32; LM (1783) 31; LM (1790) 29–30. 14 Feder, LM (1771) 32; LM (1783) 31; LM (1790) 29; cf. DSI 27, 29–30. 15 Feder, LM (1771) 32; LM (1783) 31; LM (1790) 29; cf. DSI 30–32. 16 Feder, LM (1771) 32; LM (1783) 31; LM (1790) 29; cf. DSI 32–33. Thus, Feder seems to postulate a ‘moral sense,’ following Hutcheson. For Feder, however, the moral sense is not a simple fundamental feeling to which one can appeal in disagreements. It is not an independent standard. Unlike Hutcheson, Feder held on to the possibility of rational moral judgment. See Feder’s long article on the topic titled Über das moralische Gefühl (UMG 15–40, 103–15, 287–306, 479–503). The article was published as a monograph in Copenhagen and Leipzig in 1792. 17 Related terms such as ‘inneres Gefühl’ had of course been used earlier in the century. See, for example, Meier (1757: 10, 21–22). See my discussion of Selbstgefühl in Thiel (1997: 79, 58–79). 18 Versions of Basedow’s and Feder’s account of Selbstgefühl in terms of inner sense reappeared in other prominent psychological writings of the day, for example in those by Ernst Platner, Johann Nikolaus Tetens, Christoph Meiners, and Michael Hißmann. See Thiel (1997, 2018b: 59–75). 19 See Feder, LM (1790) 29: “By Selbstgefühl is meant the immediate perception of [1] one’s own existence, of [2] one’s own inner states and properties.” See also LM (1771) 32; LM (1783) 30. 20 Feder, LM (1771) 32, my emphasis. See also LM (1783) 30; LM (1790) 29. 21 Feder, LM (1769) 134; see also LM (1771) 32; LM (1783) 31; LM (1790) 29. 22 See Basedow, Phil §§ 70–72; Feder, LM (1769) 134; DSI 25. 23 Feder (1767: 54); see LM (1769) 122–23; GLM 24–25. 24 See Feder, DSI 25; LM (1769) 134; LM (1790) 29. 25 Feder, LM (1769) 134, see LM (1771) 32; LM (1783) 31; LM (1790) 29; DSI 25. 26 Feder, LM (1769) 400; see LM (1771) 348; LM (1783) 30. See also: “By means of this inner sense, […] [we] moreover form the concepts of thinking and willing, of all the forces and qualities of our soul.” (UMG 18). 27 Feder, LM (1769) 108. 28 Feder (1789: 25). 29 Feder (1789: 26). Compare Locke, Essay, II.xxiii.1–2. 30 Feder, LM (1790) 326–27; cf. LM (1769) 404. However, Feder does not refer to Locke here. In any case, Feder’s position does not seem to be as different from Locke’s as he suggests. Like Feder, Locke holds that we cannot know the real essence of the soul but that it is the “more probable Opinion” that the soul is an immaterial substance (Essay II.xxvii.25).

114 Udo Thiel 31 See Feder, LM (1769) 403: “In particular with regard to our soul, the feeling of self [Selbstgefühl] certainly supports the simplicity of the thinking substance rather than the contrary. At least, it seems to me that one can suffciently distinguish—by means of the same—the soul from the entire mass of organised matter of which its body is constituted.” Thomas Reid, the leading philosopher of the Scottish School of Common Sense, had argued for this view prior to Feder. As Manfred Kuehn has shown, Reid’s work had a considerable impact on Feder. See Kuehn (1987: 74–85). Feder reviewed Reid’s Essays on the Intellectual Powers of Man of 1785 in Göttingische Anzeigen von gelehrten Sachen (see Feder 1787: 626–30) and again in Philosophische Bibliothek (see Feder 1788: 43–62). In the earlier review Feder refers to Reid’s An Inquiry into to the Human Mind, published in 1764, well before Feder’s main works came out. A German translation of Reid’s Inquiry did not appear until 1782. As Kuehn has noted, however, Feder refers to Reid several times even in the early editions of Logik und Metaphysik. See Feder, LM (1770) 256, 571f.; see also LM (1771) 171, where Feder recommends Reid’s Inquiry. Although the Inquiry is mainly concerned with the outer senses, the work comments also on the self. These comments are similar to Feder’s idea that Selbstgefühl suggests a simple thinking substance or soul. On this issue, see Thiel (2018a: 76–77) and Rumore (2018: 49–50). 32 Feder, LM (1790) 325–26. 33 See Feder (1789: 27–30) for an account of how we arrive at the concept of the simplicity of the soul. 34 Feder, LM (1769) 399–400. 35 Feder, LM (1769) 399–400; cf. LM (1769) 134; GLM 237. 36 Feder (1785: 12); cf. UMG 18. 37 See Tittel (1784). 38 See Sellhoff (2016: XLIV–XLIX). 39 On these developments, see, for example, Thiel (1997, 2014b: 89–102, 2007: 139–61). 40 Zart (1881: 156–57). Kuehn has shown that Lossius was strongly infuenced by James Beattie. Lossius attempted, Kuehn states, “to supply Beattie’s theory of truth with a foundation in the physiological organization of man” (Kuehn 1987: 87). See also Thiel (2016: 490–92). 41 There are, however, many entries with comments on Kant in Lossius’s Neues Philosophisches Allgemeines Real-Lexikon (Lossius 1803–6). See also Lossius’s Etwas über kantische Philosophie in Hinsicht des Beweises vom Daseyn Gottes (Lossius 1789). 42 Lossius’s distinction between inner sense and Selbstgefühl corresponds to Locke’s distinction between, on the one hand, internal sense or refection and, on the other hand, an intuitive knowledge of the existence of one’s own self. See Locke, Essay, II.i.4 and IV.ix.3. However, Locke does not make this distinction explicit. 43 “Every human being can ask of himself two questions. The frst question is: am I? The second question is: What am I? The feeling of self [Selbstgefühl] is what furnishes an answer to the frst question, and the answer to the second question is provided by the personality” (Lossius, PU 160; cf. PU 162). 44 “If these thoughts are well founded, then on the one hand there is a noticeable difference between the feeling of self [Selbstgefühl] and the feeling of my personality, of which however I cannot yet suffciently determine the boundary when I attend to the feeling itself, and on the other hand it is still just a feeling” (Lossius, PU 163). 45 “I believe that the human being would have this feeling of his I [Ich] even if he did not have any experience […]. Thus, if we wanted in thought to draw

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46

47 48

49

50 51 52 53

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the soul out of its body and think it in an entirely isolated manner, then it would not be a contradiction to assume about it this feeling of its self” (Lossius, PU 160–61). “That I am, is a frst fact [Faktum], and I do not have any principles from which I could demonstrate the truth of this proposition myself or have it demonstrated by someone else. Nevertheless, I am as convinced of it as I am of any geometrical axiom. There must therefore be something in me that takes the place of all principles and the articulation of which necessarily compels my assent, when the question arises ‘do I exist?,’ and this is what I call the feeling of my own self or Selbstgefühl” (Lossius, PU 160). The idea of a natural feeling of our own existence is a feature of common sense thought on these matters. Manfred Kuehn has documented the infuence of the Scottish Common Sense school on Lossius, as noted above, but does not deal with the issue of Selbstgefühl in particular. Aspects of Lossius’s discussion of Selbstgefühl are discussed in Wunderlich (2005: 87–90). See also Thiel (1997, 2016: 490–92). Lossius, PU 161; cf. PU 166. “But precisely this thought of change, in relation to Selbstgefühl, convinces me more than all metaphysical proofs that my I or the substance in me that is conscious of these changes is not one with this body or the same as my body, but is rather signifcantly different from it. My entire life is a series of interconnected changes in which one takes the place of another and which runs parallel to the moments of time. But I do not therefore begin to become a different I than the one I was at the very beginning” (Lossius, PU 164–65). These very early refections on a “fundamental faculty” are rarely discussed in any detail in the scholarly literature. For brief comments on this material, see, for example, Baum (2002: 107) and Schulting (2015: 94–95). See also Thiel (forthcoming). Other sources from this period also indicate that Kant regarded inner sense as a fundamental faculty that is the basis of any judgment and, hence, of any cognition. See, for example, Kant, LM Herder, 28: 868–69. Feder cites Kant’s False Subtlety in LM (1771) 99; Lossius recommends Kant’s piece in his Unterricht der gesunden Vernunft, see Lossius (1777: 171). See, for example, Wolff, PE § 25 and Merian, APE 416–41. For a discussion of Wolff and Merian on apperception, see Thiel (2014a: 372–76). Kant discusses the notion of apperception in the so-called Duisburg’scher Nachlass from the mid-1770s. Apperception, he writes, “is the perception of oneself as a thinking subject in general” (Ref. 4674, 17:647; my translation). For a detailed discussion of Kant’s development in the 1770s relating to issues of self-consciousness, see Klemme (1996: 76–138). See Motta (2018: 108–10). Motta also relates aspects of Feder’s notion of Selbstgefühl to Kant’s concept of apperception (2018: 118–20). According to Warda, Kant owned the ffth edition of Feder’s Logik und Metaphysik (1778); see Warda (1922: 48). Kant was probably aware at least of some of Lossius’s views through his reading of Tetens. Tetens discusses Lossius in his Philosophische Versuche (see PV I, 532–33, 542–44). However, these comments do not relate to the notion of Selbstgefühl. For an account of Tetens and Kant on this issue, see Thiel (2018b: 85–94). Tetens had reviewed Lossius’s work; see Tetens (1775). When Kant begins to make use of the notion of apperception in the 1770s, he does not clearly distinguish between inner sense and apperception. Moreover, he still seemed to think that the ‘I’ “expresses a rational substance” (V-Anth/Collins, 25: 10). Cf. Klemme (1996: 79, 137). This is a view that Kant of course rejects in his critical philosophy.

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56 Kant, Anthr, 7:161. See also: “Consciousness of oneself (apperception) can be divided into […] a consciousness of understanding, pure apperception […] [and] a consciousness of inner sense, empirical apperception. In this case the former is falsely named inner sense” (7:134). 57 Kant, Prol, 4:334n. 58 Some have claimed that since Kant holds that transcendental apperception is both pure and empirical (since it involves the perception of one’s own existence), he subscribes to the notion of an intellectual intuition even though he explicitly rejects it. See Frank (1991: 424–25). There is no need, however, to ascribe to Kant a notion that he explicitly rejects. 59 Kant (1940, 20:268).

Bibliography Primary Sources Basedow, Johann Bernhard (1764), Philalethie. Neue Aussichten in die Wahrheiten und Religion der Vernunft bis in die Gränzen der glaubwürdigen Offenbarung, vol. 2, Altona: Iversen (Phil). Feder, Johann Georg H., (1767), Grundriß der Philosophischen Wissenschaften, Coburg: Findeisen. ——— (1768), De sensu interno, Göttingen: Schulz (DSI). ——— (1769), Logik und Metaphysik, Göttingen und Gotha: Dieterich; 7th edn. 1790. The 1783 edn. was published in Vienna by Trattnern (LM; the different editions are cited by year). ——— (1776), ‘Über das moralische Gefühl’, in Deutsches Museum, vol. 1, 15–40, 103–15, 287–306, 472–503; vol. 2 (1777), 712–30. Repr. Copenhagen/Leipzig: Faber und Nitschke 1792 (UMG). ——— (1785), Untersuchungen über den menschlichen Willen, dessen Naturtriebe, Verschiedenheiten, Verhältniß zur Tugend und Glückseligkeit und die Grundregeln, die menschlichen Gemüther zu erkennen und zu regieren, vol. 1, 2nd edn., Göttingen/Lemgo: Meyer. ——— (1787), [Review of] Thomas Reid, Essay on the Intellectual Powers of Man, Göttingische Anzeigen von gelehrten Sachen, 63 (21 April), 626–30. ——— (1788), [Review of] Thomas Reid, Essay on the Intellectual Powers of Man, Philosophische Bibliothek, 1, 43–62. ——— (1789), ‘Ueber den Begriff von Substanz’, in Philosophische Bibliothek, 2, 1–40. ——— (1794), Grundsätze der Logik und Metaphysik, Göttingen: Dieterich (GLM). Kant, Immanuel (1926), ‘Refexionen über Metaphysik’ (Ref), in Handschriftlicher Nachlaß Metaphysik I, Gesammelte Schriften, AA 17, ed. by Deutsche Akademie der Wissenschaften, Berlin: De Gruyter, 224–745. ——— (1940), Preisschrift über die Fortschritte der Metaphysik [1793], in Gesammelte Schriften, AA 20, ed. by Deutsche Akademie der Wissenschaften, Berlin: De Gruyter, 253–332. ——— (1997), Lectures on Metaphysics Herder (AA 28), in Lectures on Metaphysics, transl. and ed. by K. Ameriks and S. Naragon, Cambridge: Cambridge University Press, 3–16 (LM Herder).

Experience and Inner Sense 117 ——— (1998), Critique of Pure Reason, transl. and ed. by P. Guyer and A.W. Wood, Cambridge: Cambridge University Press (CPR). ——— (2002), The False Subtlety of the Four Syllogistic Figures (AA 2), in Theoretical Philosophy, 1755–1770, ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press, 85–105 (FS). ——— (2004), Prolegomena to any Future Metaphysics that Will Be Able to Come Forward as Science (AA 4), transl. by G. Hatfeld, Cambridge: Cambridge University Press (Prol). ——— (2007), Anthropology from a Pragmatic Point of View (AA 7), in Anthropology, History, and Education, ed. by G. Zöller and R.B. Louden, transl. by R.B. Louden, Cambridge: Cambridge University Press (Anthr). ——— (2012), Anthropology Collins 1772–1773 (AA 25), in Lectures on Anthropology, transl. and ed. by R.B. Louden and A.W. Wood; transl. by R.R. Clewis and G.F. Munzel, Cambridge: Cambridge University Press. Locke, John (1975), An Essay Concerning Human Understanding, ed. by P.H. Nidditch, Oxford: Clarendon Press. Lossius, Johann Christian (1775 [1774]), Physische Ursachen des Wahren, Gotha: Ettinger (PU). ——— (1777), Unterricht der gesunden Vernunft, Gotha: Ettinger. ——— (1789), Etwas über kantische Philosophie in Hinsicht des Beweises vom Daseyn Gottes, Erfurt: Keyser. ——— (1803–6), Neues Philosophisches Allgemeines Real-Lexikon, 4 vols., Erfurt: Rudolphi. Meier, Georg Friedrich (1757), Metaphysik, vol. 3, Halle: Gebauer. Merian, Jean-Bernard (1751), ‘Mémoire sur l’apperception de sa propre existence’, in Histoire de l’Académie royale des sciences et belles lettres (1749), Berlin: Haude & Spener, 416–41 (APE). Tetens, Johann Nikolaus (1775), [Review of] Lossius, Physische Ursachen des Wahren, Kielische Gelehrte Zeitung, 85–94. ——— (1777), Philosophische Versuche über die menschliche Natur und ihre Entwicklung, vol. 1, Leipzig: M.G. Weidemanns Erben & Reich. Tittel, Gottlob August (1784), Erläuterungen der theoretischen und praktischen Philosophie nach Herrn Feders Ordnung, Frankfurt: Garbe. Wolff, Christian (1732), Psychologia empirica, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II.3, Hildesheim: Olms 1968 (PE).

Secondary Sources Baum, Manfred (2002), ‘Logisches und Personales Ich bei Kant’, in D. Heidemann (ed.), Probleme der Subjektivität, Stuttgart-Bad Cannstatt: Frommann Holzboog, 107–23. Frank, Manfred (1991), Selbstbewußtseinstheorien von Fichte bis Sartre, Frankfurt: Suhrkamp. Heller-Roazen, Daniel (2007), The Inner Touch: Archeology of a Sensation, New York: Zone Books. Klemme, Heiner F. (1996), Kants Philosophie des Subjekts, Hamburg: Meiner. Kuehn, Manfred (1987), Scottish Common Sense in Germany 1768–1800, Kingston/Montreal: McGill University Press.

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Kurz, Gerhard (2015), Das Wahre, Schöne, Gute. Aufstieg, Fall und Fortbestehen einer Trias, Paderborn: Fink. Mohr, Georg (1991), Das sinnliche Ich. Innerer Sinn und Bewußtsein bei Kant, Würzburg: Königshausen & Neumann. Motta, Giuseppe (2018), ‘Elemente des Kritizismus in Feders Logik und Metaphysik’, in H.-P. Nowitzki, U. Roth, and G. Stiening (eds.), Johann Georg Heinrich Feder (1740–1821), Empirismus und Popularphilosophie zwischen Wolff und Kant, Berlin/Boston: De Gruyter, 105–21. Rumore, Paola (2018), ‘Feder und die Psychologie seiner Zeit’, in H.-P. Nowitzki, U. Roth, and G. Stiening (eds.), Johann Georg Heinrich Feder (1740–1821). Empirismus und Popularphilosophie zwischen Wolff und Kant, Berlin/Boston: De Gruyter, 39–54. Schulting, Dennis (2015), ‘Transcendental Apperception and Consciousness in Kant’s Lectures on Metaphysics’, in R.R. Clewis (ed.), Reading Kant’s Lectures, Berlin: De Gruyter, 89–113. Sellhoff, Michael (2016), ‘Einleitung’, in M. Sellhoff (ed.), Johann Nicolaus Tetens: Metaphysik, Hamburg: Meiner, XI–CXXVIII. Thiel, Udo (1997), ‘Varieties of Inner Sense. Two Pre-Kantian Theories’, Archiv für Geschichte der Philosophie, 79, 58–79. ——— (2007), ‘Das Gefühl “Ich”: Ernst Platner zwischen Empirischer Psychologie und Transzendentalphilosophie’, Aufklärung, 19, 139–61. ——— (2014a), The Early Modern Subject. Self-Consciousness and Personal Identity from Descartes to Hume, Oxford: Oxford University Press. ——— (2014b), ‘Zwischen Empirischer Psychologie und Rationaler Seelenlehre. Tetens über das Selbstgefühl’, in G. Stiening und U. Thiel (eds.), Johann Nikolaus Tetens (1736–1807). Philosophie in der Tradition des europäischen Empirismus, Berlin/Boston: De Gruyter, 89–102. ——— (2016), ‘Lossius, Johann Christian’, in H.F. Klemme and M. Kuehn (eds.), The Bloomsbury Dictionary of Eighteenth-Century German Philosophers, London/Oxford: Bloomsbury Academic, 1199–1200. ——— (2018a), ‘Feder und der Innere Sinn’, in H.-P. Nowitzki, U. Roth, and G. Stiening (eds.), Johann Georg Heinrich Feder (1740–1821). Empirismus und Popularphilosophie zwischen Wolff und Kant, Berlin/Boston: De Gruyter, 55–86. ——— (2018b), ‘Kant and Tetens on the Unity of the Self’, in C.W. Dyck and F. Wunderlich (eds.), Kant and His German Contemporaries, Cambridge: Cambridge University Press, 59–75. ——— (forthcoming), ‘Consciousness, Inner Sense and Self-Consciousness in the 1760s’, in G. Motta, D. Schulting and U. Thiel (eds.), Kant’s Transcendental Deduction and the Theory of Apperception. New Interpretations, Berlin/ Boston: De Gruyter. Warda, Arthur (1922), Immanuel Kants Bücher, Berlin: Breslauer. Wunderlich, Falk (2005), Kant und die Bewußtseinstheorien des 18. Jahrhunderts, Berlin/Boston: De Gruyter. Zart, Gustav (1881), Einfuss der englischen Philosophen seit Bacon auf die deutsche Philosophie des 18. Jahrhunderts, Berlin: Dümmler, 156–66.

6

Christoph Meiners’s Empiricist ‘Revision’ of Philosophy and Michael Hißmann’s Anti-Speculative Materialism Falk Wunderlich

This chapter deals with two German empiricist philosophers, Christoph Meiners (1747–1810) and Michael Hißmann (1752–1784), who during the 1770s developed materialist theories of the mind.1 Until recently, it was hardly known or even denied that German materialism existed at all in a more than fragmented way prior to the nineteenth century.2 In fact, however, materialism was part of the German Enlightenment since the early eighteenth century, with a peak in the 1770s.3 Book-length materialist treatises were published by August Wilhelm Hupel (1737–1819), Christian Gottlieb Selle (1748–1800), Johann Gottlieb Karl Spazier (1761–1805), Karl von Knoblauch (1756–1794), and Hißmann.4 During this period, German materialism included a broad spectrum of theories. At one end of the spectrum, Knoblauch developed an ambitious metaphysics that was mainly based on Spinoza and spelled out in terms of property dualism.5 He also argued in favor of what are today called emergent properties, i.e., properties of compounds that can be reduced to neither fundamental properties nor external ones, as a way of explaining the human mind.6 At the other end of this spectrum, which is the focus of this chapter, is the pivotal role granted to experience in Hißmann’s materialism. An emphasis on experience in general is apparent from his appreciation of Locke throughout his work. In this regard, Hißmann depended on Meiners, whose empiricist manifesto Revision der Philosophie I will discuss in the frst section. Meiners was Hißmann’s academic teacher, and they seem to have cooperated on a friendly basis throughout Hißmann’s career. More specifcally, however, Hißmann does not rely on experience tout court, but on a scientifc type of experience. He argues that inner experience, obtained through introspection, is not informative about the nature of the human mind and that philosophy should rather rely on the results of medicine and physiology (Section 2). Whereas Hißmann primarily frames his materialism as a distinctly anti-metaphysical endeavor, he apparently could not avoid discussing related metaphysical questions entirely. In Section 3, I discuss two examples of his engagement with metaphysical issues, including Hißmann’s contribution to the 1779 price essay contest of the Berlin Academy.

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1 Meiners’s Programmatic ‘Revision’ of Philosophy In 1772, Meiners published his Revision der Philosophie, intended as a manifesto for the kind of philosophy that became dominant in Göttingen for at least a decade, primarily through Meiners and Hißmann, and to a lesser extent through Johann Georg Heinrich Feder (1740–1821).7 Revision does not extend to the whole of philosophy but focuses on the key disciplines of logic, psychology, and metaphysics, and also includes a part on aesthetics. The full title of the book—Revision der Philosophie. Erster Theil—makes it clear that the program was to be expanded, though that plan was not pursued in the form of further parts of the book. One of Meiners’s main targets in Revision is Christian Wolff. Accordingly, he locates Wolffan metaphysics “in the gloomy caves of cosmology and monadology” and denounces the “transcendental speculation” it contains (REV 37).8 Meiners criticizes Wolff and his followers for mistaking philosophy for a kind of “pansophy,” or science of everything, that unjustly extends its reach to the realm of other sciences. More specifcally, he complains that German philosophers, especially the Wolffans, tend to count all felds of knowledge that include general and abstract concepts among the parts of metaphysics, while these concepts in fact belong to the independent disciplines of psychology, moral philosophy, and theology (REV 202). Concepts like those of God and freedom, for example, should be dealt with in practical philosophy, according to Meiners, and for metaphysics “nothing but a vague rest of general concepts” remains (REV 203). Meiners is concerned not only with the disciplinary boundaries of metaphysics but also with those between philosophy and the sciences. In this regard, he maintains: “While other philosophers try to enhance philosophy with new sciences, and to usurp […] the realms of other sciences, my aim is primarily to hand over those lands that have been taken away unlawfully to their legitimate owners” (REV 52). Thus, it is essential to the program pursued by the Göttingen empiricists to both insist on the limits of philosophical inquiry as such and to restrict legitimate philosophical inquiry to a smaller number of subfelds than usual. According to Meiners, philosophy should take the work of John Locke as its main model. His appreciation for Locke is obvious from almost every page of Revision. As he puts it: “I owe it to you, wise Locke, that I have elevated myself from the wild chaos of scholastic soothsaying to the bright realm of distinct concepts.” (REV 161). Meiners strongly advises philosophers to study Locke diligently, and he reproaches his German colleagues with quoting Locke without having read his work in depth (REV 153). According to Meiners, the core of Locke’s method consists in tracing back general ideas to impressions of the senses. Meiners thus understands Locke’s philosophy primarily (as Locke himself does) as

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an inquiry into the origin of our most basic concepts, with the aim of determining the contents and limits of metaphysics (REV 208). He also often emphasizes the importance of Locke’s effort to determine the limits of human cognition more generally (cf. REV 159). Meiners preference for Locke is expressed by the methodological slogan that he “always likes the Lockean method better than Wolffan coercion” (REV 54). His own aim is accordingly to organize the various branches of philosophy in a Lockean fashion. Abolishing the Wolffan division of metaphysics into ontology, psychology, cosmology, and natural theology,9 he reduces the felds of theoretical philosophy to the twin disciplines of psychology and logic. Meiners claims that they are very closely connected but does not explain their connection in much detail.10 However, he goes as far as dubbing psychology “esoteric logic,” thus suggesting that psychology and logic are subdivisions of one and the same discipline. Meiners’s further division of the twofold discipline of esoteric logic resembles to some extent the four books of Locke’s Essay: the frst part treats of ideas, the second of the connection of ideas and of the powers and faculties of the mind, the third one deals with language, and the fourth one with knowledge and error as well as with the limits of human knowledge.11 This is, however, just a programmatic consideration that he does not pursue further in Revision. Notably, Revision does not include clear indications of materialism. Meiners is generally less outspoken in this regard than Hißmann, though there are a number of indirect indications of materialism in his other works.12

2 Hißmann’s Anti-Metaphysical Materialism Following Meiners, Hißmann notes in Briefe über Gegenstände der Philosophie that metaphysics is not much more than a collection of “sophisms that are passed off as the foundations of science and human knowledge.”13 Most of its parts should hence either be transferred to other disciplines or abandoned altogether as “fruitless nominal explanations or empty speculations that lack a secure philosophical grounding.”14 Accordingly, in his Psychologische Versuche Hißmann suggests to relocate cosmology to physics and rational theology to ethics, and “other remains of metaphysics” to logic. Psychology is for Hißmann the only branch of former metaphysics that has a right to exist as such when properly modifed, i.e., transformed into an empirical discipline, and thus, he maintains that rational psychology merely reduces mental phenomena to “arbitrary notions” (PsV 11). Hißmann also agrees with Meiners that the useful parts of metaphysics should be elaborated according to the example of Locke. Like Meiners, he praises Locke throughout his work and considers his refutation of innate ideas and the theory of inner sense in particular as standard-setting (PsV 93–96). Concerning his affrmation of the possibility of thinking

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matter, he claims that “Locke has seen this clearly, and undoubtedly here as in others matters much better than those who have considered him weak due to this claim [that matter can think]” (PsV 270).15 These methodological considerations are at the basis of Hißmann’s own attempts at empirical psychology. He asks the rhetorical question of “whether inquiries into the nature of the soul should be decided by deep speculation or by experience” (PsV 10), obviously giving preference to the latter. Apart from Locke, he mentions a number of philosophers who could serve as examples in elaborating the feld of human psychology: Etienne Bonnot de Condillac, Claude Adrien Helvétius, Charles Bonnet, David Hartley, Edward Search (Abraham Tucker), JeanBaptiste-René Robinet, Joseph Priestley, and Johann Christian Lossius. Signifcantly, while these authors could be rated among the empiricists, broadly conceived, not all of them are materialists. Even though Hartley and Bonnet, as well as Condillac and Lossius, advance theories that have a lot in common with materialism, they are proclaimed dualists.16 In fact, only Helvétius, Robinet, and Priestley were known as materialists. This makes it clear that Hißmann’s primary concern was not to advance a materialist account of the human mind but rather a methodological one: he supports those who investigate the mind based on observation and experience. He thus agrees with those philosophers who share this observational approach even when they arrive at different conclusions as to the fundamental nature of the mind, i.e., whether it is a material substance or an immaterial one and, hence, whether material substances can think or not.17 However, the materialism controversy is not just of secondary importance here: according to Hißmann, experience-based approaches to the human mind were often rejected precisely because they were suspected of leading to materialism, so their opponents identifed them with “the notorious doctrine of the materialists” (PsV 12) and hence ignored them because of this potential danger. As regards the method to be employed in empirical psychology, Hißmann argues that demonstrations and “dogmatism” are particularly inapt for the doctrine of soul (PsV 18). In his view, we do not have access to the soul qua simple substance. Our conceptions of such substances are merely based on negations of the known attributes of material objects: “All proofs of the possibility of immaterial, spiritual beings are insuffcient, as much as it is impossible to prove the contrary, since we have no experiential idea of spirits.” (PsV 262). He thus demands “[m]ore spirit of observation (Beobachtungsgeist), and more attention to statements of fact (Thatsätze)” and argues that one should be “content with probabilities where no certainty is possible” (PsV 19). But what kind of experience and observation of the mental is available? It would be quite common to resort to introspection and ‘inner sense’ here, but that is distinctly not what Hißmann suggests.18 According to him, also empirical psychology often includes too much

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speculation and depends on preconceptions that are not fully warranted by experience and observation. As he puts it, “[o]ne studied oneself; but with a surprising partiality that one is not used to apply to the study of the natural history of other things in the world” (PsV 247). Hißmann thus seems to think that we lack a direct experiential access to the mind altogether. At the same time, he denies that we can be acquainted with simple substances due to their very nature, as was discussed above. So we can obtain neither an a priori proof nor any experience whatsoever of an immaterial mind, and introspection is unhelpful as well. That is why Hißmann claims that the kind of observation required in psychology must be based on the sciences. Instead of relying on introspection, Hißmann emphasizes “some key observations of the medical doctors” (PsV 247), i.e., he considers physiology and medicine to be the main sources of philosophical inquiry into the human mind.19 According to him, “one must become a physiologist and anatomist in order to be a psychologist” (PsV 250). He acknowledges the importance of experimental methods and suggests, more specifcally, that psychologists, “in order to conduct experiments with the soul, set the body into an extraordinary condition, or determine those times when the body puts itself into an unusual state due to diseases” (PsV 250). In present-day idiom, one might thus call Hißmann’s materialism ‘naturalistic.’ Hißmann accordingly provides a detailed discussion of the physiology of the brain and the nerves in the frst section of Psychologische Versuche. Among other things, he advances a hypothesis about the infuence of the “specifc weight” of the brain on mental capacities (PsV 19–21) and argues that the nerves are the only parts of the body that can have sensations. 20 On his account, nerves are divided into innumerable threads, which themselves are divided into a yet higher number of invisible fbres. 21 According to Hißmann, we can conclude from the constitution of the nerves that the brain is composed like the nerves and is itself composed of nerves. 22 Hißmann conceives of the complex structure of the nerves and the brain as the physiological basis of the complexity of human thought (PsV 34). However, he acknowledges that since we are only superfcially acquainted with the inner structure of the brain, our theorizing about it is provisional. That is one of the reasons why we can obtain only probable knowledge in this feld. In addition, Hißmann addresses quite a few much-debated questions concerning nerve and brain physiology, among them the question of how the size of the brain is determined in relation to the size of the body of a living creature (PsV 35–27) and the question of whether creatures without a brain can sense (PsV 39–40).23 He denies that the nerves unite in one determinate point in the brain that allegedly constitutes the seat of the soul. Appealing to what we can learn from appearances, he argues in this regard that “the entire brain must be viewed as the collection point (Sammelplatz) of all nerves” (PsV 41). Concerning the question

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as to whether sensation takes place in the nerves or only in the brain, Hißmann argues that we are as yet unable to settle the question (PsV 42–26, 104–5). As to nervous conduction, Hißmann weighs the evidence for the traditional nervous fuid hypothesis (supported by Haller) and the Newtonian vibration hypothesis advanced by Hartley. While he sides more with Haller in this regard, he mentions a few cases that appear to support the Newtonian hypothesis (PsV 46–54). 24 Hißmann also argues against Bonnet’s hypothesis that there is a specifc kind of fbre for each kind of sensation (PsV 58–62). Moreover, Hißmann discusses a few observations that specifcally support materialism about the human mind, whereas those discussed so far seem rather neutral in this regard. Among them are, not surprisingly, the correlation of the strength of higher and lower mental capacities “with the strength of the inner and outer mechanism of the body and the advantageous or disadvantageous constitution of the solid and liquid parts of the body” (PsV 248). If the brain is impaired by diseases, early or old age, or medication, mental capacities necessarily decline proportionally, according to Hißmann. He insists, however, that experience reveals nothing more than that “in order to have the capacity of sensation and perception, the nerves must be continuously connected to the brain in the position assigned to them” (PsV 88). Thus, experience shows that we need both nerves and a brain in order to think, but does not allow us to obtain more far-reaching insights into the human mind or mental processes. According to Hißmann, what we experience suffces to explain all known mental phenomena, i.e., there is no need to resort to the notion of an immaterial soul on this score either. While we do have sense-based knowledge of composite beings such as the nerves and the brain, we have no knowledge of immaterial beings and can consistently explain all known mental phenomena without resorting to them. But we also know from experience, he writes, that corporeal substances have the basic ability to sense, an ability that is the foundation of all other abilities of the soul. Our nerves, a visible corporeal substance, have sensations, and when they are connected to another corporeal part of the human being, we are aware of the sensation. (PsV 263) Moreover, Hißmann argues that these corporeal substances also have memory and imagination. Appealing to experiments, he mentions how a glowing twig that rapidly moves in a circle causes the impression of a glowing circle. His point here seems to be that without at least shortterm memory there would be no perception of a circle. Hißmann also argues (albeit without citing further experiments) that the nerves and the brain have the capacity to compare impressions, memories, and ideas.

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This comparison is, according to Hißmann, tantamount to judgment and syllogism, which makes it obvious that he believes that reason can be explained on a material basis as well (PsV 265). Even more, Hißmann at one point argues that dualism contradicts experience due to the observations discussed above, according to which mental capacities rise and decline in proportion to the condition of the body. Since simple substances by defnition cannot lose any parts, the immaterial soul would remain unaffected by bodily states if it really existed (PsV 248–49). Thus, Hißmann eventually affrms that matter can think, though he concedes that further details of how it can do so remain as yet unknown. As he puts it: “I believe that matter indeed can think, according to the most rigorous reasonings, if it is organized in a certain way that I, however, do not want to determine any further since I have a very limited knowledge of the brain” (PsV 270). Thus, we can reasonably assume that organized matter can think, but what kind of organization exactly is required is beyond the limits of our cognition. More precisely, what we could decide in case we had the appropriate (scientifc) experience is whether the power of thought arises from “simple, non-thinking elements” or not (PsV 276). Yet another possibility that Hißmann considers is that the brain is composed of a kind of matter specifc only to brains, but again there is no way to know this for sure.

3 Metaphysical Aspects of Hißmann’s Materialism As was discussed in the previous section, the main lines of Hißmann’s materialism are distinctly anti-metaphysical. However, Hißmann does not consider metaphysical discourse in relation to materialism and philosophical psychology entirely impossible. He discusses a few metaphysical problems in Psychologische Versuche and goes into much more detail in his price essay contribution Fundament der Kräfte. Even though Hißmann’s work has attracted some attention in recent scholarship, Fundament der Kräfte has not been looked at in any detail so far, partly because it was hardly known that Hißmann is the author of this text. In what follows, I will frst provide some information on the publication history of Fundament, then discuss the metaphysical hints in Psychologische Versuche, and fnally turn to some of Hißmann’s metaphysical views in Fundament. To the best of my knowledge, this is the frst more detailed account of this complex text, which obviously cannot be treated fully suffciently here. 3.1 The History of Hißmann’s Fundament der Kräfte Hißmann’s essay “Versuch über das Fundament der Kräfte” (“Essay on the Foundation of the Powers”) was originally submitted to the Berlin

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Academy price essay contest for 1779, which had the title “Das Wesen und die Einschränkungen der Kräfte” (“The Nature and Limitations of the Powers”). 25 Hißmann published his essay anonymously in the Magazin für die Philosophie und ihre Geschichte, a periodical edited by himself. 26 Hißmann’s authorship is revealed in a letter to Johann Bernhard Merian, secretary of the Berlin Academy. In this letter, Hißmann requests a copy of the essay he had submitted to the contest of 1779, and he asks Merian not to judge my philosophical ways of thinking according to the manuscript on the foundation of power, which you have kindly read. I have said many things there that I cannot consider altogether correct; just because it was expected that way in Berlin. The entire price essay question was designed completely according to the Leibnizian system on which in particular the late Cochius had insisted too frmly. I prefer the Lockean and the Condillacean way of philosophizing greatly, and I am happy to walk with you on the same path. 27 This letter reveals not only that Hißmann was the author of the article but also that he tried to accommodate his views to the Leibnizian assumptions behind the essay competition. The letter to Merian has a tactical aspect as well, since Hißmann ostensibly sides with Merian and the empiricist faction of the academy against those who were leaning more toward Leibniz and Wolff, such as Johann Georg Sulzer. 28 In the essay itself, Hißmann discusses at some length how the contest question ought to be understood. The essay sets out from the observation that nature is full of effects and concludes that there must be determinate powers to explain them. Accordingly, Hißmann stresses that “one has to assume that something real and persisting exists that can be determined” and that this “real and persistent [being] is what is called an original and substantial power” (FU 9). In addition, he considers the prize question to aim at the notorious dispute between adherents of pre-established harmony and physical infux: whereas infuxionists are asked to provide a “distinct concept of the original, passive power and how it is affected by another power,” harmonists are requested to establish, in Hißmann’s words, “how and by what these powers are limited and why it is that the same power sometimes has an effect that at another time it cannot occasion” (FU 10). Whereas one would expect Hißmann, as a materialist, to reject both options, he in this essay in fact exhibits some sympathy with the idea of pre-established harmony, as I will discuss below. Since Hißmann elaborates on metaphysical themes in relation to materialism in more explicit terms in Psychologische Versuche, I will turn to this work frst.

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3.2 Hißmann’s Metaphysical Considerations in Psychologische Versuche In spite of the anti-metaphysical attitude Hißmann displays in Psychologische Versuche, the text contains quite a few potential metaphysical arguments in favor of materialism and against dualism. 29 He lists and briefy discusses seven of them in this work, aiming to show that a metaphysical approach to materialism is possible even though he considers that based on experience and observation more conclusive: 1

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Hißmann asserts that the principle of continuity, or the great chain of being, can be used to oppose dualism. If the principle were true, dualism would face the diffculty of how to explain both the essential difference between body and soul and that between higher animals and human beings (PsV 277). However, Hißmann acknowledges that principles such as that of continuity are not fully warranted by experience, which is why he does not attach great importance to it in his own endeavors. Hißmann refers to the notorious problem of the interaction between material and immaterial substances: how can the human being be composed of two entirely heterogeneous substances, and what kind of connection is possible between simple and material (i.e., compound) substances? (PsV 277). This diffculty does not arise in materialism since it avoids dualism altogether. A more specifc metaphysical problem Hißmann points to is the question as to how the soul is able to take up space without being extended, as it should be able to do in order to interact with the body (PsV 278). The dualist claim that souls are simple raises the problem of how they can be distinguished from one another, since they have no easily identifable differences, though one might object here that immaterial souls could be distinguished from one another by their different representational states (PsV 278). According to Hißmann, one could object to the dualists that the alleged simplicity and immateriality of the soul are merely negations of the attributes of material objects and thus not positive attributes at all (PsV 278). On a few occasions, Hißmann puts forward some more general considerations concerning the nature of matter, considerations that he elsewhere deems redundant. It was common among opponents of materialism to argue that matter is inherently passive and inert. But Hißmann argues that there is actually no proof that matter is entirely passive and that the phenomena of tempests, magnetism, electricity, or gunpowder explosions rather point to the opposite

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Falk Wunderlich (PsV 272).30 Whereas this is a widespread materialist argument, the second one Hißmann offers is less common: he also questions that thought is inherently active. As he puts it, matter “is only endowed with inertia, and inactivity, and passion.—False premises, false conclusion! Has it, then, been established that the capacity of thought is activity? […] And has it been established that matter is entirely passive?” (PsV 272). Although he does not elaborate on this issue, Hißmann affrms the possibility of emergent properties—i.e., properties of a whole that cannot be reduced to those of its parts but that genuinely arise from the combination of those parts—and that the particles alone do not possess. As he puts it: And indeed the collection and combination of certain things can have certain consequences that one would have expected from the components in vain. Is the proposition really beyond doubt that no living whole can be composed of inanimate parts, and no thinking whole from unthinking parts? (PsV 276)31

Hißmann thus considers two of the main explanatory options materialist theories have at a metaphysical level: to conceive of matter as something that is in some way self-active, i.e., able to initiate activity, or to hold that certain combinations of particles may give rise to emergent properties. 3.3 Metaphysical Issues in Fundament der Kräfte: Hume and Leibniz In Fundament der Kräfte, Hißmann claims that he has compared the relevant concepts “with many experiences, and restricted, extended, and rectifed them according to the demands of these experiences” (FU 7–8). He admits, however, that this is a diffcult endeavor, since “human knowledge is fragmentary (Stückwerk), especially in speculations of this kind” (FU 8). Hißmann thus juxtaposes experience and speculation (cf. FU 13–15, 17). He also notes that observation is essential for determining what he deems “relative” basic powers such as the force of inertia (FU 68). Hißmann provides a general explanation of power as the principle or the source of effcacy and of modifcations: effcacy is to contain a ground of a thing or an event, and a ground is “the condition, the affection of a thing, from which we can comprehend (begreifen) why another thing exists” (FU 19). He holds that we can only comprehend events that have occurred commonly and frequently. Only events of this kind can be conceived, and what differs from the common is incomprehensible. Accordingly, he characterizes power as the aspect of a thing whose existence we assume because we fnd that this or that is commonly connected to the thing; and because it

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would appear strange to us if we recognized that nothing, or at least not what is commonly connected to it, is connected to that thing (FU 20) Hißmann argues that no philosopher has been able to analyze the essence of power any deeper than this in the past and that it is probably impossible to proceed any further. He holds, however, that we can still inquire into the origin of the idea of power, which is enough to establish the reality of that idea. According to Hißmann, Locke was the frst to engage with the origin of our idea of power in an appropriate way: “The Lockean analysis of the concept, or better, the way he traces it back to its sources, is quite right” (FU 30). More specifcally, Hißmann seems to agree with Locke that the outer senses and the inner sense are two independent sources of the concept of power: through the outer senses, we recognize that external objects cause modifcations in other external objects (or destroy or replace them), and for this reason we attribute powers to the former. Our internal feeling also provides us with the concept of power, for instance when we observe that we are able to modify our ideas, pay attention to them or associate them, or when we move our bodily organs according to our will. This Lockean, genetic kind of explanation is Hißmann’s methodological ideal. Hißmann discusses two opponents to this Lockean explanation of power in the Fundament: Lord Kames (Henry Home) and David Hume. According to Hißmann’s reconstruction, Kames held that reason cannot be the source of our concept of power because “there is no syllogism that leads us to assume a power in any kind of body” (FU 34). 32 Hißmann agrees with Kames insofar as he argues that reason requires “data” to fll in the premises of syllogisms. However, contrary to Kames he thinks that these data are in fact available to us. He maintains, in other words, “that power is among the qualities and features of the things and beings in us and around us that we discover by our inner and outer senses. Hence, the most certain data that reason can process are available, namely, data provided by experience” (FU 33). Reason is not a “warehouse of knowledge isolated from experience,” according to Hißmann (FU 36). However, he contends that, since reason does not provide any a priori knowledge, the entire dispute eventually boils down to the question as to “whether experience leads us to the concept of power” (FU  36). Whereas Hißmann holds that it does, Kames denies that this is the case. Hißmann agrees with Kames that “[o]ur concept of power does not include anything beyond the constant conjunction of a pair of objects” (FU 37). Contrary to Kames, however, he believes that the concept of power refers to this constant conjunction alone. As regards David Hume, it is important to note that Hißmann does not fully reject his theory of causality but rather argues that it is true when applied to the concept of power alone. According to Hißmann, the concept of power can indeed be traced back to our perception of

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the constant conjunction of similar events. Hume’s error, according to Hißmann, is that he transferred his correct analysis of the concept of power to the concept of causation (FU 50–51). Hißmann thus seems to think that there is in fact a deeper distinction between power and causation than the one Hume acknowledged.33 He agrees with Hume that our concept of causation, like that of power, rests on the perception of constant conjunction, but he holds that “that is not all” (FU 52), i.e., that the concept of causation includes signifcantly more than that of power. According to him, we not only perceive a constant conjunction between certain events, but, as a matter of fact, also conceive of this conjunction as a necessary and coercive one. As Hißmann puts it: We notice that a certain modifcation occurs when a certain object is present, and that this modifcation never occurs otherwise, unless that object is present; eventually, [we notice that] in order to make sure we obtain a certain effect, we necessarily have to make certain arrangements, without which that effect does not occur.34 Obviously, this criticism of Hume is not very compelling, since Hißmann merely maintains that we can grasp a causal connection over and above the constant conjunction of similar events. Hume does not deny that the common notion of causation includes necessary connection. However, he argues at length that this notion lacks justifcation, since there is only an impression of repeated, regular co-appearance of certain events but not one of necessary connection.35 Yet Hißmann also has a better point against Hume: he argues that we do not conceive of all perceptions of constant conjunctions as causal connections, i.e., that some constant conjunctions are too weak to count as instances of causality: It is possible that things are constantly together, and follow constantly after one another, that do not stand in the relation of cause and effect to each other; we can also conceive of these constant successions of sensations often and constantly and yet not have the idea of cause and effect. (FU 52–53) Thus, according to Hißmann it is unclear how Hume, given the premises of his regularity theory of causality, can account for perceptions of constant conjunctions that we do not interpret in causal terms. This point resembles one of Thomas Reid’s arguments against Hume.36 What these arguments have in common is that they draw attention to cases of constant conjunction of events that have to be distinguished from causal relations proper. The second part of Fundament testifes to Hißmann’s mitigated appreciation of Leibniz’s monadology at least as a consistent hypothesis.

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This appreciation corresponds to his 1783 Versuch über das Leben des Freyherrn von Leibniz, where he, along similar lines, combines his esteem for Leibniz with harsh and polemical criticism of Wolff and his followers but without discussing metaphysical issues in much detail. 37 Although the tone of Fundament is more conciliatory, Hißmann in this text likewise takes issue with Wolff. For instance, he complains that Wolff presents a reduced version of pre-established harmony, in contrast to Leibniz’s more ambitious and “real” version of it (FU 77). Hißmann argues in Fundament that Leibniz’s Monadology convincingly demonstrates, among other things, that monads cannot physically interact because they lack parts and fgure (FU 84). 38 First, we have to distinguish simple things from composite ones (i.e., material bodies), which in reality are aggregates of substances. Second, the simple things of which the composite ones are assembled are indeed Leibnizian monads, i.e., without fgure and extension, “in a hypothetical sense” (FU 80). That Leibniz’s demonstration was successful in Hißmann’s view presumably means that he took him to have put forward a consistent theory. What renders Leibniz’s theory hypothetical, according to Hißmann, is that there remains an alternative theory that he cannot refute. This theory maintains that the elements in question are not necessarily unextended monads but could also be extended, continuous solids (FU 82). 39 Hißmann argues that it is impossible to decide in favor of one of these theories on rational grounds. But he is clear that if the world were ultimately composed of simple elements, the latter would have to be like Leibnizian monads: “Provided that the elements of bodies are composed of simple things: these could not be Epicurean atoms, not Crusian simple entities, but they would have to be Leibnizian monads.” (FU 81). This is quite a surprising statement for a naturalistic materialist. However, as was mentioned above, Hißmann qualifes his conclusion by arguing that experience does not provide us with access to the elements of bodies, and the explanatory advantage of pre-established harmony he had mentioned earlier—that monads cannot interact—is, on closer inspection, only apparent. As he puts it, “their alleged interpenetration does not appear to be advantageous because all our previous experience does not point to any method according to which we could conceive its possibility” (FU 83–84, cf. 73). Hißmann thus concludes that we cannot arrive at a satisfactory decision in favor of one of the ‘three systems’ of mind-body interaction (FU 89), even though pre-established harmony is a more consistent theory than occasionalism and physical infux. The problem that remains for pre-established harmony, according to Hißmann, is that it is based on the assumption that the world is ultimately composed of simple elements, an assumption that cannot be corroborated by experience.

132 Falk Wunderlich Hißmann’s discussion of Leibniz raises the question as to whether it is more than an intellectual exercise undertaken for the purpose of the price essay contest. There are indeed good reasons to think that Hißmann had a genuine interest in Leibniz, although at frst sight one might think that the differences between Leibniz’s ontology and a materialist one are profound: among other things, the mill example in the Monadology— where Leibniz argues that mental phenomena can in no way be explained by physical motion—suggests that Leibnizian and materialist theories have hardly anything in common.40 But this is so only if one fell prey to the myth that early modern materialism is primarily mechanistic, i.e.,  that it is based on the view that matter as such is passive and that mental phenomena can be explained completely in terms of pressure and impact.41 In fact, there were hardly any mechanistic materialists. Quite the contrary: almost all early modern materialists assumed, in a variety of ways, the possibility of self-induced activity in matter. To name a few examples: John Toland held that matter as such is active and thus can serve as the ontological basis of more elaborate activities such as thought.42 Paul Thiery d’Holbach likewise argued (on an Epicurean basis) that motion is essential to matter and thus does not depend on external impact.43 Joseph Priestley, who is of particular importance to Hißmann, argued that matter as such is composed of two forces—attraction and repulsion—and thus active at the most fundamental level.44 Against this backdrop, it is clear why Hißmann and other German materialists were to some extent attracted to Leibniz.45 First, Leibniz’s ontology is essentially monistic, since monads are the only basic elements of the world. Second, Leibniz considered these elements to be inherently active, since all monads have appetitions. Although Hißmann does not carry his own speculations as far as this, his materialism has a lot more in common with power-based monadology than with dualist ontologies, and he is apparently interested in exploring these connections in spite of his general anti-speculative attitude.46

4 Conclusion Michael Hißmann’s materialism emerged from the Göttingen antiWolffanism and empiricism represented by Christoph Meiners and, to a lesser extent, Johann Georg Heinrich Feder. For the most part, Hißmann designed his materialism as an anti-metaphysical endeavor that is based on experience. Notably, he relied not on inner experience or ‘intuitions’ (in present-day parlance), but on the sciences, in particular on medicine and physiology. On the other hand, he did not entirely avoid metaphysical discussions of issues concerning materialism, although he often denounces them as speculative, as becomes obvious both from his Psychologische Versuche and, even more, from Fundament der Kräfte.

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Notes 1 This work was supported by the Deutsche Forschungsgemeinschaft (DFG) under grant WU 695/1–2. 2 This denial dates back to Lange (1866). On the history of early modern materialism in general, see Thomson (2008), Wilson (2008), Wolfe (2016), and Yolton (1983, 1991). 3 Recent studies dealing with German materialism in the 1770s include Thiel (1997), Rumore (2013), Klemme et al. (2012), and Wunderlich (2016a). 4 See Hupel (1774), Selle (1776), (1780), Spazier (1785), Knoblauch (1787, 1790), and Hißmann (1777); for an account of other German materialists of the 1770s, see Wunderlich (2016a). 5 Knoblauch writes, for instance: “The immediate concept that a really existing single thing (an individual) has of itself is called the soul (mens) of that single thing. The single thing itself, as the immediate object of this concept, is called body” (Knoblauch 1787: 190). 6 See Knoblauch (1787: 188). 7 See Wunderlich (2012b, 2018) for more details on Göttingen philosophy and its context; see Wunderlich (2012a, 2012b) in particular on the close relation between Meiners and Hißmann and the role of Feder. 8 All translations of Meiners’s and Hißmann’s texts are mine. 9 In his German Metaphysics, Christian Wolff divided metaphysics into, on the one hand, ontology (later dubbed metaphysica generalis) and, on the other hand, empirical and rational psychology, cosmology, and natural theology (later dubbed metaphysica specialis). 10 REV 53–54. Hißmann echoes this in the subtitle of his Psychologische Versuche, ein Beytrag zur esoterischen Logik (1777). 11 REV 53–54, cf. 161–62. Meiners also here explicitly links this endeavor to Locke’s method. 12 For instance, Meiners criticized anti-materialist arguments (1776a: 25) and published sympathetic reviews of the materialist Joseph Priestley’s philosophical writings (1776b). 13 Hißmann (1778a: 43); Hißmann here explicitly refers to Meiners’s Revision as the model of his own endeavours. On this aspect, see Thiel (2012). 14 Hißmann (1778a: 19). 15 Locke argues that our cognitive means do not enable us to exclude the possibility that God might have endowed matter with the capacity of thought despite its own nature (Essay IV.iii.6). 16 See Bonnet (1770: I, 6), Hartley (1749: I, 33; I, 511), Condillac (1746: 7A), Lossius, PU 164–65, and Lossius (1777: 191). On Bonnet’s peculiar dualism, see Kaitaro (2004). 17 On this aspect, see Thiel (2012). 18 On the historical development of the role of introspection in philosophy, see Lyons (1986). 19 See Hißmann, PsV 22 and Hißmann (1778b: 150). 20 Hißmann, PsV 33; see Hißmann (1778a: 76–78). What he means by the “specifc weight” of the brain is in fact the inner complexity of the latter. 21 See the reference to William Potterfeld in Hißmann (2015: 301); see also Hißmann (1778a: 65). 22 Hißmann, PsV 34. Referring to what is today called the white matter (substantia alba), Hißmann speaks of the Gehirnmark here. See also Hißmann (1778a: 69). 23 Hißmann mentions Albrecht von Haller as his main scientifc reference here.

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24 Cf. Haller (1757–1780: vol. 4, 241–42). The entire frst part of Hartley (1749) advances his vibration theory. 25 What kind of contributions this price essay contest was aiming at was apparently not obvious, since Hißmann himself asked Sulzer and Cochius to specify what they expected. See Hißmann’s letter to Merian (Hißmann 2016: 105). 26 Hißmann (1783a). 27 Hißmann (2016: 112). Referring to the letter to Merian, Buschmann (1989: 217) also mentions that Hißmann was the author of the essay in question. 28 It is important to note that Hißmann was still seeking academic employment during this time and became außerordentlicher Professor only in 1782, which may explain some of the tactics involved. 29 This section closely follows Wunderlich (2016a: 949–51). 30 See Duncan (2016) and Wunderlich (2016b, 805–7). 31 On this, see Wunderlich (2016a: 951–52, 2016b: 805–7). 32 Hißmann’s reference is a German translation of Kames’s Essays on the Principles of Morality and Natural Religion (Kames 1786 [1751]). 33 According to Hume, the concepts of effcacy, agency, power, force, energy, necessity, connexion, and productive quality are nearly synonymous (Hume T 1.3.14.2) and are at the basis of his defnition of causation (Hume T 1.3.2.10). 34 Hißmann, FU 50. The German text is diffcult to translate here. It reads: “Wir bemerken, daß sich, bey der Gegenwart eines gewissen Dinges, eine oder mehrere Veränderungen ereignen, und daß diese Veränderungen sonst nie kommen, als wenn jenes Ding da ist; daß wir endlich, wenn wir einen Erfolg zuverlässig haben wollen, nothwendig gewisse bestimmte Anstalten machen müssen, ohne welche jener Erfolg nie zu kommen pfegt.” 35 See, for example, Hume, EHU 5.35–45 and 7.49–61. Hißmann refers to Joseph Priestley as a main source of his understanding of causality, quoting (partly incorrectly) from Priestley (1777b: 11); see FU 50; cf. 30. Priestley actually writes: “For a cause cannot be defned to be any thing but such previous circumstances as are constantly followed by a certain effect; the constancy of the result making us conclude that there must be a suffcient reason in the nature of the things why it should be produced in those circumstances.” 36 Reid (1788: 253). 37 Hißmann (1783b: 53–58) addresses monadology and pre-established harmony only by way of an outline. 38 “In addition, the inventor of the system of pre-established harmony has been able to give such a good metaphysical ground to the proposition that substances cannot act upon each other as one can imagine” (FU 79). Hißmann takes Leibniz’s Monadology to be the representative expression of the latter’s doctrine here (FU 80). He refers to the Dutens edition of Leibniz’s works, in which the Monadology is titled Principia philosophiae, Seu Theses in gratiam Principis Eugenii &c. (Leibniz 1714); the reference in Hißmann’s text is to Principia philosophiae. 39 Hißmann provides an extended discussion of this theory in the footnotes (FU 82–84). Presumably, he seeks to establish the possibility of a kind of atomism here, although he explicitly rejects Epicurean atomism (FU 81). 40 Leibniz (1714: 609). 41 For discussions of alternatives to this mechanistic understanding of early modern materialism, see Thomson (2008), Wolfe (2016), and Wunderlich (2016b). 42 Toland (1704: 163–239).

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43 D’Holbach (1770: vol. 1, 38–48). 44 Priestley (1777a) argues at length for this. On Priestley, see Wolfe and Wunderlich (2020). 45 See, for instance, August Wilhelm Hupel (1774); on Hupel, see Wunderlich (2016c). 46 On Leibniz’s metaphysics as a resource for materialism, see Wolfe (2014: 96–99; 2016: 15). Vartanian (1960: 63) discusses this issue in relation to La Mettrie.

Bibliography Author names in square brackets indicate anonymous publications. Primary Sources Bonnet, Charles (1770), Analytischer Versuch über die Seelenkräfte, transl. by C.G. Schütz, Bremen: Cramer; translation of Essai analytique sur les facultés de l’âme, Kopenhagen: Philibert 1760. Condillac, Étienne B. de (1746), Essai sur l’origine des connoissances humaines, in Oeuvres philosophiques de Condillac, ed. by G. LeRoy, Paris: Presses Universitaires de France, 1947, 1–118. [D’Holbach, Paul-Henri T.] (1770), Système de la nature, London: [s.n.]. Haller, Albrecht von (1757–1780), Elementa physiologiae corporis humani, 8 vols., Lausanne: Grasset. Hartley, David (1749), Observations on Man, His Frame, His Duty, and His Expectations, London: Richardson. [Hißmann, Michael] (1777), Psychologische Versuche, ein Beytrag zur esoterischen Logik, Frankfurt/Leipzig: [s.n.] (PsV). Hißmann, Michael (1778a), Briefe über Gegenstände der Philosophie, an Leserinnen und Leser, Gotha: Ettinger. ——— (1778b), Anleitung zur Kenntniß der auserlesenen Litteratur in allen Theilen der Philosophie, Göttingen/Lemgo: Meyer. [Hißmann, Michael (1783a), ‘Versuch über das Fundament der Kräfte. Bey Gelegenheit der von der Königlichen Akademie der Wissenschaften in Berlin für das Jahr 1779 aufgegebenen Preisfrage’, in M. Hißmann (ed.), Magazin für die Philosophie und ihre Geschichte, Göttingen/Lemgo: Meyer, vol. 6, 4–110 (FU). Hißmann, Michael (1783b), Versuch über das Leben des Freyherrn von Leibniz, Münster: Perrenon. ——— (2015), Ausgewählte Schriften, ed. by U. Roth and G. Stiening, Berlin: De Gruyter. ——— (2016), Briefwechsel, ed. by H-P. Nowitzki, U. Roth, G. Stiening and F. Wunderlich, Berlin: De Gruyter. Hume, David (2007), An Enquiry Concerning Human Understanding, ed. by P. Millican, Oxford: Oxford University Press; 1st edn. 1748 (EHU). [Hume, David] (1978), A Treatise of Human Nature, ed. by P.H. Nidditch, Oxford: Clarendon Press, 1st edn. 1738 (T). [Hupel, A. W.] (1774), Anmerkungen und Zweifel über die gewöhnlichen Lehrsätze vom Wesen der menschlichen und der thierischen Seele, Riga: Hartknoch.

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Kames, Henry Home (Lord) (1768 [1751]), Versuche über die ersten Gründe der Sittlichkeit und der natürlichen Religion, in zween Theilen, transl. by C.G. Rautenberg, Augsburg: Trattner. [Knoblauch, Karl von] (1787), ‘Ueber das Denken der Materie’, Der Teutsche Merkur. September 1787, 185–97. ——— (1790), Die Nachtwachen des Einsiedlers zu Athos (n.p.). [Meiners, Christoph] (1772), Revision der Philosophie. Erster Theil, Göttingen/ Gotha: Dieterich (Rev). Meiners, Christoph (1776a), Vermischte philosophische Schriften, Leipzig: Weygand. [Meiners, Christoph] (1776b), [Review of] Joseph Priestley, Hartley’s Theory of the Human Mind, on the Principle of the Association of Ideas, London 1775, Göttingische Anzeigen von gelehrten Sachen, 1, 249–53. Leibniz, Gottfried W. (1714), ‘Principia philosophiae, Seu Theses in gratiam Principis Eugenii &c.’, in Gothofredi Guillelmi Leibnitii … opera omnia, ed. by L. Dutens, Geneva: Fratres de Tournes 1768, vol. 2, 20–31; repr. in Die philosophischen Schriften von Gottfried Wilhelm Leibniz, vol. 6, ed. by C.I. Gerhardt, Hildesheim: Olms 1965, 607–23. Locke, John (1975), An Essay Concerning Human Understanding, ed. by P.H. Nidditch, Oxford: Clarendon Press; 1st edn. London: Thomas Basset 1690 (Essay). Lossius, Johann Christian (1775), Physische Ursachen des Wahren, Gotha: Ettinger (PU). ——— (1777), Unterricht der Gesunden Vernunft, Gotha: Ettinger. Priestley, Joseph (1777a), Disquisitions Relating to Matter and Spirit, London: Johnson. ——— (1777b), The Doctrine of Philosophical Necessity Illustrated, London: Johnson. Reid, Thomas (1788), Essays on the Intellectual Powers of Man, in The Works of Thomas Reid, D.D., ed. by W. Hamilton, vol. 2, Edinburgh: MacLachlan and Stewart 1863 (6th edn.), 215–540. [Selle, Christian G.] (1776), Urbegriffe von der Beschaffenheit, dem Ursprunge und Endzwecke der Natur, Berlin: Himburg. ——— (1780), Philosophische Gespräche, Berlin: Himburg. [Spazier, J.G.K.] (1785), Anti-Phädon, oder Prüfung einiger Hauptbeweise für die Einfachheit und Unsterblichkeit der menschlichen Seele, ed. by W. Krauss, Berlin: Akademie-Verlag, 1961. Toland, John (1704), Letters to Serena, London: Lintot. Wolff, Christian (1751), Vernünfftige Gedanken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt, 11th edn., Halle: Renger; repr. in Gesammelte Werke, I.2, Hildesheim: Olms 1983 (GM). Secondary Sources Buschmann, Cornelia (1989), ‘Die philosophischen Preisfragen und Preisschriften der Berliner Akademie der Wissenschaften im 18. Jahrhundert’, in W. Förster (ed.), Aufklärung in Berlin, Berlin: Akademie-Verlag, 165–227. Duncan, Stewart (2016), ‘Materialism and the Activity of Matter in SeventeenthCentury European Philosophy’, Philosophy Compass, 11/11, 671–80.

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Kaitaro, Timo (2004), ‘Brain-Mind Identities in Dualism and Materialism: A Historical Perspective’, Studies in History and Philosophy of Biological and Biomedical Sciences, 35, 627–45. Klemme, Heiner F., Stiening, Gideon and Wunderlich, Falk (eds.) (2012), Michael Hißmann (1752–1784). Ein materialistischer Philosoph der deutschen Aufklärung, Berlin: Akademie-Verlag. Lange, Friedrich A. (1866), Geschichte des Materialismus und Kritik seiner Bedeutung in der Gegenwart, Iserlohn: Baedeker. Lyons, William (1986), The Disappearance of Introspection, Cambridge/ London: MIT Press. Rumore, Paola (2013), Materia cogitans. L’Aufklärung di fronte al materialismo, Hildesheim: Olms. Thiel, Udo (1997), ‘Varieties of Inner Sense: Two Pre-Kantian Theories’, Archiv für Geschichte der Philosophie, 79, 58–79. ——— (2012), ‘Hißmann und der Materialismus’, in H.F. Klemme, G. Stiening, and F. Wunderlich (eds.), Michael Hißmann (1752–1784). Ein materialistischer Philosoph der deutschen Aufklärung, Berlin: Akademie-Verlag, 25–41. Thomson, Anne (2008), Bodies of Thought, Oxford: Oxford University Press. Vartanian, Aram (1960), La Mettrie’s L’Homme Machine. A Study in the Origins of an Idea, Princeton: Princeton University Press. Wilson, Catherine (2008), Epicureanism at the Origins of Modernity, Oxford: Oxford University Press. Wolfe, Charles T. (2014), ‘Materialism’, in A. Garrett (ed.), The Routledge Companion to Eighteenth-Century Philosophy, London/New York: Routledge, 91–118. ——— (2016), Materialism. A Historico-Philosophical Introduction, Dordrecht: Springer. ——— and Wunderlich, Falk (eds.) (2020), Joseph Priestley: Materialism and the Science of the Mind. Foundations, Controversies, Reception, Intellectual History Review, 30/1. Wunderlich, Falk (2012a), ‘Assoziation der Ideen und denkende Materie. Zum Verhältnis von Assoziationstheorie und Materialismus bei Michael Hißmann, David Hartley und Joseph Priestley’, in H.F. Klemme, G. Stiening, and F. Wunderlich (eds.), Michael Hißmann (1752–1784). Ein materialistischer Philosoph der deutschen Aufklärung, Berlin: Akademie-Verlag, 63–84. ——— (2012b), ‘Empirismus und Materialismus an der Göttinger Georgia Augusta – Radikalaufklärung im Hörsaal?’, Aufklärung, 24, 65–90. ——— (2016a), ‘Materialism in Late Enlightenment Germany: A Neglected Tradition Reconsidered’, British Journal for the History of Philosophy, 24/5, 940–62. ——— (2016b), ‘Varieties of Early Modern Materialism’, British Journal for the History of Philosophy, 24/5, 797–813. ——— (2016c), ‘The “Subtle” Materialism of August Wilhelm Hupel’, Quaestio, 16, 119–37. ——— (2018), ‘Materialismus und Mortalismus in der deutschen Aufklärung’, Aufklärung, 29, 193–211. Yolton, John W. (1983), Thinking Matter: Materialism in Eighteenth-Century Britain, Minneapolis: University of Minnesota Press. ——— (1991), Locke and French Materialism, Oxford: Clarendon Press.

Part III

The Berlin Academy

7

Contingency and Experience in Maupertuis’s Essay on Cosmology Anne-Lise Rey

From 1746 to 1759, Maupertuis was president of the Berlin Academy of Sciences and Belles-Lettres, which frmly opposed the foundational function of metaphysics for the natural sciences. For this reason, he has often been presented as a Newtonian and anti-metaphysician. It is true that Maupertuis was very hostile to decisive aspects of the philosophy that preeminently represented this position, namely, Leibniz’s. Thus, he rejected the idea of pre-established harmony, the theory of monads, and the principle of suffcient reason. I will argue, however, that Maupertuis’s position as to the relationship between physics and metaphysics cannot be captured by means of the opposition between Leibniz and Newton. Despite his hostility toward Descartes, Leibniz, and Wolff, Maupertuis did not abolish the idea of a metaphysics of nature but reconfgured the classical understanding of the relationship between physics and metaphysics. Commentators tend to characterize Maupertuis’s Essay on Cosmology (1750) as either Newtonian or Leibnizian. Thus, Ernst Cassirer presents Maupertuis as one of the proponents of Newton’s thought in France.1 By contrast, Mary Terrall emphasizes the kinship between Maupertuis and Leibniz.2 André Charrak, fnally, considers Maupertuis to have developed a physical theology not based on the Leibnizian conception of possible worlds. On his account, Maupertuis “contrasts the empirical character of the laws of motion with his own deduction, which starts from divine wisdom and traces their true source to a metaphysical principle.”3 Each of these portrayals of Maupertuis is, in its own way, justifed and text-based. Yet how can we integrate these different features into a coherent image, which moreover captures the signifcance of his work in the context of the eighteenth century? How should one interpret the seemingly paradoxical case of Maupertuis? How can he defend a mechanics founded on metaphysical principles without taking sides with the ‘monadists’? Given the fact that the Essay on Cosmology claims that physical proofs do not allow us to discern divine providence, is it plausible to read the text as a manifesto for a physical theology?4

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In short, how does Maupertuis in this work conjoin experiments and metaphysical principles? As I hope to show in this chapter, an adequate understanding of Maupertuis’s innovative conception of the relationship between metaphysics and physics requires that we move beyond classical historiographical oppositions such as that between Descartes and Newton, Leibniz and Newton, or physical theology and experimental philosophy. Using Maupertuis as a prism, my larger goal is to show that the epistemic trust in experimentation of many eighteenth-century natural philosophers was joined to metaphysical considerations, which, in some cases, anticipated a purely rational insight into nature. In the frst section, I aim to determine in which sense Maupertuis is a Newtonian. The second section focuses on his account of the relationship between experience and the proofs of the existence of God. In the third section, I will argue that Maupertuis’s main epistemological innovation in the Essay on Cosmology consists in a shift from truths that can be demonstrated to truths that can be discovered by experiments, that is, truths of which the modality is probability rather than necessity.

1 Maupertuis, a Newtonian? As is well known, during his trip in Lapland between 1736 and 1737, which lasted almost one year, Maupertuis attempted to prove the Newtonian conception of the shape of the earth by carrying out exact measurements. 5 Despite Maupertuis’s appeal to key features of the empirical method, including replicability, the expedition did not settle the debate.6 On the contrary, Maupertuis was attacked by many members of the Parisian Academy of Sciences, who were generally hostile to the Newtonian position. Maupertuis’s endeavor gave rise to a huge quarrel between those who considered the earth to be fattened and those who considered the earth to be oblong.7 Ultimately, this controversy made clear that experimental proofs were insuffcient to decide the matter. Maupertuis’s failure to convince the French of the fattening of the earth by means of empirical proofs had a strong effect on his thought. It led him to combine an innovative conception of experience (understood as a set of experiments) with a metaphysics centered on teleology. In The Philosophy of the Enlightenment, Cassirer notes that Maupertuis’s account of matter in his 1751 thesis—titled Dissertatio inauguralis metaphysica de universali naturae systemate—presents a solution to the problem of the continuity between Leibniz and Newton.8 Stressing the common ground of Leibniz’s dynamics and Maupertuis’s own philosophy of nature, Cassirer writes that “his principle of least action, his formulation and justifcation of the principle of continuity […] can be traced back to Leibniz.”9 Moreover, he notes that Maupertuis

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soon realized that Newton’s principle of attraction cannot serve as a suffcient foundation for a descriptive natural science, for the understanding and interpretation of organic life.10 However, for Maupertuis there is no antagonism between the Leibnizian and Newtonian epistemic models. He rather sought to employ Leibnizian principles to provide Newtonian laws with a metaphysical foundation. As Cassirer puts it, the Dissertatio is signifcant in that “here for the frst time the attempt is made to reconcile the two great opponents in the philosophy of nature of the seventeenth century.”11 But how does Maupertuis actually proceed? Maupertuis seems to use Leibniz’s principles as a sieve through which to strain Newton’s position. This can be clarifed by turning to another text he wrote prior to the Essay on Cosmology, namely, ‘On the Laws of Attraction.’ In this text, which was published in Histoire de l’Académie Royale des Sciences in 1732, Maupertuis uses the Leibnizian principle of suffcient reason to evaluate the Newtonian theory of attraction. More specifcally, he claims that the Newtonian corpus lacks the resources to provide this theory with a metaphysical foundation and maintains that one must take recourse to Leibnizian principles for this purpose. Maupertuis presents his text as a commentary of Sections XII and XIII of the frst Book of Newton’s Principia Mathematica, which contain the theory of attraction. In a few words, Maupertuis asserts that he does not “examine whether attraction is repugnant or agrees with sound philosophy,” for he treats attraction merely in the capacity of a geometer, that is to say, as a quality, whatever it may be, whose phenomena are calculable, since it is considered to be present uniformly in all parts of matter and to be acting in proportion to its quantity.12 This geometrical approach should make it possible to engage “in a particular examination of the phenomena of the attraction of bodies” (LA 344). Maupertuis goes on to claim, frst, that the equilibrium of the parts of matter presupposes that their form is that of a spherical fgure, which is the case with all celestial bodies known to us and, second, that while attraction does not fundamentally depend on the nature of bodies, the effects of the attraction can vary according to the variations of these fgures. This is confrmed, in his view, by the fact that the earth attracts bodies and, conversely, that bodies attract the earth.13 Maupertuis draws out the implications of these assertions by noting that according to the law of attraction in inverse ratio to the square of the distance in the parts of matter, the spheres exert […] on the

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He justifes this law by invoking “the metaphysical reason of preference” and “the mathematical necessity” according to which all systems must be excluded in which “the agreement of the same law in the parts and the whole could not take place” (LA 347). In this context, he does not hesitate to appeal to God: If, then, we suppose that God wanted some body to preserve the same property that was to be present in matter, to attract bodies on all sides equally, in the same proportion, then the attraction of the parts of matter had to follow a law, such that the spherical bodies that would be formed from this matter still followed it. (LA 347) Maupertuis concludes his argument by indicating that he is well aware of “the temerity of the belief that such mysteries can be penetrated” but that “everything can be proposed provided that one does not give more weight to it than it possesses.”14 The remainder of the text consists in a mathematical explanation of Newton’s text. Maupertuis here formulates various problems and provides the mathematical proof of the general law of attraction he had initially formulated. Maupertuis’s epistemic reconfguration of the relationship between Leibnizian metaphysics and Newton’s physical theory of attraction has a twofold result. On the one hand, he grounds the reason of God’s preference for one world over another on the uniformity of the laws of nature. On the other hand, he shows the endeavor to ground the concept of attraction in God’s choice to be in vain, for we can never be sure why God made this choice rather than another one. As Maupertuis writes in the passage quoted above, a theological explanation should not be “given more weight than it has.” As we have seen, in ‘On the Laws of Attraction’ Maupertuis claims to treat attraction only as a geometer.15 But immediately after asserting that he does not wish to decide if the theory of attraction is in agreement with “sound philosophy,” he develops an argument that involves the idea of divine choice. The same ambiguity also characterizes another treatise on attraction written in 1732, namely, the Discourse on the Different Figures of the Stars. In Chapter II of this text, entitled ‘Metaphysical Discussion of Attraction,’ Maupertuis assesses the idea that attraction is a metaphysical monster. He begins by asserting that attraction is a fact and not an explanation. He then seeks to determine if the theory of attraction resorts to occult qualities or not: But some of those who reject attraction regard it as a metaphysical monster; they believe its impossibility so well proven that, regardless

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of what Nature seemed to say in its favor, it would be better to admit to total ignorance than to use an absurd principle in their explanations. Let us see, then, if attraction, even if it is considered a property of matter, contains some absurdity. (DFA 13) The question that Maupertuis raises here is whether it is really a metaphysical impossibility to conceive of attraction as an inherent property of matter. Concluding that attraction is not a property, he redefnes the relationship between metaphysics and experiment as follows: All we have just said does not prove that there is attraction in Nature; I have not undertaken to prove it either. I only proposed to examine whether attraction, even if it were considered an inherent property of matter, is metaphysically impossible. If this were the case, the most pressing phenomena of Nature could not have received it. But if attraction contains neither impossibility nor contradiction, one can freely examine whether the phenomena prove it or not. (DFA 21) Thus, by arguing that attraction is only metaphysically possible (and not metaphysically necessary), even as a property of matter, the role of experience becomes essential: attraction can only be proven by empirical means. Noting that attraction itself is nothing but a phenomenon, Maupertuis concludes: It is in the System of the Universe that we must discover if [attraction] is a principle that actually takes place in Nature, to what extent it is necessary to explain phenomena, or, fnally, if it is uselessly introduced to explain facts that might as well be explained without it. (DFA 21) These passages suggest that Maupertuis held that attraction cannot be understood independently of metaphysics. However, his position must be understood in light of a broad discussion that took place at this time. This discussion—which involved, among others, Du Châtelet and D’Alembert—no longer revolved around the question as to whether attraction is an inherent property of matter. The main point of contention was rather whether attraction can be fully explained at a phenomenal level or whether its justifcation also requires metaphysical considerations. This question is crucial for two reasons. First, the debate had moved beyond the epistemic model exemplifed by Leibniz’s affrmation that mechanics suffces to explain the movements of bodies but that metaphysics is required to provide the reason of this explanation. The epistemic system had changed, precisely because the meaning of metaphysics had changed.16 Second, both Du Châtelet and Maupertuis held that Newton’s discoveries should be integrated into a metaphysical

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framework. However, as regards Newtonian attraction, Du Châtelet claimed that we can explain phenomena by phenomena without resorting to metaphysical principles. By situating Maupertuis’s refections on attraction in relation to this debate, we can see that the question he was concerned with was not whether astronomy is possible or impossible without referring to metaphysical principles but rather how one should conceive of metaphysics in the frst place. The position defended by Maupertuis is the following: we can try to identify the reason of the divine choice between different laws of attraction. By doing so, however, we do not try to determine the choice made by God but merely formulate a hypothesis as to the considerations that might have guided his choice. Thus, Maupertuis proposes that God would have preferred a uniform law of attraction. Based on this hypothesis, we can carry out experiments and use mathematical models to explain their results. As Maupertuis puts it: Assuming that God intended to provide matter with a law of attraction, he would not have considered all laws as equal. […] Once the preferred metaphysical reason has been posited, the mathematical necessity would exclude frst of all an infnite number of systems in which the law governing the parts would not be in accordance with the law governing the whole. […] Thus, the advantage of uniformity that other laws might seem to have over the law of attraction over other laws, such as the law of direct proportion, […] is not at all a real advantage as regards the analogy or conformity of the law that governs the parts and the whole. (LA 347–48) In order to understand Maupertuis’s view on the relationship between metaphysics and experimental proofs, we have to develop new historiographical categories. Ellen McNiven-Hine did this by introducing the category of ‘Cartonian’ to refer to efforts to combine Cartesian metaphysical principles and Newtonian physics.17 The framework I attribute to Maupertuis is no less paradoxical: combining the notion that God chooses in view of the greatest possible coherence with an emphasis on experience and mathematics, Maupertuis forged a new relationship between metaphysical reason and the laws of nature. As I see it, debates in natural philosophy during the frst half of the eighteenth century were defned not only by the well-known opposition between Cartesians and Newtonians but also by efforts such as Maupertuis’s to integrate metaphysical considerations and Newtonian physics into a single epistemic framework. To understand in which sense Maupertuis’s position fts this framework, we can take his principle of least action as an example. Whereas, according to Maupertuis, this metaphysical principle can be derived from the laws of nature, these laws are themselves teleologically determined.18

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For Maupertuis, the conception of physical theology put forward in the Essay on Cosmology is the Newtonian position, even if he in Philosophical Examination of the Proof of God’s Existence (1756) in fact demonstrates the Newtonian laws by means of experiments.19 Maupertuis is not convinced that the laws of nature can be deduced from the primitive idea we have of the essence of body. He rather seeks to develop the consequences of the discovery that the laws of nature are not mathematically necessary but are ‘only’ metaphysically necessary, namely, because they reveal God’s wisdom. In the Essay on Cosmology, Maupertuis considers the frst principles of nature to possess metaphysical necessity in that they must be considered to emanate from God’s wisdom: I seek to discover these laws and to draw on the infnite source of wisdom from which they have emanated […]. I advise to seek the demonstration of the existence of the Supreme Being in the universal phenomena of Nature rather than in its small details. (EC 3) In my opinion, Maupertuis’s various accounts of the laws of nature show that the standard historiographical labels do not allow one to identify the epistemic position of either individual scholars or intellectual communities. A single gesture of critique or affrmation cannot be used to determine the identity of these scholars: Wolff and Maupertuis do not belong to the same intellectual community even though they have the same position with regard to Leibniz and Newton. Thus, rather than framing Maupertuis’s work as Newtonian, Leibnizian, or as physicotheological, we need to forge a history of ideas that focuses on the practices in which knowledge of nature was generated. This means, in the case of Maupertuis, that we must be attentive to the way in which he relied on metaphysical considerations to delimit the conceptual space within which experimental proofs can be carried out.

2 The Contingency of the Laws of Nature and the Status of Experiments In this section, I analyze Maupertuis’s view on the contingency of the laws of nature and the status of experiments. I argue that the question concerning the demonstrative force of experiments was raised in the context of a debate on the contingency of the laws of nature and was subordinated to the latter. Moreover, we will see that, for Maupertuis, this question was ultimately related to God: positing the contingency of the laws of nature is a way to maintain that God could have created the world quite differently and, thus, that all efforts to understand which reasons led God to create the world as it is are vain. Clearly, God’s decision to create the world as it is cannot be understood by means of

148 Anne-Lise Rey experience. Yet Maupertuis’s account raises the following question: if the idea of a divine choice is the starting point to understand the laws of nature, which role can be played by experiments? In Contingence et nécessité des lois de la nature au XVIIIe siècle, André Charrak considers Maupertuis to be one of the major protagonists in the debate between the followers of Leibniz and Locke that, on his account, dominated the discussions in France and in Germany around 1730–1750. By calling this philosophical position “Franco-Berlin Empiricism,” he proposes an original alternative to the view according to which any type of empiricism presupposes the experimental philosophy of either the Royal Society or Newton. 20 Charrak’s thesis is based on a text Maupertuis wrote six years after the Essay on Cosmology, namely, the Philosophical Examination of the Proof of God’s Existence mentioned above. Maupertuis sent this text to the Berlin Academy in 1756 in response to objections raised to the proof of God’s existence he had presented in the Essay on Cosmology. In the Avertissement of the 1751 edition of the Essay on Cosmology, Maupertuis recalls that it is not possible to know clearly the plan of God. Rather than attempting to discover the mutual dependence of all parts of the universe, he chooses another method, one that consists in starting from the “frst principles of Nature, from those laws which we see so constantly observed in all phenomena, and which we cannot doubt are those that the Supreme Being has decided upon during the formation of the Universe” (EC, iii–iv). So how does Maupertuis think we can fnd these laws and, hence, draw the proofs of the existence of God from “the wonders of nature”?21 The supreme Being is everywhere, but it is not everywhere equally visible. We shall see it better in the simplest objects: let us look for it in the frst laws which it has imposed on Nature; in these universal rules, according to which movement is preserved, distributed, or destroyed; and not in phenomena which are nothing but overly complicated consequences of these laws. (EC 61–62) In this description of his own methodology, Maupertuis seeks to give an epistemic status to the laws of nature. On his account, we have access to God not through any phenomenon in particular, but rather through the phenomenon in general, that is, through the laws of nature and, in particular, through the principle of least action. Thus, while Maupertuis presupposes that God is everywhere, he holds that we have to fnd the proof of God’s existence primarily in phenomena that are universal rather than particular. In other words, we need to study incontestable, simple, and universal phenomena, that is, the laws of nature, rather than contemplate the details of the organization of the parts of nature.

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Interestingly, Maupertuis transfers the classical idea that the supreme being manifests itself in the spectacle of nature to the level of the laws of nature. So what is it that we ‘see’ in these laws? He begins his account of these laws by giving pride of place to movement: The greatest phenomenon of Nature, the most marvelous one, is movement: without it, everything would be immersed in eternal death or in a uniformity even worse than chaos: it is movement that carries action and life everywhere. (EC 67–68) Maupertuis explains that since the laws of motion are grounded on the principle of the best, they must have been established by God: But when it is known that all the laws of motion and rest are founded on the principle of the best, it will no longer be doubted that they owe their establishment to an all-powerful and all-wise Being. (EC 87) The universality of the principle of the best is said to be based on its observability: Thus deduced, the laws of motion and rest turn out to be exactly the same as those that are observed in nature. We can admire their application in all phenomena: in the movement of the animals, in the vegetation of the plants, in the revolution of the stars; and the spectacle of the universe becomes much bigger, much more beautiful, much more worthy of its Author. 22 Prior to this argumentation, Maupertuis had presented his famous principle of least action, which he considers to govern any type of movement: In the collision of bodies, the movement is distributed in such a way that the quantity of action implied by the change arrived is as small as possible. In rest, the bodies which are in equilibrium must be so situated that if something happened to them, the quantity of action would be the least. (EC 21–22) In sum, Maupertuis maintains that the supreme being manifests itself primarily at the level of the laws by which nature is governed, which means that he creates an intermediate level between God and nature. In my view, he considers metaphysics to be the discipline that studies this intermediate level and, thus, mediates between the disciplines of theology and physics. In his Philosophical Examination of the Proof of the Existence of God, and more precisely in its frst part, titled ‘On evidence and mathematical

150 Anne-Lise Rey certainty,’ Maupertuis evaluates his own methodology.23 He indicates that he in the Essay had not intended to produce a complete proof of the existence of God but that he saw this proof as “a reasoning stronger than all those who are drawn from these small details of Nature who suffer a thousand exceptions and where the views of the creator remain too hidden.” Whereas, on his view, “several of these proofs taken separately do not really have the force that some authors want them to give, […] all together are more than suffcient to convince us” (EP 390). Thus, while Maupertuis is conscious of the imperfections of his proof, he is convinced that it is superior to alleged proofs based on “small details of nature.” In his own proof, Maupertuis attempts to settle the question of the modal status of the laws of nature—that is, to determine whether they are necessary or contingent—not by proceeding from the operation of abstraction but rather by starting out from the meaning of, and relationship between, the basic concepts contained in the laws of nature, such as body, movement, and speed. Accordingly, Maupertuis asks in the Examination of Article V of the second part whether “the ideas we have of the body and of speed” suffce to “derive the laws observed by bodies in movement from a chain of uninterrupted consequences” (EP 402). Maupertuis begins to answer to his own question by countering a potential objection: The objection that one would like to derive from the necessity of the laws of motion is against all those who wish to prove the existence of God by the wonders of nature, as well as against those who wish to prove it by these laws, and we could let the naturalists answer it. […] But we will answer for them and for us that it is an injustice to want to attribute a mathematical necessity to laws that the most skilled mathematicians have never been able to reduce; the injustice becomes even greater when, instead of necessity, we discover reasons of choice and preference in the establishment of these laws. (EP 404) In a word, Maupertuis follows Leibniz by holding that the laws of nature are contingent in that they proceed not from mathematical necessity but from divine choice. After having rejected the conceptions of natural laws put forward by Descartes, Leibniz, and Newton, Maupertuis formulates his own principle of the conservation of the quantity of action and comments on it in the following terms: By denying all these laws the alleged prerogative of mathematical necessity, we discover another, much more precious necessity in them, namely, one that characterizes the choice of an intelligent and free being. These laws bear the imprint of the wisdom and power of the one who established them. (EP 424)

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Thus, Maupertuis attempts to deduce the laws of nature “from the infnite source of wisdom from which they have emanated” (EC 3–4), that is, from God, without seeking to give the reason of this deduction. In this regard, he can indeed be said to engage in physical theology, as Charrak has argued. By showing that the laws of nature inferred from the existence of God are the same as those that can be derived from experience, Maupertuis offers a new proof of the existence of God. In my view, however, the point of interest is not so much whether Maupertuis offers a new proof for the existence of God as the status he attributes to experimentation in a metaphysical demonstration of the laws of nature. Maupertuis’s metaphysical considerations are not drawn from the essence of the body, but from the principle of least action, which he considers to be a trace of divine wisdom. We can now see that the question Maupertuis addressed to the Berlin Academy in his 1756 Philosophical Examination, namely, whether the laws of the communication of movement are necessary or contingent (EP 422), results from a reconfguration of the problem of the modality of the laws of nature: Maupertuis poses the problem of contingency no longer in relation to God but in relation to epistemology.24 For Maupertuis, neither the primitive idea of body nor experiences are able to prove the laws of movement. Rather than determining whether they are contingent or necessary, he in the Philosophical Examination of 1756 reconfgures the problem concerning the modality of these laws, namely, by arguing that while we are not able to prove that these laws are mathematically necessary, we must consider them to be metaphysically necessary. Maupertuis’s reconfguration of the problem justifes the following conclusion: even though experiments are very useful, they do not allow us to derive the laws of nature. We rather need to consider the wisdom of God to ground these laws. As I see it, Maupertuis’s appeal to God is part and parcel of what he often calls the powerlessness to know (see EC 53–54). The next section discusses a number of passages from the Essay on Cosmology that deal with the implications of this epistemic powerlessness.

3 From Mathematical Certainty to Probability In the ‘Avertissement’ added to the 1751 edition of the Essay on Cosmology, Maupertuis very explicitly addresses our epistemic limitation. He claims we are unable to grasp the complete system of the world. Instead of pursuing this end, he argues that knowledge of the frst laws of nature, which we can discover, suffces for practical purposes: [T]he simple paths that the Creator has followed in his productions become labyrinths for us as soon as we attempt to enter them. He gave us suffcient light for all that was useful to us, but it seems

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Anne-Lise Rey that he only allowed us to see in the dark the rest of his plan. To be sure: we have managed to bind together several phenomena, to deduce them from some previous phenomenon, and to subject them to calculation. Without doubt, time and experience will form something more perfect in this regard than everything we possess. But a complete system, I do not think it is possible to hope for it, we will never succeed in following the order and dependence of all parts of the universe. What I have proposed here is very different; I have concerned myself only with the frst principles of nature, with those laws that can be constantly observed in all phenomena, and which without doubt are those that the Supreme Being has decided upon in the formation of the universe. (EC i–iv)

In the text proper of the Essay, Maupertuis claims to deduce “the laws of motion and rest […] from the attributes of the supreme intelligence” (EC 1). However, he explains that perfect knowledge of motion cannot be obtained by us: No doubt, perfect knowledge of this phenomenon has not been afforded to us; in all likelihood, such knowledge is entirely beyond the scope of our intelligence. Thus, I renounce the task of explaining how the motion of one body is transferred to another through their contact: I do not even seek to follow the physics of this phenomenon as far as the weak light of my mind allows, nor as far as the knowledge of the mechanics of our time permits. In my studies, I subscribe to a greater principle; one that is higher and more interesting. (EC 10–11) In other words, affrming the limits of our capacity to know motion, Maupertuis refuses to provide any physical explanation of it, preferring instead to explain it from a deduction that starts from God. Maupertuis repeatedly stresses the consequences of our inability to know the laws of motion. According to him, this inability can lead us to believe either that there are only elastic bodies in nature or that there are only hard bodies in nature: whereas the former follows from the Leibnizian principle of conservation, the latter follows from the Cartesian principle of conservation. As he notes, “the strongest reason for holding that there are only elastic bodies in nature is our inability to fnd the laws of motion of hard bodies” (EC 100). Maupertuis concludes from this powerlessness that the principle of least action is the only way to properly understand the laws by which both hard and elastic bodies are governed: Coming after so many great men who have dealt with this matter, I hardly dare to say that I have discovered the universal principle on which all these laws are grounded, a principle that governs hard as

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well as elastic bodies and on which depends the movement and rest of all corporal substances. (EC 105) This is the principle that I call the principle of the least action: testifying to the greatest wisdom and most worthy of the highest Being, it is the principle to which nature seems to be subjected to such an extent that it obeys the principle not only in all its changes, but even insofar as it does not change. […]. The principle not only agrees with the idea that we possess of the supreme Being, in the sense that he must always act with the greatest wisdom, but also in the sense that everything must always remain dependent on him. (EP 106–7) These passages show that, for Maupertuis, our epistemic limitations justify that we base our knowledge of nature on God. Doing so is warranted, in his view, because he assumes a convergence between the deduction of the frst principle of least action and the laws that can be observed in nature. In his view, experience does not prove anything if it is not considered to be grounded on this frst principle. Clearly, Maupertuis’s awareness of the limited cognitive capacities of the human mind leads him to defend an epistemological pessimism, which is, in a sense, the foundation of his physical theology. However, it seems to me that his renunciation of complete knowledge of the system of nature does not inhibit him. On the contrary, it leads Maupertuis to develop an original refection on the extent to which certainty is possible in physics, that is, a refection that does not concern the application of mathematics to physics or the foundation of physics in metaphysics. Thus, in the context of his evaluation of geometrical proofs of the existence of God, Maupertuis affrms that what is probable may in fact be equally certain, and more convincing, than what is geometrically proven. This is clearly stated in the following passage: Geometrical demonstrations, however evident they may be, are not the most suitable for convincing human minds. Most of them will be persuaded more by a great number of probabilities rather than by a single geometrical proof, since the force of the latter depend on an extreme degree of precision. Also, whereas Providence has destined only those truths to be proven geometrically to which we are somewhat indifferent, it has provided us with probabilities by dint of which we can know those truths that are most useful to us. We must not believe that the certainty (sureté) that can be obtained by means of these probabilities is inferior to that provided by geometrical proof. An infnite number of probabilities equals the most complete demonstration, and present the human mind with the strongest demonstration of all. (EC xvi)

154 Anne-Lise Rey Maupertuis here draws an important distinction between the precision of geometrical truths, which concerns matters to which we are indifferent, and “the infnite number of probabilities” that concern matters that are useful to us and can carry a greater weight than geometrical demonstrations. Thus, for Maupertuis, acknowledging our epistemological powerlessness is a step forward in that it allows us to lend more weight to arguments and experiments concerned with probability rather than geometrical certainty. As he puts it: Throughout time, those who have applied themselves to the contemplation of the Universe have found signs of the wisdom and power of the one who governs it. The more the study of physics progresses, the more the proofs multiply. (EC 6–7)

4 Conclusion In this chapter, I have tried to clarify how Maupertuis’s epistemological considerations led him to move beyond the seemingly exhaustive choice between a mathematical model of certainty and a metaphysical foundation of physics. In my view, Maupertuis’s conception of the relationship between the study of nature and a proof of God’s existence cannot be understood as Newtonian. On the contrary, he rather seeks to prove God’s existence from within a cosmological framework, thus giving a new turn to physical theology. However, his position is not Leibnizian either because Leibniz discusses moral certainty mainly in the context of his refections on the medical domain and rarely in relation to the treatment of physical phenomena. The latter are, through the concept of force, always connected with metaphysical considerations. As was mentioned above, I agree with Charrak (2006) that there is a physical theology at work in Maupertuis’s Essay. Maupertuis writes indeed that “[t]he entire system of nature suffciently convinces us that an infnitely powerful and infnitely wise Being authored it and presides over it” (EP xi). What I fnd more relevant, however, is how this view led Maupertuis to refect on the types of investigation of nature that allow us to understand and prove the existence of God. In this regard, I have argued that Maupertuis’s physico-theological refections gave rise to an epistemology that strikes a new balance between, on the one hand, the kind of laws of nature we can deduce from the nature of bodies and, on the other hand, experimentation. More specifically, the strategy he deploys in the Essay on Cosmology consists in affrming our epistemic incapacity to grasp the whole system of nature and, hence, in arguing that the probable truths we can obtain in physics by means of experiments are superior to the geometrical truths that Descartes and his followers sought to achieve in both physics and metaphysics.

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Notes 1 According to Cassirer, “Maupertuis is the frst great proponent of Newton’s ideas in France; he even anticipates Voltaire in this matter, paving the way for the latter.” (Cassirer 1951: 86–87). 2 “Ironically, Maupertuis’s use of metaphysical principles, and especially of fnal causes, betrayed a certain sympathy with Leibniz.” (Terrall 2003: 289). However, Terrall also points out the difference between Leibnizian dynamics and Maupertuis’s principle of least action and the latter’s disagreement with Samuel Koenig on this issue. 3 Charrak (2006: 104). 4 See, for instance, Prunea-Bretonnet (2019: 78–79), who interprets the Essay on Cosmology as a work in physical theology. 5 For a masterful analysis of this expedition and its impact on the science of the Enlightenment, see Terrall (2003). 6 Siegfried Bodenmann refers to Maupertuis’s strategy as a “rhetoric of empiricism” (Bodenmann 2018: 87–119). See also Réginal Outhier’s report (Paris: Piget Durand 1744), Journal d’un voyage au Nord en 1736 et 1737: (Outhier 1744: 114–15, 131–32, 140; quoted by Bodenmann 2018: 97). On the distinction between repeatability, replicability, and comparability, see Licoppe (1996: 7–16). 7 The latter position was ‘proven’ by an expedition to Peru led by Pierre Bouguer. On this, see Greenberg (1995). 8 Maupertuis published this thesis under the name of Dr. Baumann. 9 Cassirer (1951: 86). According to Cassirer, Maupertuis’s “personal relation to Leibniz is indeed not free from contradictions, but the objective kinship of his metaphysics, his philosophy of nature, and his theory of knowledge with Leibniz’s basic ideas is undeniable” (Cassirer 1951: 86). 10 Cassirer (1951: 87). 11 Cassirer (1951: 87). Note, however, that this is exactly what Émilie du Châtelet wrote ten years earlier in her Institutions de physique. In her view, Leibniz offered the best way of providing Newton’s laws of motion with a metaphysical foundation. For example, Du Châtelet uses the Leibnizian principle of suffcient reason as a criterion to evaluate the Newtonian theory of attraction, concluding that attraction is illusory (§ 395). See also Du Châtelet, Lettre 286, Émilie à Frédéric, avril 1740 (Kollving and Brown 2018: 576–77). 12 Maupertuis, LA 343. The translations of Maupertuis’s texts are my own. 13 Maupertuis writes: “The gravity of bodies toward the earth depends not only on the attraction that the earth exerts on them, but also on the attraction which they exert on the earth; these attractions depend on the particular fgure of the bodies on which we can experiment [sur lesquels nous pouvons faire l’expérience].” (LA 344). 14 Maupertuis, LA 348. This passage testifes to Maupertuis’s awareness of the fragility of the hypothesis that leads him to explain the choice of God. 15 Maupertuis, LA 343. I would like to point out that this is a very Wolffan strategy. In many of his works, Wolff tries to deny the innovative aspects of Newton’s philosophy by equating them with Leibnizian concepts. See, for example, his discussion of inertia in § 316 of the Cosmologia generalis. 16 As can be seen from her letters to Maupertuis from 1738, Du Châtelet conceived of metaphysics as a kind of anthropology. See, for example, her letter dated March 1738 (Kollving and Brown 2018: 337). See also D’Alembert’s account of metaphysics as a discipline based on the generalization of observations in the entry “Elements of sciences” in the Encyclopédie (Diderot and

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17 18 19

20 21 22

23 24

D’Alembert 1755: 491–97). Even though this is not the meaning of metaphysics defended by Maupertuis, it is important to keep in mind the new conceptions of metaphysics put forward by his contemporaries. See McNiven Hine (1989). On this, see Leduc (2015: 16–18). In the Essay on Cosmology, Maupertuis writes, for example, that “Newton seems to have been more touched by the evidence found in the contemplation of the Universe than by all the others he could have drawn from the depth of his mind” (vi). To support this claim, he quotes from the Optics, Book III, Query 31, and comments that “[t]his great man believed that the elements of the celestial bodies suffciently demonstrate the existence of the one who governs them” (EC vi–vii). See Charrak (2006: 6). The title of the preface is “Where one examines the proofs of the existence of God, drawn from the wonders of Nature.” EC 23–24, my emphasis. Similarly, Maupertuis asks: “If [the laws] which I fnd through this avenue are the same as those observed in the universe, does this not provide the strongest proof that this Being exists and that He is the author of these laws?” (EC, 64). My account here is line with Charrak (2006: 142–48). As Charrak puts it, “the hypothetical reduction of the laws of mechanics to the properties of the body that can be rendered in geometrical terms testifes to an epistemological investigation rather than a thesis on the ultimate organization of the world” (Charrak 2006: 113).

Bibliography Primary Sources Du Châtelet, Émilie (1740), Institutions de physique, Paris: Prault, 1740. Diderot, Denis and D’Alembert, Jean Le Rond (eds.) (1755), Encyclopédie, ou Dictionnaire raisonné des sciences, des arts et des métiers, vol. 5, Paris: Briasson et al. Maupertuis, Pierre-Louis Moreau de (1732), Discours sur les différentes fgures des astres, Paris: Imprimerie Royale (DFA). ——— (1732), ‘Sur les lois de l’attraction’, Mémoires de l’Académie royales des sciences, 343–62 (LA). ——— (1751), Essai de cosmologie, Leiden: Luzac (EC). ——— [Dr. Baumann, pseud.] (1751b), Dissertatio inauguralis metaphysica de universali naturae systemate, Erlangen [Berlin]. ——— (1758), ‘Examen philosophique de la preuve de l’existence de Dieu employée dans l’Essai de cosmologie’, Histoire de l’Académie Royale des Sciences et des Belles Lettres (1756), Berlin: Haude & Spener, 389–424 (EP).

Secondary Sources Bodenmann, Siegfried (2018), ‘Empiricism as a Rhetoric of Legitimation: Maupertuis and the Shape of the Earth’, in S. Bodenmann and A.-L. Rey (eds.), What Does It Mean to be an Empiricist?, Boston: Springer, 87–119. Cassirer, Ernst (1951), The Philosophy of the Enlightenment, Princeton: Princeton University Press.

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Charrak, André (2006), Contingence et nécessité des lois de la nature. La philosophie seconde des Lumières, Paris: Vrin. Greenberg, John L. (1995) The Problem of the Earth’s Shape from Newton to Clairaut: The Rise of Mathematical Science in Eighteenth-Century Paris and the Fall of “Normal” Science, Cambridge: Cambridge University Press. Kollving, Ulla and Brown, Andrew (eds.) (2018), La Correspondance d’Émilie du Châtelet, vol. 1, Ferney-Voltaire: Centre international d’étude du XVIIIe siècle. Leduc, Christian (2015), ‘La métaphysique de la nature à l’Académie de Berlin’, Philosophiques, 42/1, 11–30. Licoppe, Christian (1996), La Formation de la pratique scientifque. Le discours de l’expérience en France et en Angleterre (1630–1820), Paris: La Découverte. McNiven Hine, Ellen (1989), ‘Dortous de Mairan, the ‘Cartonian’, Studies on Voltaire, 266, 163–79. Prunea-Bretonnet, Tinca (2019), ‘From the Folds of the Rhino to the “Hand of Nature”: Maupertuis’s Essay on Cosmology and its Reception in the 1750s’, Archivio di Filosofa, 87/1, 75–89. Terrall, Mary (2003), The Man Who Flattened the Earth: Maupertuis and the Sciences in the Enlightenment, Chicago: The University of Chicago Press.

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The Role of Reason, Experience, and Physiology in J.H.S. Formey’s Essay on Dreams Annelie Grosse

1 The Science of the Soul between Natural Philosophy and Metaphysics The investigation of the human soul is a realm of eighteenth-century philosophy that lends itself perfectly for a study of the relationship between rationalism and empiricism such as it was discussed at the time. Generally, scholarly debates in mid-eighteenth-century Europe were marked by an enthusiasm for Newtonian empiricism and natural philosophy as well as a growing criticism of the a priori principles associated with metaphysics.1 These methodological considerations had a particular impact on the ‘science of the soul’. Since Antiquity, the soul had been considered as the seat of the vegetative, sensory, and intellectual functions of the human being, that is, as an amalgam of bodily and spiritual elements. Given this twofold conception, discussions of the soul as a whole took place in natural philosophy as well as in metaphysics. Throughout the early modern period, however, it was common practice to follow the Aristotelian tradition and to treat the soul in natural philosophy. 2 Only from the mid-seventeenth century onward—due to the rejection of Aristotelianism and the impact of the Cartesian concept of a purely rational soul—were the soul’s bodily and spiritual aspects conceptually dissociated. This development had important methodological consequences.3 As Fernando Vidal has argued, the recognition of the soul as mind, fueled by Descartes’s dualism, gave rise to modern psychology.4 At the same time, the investigation of the bodily part of the soul—the brain and the nervous system—saw an ascent thanks to the anatomical and medical studies of Thomas Willis, Hermann Boerhaave, and their disciples.5 This separation of physiological and metaphysical investigations of the human soul also informs the complex philosophical system that Christian Wolff developed from 1713 onward, frst in German and then—more extensively—in Latin. Covering all scientifc domains, he investigated the nervous system in his natural philosophy and the mental faculties in his metaphysics. Unlike Descartes, Wolff considered the soul, as bearer of mental faculties, to consist not only of the intellect

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but also of the non-distinct perceptions that occur, for instance, during sensation or imagination. Hence, Wolff’s metaphysical investigation of the soul comprises more faculties than that of cognition.6 Despite Wolff’s neat separation between natural philosophy and metaphysics, his particular epistemology seems to have paved the way for the reintroduction of the science of the mind into the realm of the natural sciences. In his Discursus praeliminaris de philosophia in genere (1728), he distinguishes between an empirical and a rational approach to the human soul within metaphysics, claiming that empirical psychology could at least in part treat the faculties of the human soul by the same methods as those used in natural philosophy, namely, observation and experimentation.7 According to Vidal, Wolff thus took an important step toward the development of a discipline that investigates the effects or faculties of the soul only insofar as they are observable through the body, that is, of a modern, ‘scientifc’ psychology that does not assume an immaterial soul and hence is dissociated from metaphysics.8 Yet Wolff himself surely did not perceive it in this way. On the contrary, he did not allocate experience to natural philosophy and reason to metaphysics but rather considered the two approaches to be universally applicable. Accordingly, each discipline of his philosophical system is divided into an empirical and a rational treatise.9 Moreover, as we shall see, Wolff held that the rational and empirical parts of the soul were closely connected. The focus of the present chapter, however, is not so much on Wolff’s own conception of psychology as on its reception in the German lands. Vidal has already portrayed the impact of Wolff’s empirical psychology on the methodological discussions among German philosophers like Gottlieb Friedrich Hagen and Johann Gottlob Krüger, who, during the second half of the eighteenth century, refected upon quantifcation and experimentation in psychology.10 Instead, I will focus on the appropriation of Wolff’s empirical psychology by francophone popular philosophers in Germany during the 1740s. More precisely, I will analyze how one of Wolff’s most ardent followers, the Huguenot pastor and member of the Berlin Academy of Sciences and Belles-Lettres Jean Henri Samuel Formey, partly drew on the methodological principles of Wolffan empirical psychology to explain the phenomenon of dreaming. Formey’s Essay on Dreams, which he presented at the Berlin Academy in 1746, neither refers to a precise debate to which it wants to contribute nor mentions its sources or intellectual forebears. This might be due to the relative novelty of experience-based dream theories at this time. In the German lands, such theories were developed in the 1740s and 1750s at the University of Halle by so-called reasonable physicians or psycho-physicians like Johann August Unzer, a disciple of the professor of medicine and philosophy Johann Gottlob Krüger. Nowadays they are considered as sensualist philosophers whose dream theories relied mainly on medical research but also drew on Wolffan metaphysics.11

160 Annelie Grosse At frst sight, Formey’s essay looks similar: as we will see in more detail below, he defnes the faculty of dreaming in a Wolffan manner, namely, as a variation of the faculty of imagination, but mixes his account with descriptions that seem to be taken from a medical textbook. Despite these similarities, however, it is diffcult to state whether Formey’s essay and its contemporary writings infuenced each other. Furthermore, in Formey’s immediate context, the Berlin Academy, no papers related to dream theories appeared in the 1740s.12 Thus, Formey defnes a very general target at the outset of his essay by claiming that he wanted to oppose “vague hypotheses” (ED 317). This claim, and the extensive methodological refections that run throughout his text, indicate that he seems to have written his Essay on Dreams mainly to refect on methodological issues. More precisely, the central role that he grants to experience in the investigation of the soul most likely stemmed from his effort to make Wolff’s school philosophy suited to the growing popularity of experimentalism and naturalism among members of the Berlin Academy. Thus, while Formey’s essay deviates not much from contemporary dream theories in terms of content, it stands out because of the way it exemplifes the struggle to integrate metaphysics and natural philosophy at a time when these two disciplines were considered to belong to opposing philosophical camps. In this chapter I will frst analyze the epistemological-methodological discourse contained in Formey’s Essay on Dreams in order to elucidate his Wolffan understanding of the nature and function of empirical knowledge and to evaluate the particularity of his empiricist rhetoric. For this purpose, I will compare the methodological considerations contained in the Essay on Dreams to Wolff’s epistemology as well as to the refections on the relationship between reason and experience that Formey made elsewhere. This will show that Formey appropriated Wolff’s concept of empirical knowledge in all its complexity, yet emphasized its single components differently according to his needs. In this respect, Formey’s case can demonstrate very well the inadequacy of assuming a sharp distinction between rationalistic and empiricist philosophical schools in mid-eighteenth century. In the second part, my focus will be on the content of the allegedly empirical knowledge of the soul that Formey establishes in his Essay on Dreams. I will analyze his explanation of the process of dreaming and show how it deviates from the rudimentary and mainly metaphysical explanation Wolff puts forward in his empirical psychology. I argue that, by employing physiological descriptions to explain a mental faculty such as dreaming, Formey broke up Wolff’s meticulously designed philosophical system and rearranged its components. As a result, he endowed Wolff’s concept of experience with a different meaning and challenged the theory of pre-established harmony between body and soul. In order to account for the circumstances that facilitated the

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philosophical discourse that is the object of my analysis, I will start with some refections on the biographical and institutional context from which Formey’s engagement with Wolff’s empirical psychology and his Essay on Dreams emerged.

2 Formey’s Essay on Dreams in the Context of the Controversy on Wolffanism Jean Henri Samuel Formey was one of the most prolifc partisans of Wolff at the Berlin Academy during the second half of the eighteenth century and, as such, a defender of a mainly rationalist metaphysics.13 As the son of a Huguenot refugee from France, he was trained in philosophy and theology by the Calvinist scholars that had founded a Huguenot colony in Berlin at the end of the seventeenth century. In 1732, soon after he had become a pastor in one of Berlin’s French churches, Formey was introduced to the Société des Aléthophiles, a private learned society founded by the count Ernst Christoph von Manteuffel. This society set itself the task of defending and disseminating Wolff’s works at a time that saw an increasing hostility toward his philosophy.14 Within a few years, Formey had not only merged Wolff’s philosophy with his Calvinist education into a Christian philosophy but had also become one of Wolff’s most prominent mouthpieces: he divulged the German philosopher’s metaphysics and natural theology through sermons and popular philosophical works to a predominantly Huguenot audience.15 Formey became a professor of philosophy at the Berlin French School in 1739 and a member of the Berlin Academy’s philosophical class in 1744, positions that increased his scholarly outreach. He became even more well-known when he, in 1748, ascended to the position of the Academy’s perpetual secretary. One of Formey’s frst achievements at the Academy, which had been renewed under Frederick II between 1744 and 1746, was to incorporate Wolff’s conception of metaphysics into the institution’s programmatic statement. Here, Formey depicts metaphysics as a source of (a priori) principles and basic notions and, hence, as the origin of evidence and certain knowledge in the other sciences.16 In 1747, he underpinned these convictions in two related academic treatises on the existence of God. Both texts defend Wolff’s metaphysical natural theology against Newtonian physico-theology. His main argument against the latter was methodological: he rejected the probative force of proofs that relied on the observation of nature. Instead, he argued that proofs of the existence of God, as any other proofs, had to be based on metaphysical notions such as the Leibnizian principle of suffcient reason.17 These and similar writings strengthened the image of Formey as a rather traditional metaphysician who conceived of deduction and a priori knowledge as the preeminent ways to obtain truth.

162 Annelie Grosse Defying this image, Formey’s Essay on Dreams, which must have been written prior to the aforementioned pieces, makes a strong case for experience as a source of knowledge of the soul.18 On the frst page of the essay, immediately after having introduced the topic of dreaming, Formey discards hypothetical a priori knowledge and promises his readers to proceed by means of a strictly a posteriori method: This is the state of dreaming; and in order to avoid mixing a philosophical dream, a vague and precarious hypothesis, with my refections, I will only follow the road of experience, and I will try to draw on the exposure of the phenomena that accompany dreams for the explanation of these phenomena. (ED 317) Similarly, he notes that “experience is the one and only Ariadne’s thread that guides me” (ED 318). Formey’s indebtedness to Wolff’s empirical psychology in this regard is confrmed by a letter he wrote to the above-mentioned patron of the Société des Aléthophiles, Ernst Christoph von Manteuffel, after his Essay on Dreams had been published in January 1748. In this letter, Formey reports proudly that his treatise had received the appreciation of King Frederick II. Since, as he states, the Essay on Dreams was based on Wolff’s empirical psychology (which Formey called “psychologie expérimentale”), the king’s appreciation extended automatically to the latter. As Formey also mentioned in his letter, he had not only concealed the source of his writing but had also presented Wolff’s philosophy “in a certain light” in order to incite his colleagues’ “taste” for this philosophy.19 Pointing to the controversy between the partisans of Wolff in Germany and the Newtonian philosophers who were associated with the Berlin Academy, this comment provides us with a frst general explanation for Formey’s seemingly odd choice—compared to his reputation as a rationalist metaphysician—to present an experience-based dream theory at the Academy. Frederick II, the patron of the Academy, was the spearhead of the antiWolffan climate that had reigned at the Academy since its renewal.20 The president of the institution, Pierre Louis Moreau de Maupertuis, newly appointed in 1746, was a renowned Newtonian and very critical of speculative sciences. 21 Infuential members of the dominant antiWolffan faction of the Berlin Academy further included the Parisian mathematician Jean le Rond d’Alembert and the Swiss mathematician Leonhard Euler. 22 Wolff himself and his supporters in the Société des Aléthophiles contributed to this anti-Wolffan climate in parts of the Berlin Academy by their anti-Newtonian and anti-French discourse. Thus, Wolff blamed the French philosophers for their scientifc superfciality and associated Newtonian philosophy with the growth of freethinking. 23

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An important outbreak of the animosities between the two philosophical camps happened around the time that Formey must have been writing his Essay on Dreams. In July 1746, the Academy devoted its 1747 essay contest to the validity of Leibniz’s monadology. 24 Shortly after the announcement of the prize question, Euler published an anonymous piece in which he rejected not only Leibniz’s theory but also the purely rational method associated with Leibniz’s and Wolff’s metaphysics. Formey—pushed by the Aléthophiles—responded in the same year by publishing an anonymous defense of rationalism and Wolffanism in general. In this piece, titled Recherches sur les élémens de la matière (Investigations into the Elements of Matter), he rejected the methodology employed in mathematics and defended metaphysics’ superiority over natural philosophy. 25 Formey thus took an active part in the controversy between Wolffans and anti-Wolffans, which explains why, in the above-mentioned letter to Manteuffel, he vaunted himself for having introduced Wolff’s empirical psychology in disguise at the Academy. In the controversy between Wolffans and anti-Wolffans, which broadly speaking was a debate between metaphysicians and natural philosophers, between alleged rationalists and empiricists, Formey clearly sided with the former. However, given his institutional affliation and career prospects, he had to fnd ways to defend his philosophical convictions without offending his peers. This should be taken into account when, in the following section, we scrutinize the epistemological and metaphysical considerations put forward in his Essay on Dreams.

3 Experience and Empirical Knowledge in the Essay on Dreams While Formey’s metaphysical treatises often contain epistemological considerations, in his Essay on Dreams each argument is accompanied by refections on how it was obtained. The essay is divided into three sections, which are concerned with the defnition of dreaming, the causes of dreaming, and the different contents and forms of dreams. Within these sections Formey draws on different functions of experience and explores the interplay between induction and deduction to obtain a type of cognition of the soul that might be considered empirical. The source from which he drew his methodological considerations was Wolff’s idea that reason and experience must cooperate in order to generate philosophical knowledge and that empirical knowledge was more than mere factual knowledge. Regarding the defnition of experience, Formey remains ambiguous compared to Wolff. The latter defnes experience generally as the knowledge we obtain through paying attention to our perceptions and the changes occurring in our soul (GM § 325). At the beginning of his empirical psychology, he specifes that he wants to rely on the experience of

164 Annelie Grosse the soul that everybody “who pays attention to himself” is able to obtain (GM § 191). This statement points to two important aspects of Wolff’s concept of experience in his empirical psychology: frst, he regarded experience as common sense experience instead of experimentation; second, this experience of the soul required a certain state of consciousness from the observer and thus can be defned as introspection. Unlike Wolff’s, Formey’s essay does not contain such an explicit defnition of experience. He only claims that he will rely on the “phenomena that accompany dreaming” (ED 317). In the course of his essay, these phenomena turn out to be derived from both common sense experience and the results of natural-philosophical and medical observations. Within Wolff’s theory of knowledge, experience has a twofold function and is intrinsically linked to reason and a priori methods. According to his Discursus praeliminaris de philosophia in genere, experience constitutes so-called historical knowledge, i.e., knowledge of observed facts (DP §§ 1, 3). As such, experience is the source as well as the object of “philosophical knowledge,” i.e., knowledge about the causes of individual facts that is established through the use of human reason. 26 Wolff explains that experience therefore has to be considered as the indispensable foundation of general principles in each feld of philosophy. 27 Furthermore, historical knowledge, i.e., experience, fulflls the function of verifying philosophical knowledge: it serves as the touchstone of the hypothetical principles established through the use of reason (DP § 26). In the generation of philosophical knowledge, the epistemic categories of experience and reason thus complement each other. 28 This general theory of the complementary relationship between experience and reason, between historical and philosophical knowledge, is also refected in the bipartite structure of Wolff’s science of the soul. 29 As was mentioned above, Wolff divided his work on the nature and faculties of the soul into an empirical and a rational part, a division which in his German Metaphysics of 1719 is refected in two different chapters (Chapters 3 and 5). In his posterior Latin works, his psychology consists in two separate treatises, titled Psychologia empirica and Psychologia rationalis.30 In the empirical part of his psychology, Wolff describes the effects (Wirkungen) of the soul such as they can be observed by a conscious human being, while in the rational part he defnes the nature or essence (Wesen) of the soul in which these effects are rooted.31 The two parts are thus intrinsically connected: while the second part explains and generalizes the phenomena assembled in the frst part, the frst part validates the principles that are established a priori in the second part. However, the empirical and the rational psychology are not simply to be equated with historical and philosophical knowledge. On the contrary, each of them constitutes a self-contained branch of philosophical, i.e., causal knowledge.32 Wolff underlines that empirical psychology contains not only descriptions of observations but also

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principles and notions that were deduced from those observations.33 The philosophical knowledge established in rational psychology differs from the one established in empirical psychology because it also contains insights into the soul that result from mere a priori reasoning.34 According to Dyck, the fact that Wolff’s rationalism is imbued with empiricist elements constitutes its “distinctive nature” as compared to classical Cartesian or Leibnizian rationalism.35 Nevertheless, Wolff’s methodological considerations on the relationship between experience and reason, especially his use of a priori methods in the establishment of empirical knowledge, fueled among his contemporaries the image of him as a rationalist opposed to Newtonian and Lockean viewpoints.36 Moreover, his avowed reliance on introspection, which was nothing else than thought, 37 could easily be regarded as a rationalist feature. Formey’s reception of Wolff largely contributed to the image of Wolff as a rationalist, but he occasionally highlighted the fundamental role of empirical methods in Wolff’s epistemology. Insofar as his writings show that one could draw on Wolff for both empiricist and rationalistic approaches, they constitute a perfect example of the way the division between rationalism and empiricism was constructed in the eighteenth century. By exercising, throughout its above-mentioned three sections, the different steps of Wolff’s empirical method, Formey’s Essay on Dreams clearly emphasizes the empiricist aspects of Wolff’s epistemology. In the frst section he seeks to provide a defnition of dreaming on the basis of principles deduced from experience. He thus introduces this section with a remark that corresponds to Wolff’s distinction between historical knowledge—a pool of facts or experiences—and empirical knowledge— distinct principles deduced from these facts: “But before anything else I have to draw a certain number of distinct principles from this general source of experience, principles that are necessary for the explanation of the subject that I am dealing with.” (ED 318). The frst principle Formey discusses is a neurological description of the sensations we have while being awake: a physical stimulus that touches the surface of our body is said to be transported via the tightened nerves to the brain, where a corresponding sensation emerges (ED 318–19). His second principle concerns the faculty of imagination. This faculty produces sensations in the soul without external stimuli modifying the state of the body. Formey claims that a physical stimulus and a sensation are not immediately connected and that it suffces for a sensation to emerge in the soul that the interior end of the nerve is shaken (ébranlé). Formey derived this principle of the missing connection between stimulus and sensation, by which the faculty of imagination is explained, from an anatomical description according to which the inner end of a nerve, where it led into the brain, was so subtle and soaked with the spiritual nerve liquid that it was easy to be shaken (ED 320).

166 Annelie Grosse The fnal principle that Formey presents is the law according to which during the process of imagination ideas are associated in the same order as they had entered our soul for the frst time during the process of sensation. That means that earlier sensations are reproduced without the help of a physical stimulus. To justify this law, Formey refers to common sense experience: he describes that, when we imagine a person we have once met, we will automatically remember the setting in which we met him (ED 321–22). From these three principles or laws Formey concludes that dreaming is nothing else than the activity of the imagination during sleep. Accordingly, he defnes the faculty of dreaming as a species of the faculty of imagination. Linked to this, he claims that dreaming must be a constant state of the mind, since the soul has continuously representations and perceptions (ED 322). We can thus say that Formey’s defnition of dreaming relies on a deductive method in the sense that he bases it on principles. The particularity of his procedure, however, is that he not only posits those principles but also uses experience to validate them: for each of the three principles he refers to ‘facts’ that he believes to confrm them. Moreover, those facts are—except for the third principle—drawn from natural philosophy or medicine. This suggests that, unlike Wolff’s empirical psychology, Formey’s essay betrays a concept of experience that includes more than common sense experience. By contrast, in the second section of his Essay on Dreams Formey draws on common sense experience to generate new principles. In this section, he seeks to explain why we remember certain representations that we had while sleeping and, hence, why we dream properly speaking. In order to do so, he uses descriptions of the conditions of sleeping people, explains them in physiological terms, and eventually infers a general principle from them. He states that two sorts of people do not remember their dreams: those of a strong physical condition and good health and those who are overworked and exhausted. He explains this observation by positing the existence of animal spirits in the human body: an abundance of animal spirits—as in people of good health—provokes chaos in the brain and prevents dreams from emerging, whereas a scarcity of animal spirits prevents the inner ends of the nerves from being shaken and hence from activating the imagination. From this explanation Formey concludes that in order for the body to have dreams, it has to be in a state between abundance and scarcity of animal spirits. In other words, Formey establishes the principle that dreaming requires a moderate physical condition (ED 323–24). After having completed this induction, Formey seeks to validate it through examples also drawn from common sense experience, such as the observation that people who are sick or depressed generally dream a lot, and that dreams usually set in shortly before we wake up in the morning because at this point the animal spirits are at their most medium

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level (ED 324–25). Such confrmations by common sense experience are necessary because otherwise, as Formey underlines, his principle would merely be hypothetical. Thus, the structure of Formey’s argument in the second section of his Essay on Dreams illustrates very well his view that, in order to establish valid philosophical knowledge, experience must serve both as a source of principles and as the touchstone of their truth. In the third section of his essay, Formey attempts to explain how dreams acquire different contents. Unlike his previous investigation into the faculty of dreaming, this means that he must explore particular dreams. For this purpose, Formey fnally takes on the role of the experimental philosopher in the sense that he carries out the observation of a dream itself: “Let us now see a dream emerging, and let us somehow assist at its birth.” (ED 326). This statement betrays an attempt to objectify the mental faculty of dreaming in the sense that a dream is presented as something that is as directly observable as a material object. However, this objectifcation quickly arrives at its limits: when Formey’s observation reaches the point at which a dream “kicks in,” he has to admit that it eluded his capacity to experience it. As he puts it: When this moment has arrived, do we instantly dream and doesn’t there have to be a more immediate cause for the emergence of a dream than this general disposition of the body? First it seems that we cannot answer this question without recklessness and that the thread of experience, which we, as we have promised, did not want to drop, leaves us here; because, one would say, since nobody can even recognize when and how he falls asleep, how could one seize what determines the origin of a dream that starts during sleep? (ED 326) Consequently, Formey seeks the support of reason in order to account for what caused an individual dream. His a priori method, more precisely, consists in drawing an analogy between waking and dreaming. Thus, he presents a principle deduced from observations of someone who is awake, namely the fact that an act of imagination is always incited and determined by a sensation. If, as he has established earlier on, a dream is nothing else than the activity of the imagination during one’s sleep, then the content of a dream must also be determined by a preceding sensation (ED 327–28). After this brief intermezzo of a priori reasoning, Formey turns again to the description of several phenomena associated with dreaming. He explains why we sometimes have coherent dreams and why they are rather confused at other times, as well as why different people have different dreams although they slept in the same environment (ED 329–31). Methodologically, Formey presents his classifcation in this regard as an application to particular facts of the universal principles established so far (ED 329).

168 Annelie Grosse This classifcation testifes to yet another kind of relationship between factual knowledge (experience) and causal knowledge (knowledge obtained through reason). In the frst two sections and the beginning of the third, Formey relies on the observation of phenomena in order to establish and validate empirical principles by means of which he constructs a theory of dreaming. In the remainder of the third section, by contrast, he uses this theory of dreaming to account for further phenomena, i.e., factual knowledge. Thus, the methodological procedure employed in Formey’s Essay on Dreams corresponds to Wolff’s account of how to establish knowledge in general, and empirical knowledge in particular. Hence, Formey’s stated claim to present an empirical dream theory at the beginning of his essay is indeed a reference to Wolff—just as he had secretly explained in his letter to Manteuffel—and therefore perfectly in line with his intellectual affliation to Wolffanism. Nevertheless, the way in which Formey evaluates the merit of experience in his Essay on Dreams is extraordinary if compared to his usual plea for a priori methods. We have observed that Formey’s entire essay is imbued with an epistemological discourse that highlights the role of experience in a very positive way. This rhetoric is interrupted at the point in the third section of his text where Formey admits the failure of his planned experimental approach to the dream and resorts to reason instead. Despite this shift, however, Formey simply continues to praise experience as a source of truth, emphasizing that the rational deduction to be carried out was “at the end nothing else than the immediate and necessary consequence of experience” (ED 326–27). Hence, even in the face of experience’s limits, Formey underlines the supportive function of experience in relation to reason rather than its inferiority. By contrast, in his Refections on Liberty, presented in December 1747 at the Academy, Formey emphasizes experience’s limitations and faws. Rejecting a popular assumption, he denies that experience is able to prove that the human will can immediately cause the body to move. According to him, while experience—understood as sensory experience— can describe what happens in the mind and in the body separately, it cannot account for the interaction between them.38 This argument is clearly inspired by the section in Wolff’s rational psychology in which he dealt with the mind-body relation. Wolff here claims that the infuence of the body on the soul cannot be established by means of experience because we cannot have clear notions of such an infuence (GM § 529). As we have seen, Wolff considers experience to result from the observation of the changes occurring in our body and soul. As such it relies mainly on the senses.39 Yet, since the senses lack reliability and certainty, according to Wolff, experiences that are directly based on them need to be processed by cognition in order to be trustworthy.40 This point is also stressed by Formey in his Refections on Liberty: he argues that the senses are subjected to change and errors, whereas the perception

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of our inner state by means of the understanding (i.e., consciousness or introspection) is constant and thus reliable.41 The reason why Formey’s Refections on Liberty highlights the faws of experience, while his Essay on Dreams omits them, might be related to the different epistemological status of the two treatises’ subjects (freedom and dreams), which require different forms of experience. The freedom of will, in Formey’s view, can be explained at least through introspection, which, strictly speaking, is a type of experience that relies not on sensory experience but on cognition.42 According to Wolff, introspection means to be conscious of one’s own perceptions; as such, it is the only way of having reliable experiences of one’s immaterial soul. By contrast, the dream, being an unconscious state of mind, cannot even be explained by introspection. This is most likely the reason why Wolff, in his psychology, did not go beyond establishing an analogy between imagination and dreaming. By contrast, Formey—and this is how his Essay on Dreams differs from both his Refections on Liberty and Wolff’s psychology—considers sensory experience to be a valuable foundation of his own dream theory. Moreover, the purposes of Formey’s two texts are also different: whereas the aim of the Refections on Liberty was to object to popular opinions based on sensory experience alone, the Essay on Dreams followed an anti-rationalist agenda and wanted to get rid of “vague and precarious hypotheses” (ED 317). I would argue, however, that Formey’s different assessments of the role of experience in philosophical knowledge had frst and foremost a rhetorical function: within the methodological debates at the Academy, which was dominated by Newtonian scholars like Maupertuis and Euler, Formey’s role was to defend Wolffan ideas. The difference between the two treatises in this regard may well be explained by the above-mentioned outbreak of the controversy between Wolffans and anti-Wolffans between 1746 and 1749. While the Essay on Dreams was most likely written before the announcement of the prize contest on monadology, the Refections on Liberty were written in the middle of the debate. This suggests that Formey decided to change his strategy: instead of stealthily infusing the thoughts of his colleagues with Wolffan philosophy, the Refections on Liberty openly opposes their trust in anti-Wolffan sensualism and experimentalism. The fact that both of Formey’s treatises relied on Wolff as a source shows the heterogeneity of the latter’s concept of experience and empirical knowledge, which in turn enabled followers like Formey to present multiple versions of it according to their needs. Most importantly, Wolff remains ambiguous about the validity of experience: on the one hand, he considers it as the indispensable touchstone of a priori principles and, on the other hand, he questions the reliability of sensory knowledge. This is the reason why Formey, drawing from a single source, could act like an empiricist (and appeal to his Newtonian colleagues) in one context

170 Annelie Grosse and like a rationalist in another. Seen in a larger context, this undercuts the theory of a clear Wolffan-Newtonian divide in eighteenth-century philosophy. However, the particularity of Formey’s Essay on Dreams lies not only in his empiricist rhetoric and the way he highlights certain aspects of Wolff’s complex and sometimes ambivalent theory of knowledge. On the contrary, as we have seen in the previous section, Formey relies partly on a different type of empirical knowledge than Wolff’s empirical psychology. He does not limit himself to using common sense experience but also includes descriptions of the nervous system. This leads me to the last part of this chapter, in which I will show how Formey elaborates Wolff’s dream theory by using physiological knowledge, and discuss the consequences of this procedure.

4 Physiological Knowledge as Experience in the Essay on Dreams Wolff can hardly be said to have developed a comprehensive dream theory. He rather refers to the nature of dreams while dealing with the question of consciousness and the different degrees of clarity of our ideas. In this context, he conceives of dreaming as a conscious state of mind in which we have clear and distinct ideas that, however, are in disorder.43 For Wolff, dreams are products of the imagination, which is to say that he considered the process of dreaming to evolve in the same way as the exertion of this mental faculty during waking.44 In line with this, Wolff claims that a dream is caused by a sensation that did not wake us up; this sensation provokes an imagination similar to this sensation in the dreamer. At that point, the dream takes its course according to the general rule of imagination, which allows for both simple and composite dreams (GM § 799). Formey’s essay clearly relies on Wolff’s sketchy remarks on dreaming in the German Metaphysics. However, he not only develops them into a genuine theory of dreaming but also takes Wolff’s reliance on experience in a different direction by providing physical explanations where Wolff had given only metaphysical ones. For example, the following passage explains the process of sensation in neurological terms: This being the state of our body, it is not diffcult to understand how during waking we obtain ideas of bodies from which emanate light, sound, taste, smell and that can be touched. The emanations of these bodies, or even of their parts, hit our nerves, shake them at the surface of our body, and, as if one touches a tight rope at any place and the whole rope wiggles, in the same way the nerve is shaken from one end to the other and the shaking of the inner end is accurately followed or accompanied (because it happens promptly)

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by the sensation that corresponds to it [i.e., the sensory stimulus]. (ED 319) Such a description approaches the subject of dreaming from a completely different angle than the one Wolff had adopted. Although Wolff states in his German Metaphysics that sensations comply with what happens to the body, he clearly distinguishes between the sensation that occurs in the sensory organ and the brain on the one hand and the corresponding “conscious idea of a bodily change” that occurs in the mind on the other.45 Wolff considers only the latter to constitute a subject of metaphysics and relegates the explanation of bodily sensations to natural philosophy.46 Wolff’s German Physiology indeed offers descriptions of the nervous system and the emergence of a sensation in the body that are taken up by Formey’s Essay on Dreams.47 Formey uses Wolff’s physiological descriptions not only to substitute parts of Wolff’s own metaphysical descriptions of the act of dreaming but also to fll the gaps in the latter’s rudimentary theory. For example, Wolff does not account for the causes of dreaming at all. In order to fll this gap, Formey resorts to different sources, namely Zedler’s article on dreams in his Universal-Lexicon, the Galenic theory of animal spirits, and the anatomical description of the nerve contained in Wolff’s German Physiologie. Zedler’s article maintains that people who work hard have no dreams and that dreams usually occur in the morning hours.48 As we have seen above, Formey explained these phenomena by referring to the level of activity of the animal spirits in the body. The existence of animal spirits in the human body served since Antiquity for the explanation of movement and sensation, yet in the eighteenth century it had been incorporated by the recent theories of the nervous system. Drawing on the Dutch anatomist Antonie van Leeuwenhoek, Wolff had already described the nerve as a tube flled with a subtle liquid that was responsible for the transportation of stimuli.49 Applying this theory to the question concerning the causes of dreaming, Formey claims that the brain produces dreams on the condition that it contains neither too much nor too little of this liquid: an abundance in the brain would cause chaos, while a lack would prevent the inner end of the nerve from being shaken; in both situations no dream could occur (ED 323). Thus, Formey uses natural-philosophical descriptions in at least two different ways to enhance Wolff’s rudimentary theory of dreaming: to substitute Wolff’s metaphysical descriptions and to establish aspects of dreaming which Wolff’s theory had not covered. By doing so, Formey’s ran against Wolff’s practice of keeping the description of bodily processes neatly separated from that of what happened in the mind. 50 Thus, he clearly departed from Wolff’s adherence to Leibniz’s theory of preestablished harmony, that is, the view according to which body and soul may appear to interact but in reality act and change independently

172 Annelie Grosse of one another.51 While Formey accepts the distinctness of body and soul at the beginning of his Essay on Dreams, he does not explicitly affrm the pre-established harmony between them. On the contrary, he claims that, for his purposes, it does not matter whether the interaction between body and soul is real or not (ED 318). His agnosticism in this regard seems to support his approach to explain the mental process of dreaming by physiological means. However, Formey does not implement this physiological approach in his Essay on Dreams in a rigorous manner: he does not strictly exclude the notions of a spiritual soul and mental processes from his descriptions. On the contrary, at the center of his explanations is the notion of the dream as “a chain of representations and perceptions” (ED 322) and his use of the term ‘soul’ suggests that he conceived of the soul as a merely spiritual entity. Apparently, he considered it diffcult, if not impossible, to prevent metaphysical and physiological notions from intermingling in a description of dreaming, thus fueling the impression that he accepted a real physical infuence between body and soul. This can be clearly seen from the following description of the act of imagination in his Essay on Dreams, which uses both the terms ‘brain’ (cerveau) and ‘soul’ (âme): The eye, the ear, are affected, but the soul is only informed when the impression reaches the inner end of the optic or the acoustic nerve, and if there is any obstacle that stops this impression on its way, so that no shaking happens in the brain, the impression is lost for the soul. Therefore, and this has to be underlined as one of the fundamental principles of our explanation of dreaming, it suffces that the inner end of the nerves is shaken in order for the soul to obtain representations. (ED 319–20) In my view, Formey here uses the term ‘soul’ to denote the spiritual mind alone rather than an amalgam of bodily and spiritual elements. This is confrmed by his claim that the soul possesses representations. Formey deals not only with the bodily part of the soul and bodily processes but conceives of the relationship between body and mind as a causal relationship: something has to happen in the brain—a bodily entity—in order for a representation in the mind to come into being. Other passages also suggest that Formey held this view. Thus, he states that “only purely physical and mechanical causes, only the state of the body, determine the perception of dreams” (ED 323) and that the succession of representations in dreams relies on “physical and necessary reasons” (ED 330). In short, despite Formey’s stated agnosticism concerning the relationship between body and mind, his Essay on Dreams actually tends toward endorsing a physical infuence between them. Arguably, to suggest such a physical infux theory was the most crucial outcome of Formey’s account of dreaming. This outcome was not unusual: since the 1730s

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physical infux theories had seen a revival in Germany even among Leibnizian and Wolffan scholars like Johann Christian Gottsched, Martin Knutzen, or Johann Peter Reusch. 52 Unlike the latter, however, Formey did not endorse physical infux to challenge the theory of pre-established harmony or its underlying theory of substance. His position in this regard rather seems to have been an unintended by-product of his undertaking to introduce a dream theory at the Academy that contained elements of Wolff’s empirical psychology presented “in a certain light.”

5 Conclusion Formey’s Essay on Dreams illustrates the increasing importance of experience in the methodological debates in mid-eighteenth-century Europe and at the Berlin Academy in particular. The essay contributed to these debates by unraveling the various functions of experience that Wolff had distinguished already. Moreover, the Essay on Dreams plays down the epistemological restrictions Wolff imposed on the role of sensory experience, while Formey’s other writings, such as the Refections on Liberty, emphasize those restrictions. This difference suggests that the empiricist discourse contained in the Essay on Dreams had a strong rhetorical function. The reception of the essay testifes to the success of this empiricist discourse: the fact that it was reprinted in the Parisian Encyclopédie53 as well as in a collection of medical and naturalphilosophical academic essays indicates that it was assigned to the camp of the Newtonian natural philosophers rather than that of Wolffan metaphysicians.54 However, Formey’s essay was also received in such a way because he genuinely went beyond the methodological premises of Wolff’s empirical psychology. Whereas Wolff, in this context, allowed only for experience in the sense of introspection, Formey relies heavily on physiological knowledge obtained through outer experience. As was seen above, Formey’s naturalistic description of the mental act of dreaming not only betrays the impact of the experimentalism fashionable among his contemporaries but also suggests that he endorsed the physical infux theory concerning the relationship between body and soul. Accordingly, the Essay on Dreams undermines Wolff’s strict separation of physiology and empirical psychology qua part of metaphysics. One reason why Formey took this path might well be Wolff’s own epistemological separation of empirical and rational psychology, as Vidal seems to believe regarding the scientists who followed in the footsteps of Wolff’s empirical psychology. Did Formey take Wolff’s claim of an analogy between empirical psychology and physics as an indication to draw on physiological descriptions to explain mental faculties? There is no clear answer to this. I do not hold, however, that Formey’s Essay on Dreams was directly

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infuenced by physicians’ observations and sensualist approaches to the soul. All elements that Formey needed to produce an extensive empirical and physiological dream theory were already contained in Wolff’s philosophical works; it was only a matter of reassembling them.

Notes 1 See Wood (2003) and Anstey (2018). 2 Serjeantson (2011: 120–21) remarks, however, that alongside this general practice, a number of scholars, for instance Jean Bodin, debated whether the soul also ought to be treated in sciences such as metaphysics. 3 For a detailed account of the development of psychology from the sixteenth to the eighteenth century, see Vidal (2006: 71–112). 4 See Vidal (2006: 87–88). 5 See Isler (2010). 6 See Wolff, GM §§ 193, 197; see also Rumore (2018: 183). 7 See Wolff, DP § 111; see also École (1966: 594–96). 8 See Vidal (2006: 23). École (1966: 595) evaluates Wolff’s empirical psychology in similar terms. 9 See Neveu (2017: 70–71). 10 See Vidal (2008). On the reception of Wolff’s rational psychology in the German lands up to Kant, see Dyck (2014), especially 43–69. 11 See Zelle (2004) and Unzer (2004). Unzer anonymously published his Refections on sleeping and dreaming in 1746—the same year in which Formey presumably presented his essay at the Academy. He claimed to attempt a combination of metaphysical and medical analyses of sleeping and dreaming. For a more detailed analysis of the development of dream theories in mid-eighteenth-century Germany, including refections on the Halle philosophers, see Gantet (2010: 429–72; 2012). 12 An interest in psychological matters more broadly emerged only with the affliation of Johann Georg Sulzer to the Berlin Academy in 1750. Since Sulzer was likewise inspired by Wolff’s empirical psychology, we can fnd certain similarities between his academic treatises of the 1750s and Formey’s early Essay on Dreams. On this, see Dumouchel (2018). 13 On the background and general aspects of Formey’s philosophy, see Häseler (2002) and Fontius (2003). 14 See Bronisch (2010: 124–231). Formey himself reported on the conditions of his acquaintance with Manteuffel in his “Notice de mes ouvrages” (Formey 1755: 106). 15 Formey’s popularizations of Wolff’s philosophy include his La Belle Wolfenne (1741–1753), a six-volume work that contained summaries and translations of Wolff’s logics and metaphysics. 16 See [Formey] 1746: sig. )(v–)(2v). 17 See Formey (1749b: 369, 377–78). The frst of Formey’s two treatises on God (1749a: 342) argues more generally that the main source of error in the sciences is the tendency to establish our judgments on proofs without tracing back the latter to the principles and universal notions on which they depend. 18 The Essay on Dreams was published in the Academy’s 1746 yearbook, which appeared in 1748. In the minutes of the Academy’s assemblies, which have been kept formally since 2 June 1746, the oral presentation of the Essay on

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19 20

21 22 23

24 25 26 27

28

29 30

31 32

33 34 35

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Dreams is not registered. This means that Formey had either presented it before June 1746 or had added it to the yearbook without having presented it. Formey to Manteuffel, 27.1.1748, University Library Leipzig, manuscript 0347. Scholars usually refer to a Newtonian–Wolffan controversy at the Berlin Academy (see Harnack 1900: 432–33 and Calinger 1969). Ahnert (2004: 483–87), however, argues that the growing anti-Wolffanism in mideighteenth-century Germany had multiple, not necessarily Newtonian sources and that Euler’s criticism of Wolff in particular was not inspired by Newtonianism. See Terrall (2002). On the differences between Maupertuis’s and Euler’s conception of metaphysics on the one hand and Wolff’s on the other, see Leduc (2015). On Euler’s rejection of Wolff’s philosophy, see Winter (1957: 8–9). Wolff’s opinion of the scientifc superfciality of French authors seems to have been inspired by Émilie du Châtelet’s letters to him; see, for example, Wolff to Manteuffel, 27.1.1741, edited by Stolzenberg et al. (2019), vol. 1, 401–2. For Wolff’s negative judgement about Newtonian philosophers, see, for example, Wolff to Manteuffel, 1.10.1740 and 19.10.1740 (Stolzenberg et al, (2019), vol. 1, 375, 379). For a detailed account of Wolff’s opinion on the renewed Berlin Academy and its members, see Bronisch (2010: 197–201). See Clark (1999: 439–44) and Bronisch (2010: 233–305). See Formey (1747: 15–19; 105–109; 141–43). See Wolff, DP §§ 6–7, 10. See Wolff, DP §§ 11–12. In § 12 Wolff uses the connubium metaphor to describe the mutually supportive relationship between historical and philosophical knowledge. The idea of a connubium rationis et experientiae is repeated several times in Wolff’s oeuvre (see, for example, LL § 985 and PE § 497). See École (1994: 134); in Arndt’s words (1986: 40), experience and reason mutually determine and inform each other in Wolff’s epistemology. For a more recent account of the interplay of reason and experience in Wolff’s philosophy, see Dyck (2014: 20–27). On Wolff’s two Latin psychologies, see École (1966) and (1969) as well as Corr (1975) and Richards (1980). It is likely that Formey relied on Wolff’s German Metaphysics, particularly on its third chapter, while writing his Essay on Dreams. This is supported by the fact that he during this period translated precisely this chapter for the ffth volume of his Belle Wolfenne. See Wolff, GM §§ 191, 727. See Rumore (2018: 181). The two parts of psychology had to function also independently from each other because psychology constituted the basis of practical philosophy (morals and politics) in Wolff’s philosophical system. As Wolff alleged in his Discursus praeliminaris, rational psychology was vulnerable to criticisms because it used a commonly questioned method, while empirical psychology was unshakable because of its reliance on experience. In order to protect his practical philosophy against attacks, he therefore founded it on the latter (DP § 112). See Wolff, DP § 111 and GM § 191. See Wolff, GM § 727; École (1966: 593) as well as Paccioni (2004: 95–96). See Dyck (2014: 20–27).

176 Annelie Grosse 36 Some modern scholars still hold on to this characterization of Wolff: Jean École, one of the most convincing supporters of Wolff’s image as a rationalist philosopher, justifed his view by demonstrating reason’s “preeminence” within the construction of knowledge in Wolff’s oeuvre (École 1994: 135). According to him, Wolff’s empirical psychology reveals a predominantly rationalistic character as well, since it uses the same method—deduction—as all other rational sciences and provides generic knowledge on the faculties of the soul (École 1966: 597–98). More recently, scholars like Kreimendahl (2007: 96) and De Felice (2017: 58) see Wolff at least partially as an empiricist who emphasizes the indispensable function of experience in the generation of philosophical knowledge. 37 See Wolff, GM § 194; see also Rumore (2018: 183). 38 See Formey (1750: 342). 39 See Wolff, GM §§ 325, 372. 40 For a more detailed account of Wolff’s distinction between common and clear experiences, see Dyck (2014: 22). As he puts it, for Wolff, clear, i.e., reliable, experiences must have a rational content. 41 See Formey (1750: 340). Compare to Wolff’s German Metaphysics, in which he declares that experience can easily be confused with imagination or opinion or could be held accountable for phenomena that in reality it did not contain (GM § 326). 42 Wolff relegates knowledge of the relationship between body and soul to his rational psychology, for, in his view, the soul cannot be conscious of such a relationship. Hence, such knowledge cannot rely on experience (GM § 530). 43 See Wolff, GM §§ 801, 803. On this issue, see Carboncini-Gavanelli (1991), who focuses however on the role Wolff attributes to dreaming in his metaphysical doctrine of truth. Within this doctrine, the disorderly state of dreaming serves as a contrast to the order and truth that characterized reality. 44 See Wolff, GM §§ 239, 799. 45 Wolff, GM § 219; cf. Wolff, GPhys § 39. 46 See Wolff, GM § 222. See also GPh § 425, where Wolff argues that the changes that happen in the mind during sensation are not to be treated in a science that deals with the body. 47 See Wolff, GPhys §§ 31, 33. Wolff himself offers this physiological description of a sensation’s transportation in the body also in his rational psychology, yet with the purpose to underline the self-suffciency of the body (see GM § 778). 48 See Zedler (1745: 176). 49 See Wolff, GPhys § 33 and GPh § 436. 50 Wolff’s practice corresponds to his ontological defnition of the soul according to which the soul is a simple and immaterial entity (GM § 742) and is animated or moved by a certain internal force rather than the body (GM § 754). He considered the body to change independently of the soul through a force inherent in it (GM §§ 779–80). 51 On pre-established harmony, as well as Wolff’s reception of it, see Fabian (1925), Casula (1975), and Poser (2004). 52 See Watkins (1998) and Wunderlich (2015: 115–16). 53 See Diderot and D’Alembert (1765: 354b–57b). Interestingly, the passage of Formey’s essay in which he claims his agnosticism toward the relationship between body and soul is omitted from the reprint of the Encyclopédie. 54 See Paul (1770: 91–102).

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9

Lambert on Experience and Deduction Paola Basso

Introduction Immediately after Johann Heinrich Lambert’s death, Lagrange wrote to D’Alembert, noting that the late mathematician, astronomer, natural philosopher, and metaphysician “possessed eminently the rare talent of applying calculus to experiments and observations and of extracting from the latter all regularities [tout ce qu’il pouvait y avoir de régulier].”1 This marvelous alliance of mathematics and experience, which is at the heart of any empirical science, also shaped Lambert’s conception of philosophy itself, which for him should be nothing but scientifc knowledge. Echoing Kant, Lambert points out that “by neglecting calculation [calcul] and the theory on which it is based, one performs experiments without choice and design,” whereas “by neglecting experiments [experiences] one runs the risk of producing chimeras.”2 This alliance is therefore recommended in all disciplines, philosophy included: philosophy, he writes, can become a science only by doing “for qualities [Qualitäten] what geometry has done for quantity [Grösse].”3 As we will see, however, Lambert considers the dependence of scientifc knowledge on experience to be both a strength and a weakness. On the one hand, he argues in the frst part of his New Organon, the Dianoiology, that “experience is in many regards absolutely necessary for the foundation (Grundlage) and enlargement of our knowledge” (NO, Dian § 551). On the other hand, he considers it to be “one of the main purposes of scientifc knowledge […] to allow one to make experiences superfuous [Erfahrungen überfüssig zu machen]” (NO, Dian § 633).4 This tension is at the heart of the idea of induction: scientists must draw on experience to establish rules, but they do so in order to replace empirical data by these rules. On Lambert’s view, the natural philosopher par excellence, Isaac Newton, was able to combine elements of a purely axiomatic science and an experimental one in an admirable way, obtaining new knowledge by drawing on nothing but the results of his previous experiments and deductive power. In order to clarify Lambert’s attempt to solve the tension between the speculative elements of scientifc knowledge (mathematics and

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deduction) and its intrinsically experimental side (experience), this chapter will analyze his attempt to conjoin the “anatomy” of concepts carried out by Locke with the geometrical method advocated by Wolff.5 I will do so by paying attention in particular to Lambert’s conception of philosophy qua science of quality. Already in the Preface to his New Organon, Lambert notes that he aimed to “combine Locke’s simple concepts with Wolff’s method” so as to “establish the foundation of different sciences that are a priori in the strictest sense” (NO iv). In this chapter I intend to focus on two points: frst, the strong continuity between observation and deduction in Lambert’s thought and, second, his effort to solve the problem concerning the ambivalent status of experience. In this regard, I will argue that he reshaped the very notion of the a priori in order to make room for experience. I will begin by explaining how Lambert proposes to combine the Lockean and the Wolffan methods into a procedure modeled on Euclid’s. Section 2 focuses on the issue of categorical truth and on the peculiarity of Lambert’s claim that we need “a supply of concepts and propositions” (Vorrath von Begriffen und Sätzen) drawn from experience, i.e., simple concepts and axioms, in order to subsequently form complex concepts and complex propositions that can apply to the real world, although not directly based on experience (NO, Dian § 577). In this way, experience can serve as a frm basis to carry out a priori deductions, an idea that, as we will see, Lambert takes over from Wolff. In Section 3, I will show how, for Lambert, deduction and induction follow parallel yet reversed paths toward the same results. Section 4, fnally, discusses the way in which Lambert, unlike his contemporaries, considers a priori cognition to be nothing but an extension of a posteriori cognition.

1 Lambert’s ‘Middle Way’ between Wolff and Locke Despite the many labels he received, such as Wolffan, Newtonian,6 “the Leibniz of our age,”7 “a forerunner of Kant,”8 or “the German Aristotle,”9 Lambert was almost entirely self-taught and did not belong to any established school of thought. Often misunderstood during his lifetime, he was known as “the man from the Moon” because of his bizarre appearance and eccentric behavior.10 Overshadowed by Kant, Lambert, as Lewis W. Beck notes in his “brief account of one of the most remarkable philosophers of the mid-century,” had no followers,11 even though he initiated a number of new philosophical sciences, ranging from phenomenology to semiotics. While Kant called Lambert “the greatest genius in Germany,”12 Hegel referred to him as “the dry-minded Lambert.”13 Due to its old-fashioned structure, Lambert’s Architectonic was considered a Wolffan work aiming to “fnish what had already ended.”14 I will argue, by contrast, that this text should be considered a modern epistemological work ahead of its time.15

Lambert on Experience and Deduction 183 While Lambert’s mathematical and scientifc research spans two decades, most of his specifcally philosophical works were written between 1761 and 1764. The frst ones are the Treatise on the Criterium of Truth (Abhandlung vom dem Criterium Veritatis), written in 1761, and his attempt to answer the Berlin Academy prize essay question about the geometrical evidence in metaphysics, On the Method to Correctly Demonstrate Metaphysics, Theology and Morals (Über die Methode, die Metaphysik, Theologie und Moral richtiger zu beweisen), written in 1762. Already in these early works, both published posthumously, Lambert sought to reconcile, so to speak, experience and deduction: Descartes and Wolff are played against each other to the advantage of Euclid, whom he regarded to complement both in his “reaching the categorical [auf das Kategorische kommen]” (CV § 91).16 Lambert’s two main works are the New Organon (Neues Organon), written between October 1762 and November 1763 and published in 1764,17 and his Architectonic (Anlage zur Architectonic). The latter work outlines the “scientifc frst discipline” (wissenschaftliche Grundlehre) that according to Lambert ought to replace traditional metaphysics. It was written in 1764, but published, with some additions, only in 1771.18 In all his works Lambert acknowledges his debt to both Wolff and Locke. In the preface to the New Organon, Lambert indicates that his position in the Dianoiology, which mainly addresses methodological issues, is “closer to Wolff” (NO vi). By contrast, in the Alethiology, which deals with the fundamental concepts of our knowledge, his position is close to Locke’s. Although there are Lockean elements in Wolff’s account of knowledge, Lambert considers Locke to complement Wolff’s position by attaining the starting point that Wolff failed to deal with. Referring to Euclid’s method, he notes that Locke, conversely, knew how to begin, but not how to proceed: “Mr. Locke began by disentangling the simple ideas, but without applying the method I have just indicated” (DR 511). What Lambert took over from Wolff is the strong conviction that philosophy could in principle be developed as a logical deductive system similar to geometry. Yet Lambert did not agree with Wolff’s conception of the mathematical method in all regards.19 In particular, he rejected Wolff’s habit of starting with nominal defnitions instead of simple concepts, as Locke had done (NO, Aleth § 38). Thus, he comments in a letter to Kant that “Wolff shows how to proceed, but how to begin was not very clear to him”20 and that “defnitions do not occur at the beginning” (Defnitionen sind nicht am Anfang). 21 In order to supply the missing part of Wolff’s method, Lambert turns to Locke. He states in the incipit of his Architectonic that “Locke anatomized the human concepts, while Leibniz analyzed them” (Arch § 7).22 Similarly, he notes that “Locke, in his dissection of concepts, imitated those who dissect the human body” (Arch § 9).

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As is well known, Locke distinguished between simple and complex ideas by conceiving of simple ideas as the atoms of experience that cannot be invented.23 Following in Locke’s wake, Lambert considers the primary elements of our knowledge to consist of ten simple concepts, namely, extension, duration, succession, solidity, force, movement, existence, conscience, will, and unity.24 While frequently comparing these frst concepts to prime factors, Lambert affrms their empirical origin so as to anchor philosophy in reality. However, he considered Locke to be unable to build a scientifc system based on the cornerstones he had discovered: Locke and Wolff thus fell short in completely opposite ways (blieben demnach auf eine ganz entgegen gesetzte Art zurücke). Locke had found simple concepts, but he lacked the method required to founding metaphysical systems (Lehrgebäude) on them. Wolff, by contrast, who had read Locke’s works, did not have a high regard of these simple concepts. […] Moreover, since he completely excluded postulates and problems from his metaphysics, […] it is not surprising that the latter does not mention elements that are either given or to be obtained. […] If, instead, Wolff had completely carried out his method in this regard as well, he would have reached Locke’s simple concepts. (Arch § 14) To sum up, Lambert held that Locke erred by betting everything on experience but that Wolff, conversely, was unable to establish the empirical foundation that any sound scientifc system requires. After this account of their shortcomings, Lambert proceeds to carry out a synthesis of Wolff and Locke’s contributions. In this regard, his view of Euclids’s method is key. On his account, Euclid anatomized rather than analyzed space. 25 As Lambert wrote to Sulzer, his colleague at the Berlin Academy, “anatomy helped me greatly to shorten my work and to achieve conclusions that Locke had not reached, since he had not paid enough attention to Euclid’s method.”26 However, Lambert held that Wolff too had misunderstood the nature of Euclid’s procedure. As he puts it, “Euclid, whom Wolff tried to imitate, proceeded completely differently” (Arch § 23). With Euclid in mind, Lambert raises a question he considers “of no small importance,” namely, whether there “might not be a difference between concepts that is similar to that between axioms [Grundsätze] and theorems [Lehrsätze]” (CV §§ 22–23). Systematically elaborating the parallel between geometry and philosophy, Lambert calls the simple concepts “fundamental concepts” (Grundbegriffe) and the complex ones “derivative concepts” (Lehrbegriffe): Grundbegriffe are self-evident like axioms, whereas Lehrbegriffe, like theorems, need a proof.27 As Wolters notes: “Lambert’s reduction of the criteria of evidence to concepts has no historical parallel in either Descartes or Wolff, but stems from a refection on the practice of ancient mathematicians, particularly Euclid.”28

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2 The Case for a “Material Beginning” of Philosophy In the fnal pages of his New Organon, Lambert reveals the results of the “middle road” (ein gewisses Mittel, NO, Dian § 641) between Locke and Wolff he has forged. His solution hinges on what Beck has called the creation of a “shaky bridge” between a posteriori and a priori knowledge.29 As Lambert explains: We reach our concepts a posteriori, since our knowledge begins with the senses. This does not mean, however, that among these concepts one should not fnd ones that, once we possess them, are subsequently conceivable by themselves. (NO, Phän § 255) In order to solve the problem concerning the relationship between experience and deduction, or between a posteriori and a priori cognition, Lambert claims that philosophy must have a “material beginning.”30 In his Inaugural Address at the Berlin Academy, he argues that, in order to prevent “chimeras,” the natural philosopher must provide “materials and ingredients” to the speculative philosopher, namely, “the frst ideas and the frst names of things.”31 Breaking with the widespread custom of starting from abstract principles, Lambert writes elsewhere that “the assumptions, which the theory of form presupposes, must consequently become categorical [kategorisch] once and for all, that is to say: one has to make sure that what one starts with [wobei man anfängt] is true” (NO, Aleth § 1).32 A revealing example of the importance Lambert assigned to categorical truths that are material rather than abstract is Lambert’s reaction to two non-Euclidean hypotheses, which he conjectured yet eventually rejected in his Theory of Parallel Lines (Theorie der Parallellinien). Indeed, despite fnding them “alluring,” he abruptly gives up on his non-Euclidean threads of thought for the sake of a more experience-based Euclidean representation of space, stating explicitly: “But I don’t want them.”33 Thus, notwithstanding the fact that the logical form of these nonEuclidean hypotheses was solid, he held that they could not provide true material beginnings.34 Lambert considers the simple concepts mentioned above, which all stem from experience, to be vehicles of material beginnings. They are, on his account, the categorical basis of our knowledge and the “frst stems [prima stamina] of concepts.”35 Since they do not contain a manifold of elements, these concepts cannot be contradictory and, thus, must be as self-evident as axioms. Lambert seems to hold that these concepts, by dint of their self-evidence, can be used in a priori reasonings regardless of the fact they were derived from experience. For this reason, they can be said to be Janus-faced. In the New Organon, Lambert goes so far as to recommend the “stockpiling” of empirical knowledge because the “supply [Vorrat] of

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concepts and propositions” thus obtained “can be used to expand and apply our knowledge” (NO, Dian § 577). This is to say that philosophers should draw on indubitable empirical concepts and propositions gathered at an early stage even if they are engaged in a priori reasoning. As was noted above, Lambert held that Locke failed to see “that one could try to perform, in reference to other simple concepts, what geometricians had done in reference to space” (Arch § 10). Thus, just like the concept of extension and its frst principles give rise to geometry, the concept of motion and its frst principles give rise either to dynamics or to phoronomy (depending on whether the concept of force intervenes or not). The concepts of force and motion give rise to mechanics, the concept of time to chronometry, and so on. However, in order to correctly understand Lambert’s comparison of philosophy and geometry, it should be noted that he considers geometry to have experimental origins as well. He frequently portrays himself as following Euclid’s procedure, which in his view involved drawing lines as a means to discover a geometrical truth: The frst inventor of geometry took for instance three lines and tried to put them together in the shape of a triangle. The experiment succeeds, the lines meet, and he notes that the angles are already given  […]. One easily sees that a modest experiment of this kind leads to further observations. (NO, Dian § 610) Geometry itself therefore reveals, to use Wolter’s expression, a “protoempirical” origin.36 From here, it is but a small step to drawing a methodological analogy between the work of the frst geometricians and that of a natural philosopher: [I]t may be said that a well-conceived experiment (une expérience bien imaginée), the execution of which fulflls all the required conditions, can always go hand in hand with the most ingenious and diffcult problem that a skilful geometrician can solve.37 In Lambert’s view, both Euclid and Newton were experimental pioneers who brought knowledge from an empirical to a purely scientifc or a priori level. On his account, Euclidean geometry is not a purely hypothetical deductive system but an abstract model of empirical reality comparable to Newtonian physics. Given what has been said so far, it is not surprising that, for Lambert, “the true method […] requires that one start from what is simple rather than from what is general” and that a philosophical system should be erected bottom-up rather than top-down.38 More specifcally, he claims that metaphysical truths can be built by starting from two simple concepts that he takes over from Locke, namely, solidity and force, rather than from an abstract concept such as ens, as he took Wolff to have

Lambert on Experience and Deduction 187 done.39 Indeed, notwithstanding the role Wolff grants to experience, Wolff’s Latin Ontology begins by asserting that “ontology, or frst philosophy, is the science of ens in general or insofar as it is ens” (PPO § 1), on the basis of his conviction that ontology should “deal with the most abstract notions” (PPO § 26). Keenly aware of the novelty of his own approach, Lambert contrasts it with former ontologies, which he considers to be nothing but empty vocabularies, as follows: In ontology, one usually starts with the concepts and defnitions of nothing, something, possible, impossible, ground, determination, thing, reality, essence, property, contingency, and necessity […]. The present exposition of the frst discipline (Grundlehre) is completely different from that approach, and few or none of those concepts appear in our table.40 On Lambert’s account, only the concepts of solidity and force are able to provide the true transition from hypothetical to categorical knowledge.41Already in the preface to the Architectonic, he stresses the concrete beginning of his Architectonic by presenting solidity and force as the frst concepts of metaphysics: “I always start from the physical forces  […] in order to be able to proceed, with much more confdence and clarity, from the physical world to the intellectual one.”42 Proud of this anti-scholastic approach, Lambert writes in a letter to Georg Jonathan von Holland that “if one, for instance, undertakes the anatomy of the frst ontological concept ens, thing, it turns out to be the most complex one among all concepts.”43 For this reason, he continues, “in the Architectonic, I completely overthrew this order and I wrote 3/4 of it before coming to the theory of the ens.”44 Holland’s reaction to Lambert is worth noting: by proceeding in this way, he writes, “we gain an experimental metaphysics [ExperimentalMetaphysik], a science nobody has contemplated yet.”45 Holland thus chooses a paradoxical neologism to describe Lambert’s radically novel conception of the procedure required to establish a scientifc ontology. He completely agrees with Lambert that experimental science and metaphysics must become allies: “If we had left motion theory in the hands of metaphysicians without pushing it forward, […] we would not have gone beyond Zeno!”46 In his work The Problem of Knowledge, Ernst Cassirer notes that “what Lambert has in mind can be clarifed and explained best through the example of a ‘geometry of colours.’47 Cassirer’s example is not randomly chosen, since Lambert held that material ontologies must be based on both a simple concept derived from experience and geometry (NO, Aleth § 127). Indeed, in the Architectonic, Lambert seems to conceive of “light, colors, sounds, warmth, being, and becoming” as simple concepts as well (Arch § 46). According to what Lambert wrote

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to Holland, we can say that he added them on purpose: “in metaphysics, one believed that the former [the concepts of color, sound, etc.] should be excluded just because they are perceptions, thus throwing out the baby with the bathwater and opening the way to idealism.”48 Since perceptions provide the anchor to the empirical world, these concepts must be included into metaphysics so as to preclude vain speculations.

3 Collecting Data for the Sake of Further Deductions As was mentioned above, Lambert praised Locke because of his emphasis on simple concepts to be derived from experience, but took him to have neglected the role of axioms and postulates. Lambert insists that the latter are key to building complex concepts from simple concepts in the correct manner. On his account, “having selected simple concepts is not enough; we also ought to see from where we can draw general possibilities in view of their composition.”49 Lambert believes that philosophy from this point onward can proceed independently of experience, that is, a priori: Finally, if we are familiar with the foundation of the possibility of their composition, we are also in the position to form composite concepts from these simple ones, without acquiring them from experience (ohne sie von der Erfahrung herzuholen). Accordingly, here our knowledge becomes a priori in the strictest sense of the term. (NO, Dian § 656) Thus, arrived at this point, Lambert abruptly closes the door to experience: once philosophy has obtained simple concepts and indubitable rules from experience, it must proceed completely a priori, that is, establish complex concepts by relying on an axiomatic system of laws. He suggests that this procedure is similar to that of an algorithm or “mechanism” and does not require that one return to empirical data.50 Phenomena should frst be observed, but as soon as general rules are found, the latter can be treated as genuine axioms within an axiomatic system. In this regard, Lambert thinks that the procedure to be followed in philosophy differs from the inductive method Newton presents at the end of the General Scholium of the Principia.51 To support his position, Lambert adduces the example of Nicholas Saunderson, a blind mathematician and author of a tactile arithmetic, 52 who, “even though he was blind, understood much of Newton’s colour theory.” Lambert states: We will quote Saunderson, the most learned among the blind and, if necessary, we will give him Newton as a master (zum Lehrer) to let him fnd, in a short time and with an appropriate guide, what

Lambert on Experience and Deduction 189 in a land of blind people, abandoned to themselves, would hardly be possible to be obtained gradually in perhaps 1000 years or more through experiments and reasoning (durch Versuche und Schlüsse). (NO, Aleth § 58) Thus, Lambert introduces axioms as a kind of shortcut to truths that would take “one thousand years or more” to be attained through experiments. Whereas the morphology of single colors lies well outside the reach of blind people, the laws of the relationship between colors can be known independently of actual observations. Seen from Lambert’s perspective, the experience required to establish the morphology is nothing but a brick inside the axiomatic wall. For Lambert, there is a strong continuity between experimentally discovered truths and deduced truths. On his account, matters of fact can be ingredients of truths of reason because experience is not limited to mere cognition of singulars. If experience takes the form of experiments or careful observations, it can provide us with knowledge that is on a par with deductive truths. In the New Organon, Lambert illustrates his objection against the dichotomy of deductive and inductive processes by means of an anecdote. Jean Richer, a French astronomer, found that at the Equator his pendulum swung more slowly: Newton, to whom this observation was reported, immediately noted that it was not only well founded, but also necessary, because the revolution of the earth around its axis diminishes the weight of the pendulum, thus slowing it down. Since Newton could derive this observation from other principles and experiences (Gründe und Erfahrungen), he turned it into a theorem and immediately deduced several other theorems from it. (NO, Dian § 562) Lambert considers the empirical proposition based on Richer’s observation to be “nothing but an occasion [Anlaß]” to discover an implicit corollary of the law of gravitation (NO, Dian § 563). Given this example, one might argue that Lambert adheres to the rationalist view according to which experience is nothing but the occasion required to generate knowledge. He deviates from this position, however, by claiming that the same theorem can be established either speculatively, as a corollary of previous theorems, or experimentally: in principle, Richter’s fnding might as well have been derived from a general law without taking recourse to experience. Consequently, Lambert can be said to merge the Euclidean and Newtonian methods. We can fnd a similar view already in Wolff’s German Logic. Wolff here counts undoubtful (ungezweifelte), correct (richtige), or clear (klare) experiences among the frst principles of an axiomatic system, thus putting them on a par with defnitions and axioms (GL, ch. 4, § 21). Insofar

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as we have noted in these experiences “precisely all of the circumstances under which something takes place” (GL, ch. 5, § 15), they are, on Wolff’s account, as immune to doubt as other premises of a demonstration and can be used as such.53 Lambert also presents his view that the same truth can be established by induction and deduction alike in the following formula: “if A can be found through B, it is irrelevant whether one can fnd A by itself, with effort, or not at all” (NO, Dian § 604); that is to say, if a truth can be derived from another truth, it is completely superfuous to search for it by means of an a posteriori procedure. While this formula seems to favor deduction over induction, it essentially highlights that there is not a strict dichotomy between the experimental and the deductive methods. Once we have a well-founded beginning, Lambert claims, the results of deduction and induction can converge to the point of being merged.54

4 The A Priori as an Extension of the A Posteriori Lambert defnes absolute a priori knowledge as a type of knowledge which owes nothing to experience (NO, Dian § 639). However, he specifes that the concepts of a priori and a posteriori must be treated as relative concepts: It is easy to see that both concepts must be considered to be relative. For if one should infer that not only immediate experiences, but everything that can be found through them is a posteriori, then the concept of a priori would be used in few of those cases in which we can determine something through inferences in advance, because in this case none of the premises could owe something to experience. On this account, our knowledge would contain next to nothing a priori. (NO, Dian § 637) On Lambert’s account, the absolute meaning of the term ‘a priori’ is too narrow because in this case a priori knowledge would be impossible. If taken in a relative sense, by contrast, any deduced truth could be considered a priori. To solve this problem, he sets off in search of “a certain middle way (ein gewisses Mittel) that brings both extremes closer together” (NO, Dian § 641). In line with the tradition, Lambert states that “we call a priori what can be deduced from the concept of the thing [was aus dem Begriff der Sache kann hergeleitet werden]” (NO, Dian § 641, my emphasis).55 However, he rejects the strict dichotomy of a priori and a posteriori knowledge by claiming that “something is more or less a priori [etwas mehr oder minder a priori sei], depending on whether we can derive it from more [or less] distant [entferntern] experiences” (NO, Dian § 640).

Lambert on Experience and Deduction 191 Turning against Leibniz, among others, he thus advocates a continuity between a posteriori and a priori knowledge. Lambert takes up the same issue in his Architectonic: [T]he beginning is, in some ways, absolute, but it can be considered relative as well. A relative beginning is a beginning only with respect to what follows. As was mentioned above in correlated terms […], the source is a beginning only with respect to the river, but not with respect to the water itself. (Arch § 492) Hence, we can affrm that Lambert uses the term ‘a priori’ to refer to a relative beginning, i.e., a beginning intrinsically indebted to preceding experiences. In most cases, this is the only possibility available to us. As he puts it: “it is hard to establish the thing completely a priori” (CV 86). On Lambert’s account, the act of deducing new truths from given ones is not a merely analytic procedure but consists in combining given concepts according to axioms and postulates a priori. 56 While each of the resulting truths implies the original contribution from experience, establishing them does not require that one return to the level of empirical observations. Lambert holds that if new truths are derived from other truths, as long as the deduction takes place on the pure plane of thought, the result should be called a priori, although it is a priori in a relative rather than an absolute sense. In other words, whenever we discover something by empirical means, we can subsequently deduce many corollaries from it by following and making explicit what the discovery implies. In this way, we can discover new truths by a priori means. For Lambert, to deduce something “from the concept of thing” is nothing but the ability to seek “what is given simultaneously with the given” (NO, Dian, § 468). For instance, Lambert argues that impenetrability is given simultaneously with the empirical concept of solidity in the same way that the angles of a triangle are given simultaneously with its sides.57 In the New Organon, Lambert exemplifes how we can move from an a posteriori procedure to an a priori one by appealing to the image of a Newton confned to his room: Scientifc knowledge, therefore, reveals the richness of our knowledge, showing us how one thing is dependent on the other, how the former can be found through the latter, and what is given simultaneously with the given and, thus, need not be found independently of other things. In this way, Newton stayed in his room and determined, by drawing on some known truths, the shape of the earth, the mechanical laws of celestial motions, and so on. Discoveries that would have been considered revelations if Newton’s genius (Geist)

192 Paola Basso and the ways of geometry (die Wege der Messkunst) had been unknown. (NO, Dian § 607) Clearly referring to experimental truths, Newton notes that a few truths suffced for the deduction of a number of other truths through the powerful method of geometry.58 Newton’s famous thought-experiments, such as conceiving the orbit of the moon in relation to gravitation, are perfect examples of how he combined a priori and a posteriori procedures. However, Lambert’s account of the scientifc method deviates from Newton’s in that he seems to forget here the well-known necessity to experimentally verify the deduced truths. It is not a coincidence that he refers to Newton and Huygens as having determined the fgure of the earth only “through reasoning” (NO, Dian § 573). What is signifcant here is that, for Lambert, the a priori cognitions achieved by reasoning come on the trail of the a posteriori ones. Accordingly, the truths that are established by a priori means do not cancel out the experimental side of scientifc knowledge but remain bound to it. This ‘hybrid a priori,’ which allows him to escape rigid dichotomies, can be regarded as Lambert’s main contribution to epistemology. However, Lambert’s mixed procedure poses a signifcant theoretical problem. Once the laws of dynamics or of mechanics that are found by means of experiments are anchored in an a priori axiomatics (such as in Newton’s Principia), it remains an open question as to “whether their opposite remains possible as well” (Arch § 375), that is, whether they are necessary in an absolute sense.59 One of Lambert’s many unfnished projects, in fact, was to investigate “whether the laws of movement we fnd in our world have a geometrical necessity or not” (Arch § 375), or, put differently, “whether the frst propositions of mechanics cannot be proven to be as necessary and a priori as Euclid did with regard to the propositions of geometry.”60 Challenging the mere a posteriori procedure of mechanics, Lambert asks “what of all this can we know a priori, or without regard for the more specifc experiences [ohne Rücksicht auf die specialern Erfahrungen]?” (Arch § 376). At bottom, this seems to be the fundamental question.61 In order to answer it, Lambert goes back to the simple concept at the basis of dynamics or mechanics, i.e., the concept of force. He notes that “if we merely assume that a certain amount of force is in the world, then we proceed a posteriori. However, the metaphysical truth of it, or the necessary possibility of its existence, should be demonstrated a priori” (Arch § 377). He therefore suggests that we regard, for instance, the transmissibility of force not as a fact that can be discovered a posteriori but as something intrinsic to the concept of force, i.e., as something that can be conceived to belong to the latter independently of experience.62 However, Lambert is well aware that experience is the ultimate touchstone for all experimental truths. Already in his frst philosophical

Lambert on Experience and Deduction 193 work, he claims that “whatever demonstration I give, experience will be required” to determine, for instance, whether air can be frozen or not (CV § 85). In such cases, demonstrations are powerless compared to the probative force of experience. Pushing further, he states that it is not only possible to develop a dynamics or mechanics a priori but, conversely, that it should also be possible to elaborate a metaphysics a posteriori. The result would be an experimental metaphysics: I do not doubt that metaphysics could be developed, completely and in good order, also a posteriori […]. The method in such a case would depend on a supply of means (Vorrat von Mitteln) that allow one to infer the true from the illusory [Schein], the light from the shadow, and the whole from the part. […] And if one wants to proceed according to Wolff’s method, one can apply what has been found a priori to what one accepts from experience in the same way that the astronomer applies the fundamental laws of mechanics to the motion of every celestial body. (CV § 87) Lambert’s reference to the astronomers is not fortuitous. He was an outstanding astronomer himself. Ultimately, Lambert held that scholars should not try to imitate the strict mathematical method, which purports to proceed completely a priori, but the “mixed” method carried out in astronomy—that is, a method that proceeds partially a posteriori and partially a priori. In fact, Wolff himself held that the empirical and theoretical parts of astronomy symbolize not only the “marriage of reason and experience” (PE § 497) but also a method that necessarily relies on conjectures. According to Wolff, “there would be no harm if in philosophy we imitated the astronomers if we are confronted with cases in which conjectures provide the basis for the investigation of the truth” (DP § 127). For Lambert, the method employed by astronomers represents the perfect method not only to move from appearance to truth but also to move from the part to the whole. As he puts it in his early Treatise on the Criterium of Truth, “from three observations of a comet, it is possible to infer its entire orbit” (CV § 87).

5 Conclusion According to Lambert, “an a priori cognition is preferable to an a posteriori one” (NO, Dian § 642). However, we have seen that he considered all scientifc knowledge to be rooted in experience and experiments. In order to solve this tension, he was compelled to adjust the meaning of a priori cognition, which he did by arguing that it necessarily relies on a posteriori cognitions of concepts that, afterwards, can also be conceived independently of experience. Without relying on experience, metaphysics would be blind at birth, destined to consume itself in idle talk and

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mere suppositions. As Lambert wrote in a letter to Kant, “a truly genuine metaphysician [ein purus putus Metaphysicus] is like someone lacking a sense, just like a blind person lacks the sense of sight.”63 Whereas thought alone produces imaginary worlds, the mere description of events lacks universality. The method of truly scientifc knowledge must consist of two different but interrelated moments: an experimental basis and a series of a priori deductions. It has been said that “Lambert did not […] solve the problem of the relation between a priori and a posteriori knowledge.”64 From a certain point of view, we can only agree, because Lambert certainly did not provide a clear-cut demarcation of the two types. I hold, however, that he took the question concerning their relation to a gnoseological level and laid the basis for a new conception of a priori cognition, namely, one that is compatible with experience. More precisely, as we have seen, Lambert considered experience to pave the way for a priori deductions and thus to make possible a priori knowledge in a relative sense. For this reason, while Wolters considers “Lambert’s determination of an axiomatic science as empirically grounded and at the same time a priori” to be contradictory,65 I have rather argued that, in this manner, Lambert seeks to forge a scientifc method that combines experience and axiomatics. It is certainly true that Lambert was not always able to integrate the two moments in a satisfactory manner. A case in point of this unresolved confict is his shifting attitude in his Theory of Parallel Lines. As was mentioned above, he here abruptly rejects his non-Euclidean threads of thought for the sake of a more experience-prone Euclidean representation of space.66 Nevertheless, by claiming that scientists and philosophers should start from empirical observations but process the data thus obtained according to axiomatic mechanisms, Lambert can be said to have anticipated the era of computer models and predictive algorithms.

Notes 1 Lagrange to D’Alembert, October 3, 1777 (Lagrange 1882: 333, my emphasis). Apart from the disciplines mentioned here, Lambert also wrote on optics, magnetism, acoustics, cartography, linguistics, and so on. 2 Lambert’s Inaugural Address (Discours de réception) at the Berlin Academy (DR 509). He explains that if the philosopher “wishes to avoid the reproach  […] of clinging only to abstract and useless speculations, it is better for him to bring them closer to practice and, consequently, to the experience […] which will serve him as a touchstone [pierre de touche]” (DR 511–12). All translations of Lambert’s works are mine. 3 See Lambert (1918: § 5). In the fourth section of his Architectonic—called Organon quantorum—Lambert tried to show how mathematics could be useful in metaphysics, and he also proposed, as the basis of a scientifc ethics, an Agathometry (NO, Aleth § 108; Arch § 110). As he wrote to Sulzer: “To be perfect and absolute, Agathology will have to change into Agathometry” (March 1, 1763, Handschriftlicher Nachlaß, Basel: Universitätsbibliothek, L.1.a. 754, 190).

Lambert on Experience and Deduction 195 4 Similarly, Lambert writes in the New Organon that “this is what it means to make experience superfuous in the most proper sense, to the extent that if one still wants to use it, experience can serve only as a test” (NO, Dian § 633). In the New Organon, Lambert dedicates chapter VIII of the Dianoiology to the issue of experience (§§ 551–98). He here distinguishes between experience in the sense of common experience, observation, and experiment (NO, Dian § 557). Chapter IX of this work is dedicated to scientifc knowledge (§§ 599–700). 5 Lambert often refers to the idea of anatomy in relation to concepts (see, among others, Arch §§ 7–9, § 49; NO, Aleth § 123). See also his letters to Holland, April 21, 1765 (1986a: 35) and Sulzer, July 24, 1763 (Handschriftlicher Nachlaß, Basel: Universitätsbibliothek, L.1.a. 745, 200). Although Dilthey considered Lambert to be “a rationalist in a seventeenth-century sense,” he also saw him as someone who “strives to combine Leibniz with Locke” (Dilthey 1927: 151). This attempt earned Lambert the accusation of a “fundamental fallacy” in his thought: according to Griffng, “Lambert sought to unite the philosophies of Leibniz and Locke,” whereas “the two methods, empiricism and rationalism, were diametrically antithetical” (Griffng 1983: 58). 6 According to Fisher, for instance, Lambert should be “ranged on the Newtonian side” (Fisher 1975: 432). 7 See Herder (1887: 469). 8 See Zimmermann (1879), Riehl (1876), and Lepsius (1881). For more recent studies on the relationship between Lambert and Kant, see Peters (1968) and Perin (2016). 9 In his Speech at the Berlin Academy on the occasion of the celebration of Lambert’s jubilee birthday, in 1828, Paul Erman is said to have declared: “Leibniz is the German Plato, and Lambert, the German Aristotle” (quoted in Wolf 1860: 334). 10 See Graf (1829: 33). Lagrange described Lambert as follows: “He had a very naive way of thinking and acting, which often annoyed people who did not particularly know him” (Lagrange 1882: 333). 11 “Generally speaking, his infuence was nil; no one took up where he left off”; see Beck (1969: 411). In fact, it was not until the work of Charles Peirce that Lambert’s semiotics received some recognition. 12 Kant to Lambert, December 31, 1765: “in all sincerity, I hold you to be the greatest genius in Germany, a man capable of important and enduring contributions to the investigations on which I too am working” (Corr, 10: 54). 13 Hegel (1986: 47). 14 According to Reinhold, for instance, Lambert mixed logic and ontology in “a mathematical game with elementary concepts” (Reinhold 1796: 184). 15 This view is in line with recent commentators such as Beck, who argues that Lambert “far exceeded all the others in originality and modernity” (Beck 1969: 402). See also Wolters (1980: 19), who stresses that “Lambert’s Architectonic is not a metaphysics, but rather a ‘theory of science’ [Wissenschaftstheorie].” 16 According to Lambert, both Wolff, “the guide” (der Wegweiser), and Descartes—who “remains very far behind” (bleibt ungleich weiter zurück) in identifying the true starting points—only offer a hypothetical beginning, bound to an “if you give” (CV § 91). 17 The New Organon introduces four philosophical disciplines, each of which is treated in one part of the work: Dianoiology (the doctrine of the laws of thought), Alethiology (the doctrine of truth), Semiotics (the doctrine of signs), and Phenomenology (the doctrine of appearances).

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18 Lambert notes in an entry titled Ontologia in his Monatsbuch: “March 1764. Ontology began. Prolegomena, fundamental ideas, axioms, and postulates” (Lambert 1915a: 26). 19 “Wolff broke the ice, but he left also many things behind” (Arch § 11). Lambert acknowledges Wolff’s very idea of systematically applying the mathematical method to philosophy but held that he neglected the constructive part, i.e., postulates, problems, and constructions. As he puts it in a letter to Kant, Wolff “has brought approximately half of the method of mathematics into philosophy. The other half remains to be worked on, so we know what to strive for” (Lambert to Kant, November 15, 1765; Corr, 10:54). On this, see Basso (2013). 20 As Lambert writes to Kant in November 1765, “Wolff took nominal defnitions free of charge, we might say” (Lambert 1968b: 338). Of this frst letter of Lambert to Kant, the Gotha Library has two radically different copies: “one, apparently older, is by Lambert’s hand, the other by a copyist’s hand” (see Anmerkungen und Register, AA 13:28). See also Lambert’s letter to Kant dated February 3, 1766 (Corr, 10:64). A later letter reiterates that simple concepts “can only be thought and not defned” (Lambert to Kant, October 13, 1770; Corr, 10:107). 21 Lambert to Kant, November 1765 (1968b: 338). 22 For Lambert’s criticism of Leibniz’s notion of analysis, see Schenk (1991: 210–11). The term ‘anatomy’ does not seem to occur in Locke’s Essay. It appears in the glossary of Baumgarten’s Acroasis logica—“analysis seu resolutio (evolutio seu anatomia)” (AL § 119)—as well as in Tschirnhaus’s Medicina mentis. Tschirnhaus notes that one can “unveil by one’s own efforts the inner constitution of bodies (interioris corporum constitution) by means of anatomy (ex anatomia)” (MM 85). In line with Locke’s idea of an anatomy of concepts, Hume compared the “anatomy of the mind” to the observations and experiments of “anatomists” (T 2.1.12.2). On this, see Demeter (2016: 143–65). We know from a not completely positive review that Lambert had read Hume. See Lambert (1770a: 297–98). 23 “These simple ideas […] are the materials of all our knowledge […]. Man’s power over this little world of his own understanding is much like his power over the great world of visible things, where he can only compound and divide the materials that he fnds available to him, and can’t do anything towards making the least particle of new matter, or destroying one atom of what already exists” (Locke, Essay II.ii.2). 24 Lambert deals with his “fundamental simple concepts” and the principles deduced from them in both the frst two chapters of the Alethiology (§§ 1–117) and the frst part of the Architectonic (§§ 45–123). 25 “Turning at once to lines, angles and triangles, etc., Euclid undertakes not the analysis but the anatomy of space [so nimmt er nicht die Analyse sondern die Anatomie des Raumes vor], and thereby creates geometry” (Lambert to Holland, April, 12, 1765; 1968a: 32). 26 Lambert to Sulzer, July 24, 1763 (Handschriftlicher Nachlaß, Basel: Universitätsbibliothek, L1a 745, 200). 27 “A fundamental concept is a simple empirical concept that cannot be resolved further” (CV § 45), whereas derivative concepts are complex concepts that can be further analyzed and require proofs of their correctness, for instance, by searching for their genesis (Entstehensart). Lambert remarks that “Wolff either did not notice the concepts that we are calling derivative concepts [Lehrbegriffe] or at least did not defne them” (CV § 26). 28 Wolters (1980: 59).

Lambert on Experience and Deduction 197 29 Beck (1969: 203). 30 See Lamberts eigene Recension seiner Architectonic (1773: 414). Risse points out that “at its deepest level,” Lambert’s theory of concepts was “not only formal but also material” (Risse 1970: 270). 31 Lambert, DR 509. Philosophy and natural philosophy are said to begin from the same empirical starting points and to differ only in terms of their further treatment of the subject matter at hand (DR 509). 32 Lambert exposes the features of this categorical truth both in the Alethiology of his New Organon and in the third part of his Architectonic, which is titled Das Reale der Grundlehre. 33 See Lambert (1786: § 80). 34 On this, see Papadoupulos and Théret (2015). 35 Lambert (2008a: 421). 36 Wolter (1980: 83). 37 Lambert, DR 510. He proceeds with an analogy between nature and algebra: “[L]ike Nature, algebra responds to the true conditions of the problem, and defes [élude] the geometrician’s expectation whenever he has misconceived this conditions.” See also Dian § 58. 38 Lambert (1969: 392). He repeats the same sentence in his frst letter to Kant, dated November 1765 (1968b: 340). 39 Lambert to Holland, April 21, 1765 (1968a: 34). 40 Lambert, Arch § 75, cf. § 41. Earlier on, he offers a synoptic “table” that presents simple concepts in relation to the various sciences based on them (§ 53). 41 As Beck points out, Lambert held that the concepts of force and solidity made it possible to cross “the chasm between logical and metaphysical truth” (Beck 1969: 203). 42 Lambert, Arch, Preface, xi. 43 Lambert to Holland, April 21, 1765 (1968a: 34). On Lambert’s account, the concept of ens, far from being simple, “entails notions such as unum, verum, bonum, quale, quantum, existentiae capax, relationis capax, cogitabile, and qua compositionem spectabile” (1968a: 3). The reference to Locke is straightforward: in line with the latter, Lambert argues that language misleads the Aristotelian, who goes as far as to consider the idea of substance as simple, while it is in fact complex. On this, see Ayers (1991: 25). 44 Lambert to Holland, April 21, 1765 (1968a: 34). 45 Holland to Lambert, September 22, 1765 (1968a: 92). 46 Holland to Lambert (1968a: 92). 47 Cassirer (1907: 419). 48 Lambert to Holland, May 17, 1765 (1968a: 57). Concerning the project of a “geometry of colors,” the frst phenomenological axioms seem to concern the fact that they possess gradations. As he puts it, “colors have gradations” and “the concepts of these gradations are simple in themselves.” Moreover, he writes that “in the mixed ones we perceive what is heterogeneous” (NO, Aleth § 28). 49 Lambert, NO, Aleth § 29 (my emphasis). General possibilities are given by general principles, that is, axioms and postulates. Particularly, postulates suggest possibilities that are “conceivable for themselves” and are “the basis of all the possibilities to be posed [basis possibilitatis ponendae]” (Lambert 2008b: 845). According to Lambert, since simple concepts admit of modifcations and connections, they contain the frst principles of their combination. On the role of postulates in Lambert’s philosophy, see Dunlop (2009: 33–34).

198 Paola Basso 50 On Lambert’s use of the term ‘rule’ in this regard, see Bullynck (2010: 70). 51 At the end of his Principia, Newton explains this inductive method by noting that “[i]n this experimental philosophy, propositions are deduced from the phenomena and are made general by induction” (Newton, PM 276). 52 Saunderson was the author of The Elements of Algebra, published in Cambridge in 1740; the French title is more explicit: L’arithmétique palpable du docteur Saunderson (Paris 1756). 53 In the Psychologia empirica, Wolff likewise states that “we make inferences from principles established through experience” (PE § 434). On this, see Dyck (2014: 7, 40). 54 “In nature, many effects and modifcations can be determined in advance [lassen sich voraus bestimmen] without having to resort to any further experience [ohne weitere Erfahrung]” (NO, Dian § 615). 55 According to Wolters, the “term ‘a priori’ considered as a foundational principle [grundlagentheoretisch] was introduced into philosophical terminology by Lambert” (Wolters 1980: 77). 56 By contrast, for Descartes and Leibniz the main road to a priori cognition was analysis. As Descartes puts it in the Meditations: “Analysis shows the true way [veram viam] by means of which things are methodically found and as it were a priori. Synthesis, on the other hand, proceeds only in the opposite way and is requested only a posteriori” (AT 7: 155). On this, see Engfer (1982). 57 Refecting on how “Euclid proceeded in reference to space to demonstrate the limits of the possibilities of fgures” (Arch § 251), Lambert concludes that we understand “that something is not applicable to the things themselves, or not possible [nicht angehe oder nicht möglich sey] […] in a direct, immediate way from the solid and the limits [Schränken] of the forces applied to it” (Arch § 273). Lambert’s notion of conceivability recalls Crusius’s principle of non-separability; see Crusius, Entwurf §§ 967–70. Related to this, Lewis Beck considers Lambert and Crusius to have developed antecedents of the Kantian synthetic a priori judgment. As he puts it, “perhaps their greatest contribution was to openly use a type of connection between concepts that Wolff had used surreptitiously” (Beck 1969: 411). On Crusius, Lambert notes that “those who want to derive the maximum proft from Wolff’s works […] do well to look for philosophical writings more or less deviant from Wolff, among which I have no scruple to name Darjes and Crusius” (Arch § 11). 58 Newton’s view is in line with Lambert’s idea, mentioned above, that we need a “supply” (Vorrat) of experience to be used for further deductions. Lambert notes that “there are always as yet unobserved things in front of us,” such as the different sounds of a blacksmiths’ hammer on different surfaces (Dian § 564). Drawing on such experiences, scientists such as Pythagoras, Galileo, or Newton can proceed a priori to detect principles and theorems that pertain to the actual world. 59 According to Carl Koch, “Wolff did not succeed in clarifying the relation between the a priori knowledge of logic and mathematics and the a posteriori knowledge of the empirical sciences, for which he was later criticised by Lambert, who drew the attention of the Wolffans to the problem regarding the foundation of the empirical sciences” (Koch 2006: 62). 60 Lambert (1770b: § 1, 363). 61 As Wolters notes: “Until Lambert, the a priori was basically used as metapredicate for theoretical-demonstrative contexts and therefore not yet in connection with the question of the possibility of the validity—independent

Lambert on Experience and Deduction 199

62

63

64 65 66

of experience—of scientifc propositions concerning the world” (Wolters 1980: 77). Lambert notes that only Zeno could really contest the conceivability of simple concepts such as force and movement (Arch § 379). Even though the model of reasoning offered by mathematics is opposite to that offered by experience, Lambert holds—following Newton and Galileo—that the outcome should be the same. The limit of Lambert’s project, as Dilthey points out, was to hold on “to the metaphysical presupposition according to which determinations in thought are in agreement with those in reality” (Dilthey 1927: 151). Lambert to Kant, October 13, 1770 (1968b: 356–57). Lambert here notes that a reform of metaphysics should be carried out by “philosophers who should be skilled in physics and mathematics as well.” Purus putus is a technical term that denotes the purity of gold. Lambert’s analogy echoes a passage in Newton’s General Scholium: “As a blind man has no idea of colours, so have we no idea of the manner by which the all-wise God perceives and understands all things” (PM 942). Koch (2006: 62). Wolters (1980: 58). See Lambert (1787: § 80).

Bibliography Primary Sources Baumgarten, Alexander Gottlieb (1761), Acroasis logica, Halle: Hemmerde (AL). Crusius, Christian August (1747), Weg zur Gewißheit und Zuverläßigkeit der menschlichen Erkenntnis, Leipzig: Gleditsch; repr. in Die philosophische Werke, vol. 3, Hildesheim: Olms 1965. Descartes, René (1996), Meditationes de prima philosophia, in Œuvres de Descartes, vol. 7, ed. by C. Adam and P. Tannery (AT), Paris: Vrin. Kant, Immanuel (1922), Briefwechsel, Anmerkungen und Register, in Gesammelte Schriften (AA 13), ed. Deutsche Akademie der Wissenschaften, Berlin: De Gruyter. ——— (2010), Correspondence, transl. and ed. by A. Zweig, Cambridge: Cambridge University Press 2010 (Corr). Lagrange, Joseph-Louis (1882), Correspondance inédite de Lagrange et d’Alembert, in Œuvres, vol. 13, Paris: Gauthier Villars; repr. Hildesheim: Olms, 1973. Lambert, Johann Heinrich, 5 Lettres de Lambert et Sulzer, in Handschriftlicher Nachlass, Basel: Universitätsbibliothek, L.1.a. 754: 183–203. ——— (1764), Neues Organon, oder Gedanken über die Erforschung und Bezeichnung des Wahren und dessen Unterscheidung von Irrthum und Schein, 2 vols., Leipzig: Wendler; repr. in Philosophische Schriften, vols. 1–2, Hildesheim: Olms 1965 (NO; the different sections are abbreviated ‘Dian’, ‘Aleth’ and ‘Phän’). ——— (1767) ‘Discours de réception’ (‘Sur la liaison des connaissances qui sont l’objet des quatre classes de l’Académie’), in Histoire de l’Académie Royale de Berlin (1765), Berlin: Haude & Spener, 506–14 (DR).

200 Paola Basso ——— (1770a), Hume: Vier Philosophen, Allgemeine Deutsche Bibliothek, 12/2, 297–98. ——— (1770b), Gedanken über die Grundlehre des Gleichgewichts und der Bewegung, in Beyträge zum Gebrauche der Mathematik und deren Anwendung, vol. 2.2, Berlin: Verlag der Buchhandlung der Realschule, 363–628. ——— (1771), Anlage zur Architectonic, oder Theorie des Einfachen und des Ersten in der philosophischen und mathematischen Erkenntniß, 2 vols., Riga: Hartknoch; repr. in Philosophische Schriften, vols. 3–4, Hildesheim: Olms 1965 (Arch). ——— (1773), ‘Lamberts eigene Recension seiner Architectonic’, Allgemeine Deutsche Bibliothek, 12–25; repr. in Philosophische Schriften, vol. 7, Hildesheim: Olms 1969. ——— (1786), ‘Die Theorie der Parallellinien’, Leipziger Magazin für die reine und angewandte Mathematik, 3, 142–64; 325–58. ——— (1915a), Johann Heinrich Lamberts Monatsbuch, ‘Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften’ (Math. phys. Klasse, vol. 27, 6, 1915), ed. by K. Bopp, München: Verlag der Königl. Bayer. Akademie der Wissenschaften. ——— (1915b), ‘Abhandlung vom Criterium veritatis’, ed. by K. Bopp, KantStudien, 36; repr. in Philosophische Schriften, vol. 10.2, Hildesheim: Olms 2008, 422–92; partially translated as Treatise on the ‘Criterium of Truth’, in E. Watkins (ed.), Kant’s Critique of Pure Reason: Background Source Materials, Cambridge: Cambridge University Press 2009, 233–57 (CV). ——— (1918), ‘Über die Methode, die Metaphysik, Theologie und Moral richtiger zu beweisen’, ed. by K. Bopp, Kant-Studien, 42; repr. in Philosophische Schriften, vol. 10.2, Hildesheim: Olms 2008, 493–529. ——— (1968a), ‘Lamberts und Hollands philosophische Briefe’, in Briefwechsel, Philosophische Schriften, vol. 9, Hildesheim: Olms, 6–332. ——— (1968b), ‘Lamberts und Kants, philosophische Briefe’, in Philosophische Schriften, Briefwechsel, vol. 9, Hildesheim: Olms, 333–68. ——— (1969), Fragment einer Systematologie, in Philosophische Schriften, vol. 7, Hildesheim: Olms, 385–411. ——— (2008a), Versuch über die ontologischen Grundsätze, in Philosophische Schriften, vol. 10.2, Hildesheim: Olms, 408–22. ——— (2008b), Zur Grundlehre, Philosophische Schriften, vol. 10.2, Hildesheim: Olms, 844–57. Locke, John (1975), An Essay Concerning Human Understanding, ed. by P.H. Nidditch, Oxford: Clarendon Press (Essay). Hegel, Georg W. F. (1986), Wissenschaft der Logik, Gesammelte Werke, vol. 12, Hamburg: Meiner. Herder, Johann G. (1887), Gott. Einige Gespräche über Spinoza’s System nebst Shaftesbury’s Naturhymnus, Sämmtliche Werke, vol. 16, ed. by B. Suphan, Berlin: Weidmannsche Buchhandlung. Hume, David (1978), A Treatise of Human Nature, ed. by P.H. Nidditch, Oxford: Clarendon (T). Newton, Isaac (1999), The Principia: Mathematical Principles of Natural Philosophy, transl. by I.B. Cohen and A. Whitman, Berkeley: University of California Press (PM).

Lambert on Experience and Deduction 201 Reinhold, Karl L. (1796), Preisschriften über die Frage, welche Fortschritte hat die Metaphysik seit Leibnizens und Wolffs Zeiten in Deutschland gemacht?, Berlin: Maurer, 171–254. Saunderson, Nicholas (1740), The Elements of Algebra, Cambridge: Cambridge University Press. Tschirnhaus, Ehrenfried W. (1695), Medicina Mentis sive artis inveniendi praecepta generalia, Amsterdam: Fritsch Leipzig; 1st edn. 1687 (MM). Wolff, Christian (1713), Vernünfftige Gedancken von der Kräfften des menschlichen Verstandes, Halle: Renger 1713; repr. in Gesammelte Werke, I.1, Hildesheim: Olms 1978 (GL). ——— (1729), Philosophia prima sive Ontologia, Frankfurt/Leipzig: Renger; repr. in Gesammelte Werke, II.3, Hildesheim: Olms 1962 (PPO). ——— (1963), Discursus praeliminaris de philosophia in genere / Einleitende Abhandlung über Philosophie im Allgemeinen, ed. by G. Gawlick and L. Kreimendahl, Stuttgart-Bad Cannstatt: Frommann-Holzboog; 1st edn. Frankfurt/Leipzig: Renger 1728 (DP). Secondary Sources Arndt, Hans W. (1978), ‘Lambert et l’esthétique du XVIII siècle’, Bulletin de la Société française de philosophie, 73, 103–15. ——— (1983), ‘Rationalismus und Empirismus in der Erkenntnislehre Christian Wolffs’, in W. Schneiders (ed.), Christian Wolff 1679–1754. Interpretationen zu seiner Philosophie und deren Wirkung, Hamburg: Meiner, 31–47. Ayers, Michael (1991), Locke. Epistemology and Ontology, London/New York: Routledge. Barone, Francesco (1957), Logica formale e logica trascendentale. Da Leibniz a Kant, Torino: Edizioni di Filosofa. Basso, Paola (2011), La fligrana ontologica del metodo matematico wolffano, in F. Fabbianelli et al. (eds.), Zwischen Grundsätzen und Gegenständen. Untersuchungen zur Ontologie Christian Wolffs, Hildesheim: Olms, 89–100. ——— (2013), The Other Side of Euclid. Lambert’s Epistemology of Constructive and Diagrammatic Strategies, Milano: Ledizioni. Beck, Lewis White (1969), Early German Philosophy. Kant and His Predecessors, Cambridge: Harvard University Press. Bullynck, Maarten (2010), ‘Johann Lambert’s Scientifc Tool Kit. Exemplifed by the Measurement of Humidity’, Science in Context, 23/1, 65–89. Cassirer, Ernst (1907), Das Erkenntnisproblem in der Philosophie und Wissenschaft der neueren Zeit, vol. 2, Berlin: B. Cassirer. Demeter, Tamás (2016), David Hume and the Culture of Scottish Newtonianism. Methodology and Ideology in Enlightenment Inquiry, Leiden/Boston: Brill. Dilthey, Wilhelm (1927), Studien zur Geschichte des Deutschen Geistes, Wiesbaden: Vieweg und Teubner Verlag. Dyck, Corey W. (2014), Kant and Rational Psychology, Oxford: Oxford University Press. Dunlop, Katherine (2009), ‘Why Euclid’s Geometry Brooked no Doubt: J.H. Lambert on Certainty and the Existence of Models’, Synthese, 167/1, 33–65.

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Eisler, Rudolf (1899), Wörterbuch der philosophischen Begriffe und Ausdrücke, Berlin: Mittler. Engfer, Hans Jürgen (1982), Philosophie als Analysis. Studien zur Entwicklung philosophischer Analysiskonzeptionen unter dem Einfuß mathematischer Methodenmodelle im 17. und frühen 18. Jahrhundert, Stuttgart-Bad Cannstatt: Frommann-Holzboog. Fischer, Klaus P. (1975), ‘John Locke in the German Enlightenment. An Interpretation’, Journal of the History of Ideas, 36/3, 431–46. Graf, Matthias (1829), ‘J.H. Lamberts Leben’, in D. Huber (ed.), J.H. Lambert nach seinem Leben und Wirken aus Anlass der zu seinem Andenken begangenen Secularfeier in drei Abhandlungen dargestellt, Basel: Schweighauser’schen Buchhandlung, 1–66. Griffng, Harold (1983), ‘J. H. Lambert: A Study in the Development of the Critical Philosophy’, The Philosophical Review, 2/1, 54–62. Koch, Carl Heinrich (2006), ‘Schools and Movements’, in K. Haakonssen, (ed.), The Cambridge History of Eighteenth-Century Philosophy, vol. I, Cambridge: Cambridge University Press, 45–68. Lepsius, Johannes (1881), Johann Heinrich Lambert – eine Darstellung seiner kosmologischen und philosophischen Leistungen, München: Ackermann. Perin, Adriano (2016), ‘Lambert’s Infuence on Kant’s Theoretical Philosophy’, International Journal of Philosophy, 3, 44–54. Peters, Wilhelm S. (1968), ‘Kants Verhältnis zu J. H. Lambert’, Kant-Studien, 59, 448–53. Piché, Claude (2004), ‘Kant, heredero del método fenomenológico de Lambert’, Éndoxa: Series Filosófcas, 18, 45–67. Riehl, Alois (1876), Der philosophische Kriticismus und seine Bedeutung für die positive Wissenschaft, vol. 1, Leipzig: Engelmann. Risse, Wilhelm (1970), Die Logik der Neuzeit, vol. 2, Stuttgart-Bad Cannstatt: Friedrich Frommann. Schenk, Günter (1991), ‘Lamberts Suche nach einer eigentümlichen Methode der Metaphysik in Abgrenzung zu Leibniz’, in H. Hecht (ed.), Gottfried Wilhelm Leibniz im philosophischen Diskurs über Geometrie und Erfahrung, Berlin: Akademie Verlag, 208–42. Wolf, R. (1860), Johann Heinrich Lambert von Mühlhausen, 1728–1777. Biographien zum Kulturgeschichte der Schweiz, Zürich: Cyclus, 317–56. Wolters, Gereon (1980), Basis und Deduktion. Studien zur Entstehung und Bedeutung der Theorie der axiomatischen Methode bei J. H. Lambert (1728–1777), Berlin: De Gruyter. Zimmermann, Robert (1879), Lambert der Vorgänger Kants. Ein Beitrag zur Vorgeschichte der Kritik der reinen Vernunft, Wien: Gerold.

10 On the Mitigated Phenomenalism of J.-B. Merian Tinca Prunea-Bretonnet

“Try as one might to denounce empiricism, it will preserve its unassailable rights” (PHPN 88). This statement from 1797 may be considered Jean-Bernard Merian’s defnitive standpoint on empiricist philosophy in the debate with the proponents of speculative philosophy. It should be pointed out, however, that Merian refers to a particular kind of empiricism, namely, the approach he equates with eclecticism and considers to be one of the main philosophical movements in Prussia “between Wolff and Kant” (PHPN 91). One of the most infuential and prolifc members of the Berlin Academy, Merian himself belonged to these ‘new empiricists’ or ‘eclectic philosophers,’ as he explicitly labeled them at the end of the eighteenth century. A “man of no sect” (homme de nulle secte), for more than fve decades he undertook to forge a ‘third’ or ‘middle path’ that combines empiricist and speculative features. His aim was to articulate a philosophically sound position that is both attentive to reality and capable of countering radical skepticism and the arbitrariness of dogmatic speculations. In this chapter I will examine Merian’s treatment of experience—a notion which, according to his explicit statements, plays a crucial role in his methodology. His views on experience were developed in relation to four interconnected topics: the problem of apperception, the question of the appropriate method in philosophy, the refutation of skepticism, and the classifcation of the sciences. Drawing on the Lockean and Newtonian legacies, he addressed the question of experience with remarkable consistency and throughout his career. Hume’s philosophical stance and—mostly in a negative way—Wolff’s thought were also infuential in the development of Merian’s eclectic philosophy. Close to the conception of Maupertuis, but without adopting the latter’s “ultraphenomenalism,”1 he elaborated a phenomenalist perspective completed by a novel account of apperception and the articulation of an eclectic methodology. As we will see, Merian combined seemingly radical empiricist statements such as “it is not permitted to go beyond experience, nor to pretend to explain that to which we have only given a name” (APID 468), or “let us be satisfed with the few truths to which experience leads us” (APID 444), with speculative theses such as those concerning the

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immaterial and substantial nature of the self and the foundational and guiding role played by metaphysics with regard to the sciences. To set the background for the analysis of Merian’s conception of experience, I begin by outlining his life and main convictions in Section 1. I then discuss his novel treatment of apperception in Section 2. Sections 3 and 4 consider Merian’s reception of Hume’s thought and the strategy he elaborates in order to reject radical skepticism and what he takes to be the latter’s ‘generalized phenomenalism’. I fnally analyze Merian’s classifcation of the sciences and his views on metaphysics in Section 5. The conclusion sums up Merian’s assessment of the empiricist arguments endorsed by academic eclectic philosophers.

1 Merian and the Berlin Academy Jean-Bernard Merian (1723–1807) joined the Berlin Academy in 1750 as member of the class of speculative philosophy. A prolifc writer and dynamic thinker, he became director of the class of belles-lettres in 1771 and permanent secretary of the Academy in 1797. Of Swiss origin, he was fuent in German, French (the offcial language of the Berlin Academy), and most modern languages, as well as profcient in Greek and Latin. His erudition, bright personality, freedom of thought, impartiality, and linguistic skills gained him the trust and appreciation of his peers and of the kings Frederick the Great and Frederick William II. The members of the Berlin Academy took an active part in the philosophical debates of the time. At least during the frst two decades after the reorganization of this institution by Frederick the Great in 1744–1746, they defended either the ‘Leibnizian-Wolffan’ heritage or the English and French enlightened ideas and Newtonian physics, thus dividing the Academy in two main camps. Maupertuis, the president of this institution, led the latter, more infuential group, hostile to the German speculative philosophy. Notwithstanding his association with this group, Merian was regarded on the whole as an impartial thinker, and even as a “mediator” (arbitre)2 who also admired and promoted German philosophers, including Moses Mendelssohn, Johann Heinrich Lambert, and Christian Garve. He never showed, however, any sympathy for Wolff’s philosophy, which, unlike other academicians, he had thoroughly read. The opposition between the two factions tended to fade over time, even if up to the 1760s the Academy was accused of encouraging anti-Wolffan standpoints. Conversant with the German, French, and English traditions, Merian published numerous essays and translations, and showed a great interest in literary topics. F. Ancillon, in his Éloge of Merian, highlights the fruitful and uncontested infuence the latter exerted on the Academy and the public instruction in Prussia

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for over half a century.3 Dilthey as well considers him to be the central fgure of this institution: During all these numerous years, he had completely grown together with the interests of the Academy. There are people towards which the members of a corporation are able to orient themselves at any given time with regard to its vital interests; they provide this understanding to outsiders, too. Merian had this signifcance for the Berlin Academy, from the days of Maupertuis to those of the two Humboldts.4 Merian shared with Maupertuis two interrelated convictions, which deeply infuenced his philosophical stance, namely, that we can neither attain the big picture of the universe nor reach the essence of things—in other words, that we can cognize phenomena alone. We must accept, Merian argues, that our fnite understanding has access only to a small part of the universe: human beings are “atoms in the immense city of the universe, [and] our sphere is a mere point” (DM 37). Despite these skeptical elements, which were rather common at the time, 5 Merian considered radical skepticism a serious threat to the analysis of the mind and the investigation of nature. He also rejected the dogmatic claims he attributed to rationalist thinkers, such as Wolff and his disciples, and regarded speculative systems as “castles built on air” (APE 441). The only correct answer to the equally destructive stances of skepticism and dogmatism consists, he contends, in a philosophical attitude that simultaneously accepts the limitations of our senses and cognitive faculties and maintains the existence of indubitable truths on which all knowledge and solid principles can be founded. Around the mid-eighteenth century, starting with his two memoirs on apperception in 1749, Merian elaborated a phenomenalist position founded on empiricist premises. On his account, all knowledge starts with sense perception. While our mind is at frst a tabula rasa, Merian argues in his essay On Moral Sense (1758), we are created with the innate faculty to perceive (sentir) and this faculty manifests itself in the presence of objects.6 Through our senses, we are affected by outer things, but the bodies that affect us are “mere phenomena” and represent “realities that no one knows” (RPR 36, 38). The produced perceptions “modify” our mind and leave in our imagination “a shadow fxed by a sign,” that is, an idea—a term which Merian uses interchangeably with ‘perception’ despite this distinction. Defning ideas as “ways of being of the soul [manières d’être de l’âme]” (APID 454) that we experience in both the contemplation of the “inner world” and in our interaction with external reality, he argues that they are “the only things we can talk about” (RPR 47, 51). Merian seems to assume that there may be outer

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objects beyond our ideas, but they remain “perfectly unknown to us” (RPR 40). The fact that we call them ‘subjects’ or ‘substances’ merely testifes to our inability to cognize them. For Merian, the reality of perceptions is “far more indubitable” (RPR 43) than that of external objects and can thus form the basis for philosophical investigation. On his account, there are several “primitive truths” that provide indubitable certainty and, thus, a solid ground for our inquiries. They are said to be founded on the “natural evidence” (évidence naturelle) that alone is “more powerful and more triumphant than all systems taken together” (RPR 54). Merian calls them experiential truths (vérités d’expérience) and claims that they can be neither contradicted nor counterbalanced by truths of reasoning (vérités de raisonnement, RPR 54). These truths, to which the apperception of the self eminently belongs, both stop the thinker from falling into radical skepticism and represent limits not to be overstepped.

2 Certainty and Apperception Merian frst outlined his novel theory of apperception in two essays published in 1749, Memoir on the Apperception of Our Own Existence (Mémoire sur l’apperception de notre propre existence) and Memoir on the Apperception Considered with Respect to Ideas or, on the Existence of Ideas in the Soul (Mémoire sur l’apperception considérée relativement aux idées, ou, sur l’existence des idées dans l’âme). Two later texts, On Numerical Identity (Sur l’identité numérique, 1755) and On the Phenomenalism of David Hume (Sur le phénoménisme de David Hume, 1793), provide important complements to his treatment of apperception. While advocating an empiricist method regarding the investigation of the self, Merian in fact goes beyond experience and elaborates an original position on the apperception of the self that addresses the conditions of knowledge. His account would prove to be particularly infuential during the second half of the eighteenth century, for instance for Tetens and Kant.7 In the two 1749 essays, apperceptions, also called ‘intuitions’ or ‘simple visions,’ are understood as the primitive perceptions that form the elements of all human cognitions (APE 416). They are reached by the analysis of our cognitions and can be neither further decomposed nor properly defned. On Merian’s account, the “sole means” to treat the question of apperception is to take “experience as a guide” and establish one’s claims on the “small amount of observations” the latter provides (APE 418). The frst fact confrmed empirically and also “proven by demonstration,” he contends, is that our cognitive faculties can be analyzed and understood only a posteriori, as we do not have direct access to the changes they produce in the mind prior to their application to objects. Merian divides apperceptions in three classes: those that

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apply to the self, to our ideas, and to our actions (APE 419). He radically distinguishes between the apperception of ideas and the apperception of the self and devotes the frst essay to the consideration of the latter, which he takes to be an independent yet fundamental act of the human mind that has received little attention from past philosophers. “I know that I exist,” Merian affrms, and this knowledge has been obtained either immediately or mediately. Upon closer examination, he rejects the latter option, which he takes to have been elaborated by Descartes and Wolff but also by Spinoza.8 On Merian’s account, no syllogism or refection can teach me that I exist, and no demonstrative proof can provide the certainty of my own existence. He refutes Wolff’s syllogistic account of the cogito, contending that both the major and the minor premises already contain the question (‘to think’ means ‘to exist thinking’) and that, therefore, this proof only shows that I knew I existed when I was thinking. The conscium sui or apperception of the self is already present in any thought I consider, and the conclusion of the cogito is correct “only by chance.” Refection can give me the notions of my faculties, such as memory or judgment, but these notions “result only from the combination of the conscium sui with our other thoughts” (APE 433). If the refective, mediate path is refuted, Merian concludes, we can safely assume that the certitude of my own existence is given immediately by intuition or apperception and is an ‘immediate truth.’ All our mental acts presuppose, he claims, the apperception of the self as the frst, foundational act, which is radically different from and independent of any other thought. He regards this apperception as “the frst act and an essential act of the intelligent being as such, given that all our cognitions presuppose it while it alone does not presuppose anything” (APE 434). Indeed, Merian maintains against Wolff that the apperception of the self is prior to the act of distinguishing things (discernement),9 and against Rüdiger that it does not depend on another act of the mind in order to take place.10 He holds that I can renounce all my thoughts and still apperceive my existence: The conscium sui is thus presupposed by all the other cognitions, and cannot be subordinated to any previous thought; […] all other thoughts are contingent on the intelligent being, while sole the apperception of oneself is necessary and essential to it. […] I could dismiss (congédier) thought after thought, faculty after faculty, [I could] annihilate refection, erase imagination, drown memory in the waves of Lethe, in sum, if I may say so, delete myself completely up to the apperception of my self, without ceasing to subsist as an intelligent being. If, on the contrary, I start with [dismissing] the conscium sui, I take with it in a breath all my intelligence and all my personality. (APE 434)

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Thus, the conscium sui grounds and accompanies every act of the soul: “everything that one apperceives is accompanied by the ad-apperception or co-apperception of one’s own existence.”11 It is, therefore, understood as necessary for and logically prior to—even if sometimes chronologically simultaneous with—all our other thoughts. However, on Merian’s account, I am not able to further analyze the conscium sui, which never becomes the object of a further apperception— “one does not apperceive oneself apperceiving” (APE 435)—or else we would have to accept the duplication of the self and even an infnite multiplication of the thinking being. The apperception of the self, therefore, does not provide any specifc knowledge about the nature of the self. Nevertheless, Merian holds that the self is most probably a thinking substance apperceiving itself, or an immaterial thinking being, as he contends in 1749 as well as in his 1755 essay On Numerical Identity.12 Here, Merian claims against Locke that moral personal identity is not given by memory but founded on the feeling (sentiment) of my own being or of the self: the continuous consciousness of the self is so inseparable from our intelligence and essential to our soul that “without this sentiment [there is] no memory, no thought, and probably no soul.”13 Understood as an immediate intuition, self-apperception (autoapperception) also provides the immediate certainty about our existence. Not only does this certainty not spring from demonstration, Merian contends, but it grounds all other types of certainty, immediate or mediate. On his account, it belongs to the necessary primitive truths and provides the stable ground and condition for our cognitions in general. It is worth noting that while agreeing with the rationalist tradition that “no certainty surpasses that of our own existence” (APE 423), Merian understands this certainty as an immediate certainty given by the apperception of the self. Even though “there are certain limits, beyond which one can neither inquire nor respond,” the certainty provided by the apperception of the self represents one of the main arguments in Merian’s fght against the “incurable evil” of “absolute skepticism” (APE 428). It is obvious that his account of the pre-existence, the independence, the foundational character, and the necessity of the conscium sui rests neither on mere observation nor on the sole empiricist analysis of the inner sense he had originally announced. Rather, Merian makes epistemological claims that go beyond his initial empiricist restraint and combine indubitable experiential ‘facts’ with speculative arguments. In this regard, he undoubtedly anticipates the Kantian investigation into the conditions that make knowledge possible.14 Despite closing his essay by quoting Maupertuis’s assessment of the greatness and diffculty of such inquiries,15 Merian’s theses signifcantly diverge from the position the former defended. Indeed, in his Letters of 1752, Maupertuis confates what he names the sentiment of the self or consciousness with perceptions in general, or rather considers

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perceptions to be the modifcation of the sentiment of the self. In Letter V, On the soul of the animals, Maupertuis contends: Every feeling, every perception is a thought; it is necessarily accompanied by the sentiment of the self, by what philosophers call consciousness. Or rather it is only this very sentiment modifed differently, according to the various objects it is applied to.16 Consistent with his generalized phenomenalism, according to which “all objects are mere phenomena,”17 he grounds the sentiment of the self on the perception of one’s body, thus reducing it to a phenomenon.18 Moreover, unlike Merian, he ascribes this feeling to both humans and animals and even to plants. In his Memoir on the Apperception Considered with Respect to Ideas, Merian further elaborates his views on the second type of apperception, i.e., the apperception of ideas. He conceives of ideas as “representing themselves,” that is, not as representations of mind-independent entities. In this context, he advocates the same empiricist method of investigation as in the treatment of the apperception of the self: it is, he insists, by paying attention to what happens in our soul that we can analyze to a certain extent our apperception of ideas, experience being “the only source of discoveries” in this respect as well (APID 444). He lists four indubitable truths or “facts of experience” (faits d’expérience, APID 445) that are immediately given through the observation of our mind and can also be supported to a certain extent with rational, discursive arguments: (1) the distinction between the apperception of the self and the apperception of ideas, (2) the passivity of the soul with respect to perceptions, (3) the difference between perceptions or between the ways in which they affect the soul, and (4) the common presence or existence of the perceptions in a same soul. The last two points are explicitly directed against Leibniz’s views on indiscernibles and obscure perceptions. Merian explains that two concomitant causes concur in the production of perceptions: an external cause which affects the senses in a concealed way and a ‘principle of action’ present in us, namely, the force of apperception. Due to the weakness of our understanding this is as far as we can go in explaining how the apperception of ideas takes place, and we are unable to properly defne it (APID 446). We “feel” (sentir) that there is a productive cause entirely different from ourselves, over which our will to perceive has no power, even if the self can be said to consent to being acted upon by this external cause.19 As he puts it: “I decide myself for the action of an external cause” (APID 445). This passage suggests Merian’s commitment to a causal theory of perception, but in fact he rejects again any representationalist account by insisting that we cannot know whether there are outer objects corresponding to our ideas and should therefore assume they are mere phenomena. We can go as far

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as to consider this type of apperception a ‘perception of the soul’ and its object an idea rather than an external object. Inner experience further teaches us that each perception affects the soul in a specifc way. Therefore, he contends, not only do ideas exist in our soul, but they are also distinct from one another. For Merian, this means that they are apperceived as present and that we are always conscious of them (APID 456). In a detailed discussion based on extensive quotes from Leibniz, Wolff, and Bilfnger, he categorically dismisses the Leibnizian-Wolffan stance according to which ideas can exist independently of our apperception and be unconsciously present in the mind (petites perceptions).

3 Excessive and Moderate Forms of Skepticism To my knowledge, before the 1750s Merian does not refer to Hume’s writings. We can thus assume that, unlike Descartes, Locke, or Wolff, for instance, Hume did not play a signifcant role in the elaboration of Merian’s theory of apperception as it is developed in the two 1749 essays discussed above. However, from 1755 to the end of the eighteenth century, Hume’s philosophy came to decisively infuence Merian’s epistemological and methodological commitments as well as his anti-skeptical stance. This section will therefore focus on Merian’s nuanced reception of Hume, which, I argue, helped him clarify his theses and situate his own position with respect to phenomenalism, empiricism, and metaphysics. In 1755 and 1756, Merian published a detailed review of Hume’s Enquiry Concerning Human Understanding in the Berlin journal Mélanges littéraires et philosophiques. 20 This review came at a time when the interest in Hume’s philosophy was growing in Europe and the Berlin Academy actively participated in the dissemination of his ideas within the German Enlightenment. In 1755, J.G. Sulzer, another prominent member of the Berlin Academy, published the translation of the Enquiry into German. Merian himself, at Maupertuis’s request, translated this work into French and published it in 1758 with a preface by the permanent secretary of the Academy, J.H.S. Formey. 21 This interest in Hume’s writings was motivated at least partly by the lively debates regarding skepticism, or Pyrrhonism as it was often called, a movement with which Hume’s philosophy came to be identifed from the middle of the eighteenth century. 22 This explains why some of the translations and commentaries, including those by Sulzer and Formey, had an overt polemical aim and rejected Hume’s views despite a favorable assessment of his philosophical style. I believe, however, that the issue of skepticism was not the driving force of Merian’s review of the Enquiry. 23 From the outset, Merian praises the novelty, subtlety, and elegance of the book. He regards Hume as “one of those rare geniuses who know how to cut new routes and leave luminous

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traces wherever they go,” as “the most subtle, the bravest and maybe the most singular metaphysician […] since the renewal of philosophy,” and declares that “his sentiments, his method, his style, even his errors, everything deserves the attention and investigation of those who profess to love and cultivate abstract sciences” (MLP1 49–50). Merian explicitly refrains from critical remarks and presents Hume’s position on its own terms, as faithfully and completely as possible. He indeed offers a detailed and benevolent summary of the Enquiry, sometimes even rephrasing Hume’s statements in order to make them less radical and more acceptable to the reader. 24 However, two passages stand out by their particularly appreciative tone, namely the discussion of Sections I and XII, where Merian’s adherence to Hume’s viewpoint seems palpable. Presenting Hume’s distinction between the ‘popular’ and the ‘abstruse’ manner of philosophizing as elaborated in Section I of the Enquiry, Merian focuses on the importance of the latter while ignoring some of the disadvantages mentioned by Hume. He explains that the “easy and popular” approach, which is also agreeable and useful, considers human beings with respect to action, while the “profound and abstruse” one regards them as reasonable beings by examining “the nature of understanding and […] the frst principles of action” (MLP1 51). Although the advantages of the latter approach are less obvious, it would be an error to condemn it altogether. If abstract philosophy or metaphysics is redefned as the “anatomy of the mind” or “the study of the faculties of the soul” that, by separating them, traces an indispensable “mental geography,” it is crucial for the advancement of knowledge. 25 When properly conducted, Hume claims, “true metaphysics” (EHU 1.12) analyzes the capacity and the limits of our cognitive powers and ensures the accuracy and exactness of knowledge. It pushes back against superstition, error, and prejudice by correctly assessing the “province of human reason” where our claims of knowledge can be legitimate. Moreover, it nourishes the “genius of philosophy”—in Merian’s terms the “philosophical spirit” (esprit philosophique)—that Hume describes as follows: [W]e may observe, in every art or profession, even those which most concern life or action, that a spirit of accuracy, however acquired, carries all of them nearer their perfection, and renders them more subservient to the interests of society. And though a philosopher may live remote from business and employment, the genius of philosophy, if carefully cultivated by several, must gradually diffuse itself through the whole society, and bestow a similar accuracy in every art and calling. (EHU 1.9) We will see that these arguments are central to Merian’s conception of eclectic philosophy. If metaphysics in this true sense turned out to be chimerical, Merian and Hume agree, there would be only one solution

212 Tinca Prunea-Bretonnet left, namely a skepticism that is “destructive of all speculation and practice: there is neither falsity nor truth, no certainty for our knowledge” (MLP1  54). However, their respective views on the rehabilitation of metaphysics as well as on skepticism diverge. The closing section of the Enquiry, titled ‘Of the Sceptical or Academical Philosophy,’ is famously dedicated to the distinction between types of skepticism. Merian, who addressed ancient skepticism in his essays on apperception and showed enduring interest in this topic, presents them in detail. The frst form, antecedent skepticism, is attributed to Descartes and considered to precede any investigation. Hume notes that “it recommends an universal doubt, not only of all our former opinions and principles, but also of our very faculties” until a certain original principle is found through reasoning (EHU 12.3). As, on Hume’s account, such a certain principle is impossible, Cartesian doubt “would be entirely incurable; and no reasoning could ever bring us to a state of assurance and conviction upon any subject” (EHU 12.3). However, Hume contends, there is also a ‘moderate’ or ‘reasonable’ version of this form of skepticism, one that should be regarded as a necessary preparation to the study of philosophy. Moderate antecedent skepticism preserves impartiality, chases prejudice, starts with clear and self-evident principles, proceeds with cautious steps, frequently reviews its conclusions, and analyzes all their consequences. According to Hume, it represents the only method “by which we can ever hope to reach truth, and attain a proper stability and certainty in our determinations” (EHU 12.4). Merian would later attribute these very features to the eclectic philosophy without any reference to skepticism (PHPN 88–91). Consequent skepticism, the second form, is a result of science and philosophical enquiry, which seem to have proved (1) the “absolute fallaciousness of our mental faculties or [2] their unftness to reach” any certain conclusions as regards “curious subjects of speculation” (EHU 12.5). The frst of these alleged conclusions also contests the veracity of the senses, the maxims of everyday life, and the metaphysical and theological principles. As is well known, Hume opposes to this excessive form of skepticism—that he identifes with Pyrrhonism—a rather unexpected argument: the view that “nature is too strong for it.”26 Hume means by this that it is impossible to persevere in the state of lethargy, amazement, and confusion produced by radical skepticism, and its proponents, when confronted with daily life, necessarily return to common—if unfounded and blind—beliefs in causality, in the veracity of reason and senses: mankind “must act and reason and believe” (EHU 12.23). However, in the second alleged conclusion, Hume suggests that radical doubt may be circumscribed to specifc “curious” topics and, thus, that if one renounces them, and choose issues that are within the reach of our cognitive faculties, a different outcome is possible.

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Hume further draws a distinction between two types of mitigated or academical skepticism—a form of skepticism Merian readily recommends, without however endorsing its justifcation. The frst type, which is more durable and useful, springs from the combination and mutual correction of, on the one hand, Pyrrhonism and, on the other, common sense and refection. Hume emphasizes its benefcial effects on the attitude of thinkers, who become “just reasoners” by accepting the “strange infrmities of human understanding” and adopting a more modest, cautious, open minded, and less bellicose approach to knowledge (EHU 12.24). The affrmative and dogmatic tendencies that are naturally present in the human mind are thus counterbalanced by skeptical doubts, although without being overcome by despair, and both the learned and the illiterate end up by agreeing on the probable status of knowledge. I take the second type of mitigated skepticism advanced by Hume to be closer to consequent skepticism, as it promotes the limitation of philosophical enquiries to the topics that can be attained by our limited understanding, namely those that “fall under daily practice and experience” (EHU 12.25). Once both the excessive skepticism produced by reasoning and the force of natural instinct which triumphs over it have been experienced, Hume contends, those who still wish to philosophize will continue to do so by refecting on common life alone according to a novel methodology. This implies a strict separation: abstract or demonstrative sciences deal with quantity and number, and, since they are founded on relations of ideas, are a priori and certain. All the other subjects of our investigations refer to matters of fact or existence and cannot pretend to certainty: they are a posteriori and merely probable, they rely on causality—that is, on habit or custom, on Hume’s account—and their contrary is conceivable. In the third part of the review, published in 1756, Merian confesses his wish that the three fnal sections of the Enquiry be read by philosophers alone, or rather only by some philosophers. Two types of readers are unsuited for Hume’s refections, he contends, namely superfcial minds and systematic philosophers. The former would not understand his theses and wrongly believe that they were already familiar with his views, while systematic philosophers would see their notions and approach contested, and their rigid minds would be incapable of grasping Hume’s subtle and ingenious arguments (MLP2 84). But the readers he dreads the most are those who, shocked by Hume’s “free sentiments,” would attribute his views to Merian himself. In fact, he claims, “I am very distant” (éloigné) from Hume’s conception (MLP2 84). True to his decision not to criticize Hume’s theses in the review, Merian does not elaborate on this difference but would polemically engage with Hume some forty years later.

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4 The Refutation of Hume’s ‘Phenomenalism’ In an important essay from 1793, titled On the Phenomenalism of David Hume, Merian again addresses Hume’s doctrine and takes up the question of apperception and the problem of phenomenalism. However, as we shall see, his tone has substantially changed in the meantime. 27 While aware that he focuses on a term—‘phenomenon’—which Hume rarely used, 28 Merian attributes to the latter radical claims such as “All that we feel, imagine, think, know, is reduced to phenomena, coexisting or successive” (PH 179) and “experience and observation persuade you to affrm that we only know phenomena because they only present phenomena to us” (PH 189). Merian inscribes Hume’s philosophical stance within what he calls “the history of philosophy in Great Britain” starting with Locke. On his account, Berkeley “notably changed” Locke’s perspective by renouncing the distinction between secondary qualities and beings existing “independently from us” and by reducing reality to mental substances alone. In Merian’s narrative, this idealism was signifcantly modifed when turned into an “egoist” doctrine according to which only one’s own existence is certain, whereas all other entities, physical or mental, are regarded as mere “phenomena, ideas, modifcations of my being” (PH 178). He considers this position to have been further radicalized by Hume, who is said to have taken “a step of unequalled boldness” and to have buried all preceding positions “in the night of chaos” (PH 179).29 Merian argues that Locke, Leibniz, as well as idealists in general and even “egoists” at least accepted “subjects in which these phenomena show themselves” and advanced relatively coherent perspectives (PH 184). Hume, on the contrary, is said to have embraced an “unintelligible” position that manipulates meaningless words and, by transforming everything (the self included) into mere phenomena, to have “engulfed” all previous theories in “a common ruin” (PH 179). Merian considers the Enquiry to have accentuated the “paradoxical” character of the perspective presented in the “stillborn” Treatise of 1738 and to have given it a more seductive form that helped ensure a readership. While claiming to analyze Hume’s doctrine in general, he primarily refers, as we will see, to the theses advanced in the Treatise.30 In Hume’s philosophy, he writes, [a]ll that we feel, imagine, think, know, is reduced to phenomena, coexisting or successive, which join together, separate, come and go, endure more or less, appear, disappear, reappear, sometimes under different aspects, sometimes under the same. […] We know absolutely nothing as to which of them we might guarantee permanence to, still less substantiality. Subject and substance, taken in this sense, are terms empty of meaning, pure creatures of reason, that is to say phenomena, or the succession or accumulation of phenomena. (PH 179–80)

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In Merian’s view, this phenomenalist stance needs to be opposed because it plunges our mind into “desperate skepticism.” As for himself, he declares merely a “war on a small scale” (PH 180) against this standpoint, ironically inviting systematic philosophers, whom he in fact distrusts, to engage in an all-encompassing combat. By a ‘small scale’ fght Merian actually means a two-step strategy comprising a tentative defense of the double existence theory regarding the external world and, more importantly, a renewed exposition of his theory of the apperception of the self. According to his use of the term, a ‘phenomenon’ is something that manifests itself or makes itself perceptible. Hence, phenomenalism of any kind must offer a consistent response to the questions: before whom or before what does the phenomenon appear? By whom or by what is it perceived? (PH 181). It would be absurd and subject to infnite regress to assume that a phenomenon perceives itself or that phenomena perceive each other. Therefore, on Merian’s account, only a third possible response remains, namely, to posit that there is “a being, a substratum, a subject, an animate substance, whatever you would call that which is not a phenomenon, which would be affected by these phenomena, which or before which they would come to appear or represent themselves” (PH 182). But, Merian argues, since Hume considers the subject to be a fction, the inductive method to lack rigor, and truth itself to be “a feeting phenomenon, a transitory appearance” (PH 183), Hume’s position is unconvincing and in fact incomprehensible.31 There are only two ways in which phenomenalism can avoid meaninglessness, Merian contends, although he is fully aware that Hume had explicitly refuted both of them in his Treatise.32 The frst consists in the endorsement of the double existence theory which postulates an independent external world corresponding to our perceptions or at least simple beings that constitute the “basis of all the sensible phenomena that strike us” (PH 184). On Merian’s account, Leibniz’s phaenomena substantiata are the best example of such beings. Thus, the “belief”—a Humean term that Merian consciously employs here—in an external world, founded on the impressions given by our senses, is grounded. Even Epicurus’s phenomenal world composed of elementary parts, albeit part of a doctrine that Merian takes to be false, should, on his account, be preferred to Hume’s position, since atoms at least offer “a handle” which allows our understanding to “seize” and represent bodies (PH 185). As Merian does not favor representationalist theories, as we have seen, he refrains from further developing the justifcation of an outside world beyond our perception and advances his main thesis: “I will cross out, if you desire it, all external objects; but it is impossible for me to scratch myself out” (PH 186). The second and most important argument Merian uses to reject Hume’s conception is the non-phenomenal character of the self. On Merian’s account, experience teaches us that the observer is radically different from

216 Tinca Prunea-Bretonnet what is being observed, i.e., that the being which perceives phenomena is not in turn a phenomenon. The perceiver who perceives is engaged in cognitive processes: he or she examines, compares, refects upon, and remembers phenomena. But he or she is continuously conscious that these phenomena are distinct from itself: “all these things [which] reach me from without, or trace themselves within me […] are, however, not me. I distinguish myself from all of these things” (PH 185–86). The spectator is different from the spectacle and must be comprehended as a ground if we wish to advance a coherent and consistent conception. It is worth noting that in this context Merian employs an image Hume uses with respect to personal identity, namely that of a labyrinth.33 Echoing Hume’s words, Merian argues that as long as we maintain that the self is an “illusory phenomenon” or a “fantasy,” we are stuck in a labyrinth and see no way out (PH 187). It is remarkable that Merian also employs Hume’s famous theater metaphor (PH 184–85) in order to refute his conclusions and to explicitly rehabilitate not only the non-phenomenal character of the self but also its substantial nature that Hume had denied.34 We do not have direct knowledge of the nature of the self we apperceive, Merian contends, since this apperception provides only the certainty of its existence. Nevertheless, we need to assume that it grants stability and consistency: Then what is this me? Would it not seem necessary for it to be something constant, a solid ground, a permanent canvas where all these varieties would be painted and displayed; and furthermore, something capable of grouping, separating, and diversifying them? […] Considering it in this way, what am I relative to these modifcations? The thing, the being, the subject, the substance that experiences them; for this is exactly what I mean by these terms. And in spite of your aversion to them, I do not see how one can avoid them, if one wishes to understand or explain himself to others. (PH 186, my emphasis; translation slightly modifed) Merian, therefore, deems phenomenalism as such to be inconsistent: if it is generalized, it is coherent but unintelligible; if it surreptitiously reintroduces causality and non-phenomenal entities, it contradicts its own premises.35 Thus, despite his indisputable earlier affnities with this position, he now explicitly distances himself from it. Perfectly aware of Hume’s distrust in both the senses and reason, as well as of his theory of belief, Merian opposes him by positing the necessity of a nonphenomenal and substantial self that plays a foundational role in knowledge acquisition. This standpoint completes his account of the certainty provided by the apperception of the self discussed above. This certainty, albeit indemonstrable by reasoning, Merian insists, is indubitable and able to keep desperate skepticism at bay.

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The non-phenomenal self can therefore be conferred the epistemic status of a principle of the human mind. Indeed, in this essay Merian explicitly calls it a “constitutive principle” of the mind and brings forth a fnal argument to support his views (PH 190). I take this argument to provide a particular experiential confrmation of this principle and thus to constitute the fnal step of a valid theory according to experimental methodology.36 Merian advances that the reality of the self is clearly expressed in the personal pronouns that everyone uses, a fact which is said to confrm the radical distinction of the subject from all possible phenomena and, thus, its non-phenomenal character.37 All known languages, those of civilized people as well as those of “barbaric” ones, bear the “mark” of this something which is called mind, soul, or intelligence. Unlike superstition, error, and prejudice, which vary in time and space, personal pronouns reveal the apperception of the self as common to all peoples: no thinker, he contends, is able to renounce them and still be intelligible, because they precede, survive, and surpass any individual initiative. The fact that common people have articulated these “forms of thinking, speaking, acting” attests, in Merian’s view, that they are uttered by the “universal voice of human nature” and indicate a particular kind of immediate certitude (PH 190–91). Their universality testifes to their legitimate usage and to the essential, necessary character of the reality they express: what is common to all of them [i.e. to personal pronouns] belongs to language in general, not to such and such language in particular, clearly revealing a common origin, something essential or a constitutive principle of what we call the human mind, a primitive form where this mind is, so to speak, molded, which is inseparable from it, and from which it would not know how to deviate in the simplest development of its faculties. (PH 190, my emphasis) Merian offers this example as confrmation of the self’s status as a “constitutive principle” that grounds knowledge acquisition. Until Hume’s disciples invent a language devoid of personal pronouns and remain intelligible, he ironically contends, this argument should be regarded as irrefutable.

5 The Classifcation of the Sciences Merian’s treatment of experience is signifcantly completed by his considerations on the role that metaphysics plays within the classifcation of sciences. Already in 1749, Merian holds, probably under the infuence of Rüdiger and Crusius, that one should distinguish between ideal and real sciences and assign each science its appropriate status (APID 443). An ideal science is arbitrary insofar as it is established on defnitions and

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follows the synthetic method. Like many of his contemporaries, Merian believes that mathematics is such an ideal science. A real science, on the other hand, follows the analytical method, is founded on experience, and is therefore as real as the experience from which it takes its content. Merian seems to limit the topics of real science to those that fall within the realm of sense perception. As he puts it, “we prefer the little amount of real knowledge made possible by it [experience]” (APID 444). Therefore, sciences dealing with existence, such as the natural philosophy and metaphysics, are incompatible with the methods employed by ideal sciences. However, some ffteen years later, in his Discourse on Metaphysics (Discours sur la métaphysique), Merian offers a revised treatment of the classifcation of the sciences and of their relationship to experience. Written in 1763 and published in 1765, the Discourse represents his response to the Berlin Academy’s prize essay question for 1763 on the problem of method in philosophy.38 While he agrees here that metaphysics is going through a serious crisis, Merian advances a strategy that is apt to restore its credibility and dignity among sciences. He begins the Discourse by restating his empiricist commitment that “all our cognitions have their origin in the senses” (DM 1) and sketches the progression in the acquisition of knowledge as refected in the hierarchical articulation of the sciences. Because the senses play a foundational role, he argues, human curiosity has frst been attracted by individual material (or sensible) bodies. Observation and comparison have then allowed for relations—analogies, hypotheses, and generalizations—to be progressively established among bodies. Thus, Merian argues, natural philosophy (physique) gradually succeeded in analyzing all spatialtemporal phenomena in its search for their natural causes. On his account, matter and motion represent the highest frontier that can be attained in this science, as they already belong to a ‘transcendent world’ that is inaccessible to sense perception. The laws of nature that pertain to these two phenomena—matter and motion—open “a new perspective,” namely a science dealing with atoms, elements, simple beings, forces, and representations. This science, called cosmology, deals with “the machines and frst springs [ressorts] of the mobile theater of the universe that are concealed to our senses” (DM 2). After these inquiries about the external world, the “contemplator” naturally turns to the question of the human faculties, that is, to psychology, which is said to deal with the “abyss” of the human mind. According to Merian, this investigation ushers in another science, namely, theology. Revealing the common origin of minds and bodies, it examines the supreme cause and focuses on the attributes of the divine being. A fnal, eminent science closes this classifcation: called frst science, ontology, or metaphysics in a narrow sense, it contains the “ideas” produced by the human mind, which are ordered in classes, species, and genres, and form the principles, elements, and materials of all the other sciences (DM 5).

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It is worth noting that Merian endorses here the Wolffan division of sciences, according to which metaphysics in a broader sense is composed of ontology (general metaphysics or frst science) and the three disciplines of special metaphysics, i.e., cosmology, psychology, and natural theology. However, unlike Wolff, 39 he emphasizes that “metaphysics starts where natural philosophy [physique] ends” and that both are founded on experience. On his account, “[o]bservation and experience are the common basis of the science of bodies and of that of immaterial beings” (DM 5, 15). The comparison of their respective aims and chances of success apparently favors natural philosophy over metaphysics: unlike the latter, the former is practically useful, has made obvious progress in recent times, analyzes “permanent” or “recurrent” facts, and can count on the signifcant help of other sciences such as mathematics. Moreover, scientists can attain a deeper level of perception because they have the means to “force” nature to yield answers to their inquiries and unveil “secret” connections thanks to instruments and experiments (DM 17). However, Merian argues that natural philosophy, despite these advantages, no less than the other sciences needs the help of metaphysics: experience and observation do not suffce but must be completed by reasoning.40 In accordance with the double meaning he confers to the term, Merian offers a two-fold account of the necessary contribution of metaphysics.41 First, natural philosophy often needs to be “rectifed” (DM 12) by speculative thought, because the limits of our senses are uncertain and we mistake one sense for another, thus falling into error unless a superior science comes to the rescue. In line with Hume’s notion of a true metaphysics, Merian argues here for the indispensable support granted by the study of the human mind and the separation of faculties in the acquisition of scientifc knowledge, a task the Discourse confers, as we have seen, to special metaphysics. Second, and more importantly, metaphysics, understood as general metaphysics or ontology, is considered to provide the principles and the “true method” for all sciences, the disciplines of special metaphysics included. The cognitions acquired in natural philosophy, as well as in cosmology, psychology, theology, and morals, are said to “themselves depend on metaphysics.” Moreover, from Aristotle to Leibniz, “all great men have admitted that it [metaphysics] spreads its benefcial infuences on all sciences, that it provides them with valid principles, directing notions, sound perspectives and the true method” (DM 7). Insofar as it provides the principles that are common to every science, metaphysics is the frst science or meta-science.42 Natural philosophy delivers the facts, while “metaphysics converts them into proofs” (DM 12) and, thus, confers them a scientifc status. These arguments suggest that, despite the usage of the concept ‘guiding notions’ associated with Wolffan philosophy at the time, Merian rather commits to the Baconian view that we must start with observation and experiment, analyze

220 Tinca Prunea-Bretonnet observed phenomena, and on this basis formulate simple and general principles (DM 13). Only principles that are founded on experience should be accepted, and, due to our limited cognitive powers, Merian argues, we should be ready to revise them if necessary.43 This is why Merian, appealing to a trope common in British and French enlightened writings of the time, denounces speculative systems that are built on arbitrary principles according to the demonstrative method and disconnected from reality. Moreover, every physical inquiry demands a development beyond the limits of natural philosophy and into the metaphysical realm. Thus, for instance, whereas optics teaches us about invisible angles, lines, and distances, metaphysicians are needed to make sense of these notions and to elaborate a theory of vision as such (DM 12–13). It is, therefore, indispensable to go beyond sense perception and experience and grasp the bigger picture of the world. This advancement, which Merian insists can only be derived from metaphysics, requires the endorsement of a set of methodological principles founded on what he calls the “philosophical spirit.” In a passage echoing Hume’s treatment of the “genius of philosophy” mentioned above, Merian contends that it is by cultivating the “philosophical sense” (or “philosophical spirit”) that the savant can embrace a larger picture of the world and thus become more than a “mere observer” or an erudite and “laborious scientist” (DM 7). Defning this spirit as “a sentiment of truth,” Merian argues that it can only be developed with the help of frst principles, i.e., “of what is metaphysical within the sciences” (DM 8). While scientifc inquiries should start from experience, they must be completed by a speculative dimension which is left rather undetermined in the Discourse: There is a sentiment of truth, a sagacity, which brings together distant connections […]. This philosophical sense germinates and fertilizes our ideas: it raises the natural philosopher above the mere observer, who, so to speak, organizes the heavy mass of erudition, and it distinguishes the man of genius from the laborious scientist in all domains. This sentiment, I confess, is a precious gift of nature, which must nevertheless be cultivated; it is only by nourishing it with frst principles or [with] what is metaphysical in the sciences, that it can be developed and turned into a habit. (DM 7–8) Even if, on his account, we cannot take for granted that the very frst and simple principles will be discovered, the task of the true philosophers is to never give up looking for them.44 Thinkers should both concede the fnite and provisional character of all knowledge and admit that there are far more domains to be examined and truths to be unveiled than

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what observations and experience suggest. Emphasizing the arduousness of this lofty task, Merian insists that only scholars who are nourished by metaphysics can contribute to the progress of knowledge and overcome the perils of a radically skeptical attitude.

6 Conclusion In a 1797 essay devoted to Wolff and Kant and titled Historical Parallel between Our Two National Philosophies (Parallèle historique de nos deux philosophies nationales), Merian sums up the features of the “middle path” he had elaborated and advanced for half a century. He now explicitly calls it academic or eclectic philosophy and identifes it with the activity of the Berlin Academy at large. He restates that experience and observation have epistemic priority and offer the frm foundation on which all knowledge must be built (PHPN 88). Since our cognitive capacities are limited, knowledge has a provisional status. Eclectic thinkers must therefore be prepared to discern novel truths and revise their position if faced with new proofs without, however, falling prey to Pyrrhonism. Moreover, they should admit that knowledge is a collective endeavor that requires the collaboration of scientists and philosophers. Most importantly, eclectic philosophers must cherish autonomous thinking and cultivate a critical spirit, refusing to bow to authority and sects. All these features characterize the philosophical spirit which, as we have seen, founds the eclectic art of philosophizing as Merian understands it: [T]he philosopher who observes and experiments can fearlessly advance the result of his experiments and observations; he can come back to them, do them once again, modify and vary them as he wishes: similarly, the philosopher who chooses, because this is what the word eclectic means, always remains the master of his choice [and] can adjust and re-adjust according to the circumstances; on the contrary, the systematic concatenation rules out this fexibility; its stiffness resists it; all or nothing, either to endure or to perish, this is its slogan. (PHPN 91) Merian’s own treatment of experience offers an outstanding example of the eclectic approach he defended. He does not merely attempt to reconcile distinct schools of thought and dissimilar theses, such as Newton’s analysis, Locke’s views on the human mind, and Hume’s account of academic skepticism. He grounds his approach in strong and consistent convictions, such as the foundational role of experience, the nonphenomenal nature of the self, and the guiding role of metaphysical principles. He acknowledges that the empiricist methodology and moderate

222 Tinca Prunea-Bretonnet skeptical claims should be taken into account. This notwithstanding, Merian believes, as we have seen, that the fallibility of the senses and our limited cognitive access to the external world are counterbalanced by the certainty provided by the apperception of the self and the speculative support offered by metaphysics. His position, therefore, testifes to his commitment to avoid both the arbitrariness of systems detached from experience and the generalized phenomenalism he attributes to Hume’s skeptical views. Merian genuinely strove to embody this eclectic ideal, and his “middle path” between empiricism and dogmatism, albeit largely neglected by modern scholarship, represented a signifcant contribution to the philosophy of the Berlin Academy and to the postWolffan Enlightenment in general.45

Notes 1 2 3 4 5 6 7

8

9 10 11 12 13 14

15 16 17 18 19

Tonelli (1987: 8). Ancillon (1815: 67). Ancillon (1815: 66–83). Dilthey (1926: 139). Tonelli (1997). See Merian (1765a: 395). For a detailed analysis of Merian’s theory of apperception and personal identity, see Thiel (2011). On Merian’s infuence on Kant, see Thiel (2011: esp. 376f). Thiel points out that Tetens, Platner, Schulze, Maine de Biran, and Cousin, among others, also addressed Merian’s views on apperception. Merian later contends that, in his view, Descartes rather understood the knowledge of one’s own existence as an intuitive truth and not a demonstrative one, as Wolff advanced (APE 430). On Merian’s debt to the Cartesian tradition, see Baertschi (1996). However, Baertschi does not address Wolff’s treatment of consciousness, which plays a crucial role in Merian’s account of the Cartesian proof. According to Merian, “[a]pperception always precedes [devance] distinguishing, at least in the order of nature and often even in the order of time” (APE 438). On self-consciousness in Wolff and its critique by Rüdiger, see Thiel (2011: 304–14, 343–47). Merian, APID 445; see also Merian (1757: 469). See Merian (1757: 471). Merian (1757: 470). As Thiel (2011: 376) puts it: “In arguing for the ‘pre-existence’ and necessity of self-consciousness Mérian clearly goes beyond his own offcial empiricist approach to the issue of apperception and his critique of Wolff. […] The ‘originality’ or ‘pre-existence’ of self-consciousness is to be understood in terms of a universal and necessary condition of thought in general.” See Maupertuis (1768a: 26–27). See Maupertuis’s ‘Lettre IV: Sur la manière dont nous appercevons’ (1768b: 247). Maupertuis (1768b: 233). On this, see also Maupertuis (1768b: 250). Merian refuses to endorse idealism as such, even if his attitude remains ambiguous in this respect (see RPR 43).

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20 Merian refers to the 1748 edition of the Enquiry, which was titled Philosophical Essays on Human Understanding. In 1758, Hume renamed the book An Enquiry Concerning Human Understanding (4th edn.). 21 Merian also translated other essays by Hume into French. On the translations of Hume’s works in the German Enlightenment, see Gawlick and Kreimendahl (1987: 14–44). 22 See for instance Crousaz (1733). On the seminal role of Bayle’s skeptical views for the Enlightenment in general and for Hume in particular, see Popkin (1997). It is worth noting that Merian proposed an academic prize question on Bayle’s philosophy several times. On his failed attempts in this regard, see Buschmann (1996). Tonelli (1997) provides groundbreaking views on skepticism in the Enlightenment. For recent treatments of this topic, see Charles and Smith (2013). On skepticism at the Berlin Academy, see Laursen (1996) and Laursen and Popkin (1997). 23 Contrast with Gawlick and Kreimendahl (1987: 85). 24 Merian slightly rephrases, for instance, the famous concluding passage of the Enquiry and downplays its implications: on his account, Hume imagined a person who, animated by the principles advanced in this work, enters a library and could produce “terrible damage” by burning all the books which do not contain any abstract reasoning concerning quantity or number or any experimental reasoning concerning matters of fact. See Merian, MLP2 117 and Hume, EHU 12.34. 25 “It becomes, therefore, no inconsiderable part of science barely to know the different operations of the mind, to separate them from each other, to class them under their proper heads, and to correct all that seeming disorder, in which they lie involved, when made the object of refection and enquiry. This task of ordering and distinguishing, which has no merit, when performed with regard to external bodies, the objects of our senses, rises in its value, when directed towards the operations of the mind, in proportion to the diffculty and labour, which we meet with in performing it. And if we can go no farther than this mental geography, or delineation of the distinct parts and powers of the mind, it is at least a satisfaction to go so far” (Hume, EHU 1.13). 26 Hume (1740: 657). 27 Thus, in his 1758 essay On Moral Sense, Merian praises Hume for having “carried the torch of experience and tried to make the case for it on factual proofs” (1765a: 390). 28 Gawlick and Kreimendahl (1987: 91) wrongly advance that Hume never used this concept. See, for instance, THU 60, where the term ‘phaenomenon’ is used three times in one page. 29 Merian regards Kant as Hume’s successor (PH 179, 188–89) but refrains from discussing Kant’s position in detail in this essay; he does so in his 1797 essay Historical Parallel. 30 For a comparative analysis of Hume’s skepticism in the Treatise and the Enquiry, see Fogelin (2009: 139–58), who argues for a “fundamental difference between the employment of skeptical arguments” in the two texts (2009: 155). On his account, Hume endorses a much more radical skepticism in the Treatise. 31 Merian questions Hume’s disciple: “You will tell me that this was precisely your intention, because you want to preach universal skepticism? […] But I do not understand you. You would like to prove to me that all is phenomenon. But your proof itself supposes that one can prove nothing. You have then proved nothing” (PH 183). Despite its polemical and dismissive tone, Merian’s reading is text-based and consistent with Hume’s summary of his

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32

33

34

35

36 37 38

39 40

own perspective in a decisive passage from his 1740 Abstract to the Treatise: “By all that has been said the reader will easily perceive, that the philosophy contained in this book [the Treatise] is very sceptical, and tends to give us a notion of the imperfections and narrow limits of human understanding. Almost all reasoning is there reduced to experience; and the belief, which attends experience, is explained to be nothing but a peculiar sentiment, or lively conception produced by habit. Nor is this all. When we believe any thing of external existence, or suppose an object to exist a moment after it is no longer perceived, this belief is nothing but a sentiment of the same kind. Our author [Hume] insists upon several other sceptical topics; and upon the whole concludes, that we assent to our faculties, and employ our reason only because we cannot help it. Philosophy would render us entirely Pyrrhonian, were not nature too strong for it” (1740: 657). For an illuminating analysis of Hume’s skepticism, see Fogelin (2008). Fogelin (2008: 212–13) distinguishes two skeptical strategies in Hume: one genetic and the other argumentative (the latter also comprising his skepticism concerning induction, the senses, and reason). Hume writes with regard to the Treatise that “upon a more strict review of the section concerning personal identity, I fnd myself involv’d in such a labyrinth, that, I must confess, I neither know how to correct my former opinions, nor how to render them consistent” (1740: 633). “The mind is a kind of theater, where several perceptions successively make their appearances; pass, re-pass, glide away, and mingle in an infnite variety of postures and situations. There is properly no simplicity in it at one time, nor identity in different; whatever natural propension we may have to imagine that simplicity and identity. The comparison of the theater must not mislead us. They are the successive perceptions only, that constitute the mind; nor have we the most distant notion of the place, where these scenes are represented, or of the materials, of which it is compos’d” (T 1.4.6.4). Fogelin (2009: 112) advances a similar reading of this passage. “If it [the phenomenal me] perceives them [other phenomena], or is perceived, they have an effect on it, or it has an effect on them. And you summon from its exile causality, which you have so solemnly proscribed. In general what I have observed from the beginning on the nature of phenomena still applies here, and makes apparent the inconsistency of phenomenalism, whatever aspect, whatever direction one wishes to give it. For if the phenomenon cannot exist without being perceived, it fnally leads us always to something that is no longer a phenomenon. And what can this be if not a substance capable of perception and of what follows from it? […]. The phenomenalist philosophers sometimes seem to have sensed that their phenomena, straying they know not where, and making themselves perceptible they know not to whom not to what nor how, do not present a very luminous idea” (Merian, PH 188). See Anstey (2018: 140). Contrast with Charles (2010: 147). This argument is already briefy mentioned in 1749 (see APE 422). The members of the Berlin Academy did not have the right to compete but often took part in the discussions related to the topics chosen for the academic contests. On the controversies related to this prize essay question and its outcome, see Prunea-Bretonnet (2015). For the classifcation of philosophical disciplines in Wolff, see DP §§ 55–114. For a similar account of the role of reasoning, see Maupertuis’s 1750 treatise On the Duties of the Academician (Maupertuis 1768a: 288–89).

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41 On the contemporary bipartite theory of the nature of metaphysics in D’Alembert (and Diderot), as well as on Condillac’s infuential methodological commitments, see Anstey (2018: 139–45). Merian was quite conversant with their views. 42 On the distinction between common and proper principles, see Anstey (2020). 43 Anstey holds these two claims (i.e., the epistemic priority of observation and experiment and the readiness to revise systems built on principles and axioms founded on experimental evidence) to be the core doctrines of experimental philosophy and to have decisively infuenced eighteenthcentury thought. On this point and Boyle’s contribution, see Anstey (2018: 136–37). 44 On metaphysics as the science of necessary and universal common principles that may never be fully discovered but are to be forever pursued, see also Ancillon (1815: 67). 45 On the eclectic philosophy at the Berlin Academy, see Prunea-Bretonnet (forthcoming). This chapter is published within the research project PN-IIIP4-ID-PCE-2020-2579 (UEFISCDI).

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——— (1757), Sur l’identité numérique, in Histoire de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1755), Berlin: Haude & Spener, 461–75. ——— (1765a), Sur le sens moral, in Histoire de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1758), Berlin: Haude & Spener, 320–413. ——— (1765b), Discours sur la métaphysique, Berlin: Voss; repr. in Histoire de l’Académie Royale des Sciences et des Belles-Lettres de Berlin, Berlin: Haude & Spener 1767, 450–74 (DM). ——— (1798), Sur le phénoménisme de David Hume, in Mémoires de l’Académie Royale des Sciences et des Belles-Lettres depuis l’avènement de Frédéric Guillaume II au thrône (1793), Berlin: Decker, 417–37 / On the Phenomenalism of David Hume, transl. by P. Briscoe, Hume Studies, 23/1, 1997, 178–91 (PH). ——— (1800), Parallèle historique entre nos deux philosophies nationales, in Mémoires de l’Académie Royale des Sciences et des Belles-Lettres de Berlin (1797), Berlin: Decker, 53–96 (PHPN). Maupertuis, Pierre-Louis Moreau de (1768a), ‘Des devoirs de l’académicien: Discours prononcé dans l’Académie Royale de Sciences & Belles-Lettres’ (1750), in Œuvres, vol. 3, Lyon: Bruyset, 283–302. ——— (1768b), Lettres, in Œuvres, vol. 2, Lyon: Bruyset, 217–431. Secondary Sources Anstey, Peter (2018), ‘The Principled Enlightenment: Condillac, d’Alembert, and Principle Minimalism’, in G. Boucher and H.M. Lloyd (eds.), Rethinking the Enlightenment: Between History, Politics, and Philosophy, Lanham: Lexington, 131–50. ——— (2020), ‘Principles in Early Modern Philosophy and Science’, in D. Jalobeanu and C.T. Wolfe (eds.), Encyclopedia of Early Modern Philosophy and the Sciences, Dordrecht: Springer. Baertschi, Bernard (1996), ‘La conception de la conscience développée par Mérian’, in M. Fontius and H. Holzhey (eds.), Schweizer im Berlin des 18. Jahrhunderts, Berlin: Akademie Verlag, 231–48. Buschmann, Cornelia (1996), ‘Schweizer in den Diskussionen über die Preisaufgaben der Berliner Akademie im 18. Jahrhundert’, in M. Fontius and H. Holzhey (eds.), Schweizer im Berlin des 18. Jahrhunderts, Berlin: Akademie Verlag, 305–24. Charles, Sébastien (2010), ‘Lumières allemandes et scepticisme. Le cas de l’Académie de Berlin’, in M.-H. Quéval (ed.), Orthodoxie et hétérodoxie dans l’Europe des Lumières, Rennes: Presses de l’Université de Rennes, 139–49. ——— and Smith, Plinio J. (eds.) (2013), Scepticism in the Eighteenth Century: Enlightenment, Lumières, Aufklärung, Dordrecht: Springer. Dilthey, Wilhelm (1926), ‘Friedrich der Grosse und die deutsche Aufklärung’, in Gesammelte Schriften, vol. 3, Stuttgart: Teubner, 83–200. Fogelin, Robert (2008), ‘Hume’s Skepticism’, in D. Norton and J. Taylor (eds.), The Cambridge Companion to Hume, Cambridge: Cambridge University Press, 209–37. ——— (2009), Hume’s Skeptical Crisis: A Case Study, Oxford: Oxford University Press.

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Gawlick, Günther and Kreimendahl, Lothar (1987), Hume in der deutschen Aufklärung, Stuttgart-Bad Cannstatt: Frommann-Holzboog. Laursen, John Christian (1996), ‘Swiss Anti-skeptics in Berlin’, in M. Fontius and H. Holzhey (eds.), Schweizer im Berlin des 18. Jahrhunderts, Berlin: Akademie Verlag, 261–82. ——— and Popkin, Richard H. (1997), ‘Hume in the Prussian Academy: Jean Bernard Merian’s “On the Phenomenalism of David Hume”’, Hume Studies, 23/1, 153–62. Popkin, Richard H. (1997), ‘Scepticism in the Enlightenment’, in R. Popkin, E. de Olasio, and G. Tonelli (eds.), Scepticism in the Enlightenment, Dordrecht: Springer, 1–16. Prunea-Bretonnet, Tinca (2015), ‘La méthode philosophique en question. L’Académie de Berlin et le concours pour l’année 1763’, Philosophiques, 42/1, 107–30. ——— (forthcoming), ‘Eclectic Philosophy and “Academic Spirit”: the Berlin Academy on Metaphysics and the Thomasian Legacy’, in P. Anstey and T. Prunea-Bretonnet (eds.), Philosophy at the Berlin Academy in the Reign of Frederick the Great, Oxford Studies in the Enlightenment. Thiel, Udo (2011), The Early Modern Subject, Oxford: Oxford University Press. Tonelli, Giorgio (1987), La pensée philosophique de Maupertuis. Son milieu et ses sources, Hildesheim: Olms. ——— (1997), ‘The “Weakness” of Reason in the Age of Enlightenment’, in R. Popkin, E. de Olasio, and G. Tonelli (eds.), Scepticism in the Enlightenment, Dordrecht: Springer, 35–50.

Part IV

Tetens and Kant

11 The Role of Experience in Kant’s Prize Essay Courtney D. Fugate

1 Introduction Kant wrote an Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality in response to the 1763 competition proposed by the Berlin Royal Academy. In this treatise, Kant claims to show, with all requisite certainty, “the true degree of certainty to which it [i.e. metaphysics] may aspire as well as the path by which certainty may be attained.”1 This Prize Essay (as it is commonly known) deserves our attention because it contains Kant’s frst published attempt to establish a proper method for metaphysics, and it is relevant to the theme of the present volume because a signifcant component of that method consists in an appeal to experience. Indeed, in the very frst paragraph of the Prize Essay, Kant makes a most remarkable, but hitherto largely underappreciated claim, namely, that he intends to establish his new method upon “nothing but propositions of experience that are secure, and the inferences that are drawn immediately from them” (Inq, 2:275). His reason for taking experience as his basis, he proceeds to explain, is that: If what is presented in this treatise is itself metaphysics, then the judgment of the treatise will be no more certain than has been that science which hopes to beneft from our inquiry […] and then all our efforts will have been in vain. (Inq, 2:275) In other words, Kant appeals to experience as a basis for determining with certainty the method of metaphysics itself, something which he believes metaphysics is unable to accomplish on its own. Although Kant was awarded a close second in the prize competition, the Wolffans in the Academy must have read such bravado with disapproval, if not bewilderment, while the ever-present Newtonians— Euler, as president of the Academy, being frst among them—must have been delighted to see such words written by an ambitious young German academic. The parties on both sides were only too keenly aware that Wolff, following in the spirit of Descartes and Leibniz, claimed for metaphysics the role of supreme and sole guarantor of certainty in scientifc knowledge.

232 Courtney D. Fugate However, Kant and a few of his contemporaries ultimately held that Wolff had failed to recognize that experience makes a material contribution to knowledge, i.e., a contribution that cannot be derived from the single principle of non-contradiction. Lacking material principles, Wolff’s attempt to build a philosophy that could suffciently explain what is given in experience was doomed to failure. On their view, Wolff really just ended up espousing the account of innate ideas put forward by Leibniz in the New Essays, according to which experience is indeed the beginning and necessary condition of all knowledge, whereas the universality and strict necessity of such knowledge, and hence its certainty, is a product of reason alone. 2 Moreover, they took Wolff to claim that the certainty of our experience is grounded on principles proven in metaphysics, and ultimately on the principle of contradiction, which Wolff unequivocally held to be both a necessary and suffcient source of all certainty in human knowledge.3 The Newtonians in the Academy must have been even more pleased to see Kant claim later in the essay that “the true method of metaphysics is basically the same as the one introduced by Newton into the natural sciences” (Inq, 2:286). With this statement, Kant announces clearly and forcefully which side he intends to take in the longstanding debate between the Newtonians and the Wolffans in the Academy. By doing so, he also implicitly rejects what was supposed to be a signal achievement of the Wolffan philosophy, namely its ability to establish metaphysics as a true science. But does Kant truly succeed in articulating a method that is distinct from the one proposed by Wolff? Despite Kant’s stated intentions in the Prize Essay, modern interpreters have struggled to answer this question in the affrmative. Anderson even claims that the method of the Prize Essay “does not yet underwrite any criticism” of Leibnizian and Wolffan metaphysics.4 Indeed, most commentators have concluded that Kant in this treatise ultimately fails to free himself from a rationalist framework, even if he succeeds in placing renewed emphasis on the importance of experience within that framework. Two main reasons have been provided in support of this view. The frst was voiced by Herman de Vleeschauwer, who otherwise places the greatest emphasis on Kant’s so-called Newtonian empiricism during this period. However, he believes this empiricism to be spoiled by a single “embarrassing remark” in the Prize Essay, namely, Kant’s suggestion that metaphysics may one day proceed synthetically.5 De Vleeschauwer sees this as a profound violation of the brand of empiricism found in Newton’s writings. As he puts it, despite the empiricism which is evident in Kant at this moment, the ideal of an a priori construction of universal science retains for him all its attraction and force. In spite of everything, the ideal of

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Descartes and of Hegel remains the Kantian ideal. And this dream […] removes Kant from the Newtonian and positivist orbit. […] Kant is not an empiricist.6 Thus, on De Vleeschauwer’s view, since genuine empiricism is impossible without a total rejection of the synthetic method, Kant remains a rationalist in spirit. Michael Friedman provides a different reason for seeing the Prize Essay as covertly rationalist. According to Friedman, the Prize Essay is deeply Newtonian in the sense that it gives priority to the analytic method and, most of all, recommends the incorporation of mathematical propositions into metaphysical analysis, but not because of its apparent appeal to experience. As he explains, “there is no suggestion at all that what will later be called sensibility plays any essential role in the ‘secure inner experience’ that furnishes Kant’s data.” As for analysis, Friedman claims that “all Kant’s examples are a priori judgments of conceptual connection.”7 In support of this view, Friedman does not point to any explicit remarks in the essay but, instead, to a couple of examples in which the use of mathematics is particularly apparent.8 My aim in this chapter is to challenge such views by analyzing the essential features of Kant’s method in the Prize Essay. I will argue that, even if Kant fails to present a perfectly clear and defensible account of a method for metaphysics, the manner in which he describes this method and the kind of transformation of metaphysical inquiry that he hopes it will accomplish do not testify to a broadly rationalist approach but, in fact, embody the anti-rationalist spirit of Bacon and Newton. While Kant does indeed believe that metaphysics will one day be able to readopt the synthetic method, I argue that this is perfectly consistent with the views of Bacon and Newton as he understood them. In contrast with Friedman’s claim, I will also show that experience does play a role in Kant’s conception of data and that this is particularly clear if we take into account other texts of the same period. Before turning to the role of experience in Kant’s Prize Essay, however, I think it is imperative to clarify the way Kant and his contemporaries understood the empiricism associated with Bacon and Newton.

2 The ‘Empiricism’ of Bacon and Newton in Perspective The term ‘empiricism’ in its modern sense is a coinage of Kant’s critical philosophy, and many of the current connotations of that term are not found in his writings. Also, the sharp distinction between impressions and concepts, which is now used to formulate the empiricism-rationalism divide, is notably absent from the works of Wolff and the young Kant.9 To clarify this matter, I propose to carefully examine the writings Kant himself would have studied in the 1760s and to reconstruct, on this

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basis, a more accurate picture of the choice facing the young Kant. To aid in this reconstruction, I will also draw upon the few synoptic accounts of the British philosophy that we know him to have read, namely those found in Brucker’s monumental Historia critica philosophiae (1742–1744) and Formey’s Abrégé de l’histoire de la philosophie (1760). Let us begin by considering Bacon. In De augmentis scientiarum, Bacon claims that philosophy is still defective and in need of a complete renovation. Such a renovation, he suggests, must begin with the creation of a single “universal science, [that is] to be the mother of the rest.” This science would therefore be opposed to no other science, “treating only of the highest stages of things,” and would be “a receptacle for all such axioms as are not peculiar to any particular of the sciences, but belong to several of them in common” (AS 337). Since this science is to provide the basis for all other branches of philosophy, Bacon gives it the title of Philosophia prima and further explains that its “true offce” is “displaying the unity of nature” by investigating and collecting those axioms which show “plainly the same footsteps of nature treading or printing upon different subject matters” (AS 339). Bacon believes that this universal science must follow a method unlike any previously applied to such matters in the past. Instead of consulting logic and linguistic usage (as Aristotle had done), philosophers should consult nature itself through study and experiment even in order to discover the most basic and universal of all principles. More specifcally, he notes that we must search out what is universal and frst in this science insofar as it can be abstracted from the specifc contents of the individual sciences themselves. To illustrate what he has in mind here, Bacon mentions such axioms as “if equals be added to equals the wholes will be equal,” which applies as much in mathematics as in distributive justice, and “[t]he Quantum of nature is neither diminished nor increased,” which applies as much in physics as in natural theology (AS 338). Similarly, he asserts that the concepts of similitude and diversity require us to “assign a reason […] why betwixt different species there almost always lie certain individuals which partake of the nature of both” (AS 340). In other words, the true meaning of such terms must be sought in the universal “laws of nature and not of language,” laws which are discovered in and corroborated by the empirical sciences (AS 340). Subordinate to this Philosophia prima are the three main branches of science—natural theology, natural philosophy, and civil philosophy— which are distinguished by their subject matters, namely God, nature, and man. Natural philosophy branches further into a speculative part, or “Inquisition of Causes,” and an operative part, or “Production of Effects.” These parts “must in a certain way be united and conjoined” since “all true and fruitful Natural Philosophy has a double scale or ladder, ascendant and descendent, ascending from experiments to axioms [i.e., analytically], and descending from axioms to the invention of new

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experiments [i.e., synthetically]” (AS 343). Speculative natural philosophy in particular can treat either what is “inherent in matter and therefore transitory,” , i.e., “the Material and Effcient Causes” in nature, in which case it is called physics, or instead what is “more abstracted and fxed,” i.e., “the Formal and Final” causes, in which case it is called metaphysics (AS 346). The metaphysics of formal causes, Bacon further explains, is the most excellent […] because it is the duty of all knowledge to abridge the circuits and long ways of experience (as much as truth will permit). […] And this is best performed by collecting and uniting the axioms of the sciences into more general ones, and such as may comprehend all individual cases. (AS 361) These passages make it clear that Bacon, like all so-called rationalists, is fully committed to the ideal of a frst philosophy concerned with universal concepts and axioms, to the view that the more general truths provide the real underlying reasons for individual cases, and to the necessity of using both analysis and synthesis. Bacon’s originality lies, therefore, not in the overthrow of these traditional doctrines but in the assertion that they must be understood within the context of an entirely new method in the sciences, one in which “the order of demonstration also is completely reversed.”10 As the Novum organum makes evident, Bacon indeed relocates the positive task of philosophy, and in particular that of metaphysics, from a search for rational insight into frst principles to an inductive analysis of the results already established in the empirical sciences.11 The latter investigate the particulars presented by the senses, but then ascend, through carefully conducted experiments, to increasingly higher and more abstract principles, until they fnally reach general axioms and the knowledge of forms. Only after this analytic process is accomplished can philosophers proceed to an analysis and comparison of the axioms thus established, which allows them to ascend to a knowledge of the most universal axioms and concepts and, thus, to frst philosophy. Contrary to the one embraced by ‘rationalist’ philosophy, the order of demonstration Bacon defends goes from experience to science, from science to metaphysics, and from metaphysics to frst philosophy. From this brief sketch we can see that there is actually very little Kant could have read in Bacon’s account of the arbor scientiarum (or Brucker’s summary of it) that one would expect to fnd in a narrowly ‘empiricist’ account of knowledge. Two points should be emphasized in this regard. First, although Bacon clearly approves of the use of both the analytic and the synthetic methods in philosophy, he believes that the cognitive predicament of human beings requires that they start from inductive analysis and that measures be taken to counter their innate

236  Courtney D. Fugate tendency to ‘leap’ from analysis to a synthesis based upon spurious first principles and the belief in the possibility of purely rational insight into their truth. Consequently, despite its great importance and utility, first philosophy must be regarded as the most distant goal of our efforts. Second, Bacon can allow the axioms and concepts that used to be treated in first philosophy, and likewise the complete definitions and logical demonstrations based upon them, to be among the very last achievements of science only because they play no role in lending it a scientific character. Unlike Descartes and Wolff, Bacon locates the only certain basis for demonstration in propositions and concepts derived from a carefully regimented analysis of particulars by means of the rigorous study of human nature and supplemented with the probative use of intermediate syntheses. Accordingly, he holds that the empirical sciences themselves provide both the material and the evidential basis for the principles arrived at by analysis in metaphysics. Turning now to Newton, there can be no doubt that Kant knew Newton’s writings in the originals and was familiar with the accounts of it in historical compendia and the lectures of Knutzen. He also owned, studied, and sometimes referred to the works of Willem Jacob 's Gravesande, which contain a thorough discussion of the unique features of the Newtonian method and were instrumental in giving shape to the discussion of it on the continent. Two of Newton’s own texts deserve our attention here, namely Query 31 of the Optics and the Philosophiae naturalis principia mathematica. The former not only most clearly attests to Newton’s Baconian heritage but also contains the locus classicus for his views on the analytic and synthetic methods. I have inserted roman numerals and italics in the following passage in order to facilitate its finer anatomization: As in mathematics, so in natural philosophy, the investigation of difficult things by [i] the method of analysis ought ever to precede the method of composition. This analysis consists in making experiments and observations, and in [ii] drawing general conclusions from them by induction, and [iii] admitting of no objections against the conclusions but such as are taken from experiment, or other certain truths. For hypotheses are not to be regarded in experimental philosophy. And although the [iv] arguing from experiments and observations be no demonstration of general conclusions, yet it is the best way of arguing which the nature of things admits of, and may be looked upon as so much stronger by how much the induction is more general. And if no exception occur from phenomena, the conclusion may be pronounced generally. But if at any time afterward any exception shall occur from experiments, it may then begin to be pronounced with such exceptions as occur. [v] By this way of analysis we may proceed from compounds to ingredients

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and from effects to their causes and from particular cases to more general ones, till the argument end in the most general. This is the method of analysis; and the synthesis consists in assuming the causes discovered and established as principles, and by them explaining the phenomena proceeding from them and proving the explanations.12 As Newton goes on to explain, the frst books of the Optics consist mainly in this kind of analysis, but the results “may be assumed in the method of composition [i.e. of synthesis] for the explaining of the phenomena arising from them, an instance of which method I gave in the end of the First Book.”13 At frst blush, the methodology described in this passage appears to be perfectly compatible with the views of Wolff, and perhaps even those of Leibniz, particularly in respect to points [i] and [v]. Both would agree with Newton that analysis must always precede synthesis (since the latter should begin from simples), that it must begin from experience (but as the occasion, not the source of concepts), and that its goal is to proceed from complex, particular experiences to their simple and general “ingredients” or “causes.” The other three marked passages, however, show why this agreement is merely superfcial, and why Newton is rightfully to be considered a follower of Bacon. In [ii], Newton asserts that the analysis in question is always inductive, and so never results in knowledge that is absolutely certain, as Leibniz and Wolff believed it could. In [iv], he concludes from this that our inferences of principles and causes from experience will always be less certain than the experiences from which they are derived. This in turn implies—again contrary to Leibniz and Wolff—that employing such principles in order to synthetically demonstrate the necessity of what happens in experience is entirely misguided. Newton employs synthesis, to be sure, but only for the sake of ‘illustrating’ that certain phenomena really do follow from the principles that have been inferred. All of this amounts to an acceptance of Bacon’s reversal of the order of demonstration. A similar but more nuanced picture can be gathered from the layout of the Principia, which appeared many years prior to the Optics. In the Preface, Newton states that “the basic problem of philosophy seems to be to discover the forces of nature from the phenomena of motions and then to demonstrate the other phenomena from these forces” (PM 382). In other words, philosophy is to frst employ analysis and then synthesis. The Principia follows this path by beginning with a list of fundamental defnitions accompanied by the three famous Newtonian laws of motion. Although these defnitions provide the axiomatic basis of the work, they are accepted not because they are self-evident or simple but because they have been established beyond any reasonable doubt based on the analysis of experiments. Books 1 and 2 then develop the mathematical tools for using these axioms to demonstrate the specifc motions that

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would be observed in various constellations of objects if the latter were acted on by hypothetical forces. For example, Book I, Proposition 4, Corollary 6 states that “If the periodic times are as the 3/2 powers of the radii, and therefore the velocities are inversely as the square roots of the radii, the centripetal forces will be inversely as the square of the radii, and conversely” (PM 451). Since such propositions do not “discover the forces of nature from the phenomena of motions” (PM 382) but merely express the relationships between certain possible motions and the forces one would have to assume in order to explain them, they are not philosophical but merely mathematical in character. Book 3 contains what is certainly one of the most famous and discussed parts of all Newton’s writings, namely the ‘Rules for the Study of Natural Philosophy.’ These rules provide the methodological foundation for the transition from a purely mathematical investigation to natural philosophy proper and are thus intended to serve the same role as Leibniz and Wolff attributed to the principle of suffcient reason. The correct scientifc method, as Newton explains it, is based upon four essential rules. The frst two are rules of economy that provide the basis for induction by analogy: “No more causes of natural things should be admitted than are both true and suffcient to explain their phenomena,” and “the causes assigned to natural effects of the same kind must be, so far as possible, the same” (PM 795). The third rule states that qualities “that cannot be intended or remitted and belong to all bodies on which experiments can be made should be taken as qualities of all bodies universally” (PM 795). This rule is required to generalize the properties and laws belonging intrinsically to particular natural kinds. Finally, the fourth rule codifes Newton’s reasons for excluding hypotheses. It reads: “In experimental philosophy, propositions gathered from phenomena by induction should be considered either exactly or very nearly true notwithstanding any contrary hypotheses, until yet other phenomena make such propositions either more exact or liable to exceptions” (PM 796). Rather than providing a deductive foundation for demonstrating or refuting particular doctrines, which is their function in Leibniz and Wolff, Newton sees such rules as serving at most as heuristic guidelines for collecting, comparing, and inductively inferring laws from the phenomena. These four rules of method are followed by two further chapters. The frst of them describes six different celestial “phenomena,” while  the second applies the four methodological rules to these phenomena in order to infer a number of propositions, including the central claims that “[g]ravity exists in all bodies universally and is proportional to the quantity of matter in each” and that the strength of this force varies with the inverse of the square of the distance between bodies (PM 810). Newton fnally proceeds from analysis to synthesis by assuming universal gravitation in order to mathematically demonstrate the reasons for various other phenomena found in nature.

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From this brief outline we can abstract the basic pattern of the reasoning found in the Principia. The work commences with a preparatory study that is purely mathematical. This is followed by a phenomenological description of certain basic experiences. This description is then inductively analyzed with the help of mathematics and guided by the four rules of method. All of this makes up the analytical stage of his investigation. After this, a synthetic explanation of further phenomena, which is based upon the principles inferred by the previous analysis, is fnally used to corroborate and illustrate said analysis. With this pattern of argumentation, Newton adheres essentially to the spirit of Bacon’s attempt “to abridge the circuits and long ways of experience.” However, he extends it, frst, by including a mathematical foundation for his inductive analysis and, second, by explicitly recognizing not only a practical but also a corroborative role for synthesis. The various textbooks always list the four basic rules of induction mentioned in the Principia, or some variation thereof, under the title of the ‘Newtonian analytical method.’ Hence it is most likely that they would be foremost on Kant’s mind when he speaks of the Newtonian method in the Prize Essay.

3 The Method of the Prize Essay The frst part of the Prize Essay takes the form of a comparison between the method of mathematics and the one which Kant believes is proper to philosophy. He bases his comparison on “propositions [treated] only as conclusions derived from our experiences” (Inq, 2:278), that is, from observations regarding the practice and success of the two sciences. In § 1, he asserts that the philosophical method must proceed analytically instead of synthetically, and thus in the opposite direction of mathematics and the ‘rationalist’ philosophy modeled after it. Kant writes: If this procedure [i.e., the analytic method he proposes for metaphysics] is compared with the procedure […] which is currently in vogue in all the schools of philosophy, one will be struck by how mistaken the practice of philosophers is. With them, the most abstracted concepts, at which the understanding naturally arrives last of all, constitute their starting point, and the reason is that the [synthetic] method of the mathematicians, which they wish to imitate throughout, is frmly fxed in their minds. (Inq, 2:289) Kant says something similar in the announcement for his lectures for the winter semester of 1765–1766: Its [i.e., metaphysics’s] method is not synthetic, as is that of mathematics, but analytic. As a result, what is simple and most universal

240 Courtney D. Fugate in mathematics is also what is easiest, whereas in the queen of the sciences it is what is most diffcult. In mathematics, what is simple and universal must in the nature of things come frst, while in metaphysics it must come at the end. In mathematics one begins the doctrine with the defnitions; in metaphysics one ends the doctrine with them; and so on in other respects.14 It is diffcult to believe that in writing such passages Kant did not intend to echo Bacon’s proposal of a new method in which “the order of demonstration […] is completely reversed,”15 thereby rejecting the probative role given to synthesis by rationalists. And yet De Vleeschauwer’s claim that Kant’s comment about synthesis in the Inquiry places him in the rationalist camp, which was quoted in the introduction to this chapter, would require us to think otherwise; for Kant truly belongs in the rationalist camp only if he also believes that the synthetic method can provide demonstrations. Bacon’s reversal, we should recall, consists in shifting the burden of demonstration from synthesis to analysis, not in the rejection of synthesis itself. As the Prize Essay further explains, mathematics creates or defnes its more complex concepts by relying upon simpler concepts already accepted “as given in accordance with his [i.e., the mathematician’s] clear and ordinary representation” (Inq, 2:278). By contrast, the task of philosophy is to make such given concepts fully distinct and, if possible, to discover their defnitions or complete general concepts. In other words, although both mathematics and philosophy begin from given clear concepts, the primary business of mathematics is to synthesize new complex concepts out of them, while that of philosophy is rather to infer their underlying simple and universal concepts by means of analysis. As Kant explains: In philosophy, the concept of a thing is always given, albeit confusedly or in an insuffciently determinate fashion. The concept has to be analyzed; the characteristic marks which have been separated out and the concept which has been given have to be compared with each other in all kinds of contexts; and this abstract thought must be rendered complete and determinate. (Inq, 2:276, cf. 283–84) To illustrate what he means by analysis here, Kant gives the example of time, of which he says that “everyone has a concept”: The idea of time has to be examined in all kinds of relations if its characteristic marks are to be discovered by means of analysis; different characteristic marks which have been abstracted have to be combined together to see whether they yield an adequate concept;

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they have to be collated with each other to see whether one characteristic mark does not partly include another. (Inq, 2:277) The basic idea in these passages appears straightforward, but many key details are left in the dark. First, although Kant indicates that the concepts in question are given clearly but not yet distinctly, he does not further specify precisely how they are given. The phrase “inner experience,” which occurs in another key passage (Inq, 2:286), suggests that these concepts are given through sense, since experience is generally defned by Kant’s contemporaries (and by Kant too in later works) as whatever originates in sense rather than the intellect.16 Second, Kant states here that given concepts must be analyzed by being “compared with each other in all kinds of contexts.” But what kind of comparison does he have in mind? Third, in the passages quoted above, Kant does not indicate the source of the certainty of philosophical analysis. Does it stem from the intellect and from the self-evidence of the principles it discovers, as a rationalist would maintain, or rather from the clarity and reliability of the originally given representation and the care taken in its analysis, as an empiricist would? The nature of the Prize Essay thus depends upon the specifc answers Kant would give to these three questions regarding the givenness of the data for analysis, the exact nature of the analysis itself, and, fnally, the source of the certainty of the fundamental principles reached in such analysis. I will therefore turn to an examination of these three questions. The Question of Givenness. Kant’s emphasis in the Prize Essay on the essential givenness of metaphysical concepts refects a deep and persistent feature of all his writings in the 1760s. This emphasis is marked by Kant’s frequent use of the Latin term ‘datum’ to indicate the proper starting point of all fruitful philosophical analysis. According to the method proposed by Wolff, metaphysics must begin with proper defnitions. Moreover, proper defnitions require the philosopher to both enumerate the essentials or possibilia of a certain concept and to guarantee the possibility—or objective reality—of the concept itself by proving that it does not contain a contradiction. But Wolff and Baumgarten went even further by asserting that the possibility of a concept consists in nothing but its being non-contradictory. For this reason, the ideal for the metaphysician would be to prove the possibility of concepts entirely through a priori conceptual analysis. However, since such an analysis is not always feasible, they argued that it sometimes suffces to locate an object answering to the concept among the objects that actually exist or to explain the manner in which it could be made actual; for if the object exists or could exist, then surely its concept must be possible and hence non-contradictory.

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Kant’s consistent use of the term ‘datum’ in the 1760s is based upon his rejection of the idea that possibility consists in being non-contradictory alone. As he writes in the Only Possible Argument, which was published just prior to the Prize Essay: It is clear from what has now been adduced that possibility disappears not only when an internal contradiction, as the logical element of impossibility, is present, but also when there exists no material element, no datum, to be thought. (OPA, 2:78) For Kant, the real possibility of a concept, unlike its logical possibility, is “given in something actual, either as a determination existing within it or as a consequence arising from it” (OPA, 2:79). For this reason, philosophical analysis must always begin from something actual, and hence from something empirically given. According to Kant, it was the failure to do just this that made it possible for Leibniz to mistakenly believe that he had provided a real defnition of a spiritual monad when in fact he had only invented it (Inq, 2:277). Just how profoundly this should affect philosophical analysis is clear from a passage from The Only Possible Argument in which Kant challenges an imaginary interlocutor to prove that the concept of a fery body is indeed a concept of something that is possible without appealing to an existence of some kind. Kant admits, of course, that the existence of neither a fre nor even a body is required as ‘data’ in order for such a being to be possible. He also admits that there is no logical contradiction to be found between the concepts of fery and body. But he then presses the inquiry further concerning just one of the relevant component concepts, asking: “is then a body itself possible in itself?” To establish the possibility of a fery body, we must surely frst establish the very possibility of a body. In answer to this demand, Kant’s imaginary interlocutor is permitted to further “enumerate the data of its [i.e. body’s] possibility, namely, extension, impenetrability, force, and I know not what else” and to assume that still no contradiction is to be found. But Kant is still not satisfed, explaining: You must, however, give me an account of what entitles you so readily to accept the concept of extension as a datum. […] Suppose that you can no longer break up the concept of extension into simpler data in order to show that there is nothing self-contradictory in it—and you must eventually arrive at something whose possibility cannot be analysed—then the question will be whether space and extension are empty words, or whether they signify something. The lack of contradiction does not decide the present issue; an empty word never signifes anything contradictory. If space did not exist, or if space was not at least given as a consequence through something existent, then the word ‘space’ would signify nothing at all. (OPA, 2:81)

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Believing he has hereby demonstrated the futility of trying to establish the possibility of a simple material concept by appeal to pure thought alone, which for him constitutes a hallmark of the Wolffan methodology, Kant concludes that “in the end, when you consider how this [i.e., space] is then given to you, the only thing to which you can appeal is an existence” (OPA, 2:81). Now, since the existence of no being aside from God can be demonstrated except through experience, to say that a thing exists is to say that its representation “is an empirical concept; in other words, it is the representation of an existent thing” (OPA, 2:72). It follows immediately from this that all the particular data of possibility can only be given in experience and that the proper analysis of a complex metaphysical concept must trace the concepts of all its component representations back to the original experiences in which the data of their possibility were frst encountered. The negative consequence of Kant’s thesis here is easy to grasp: if no relevant datum is extant, or perhaps even possible, then in principle no amount of logical analysis could ever show the concept to possess real content. Hence, whereas Wolff has recourse to experience only when purely conceptual analysis would be too demanding, Kant believes that the metaphysical method must always and essentially begin from something given in experience. Yet the positive application of the thesis requires further elaboration. Where are we to locate and how are we to recognize the right kinds of experiences and concepts? Surely not just any commonly received information can serve as data to guide the metaphysician. Again, the Prize Essay is not particularly helpful when read on its own. In a couple of instances, Kant refers to such data as concerning what “the understanding initially and immediately perceives in the object” (Inq, 2:281), a claim that, beyond being unhelpful, obscures the fact that he clearly does not have in mind purely rational or a priori concepts. However, in elucidating this very claim, Kant refers to a number of items that resist a rationalist reading. Among these items are the manifoldness of physical space, the insubstantiality of its parts, and its threedimensionality, all of which he remarks are “cognized intuitively; but […] can never be proved.” Kant further adduces the fact that “every appetite presupposed the representation of the object of the appetite; that this representation was an anticipation of what was to come in the future; that the feeling of pleasure was connected with it,” all of which “everyone is constantly aware of […] in the immediate consciousness of appetite” (Inq, 2:284). Similarly, as part of a later analysis of the Newtonian concept of action at a distance, Kant notes: First of all, bodies are at a distance from each other if they are not touching each other. That is the exact meaning of the expression. Now, suppose I ask what I mean by ‘touching.’ Without trouble about the defnition, I realize that whenever I judge that I am touching a

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Contrary to the claim made by Friedman, discussed in our introduction, the data Kant has in mind are neither a priori conceptual connections nor raw empirical data, but instead seem to include just about any long-received and publicly verifable knowledge, regardless of whether it is drawn from mathematics, physics, common physical experience, or even simple introspection. Therefore, to “initially and immediately perceive” something with one’s understanding does not involve some kind of purely intellectual examination, such as is required for Cartesian or Leibnizian conceptual analysis, but rather only the plain and apparent consciousness of such things as the resistance felt by the hand, the physical feeling of pleasure, or other facts established in the mathematical and empirical sciences. Indeed, even when Kant cites mathematical or physical propositions as data, he seems to put stock in them not because they are considered self-evident or rationally demonstrated from frst principles but because they have proven useful and well-tested by a community of scholars. From the full range of examples Kant gives in the Prize Essay, it seems clear that the immediacy he has in mind is characteristic of what is given directly to the senses rather than of an intellectual vision. This strongly suggests that Kant’s idea is simply that metaphysics should borrow its data from sciences based upon experience that we know are more reliable than it. The best evidence to confrm this interpretation is found in another essay altogether, namely Negative Magnitudes, which was composed just after the Prize Essay. In my view, this essay should be read as Kant’s most complete attempt to apply the method of the Prize Essay to the analysis of a single metaphysical concept. Negative Magnitudes begins with an outline of two ways in which philosophy can make use of mathematics. The frst consists in copying its method, which Kant says has manifestly failed. The second consists in borrowing the doctrines established in mathematics as data for further metaphysical analysis. Here he cites the radically anti-Wolffan view of Leonhard Euler, who had argued that the principles of mechanics are so well-established that not only should any metaphysics contradicting them be rejected, but also that “the principal ideas of metaphysics will be necessarily regulated and determined” by the conclusions of mechanics.17 In Kant’s terms, this would just mean taking the empirically verifed principles of mechanics as the ‘data’ for metaphysical analysis. Now, in Negative Magnitudes, Kant claims that mathematics could have proven useful to metaphysics in a similar way, if only the practitioners of the latter had not set themselves against the results of mathematics, so that rather than gaining “secure foundations on which to base

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its refections, it is seen to be trying to turn mathematical concepts into subtle fctions” (NM, 2:168; translation emended). Metaphysics, Kant explains, seeks to discover the nature of space and establish the ultimate principles, in terms of which its possibility can be understood. Now, nothing could be of more use in such an undertaking than the capacity to acquire reliably established data from some source or other, with a view to using them as the foundation of one’s refections. Geometry furnishes a number of such data relating to the most universal properties of space, for example, that space does not consist of simple parts. (NM, 2:168) In agreement with my earlier interpretation of the Prize Essay, Kant here cites accepted mathematical results as possible data for metaphysical analysis.18 As we saw above, mathematics itself rests on given, clear concepts, which are subsequently subjected to synthesis. Interestingly, Kant implies in the frst part of the passage that such data will not simply be accepted and combined by the metaphysician into a defnition of space (this, after all, is what mathematics does) but will instead be taken as the starting point of an analytical procedure that aims to infer something about the concept of space that grounds and unifes the various data associated with it. This is perfectly in line with Euler’s suggestion that metaphysics use the results of another science to “regulate and determine” its ideas. With these comments, Kant sets the stage for the real task of the Negative Magnitudes, which is to analyze the mathematical concept of a negative magnitude in order to gain an understanding of a potential metaphysical version of the same concept. In the frst part, Kant “elucidates” the general mathematical concept of a negative magnitude simply by recounting the main ways in which mathematicians commonly employ the sign for negation (as opposed to mere subtraction) and calculate with negative integers. He then proceeds to “extract what is philosophically signifcant from this concept,” and is therefore not restricted to considerations of quantity, by introducing the concepts of grounds and of the real opposition of grounds, which must be assumed in order for the mathematical concept to be applicable to actual objects (NM, 2:175). In bringing together these two sets of ideas, Kant dismisses certain misunderstandings, while analytically inferring two fundamental and hence more general “laws” governing the interaction of grounds that stand in real opposition (NM, 2:177). Yet the frst mathematical section of Kant’s essay is merely preparatory and serves to formulate a more distinct understanding of the general concept of negative magnitudes such as it is found and used in mathematical practice and, hence, in common experience. The second

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section then searches for a more universal concept of negative magnitudes by showing its real application in philosophical disciplines such as the metaphysics of corporeal nature, psychology, moral philosophy, and natural science. These felds of ‘data’ show for the frst time that the laws adduced in the frst section, once assumed to be universal, explain similar or analogical calculations made throughout all areas of philosophy. Whether Kant intended this portion of the essay to exactly parallel Newton’s chapter on celestial phenomena in the Principia is impossible to determine with certainty, but I take this to be strongly suggested by the overall structure of the essay, the kinds of examples this section contains, and by Kant’s explicit reference to several of his examples as “phenomena” of negative magnitudes (e.g., NM, 2:187). In any case, the overall procedure in the frst two parts of Negative Magnitudes, as well as the kinds of data Kant adduces, prove that the analysis referred to in the Prize Essay has very little in common with the so-called rationalist model of analysis. Instead, what we fnd is a complex procedure closely refecting Newtonian induction by analogy. Moreover, also like Newton, Kant clearly regards the various data as already suffciently established through their long and successful use in their respective philosophical disciplines. These provide the best evidence for general principles, not the other way around, just as Euler had recommended. Thus, if read in the context of his stated opposition to the Wolffan method and the many examples he provides in contemporaneous texts, it seems reasonably clear that Kant in the Prize Essay thinks that metaphysics ought to begin from data that are given to the intellect not by the intellect itself but rather by sense in the course of ordinary experience. Nevertheless, it must be admitted that Kant does not seem comfortable fully and explicitly stating the matter in such univocal terms until the middle of the 1760s. Thus, only in Dreams of a Spirit-Seer are we informed frankly that a chief goal of metaphysics lies in knowing whether the task of answering a given question “has been determined by reference to what one can know, and in knowing the relation the question has to empirical concepts, upon which all our judgments must at all times be based” (Dreams, 2:367). The Questions of Analysis and Certainty. The strongest and most well-known statement of Kant’s allegiance to the methodological tradition of Bacon and Newton is found in the second part of the Prize Essay. “The true method of metaphysics,” Kant here writes, is basically identical (im Grunde einerlei) to that introduced by Newton into natural science and which has been of such beneft to it. Newton’s method maintains that one ought, on the basis of certain experience and, if need be, with the help of geometry, to seek out the rules in accordance with which certain phenomena of

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nature occur. Even if one does not discover the fundamental principle of these occurrences in the bodies themselves, it is nonetheless certain that they operate in accordance with this law. […] Likewise in metaphysics: by means of certain inner experience, that is to say, by means of an immediate and self-evident inner consciousness, seek out those characteristic marks which are certainly to be found in the concept of any given property. And even if you are not acquainted with the complete essence of the thing, you can still safely employ those characteristic marks to infer a great deal from them about the thing in question. (Inq, 2:286; translation emended) The comparison in this passage contains a number of notable points. First, in partial confrmation of the results of our last section, Kant’s claim that we must proceed by means of “certain inner experience” is clearly intended to provide a direct parallel to Newton’s “certain experience.” If we are to take Kant’s claim seriously, then such “certain inner experience” must not be equated with self-evident conceptual connections as understood by so-called rationalists, for these connections are always the terminus of rationalist analysis. For Kant, by contrast, certain inner experiences—following the Newtonian idea—provide the starting point for metaphysical analysis. Second, the passage is clearly intended to assert that the method employed by Newton and the one Kant wishes to be adopted by metaphysics are “basically identical.” As we saw in our previous section, the kind of analysis that is part of the Newtonian method is fundamentally distinct from the one found in the writings of Descartes, Leibniz, and Wolff: whereas the former is inductive and draws its support from experience, the latter, though it may begin from experience, is not inductive and draws all of its strength from rational insight. Thus, if we combine Kant’s assertion of an identity between Newtonian and metaphysical method with his repeated claims that the method employed in metaphysics is essentially that of analysis, there should be little doubt that the analysis he has in mind here is the one described by Newton and not that of Wolff. Indeed, it seems reasonable to assume that Kant intended his parallel to signal to his readers in the Academy, who were no doubt aware of the details of Newton’s discussion of analysis, that the type of analysis metaphysics should employ was precisely that outlined in the famous passage from the Optics and in the four rules of inductive method found in the Principia. Returning to the passage quoted above, the third notable feature is the clear parallel implied between its third and its last lines: Even if one does not discover the fundamental principle of these occurrences in the bodies themselves, it is nonetheless certain that they operate in accordance with this law.

248 Courtney D. Fugate And even if you are not acquainted with the complete essence of the thing, you can still safely employ those characteristic marks to infer a great deal from them about the thing in question. The frst of these two lines refers to Newton’s view that certainty has its source entirely in experience and carefully conducted inductive analysis and does not require a more fundamental principle of explanation. Only the laws that we inductively infer immediately from our experiences are as certain as the latter. In the second of these two lines, Kant bids us to adopt exactly the same method in metaphysics. In other words, he bids us to place the greatest certainty only in what is directly given to us and can be inferred immediately from such data through analysis. And just as in the frst line, the implication in the third is clearly that the certainty of metaphysical truths does not require, and would not be served by, the discovery of even more fundamental principles. Having examined this passage in detail, let us now ask whether our interpretation of it agrees with what Kant says more generally about the process of analysis in writings of this period. As we have seen, Kant states that in analyzing a concept “the characteristic marks which have been separated out and the concept which has been given have to be compared with each other in all kinds of contexts; and this abstract thought rendered complete and determinate” (Inq, 2:276). Elsewhere, he writes that “many operations have to be performed in unfolding obscure ideas, in comparing these with each other, in subordinating them to each other and in limiting them by each other” (Inq, 2:284). As in other cases we have examined, it is not immediately clear what Kant means by such operations. In the frst section of the Prize Essay, however, he states that in metaphysics we “arrive at a general concept […] by abstracting from that cognition which has been rendered distinct by means of analysis” (Inq, 2:248). Similarly, in the third part of Negative Magnitudes he explains that he plans on “advancing to general principles from the examples which have been introduced and are easy enough to understand” (NM, 2:289; my emphasis). As the sequel shows, this advance is from propositions secured in particular philosophical sciences to genuinely metaphysical, and therefore fully universal, principles. With such generalizations, Kant proceeds seemingly in full confdence of being able to suffciently establish original metaphysical principles—which are supposed to be intrinsic to the meaning of concepts such as reality, negation, cancellation, and something—through a process of collecting analogies à la Newton that can be called nothing if not inductive in character. If this interpretation is correct, then the young Kant believed that a general concept, and eventually perhaps also a defnition, can be reached by abstraction from the initial data, once these data have been rendered

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distinct by analysis. The overall process here would be distinctly inductive, moving from particular data to general concepts based upon widespread analogies. This process would be distinct from Wolffan analysis, which also involves abstraction and comparison, in that it does not attempt to provide a metaphysical guarantee for this process by assuming that the general is already contained and perceived in the particular. Likewise, as for Newton, for Kant the move from data to general principles is a move away from the source of certainty and does not hold the promise of any future rational insight into necessary truths. The above interpretation is consistent with Kant’s frequent talk in texts from this period of performing experiments (Versuche) on concepts. For example, in Negative Magnitudes Kant states that his analysis rests on “incomplete experiments, presented in the form of abstract cognition in a problematic fashion,” which he believes “can contribute a great deal to the growth of higher philosophy” (NM, 2:197). In Dreams, Kant explains his procedure as follows: I shall compare my ill-understood concept with all its different applications. By noticing with which cases my concept is compatible and with which it is inconsistent, I hope to unfold the concealed sense of the concept. (Inq, 2:320) Nothing here or in similar instances reminds us of either a Cartesian or Leibnizian form of analysis, which consists in the separation of what is already given in our purely intellectual consciousness of a concept. Instead, Kant proposes that in metaphysics, much as in chemical analysis of the kind described by Newton in the queries to the Optics, we search out, compare, and abstract from all the particular positive and negative instances in which we encounter the concept in question. This interpretation also agrees with what Kant says about the investigation of principles or indemonstrable fundamental truths, which he claims is “the most important business of philosophy.” About these truths he states that: No matter what the object may be, those characteristic marks, which the understanding initially and immediately perceives (unmittelbar wahrnimmt) in the object, constitute the data for exactly the same number of indemonstrable propositions, which then form the foundation on the basis of which defnitions can be drawn up. (Inq, 2:281) Notice that Kant does not say that the data are these propositions. Rather, he says the data are the characteristic marks “immediately perceived” as connected in a given object. It is these data that must be

250 Courtney D. Fugate analyzed in order to arrive at indemonstrable propositions. And only once a suffciently large number of such propositions are known can one hazard a tentative defnition. The defnition is still more general, since it goes beyond the particular data and relies upon an inference from the latter to a single underlying concept, which will then provide a unifying ground and explanation of the data. This procedure parallels the one described by Newton, according to whom we can draw on immediate propositions regarding the motions of particular terrestrial and celestial bodies to infer the concept of universal gravitation which explains them. In traditional rationalist methodology, the next step would be to use the resulting concept in order to prove and certify the propositions from which one began. Yet Kant again sides with the Newtonians: although we can come to know these propositions immediately or intuitively, “they can never be proved,” for, he asks, “on what basis could such a proof be constructed, granted that these propositions constitute the frst and simplest thoughts I can have of my object, when I frst call it to mind?” (Inq, 2:281). We can now see that by answering the two previous questions we have already generated an answer to the fnal one, namely that, for Kant, the certainty of metaphysical knowledge can rest on nothing more than the immediate evidence of the data, the care taken in their analysis, and the restraint exercised in limiting our claims to what is sanctioned by the same. The intellect alone is not a source of knowledge or certainty. This is the empiricist standpoint of Bacon and Newton.

4 Conclusion Nearly all previous commentators have recognized, and some have even emphasized, the empiricism apparent in Kant’s Prize Essay. In fact, the present chapter has benefted greatly from these earlier studies and should be understood as an attempt to build upon them. Nevertheless, in sharp contrast to my core thesis, all previous interpretations, including Friedman’s, have concluded that the Prize Essay ultimately falls back on a broadly Cartesian or rationalist model of metaphysics. The central reasons provided in support of this claim are, however, quite unconvincing, and really amount to a misunderstanding of the brand of empiricism to which Kant subscribes. Kant never seems to have been anything like a Lockean empiricist, but instead followed the method espoused by Bacon, Newton, and Euler, among others. This brand of empiricism gives experience priority because it is thought to be the only way in which we make immediate contact with reality. Kant’s empiricism in metaphysics builds on such an approach by following Euler’s idea—which can already be found in Bacon—that metaphysics should borrow its data from the empirical sciences. Kant not only follows and generalizes this

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method but also provides a metaphysical basis for the necessity of it through his conception of real as opposed to logical possibility. Moreover, Kant’s reversal of the Wolffan method does not commit him—any more than it would Bacon, Newton, or Euler—to an outright rejection of the synthetic method. Instead, it commits him only to denying that the synthetic method can be used to provide metaphysical propositions with more certainty than is contained in the original data from which they are drawn.

Notes 1 Kant, Inq, 2:275. 2 See, e.g., Leibniz (1996: 49, 80). 3 See Wolff, PPO § 55; cf. GM § 391. Christian August Crusius, following Adolph Friedrich Hoffmann, criticized Wolff both for failing to give experience a suffciently robust role in the production of knowledge and for not recognizing the necessity of material principles (see Weg §§ 259–60). 4 Anderson (2015: 156). 5 De Vleeschauwer (1962: 35); see Kant, UD, 2:290. 6 De Vleeschauwer (1962: 36); cf. Clewis (2014). 7 Friedman (1992: 24, n.39). 8 However, as we will see below, Kant provides far more examples of data that consist in nothing more than propositions drawn from various empirical sciences. Moreover, even when he speaks of mathematical propositions as ‘data’ he seems to refer to propositions applied to empirically given space rather than truths available to us in a purely internal or intellectual way. 9 On this basis, it would perhaps be better to avoid the terms ‘empiricism’ and ‘rationalism’ altogether in discussing Kant’s Prize Essay. Unfortunately, however, this is the framework within which the scholarly debate has evolved, and so such terms cannot be avoided. One goal of this section is to redraw the distinction more accurately by reference to the writings of the two fgures at the heart of the brand of ‘empiricism’ to which Kant ascribes in the Prize Essay. It should be noted that in the following, I use the term ‘empiricism’ as it has been used by commentators when discussing the Prize Essay, i.e. in reference to the British experimental tradition of Bacon and Newton rather than to Locke and those infuenced by him. 10 Bacon (2000: 16). 11 Of course, the negative work of philosophy still concerns the examination of the deceptions of both sense and intellect. 12 Newton (1953: 178–79). 13 Newton (1953: 179). Brucker too notes that Newton makes use of a “double method,” combining both analysis and synthesis, just as Bacon had done (1742–1744: vol. 4.2, 641). 14 Kant, Announcement, 2:308. 15 Bacon (2000: 16). 16 See Knutzen (1747: § 287); cf. also Wolff, GL, ch. 5, § 1 and Crusius, Weg § 461. 17 Euler (1967: 117). 18 Of course, Kant is also just echoing Leonhard Euler, whom he explicitly mentions in this context (NM, 2:168). See Euler (1967: 1–4).

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Bibliography Primary Sources Bacon, Francis (1860), The Dignity and Advancement of Learning (De dignitate et augmentis scientiarum), in The Works of Francis Bacon, vol. 4, ed. by J. Spedding, R.L. Ellis and D. Denon Heath, London: Longman, 275–498; repr. Stuttgart-Bad Cannstatt: Frommann Holzboog 1986 (AS). ——— (2000), The New Organon, ed. by L. Jardine and M. Silverthorne, Cambridge: Cambridge University Press. Brucker, Johann Jakob (1742–1744), Historia critica philosophiae, 5 vols., Leipzig: Breitkopf. Crusius, Christian August (1965), Weg zur Gewissheit und Zuverlässigkeit der menschlichen Erkenntnis, in Die philosophische Werke, vol. 3, Hildesheim: Olms (Weg). Euler, Leonhard (1967), ‘Refections on Space and Time’, in A. Koslow (ed.), The Changeless Order, New York: George Braziller, 115–25. Formey, Jean H. S. (1760), Abrégé de l’histoire de la philosophie, Amsterdam: Schneider. Kant, Immanuel (1992a), The Only Possible Argument in Support of a Demonstration of the Existence of God, in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press, 107–201 (OPA). ——— (1992b), Attempt to Introduce the Concept of Negative Magnitudes into Philosophy in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press, 203–41 (NM). ——— (1992c), Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality, in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press, 243–75 (Inq). ——— (1992d), Dreams of a Spirit-Seer Elucidated by Dreams of Metaphysics, in Theoretical Philosophy, 1755–1770, transl. and ed. by D. Walford and R. Meerbote, Cambridge: Cambridge University Press, 301–59 (Dreams). Knutzen, Martin (1747), Elementa philosophiae rationalis seu logicae, Königsberg/Leipzig: Hartung; repr. Hildesheim: Olms 1991. Leibniz, G. W. (1996), New Essays on Human Understanding, transl. and ed. by P. Remnant and J. Bennett, Cambridge: Cambridge University Press. Newton, Isaac (1953), ‘Questions from the “Optics”’, in Newton’s Philosophy of Nature: Selections from His Writings, ed. by H.S. Thayer, London/New York: Hafner Press, 135–80. ——— (1999), The Principia: Mathematical Principles of Natural Philosophy, transl. by I.B. Cohen and A. Whitman, Berkeley: University of California Press (PM). Wolff, Christian (1713), Vernünfftige Gedancken von den Kräfften des menschlichen Verstandes, Halle: Renger (GL). ——— (1720), Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt, Halle: Renger (GM). ——— (1729), Philosophia prima sive Ontologia, Frankfurt/Leipzig: Renger (PPO).

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——— (1732), Psychologia empirica, Frankfurt/Leipzig: Renger (PE). ——— (1735), Philosophia rationalis sive Logica, 3th edn., Verona: Ramanzini. ——— (1963), Preliminary Discourse on Philosophy in General, transl. by R.J. Blackwell, Indianapolis/New York: Bobbs-Merrill (DP).

Secondary Sources Anderson, Lanier R. (2015), The Poverty of Conceptual Truth, Oxford: Oxford University Press. Clewis, Robert (2014), ‘Kant’s Empiricist Rationalism in the Mid-1760s’, Eighteenth-Century Thought, 5, 179–225. De Vleeschauwer, Herman J. (1962), The Development of Kantian Thought, London: Thomas Nelson and Sons. Enfeld, William (2001), The History of Philosophy. From the Earliest Periods: Drawn up from Brucker’s “Historia critica philosophiae”, intr. by Knud Haakonssen, 2 vols. (reprint of the 1837 edn.), Bristol: Thoemmes Press. Friedman, Michael (1992), Kant and the Exact Sciences, Cambridge/London: Harvard University Press. Fugate, Courtney (2014), ‘“With a Philosophical Eye”: The Role of Mathematical Beauty in Kant’s Intellectual Development’, Canadian Journal of Philosophy, 44, 759–88. Menzel, Alfred (1911), Die Stellung der Mathematik in Kants vorkritischer Philosophie, Halle: Hofbuchdruckerei C. A. Kaemmerer & Co. Schönfeld, Martin (2000), The Philosophy of the Young Kant, Oxford: Oxford University Press. Tonelli, Giorgio (1959a), Elementi metodologici e metafsici in Kant dal 1745 al 1768, Turin: Edizioni di Filosofa. Vanzo, Alberto (2013), ‘Kant on Empiricism and Rationalism’, History of Philosophy Quarterly, 30, 53–74.

12 Tetens on the Nature of Experience Between Empiricism and Rationalism Clinton Tolley and R. Brian Tracz 1 Tetens and the Critical Reception of Empiricism in Germany As recent scholarship has documented,1 the writings of Johann Nikolaus Tetens (1736–1807) served as one of the key channels of transmission of the views of empiricist philosophers such as Locke and Hume to Germany during the period between Leibniz and Kant. Despite the tendency to caricature eighteenth-century German philosophy prior to Kant as predominantly rationalist, there was an unmistakable increase in interest in the empiricists in the 1750s, brought about in no small part by the translation of some of their works into German. Hume’s Enquiry Concerning the Human Understanding was translated by Johann Georg Sulzer in 1755, with the title rendered as Philosophische Versuche über die menschliche Erkenntnis; Locke’s Essay Concerning Human Understanding was translated in 1757 by Heinrich Engelhard Poleyen as Versuch vom menschlichen Verstande. 2 A comparison of these titles with that of Tetens’s own 1777 masterwork, his Philosophische Versuche über die menschliche Natur und ihre Entwickelung (Philosophical Essays on Human Nature and Its Development), suggests that Tetens intended, at the very least, to be in conversation with Locke’s and Hume’s Versuche.3 This intention is confrmed by Tetens’s opening remarks in the Philosophical Essays itself, where he states explicitly that the method he will be pursuing in his work is the “observational [beobachtende] one that Locke pursued with the understanding” (PV I, iii–iv)—albeit by encompassing not just the understanding but also “the active power of willing, the basic character of humanity, freedom, the nature of the soul, and its development” (PV I, iii). With respect to his account of the understanding or power of thinking (Denkkraft) itself, Tetens’s views might seem to tend toward an even more radical empiricism than Locke’s, insofar as this account is not only preceded by an account of sensation (Empfndung) and feeling (Gefühl), but eventuates in the claim that “all ideas and concepts are without exception processed [bearbeitete] representations of sensation” (PV I, 340). Remarks such as these are surely behind the estimation codifed in a later remark by Hegel’s student and biographer Karl Rosenkranz, who in 1840 dubbed Tetens

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“the German Locke.”4 More generally, these remarks have led many readers to attribute to Tetens some version of empiricism, over and against the Leibnizian commitment to concepts or ideas that are in some sense innate, i.e., drawn from a source other than sensation or perception.5 As we will argue below, however, a closer look at Tetens’s account of the ‘processing’ that is involved in concept formation shows that his work bears a much more complicated relation to empiricism than is commonly acknowledged.6 For one thing, in the Essays itself, as well as in his earlier 1775 essay Über die allgemeine speculativische Philosophie (On Universal Speculative Philosophy), Tetens in fact shows himself to be quite sympathetic to specifcally Leibnizian arguments concerning the impossibility of accounting for the origin of all of our concepts on the basis of sensation alone. Perhaps most importantly, he endorses Leibniz’s claim that concepts such as substance and cause must have a non-empirical origin.7 What is more, Tetens goes beyond what he takes to be found in Locke and Hume’s accounts by rigorously differentiating between the mere having of a sensation in the mind and what must be involved over and above sensation for a mental state to merit the name of experience (Erfahrung). Finally, Tetens takes an even more decidedly non-empiricist line on the source of our cognition by arguing—in a way that echoes Leibniz’s own criticisms in the Preface to the Nouveaux Essais—that neither sensations nor even experiences suffce to account for our knowledge of universal and necessary principles and the laws treated in philosophy and psychology in particular.8 While the foregoing remarks indicate obstacles to any simplistic characterization of Tetens as an empiricist, they also help clarify which exact elements of Locke’s approach Tetens nevertheless meant to endorse. As we will also show below, Tetens’s criticism of the ‘mathematical’ methodology of the Leibnizians makes clear that he fnds an important virtue in Locke’s contrasting ‘developmental’ or ‘synthetic’ approach to the understanding and its cognitions. Tetens thinks that only a version of Locke’s method might be able to address Hume’s rightful challenge concerning the alleged objective validity of the concepts and principles presented within ontology or metaphysica generalis as well as within metaphysica specialis, psychology included. Tetens’s own positive proposal in his Essays is to make use of a broadly Lockean method to demonstrate concretely and directly, by means of ‘observation,’ how actual mental phenomena emerge developmentally in relation to sensation and grow into experiences in a way that is coordinate with the system of concepts and principles presented only abstractly in the Leibnizian textbooks on psychology. Thus, Tetens aims to move philosophy forward by complementing the Lockean observational method with that of Leibnizian systematization, albeit that the technical terminology he uses to describe the different stages of the mind’s development is drawn almost entirely from the Leibnizians rather than the empiricists.

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2 From ‘Experience’ to ‘Erfahrung’: The Reception of British Empiricism in Post-Leibnizian German Philosophy As was noted above, Tetens’s mature philosophy—as represented in the 1777 Essays, along with his programmatic essay of 1775—came to fruition during the reception of British empiricism in Germany, which was facilitated by the publications of German translations of Hume (1755) and Locke (1757) as well as by the frst (posthumous) publication of Leibniz’s Nouveaux Essais (1765). One key step in assessing Tetens’s relation to British empiricism and what he himself means by ‘experience,’ then, consists in becoming familiar with the German psychological terminology that was used to convey these positions to the new audience. In the 1757 translation of Locke’s An Essay Concerning Human Understanding, for example, the claim that experience is that in which “our knowledge is founded” and “from which it derives itself” (II.i.2) is rendered by Poleyen as the claim that Erfahrung is that in which “our Erkenntnis is grounded (gründet) and originates (ihren Ursprung nimmt).”9 When Locke then splits experience itself into two “fountains,” according to whether our observation is “employed either about external sensible objects, or about the internal operations of the mind, perceived and refected on by ourselves” (II.i.2), the translation has it that our Beobachtung is occupied with either “outer objects” or with “inner effects of our soul that we empfnden and überdenken.”10 What Locke calls ‘sensation,’ that is, the outer source of ideas, is rendered as sinnliche Empfndung, whereas the term ‘refection,’ which denotes the inner source of ideas, is rendered as Überdenken.11 The term ‘idea,’ which denotes that which these two sources supply to the mind, or what our mind has before itself when it is conscious (bewußt) and when it thinks (denkt), is rendered as Begriff (concept).12 In the 1755 translation of Hume’s Enquiry, we fnd a largely parallel usage, along with a few further terms worth fagging that concern Hume’s analysis of the origin of ideas. Hume’s claim that thoughts or ideas and impressions are two classes or species of perceptions is rendered by Sulzer as the claim that Gedanken or Begriffe (concepts) and Eindrücke (impressions) are two classes or species of “Empfndungen in der Seele.”13 Begriffe are then designated as those Empfndungen that “we are conscious of when we refect [nachdenken] on impressions [Eindrücke].”14 Begriffe are also said to arise when the “capacities of the mind mimic [nachäffen] or copy [abcopiren]” previously had sensations.15 Hume’s claim about the origin of our ideas in copies of impressions thus becomes the claim that “all of our concepts or more feeble sensations [Empfndungen] are outlines [Abrisse] of our impressions [Eindrücke] or lively sensations [Empfndungen].”16 Capacities that are capable of bringing about these copies include memory (Gedächtnis)

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and the power of imagination (Einbildungskraft); the capacity for engaging with Begriffe and Gedanken themselves is again that of Denken (thinking).17 Given our purposes, two points concerning these translation choices are especially worth highlighting. First, we fnd that the term Empfndung is used to track the elementary stage of what initially arises in the mind or the soul due to impressions upon it, which is to say that the term covers over the distinction between the English terms ‘sensation’ and ‘perception.’ By contrast, the term Begriff is used to track the contents of thinking, or what arises in consciousness through refection or the act of thinking over something. Second, we fnd a fairly capacious use of the term Erfahrung. In line with the broad use of the term ‘experience’ by Locke and Hume, it denotes not only mere Empfndung but also acts of Beobachtung and Nachdenken or Überdenken. As we will see in the following section, Tetens’s Essays go beyond both Locke and Hume on both fronts: he not only more sharply delineates the different stages involved in the transition from mere sensation to thought but also more sharply differentiates mere sensation from what merits the name of experience—not least by considering only the latter to involve acts of thinking and, more specifcally, acts of refection and representation through concepts. Before turning to Tetens’s own analysis, however, we should attend to the exposition of the term experientia in several Latin texts that Tetens would have been familiar with from the Leibnizian tradition in early modern German philosophy, for many of the conceptual and terminological distinctions that Tetens himself draws upon, in departing from the simplistic empiricism he attributed to Locke, Hume, and some of the French psychologists, are already present in the writings on empirical psychology by Christian Wolff and Alexander Baumgarten. In Wolff’s 1732 Psychologia empirica, for example, we fnd a sharp distinction, frst, between mere perceptio, as one of the initial “acts of mind which represent” some object (PE § 24), and apperceptio, which is said to consist in the mind’s being conscious (conscia) of a perception.18 According to Wolff, all thought (cogitatio) “involves both perception and apperception” (PE § 26). Sensations (sensationes), by contrast, are cases of mere perception (PE § 65). Experiencing (experiundo) goes farther than thinking, insofar as it involves not only being conscious of things or “attending to that which we perceive” but also having cognition (cognitio) (PE §§ 434–35).19 Cognition itself is achieved when we are not only “attending to our thoughts,” and not only “noticing in what way some object is represented” in a perception, but also noticing “what sort of a change [mutatio] occurs in the soul” (PE § 28)—seemingly, a change due to the object which the perception represents. 20 Baumgarten adopts this set of Latin terms and coordinates them with German terms in footnotes in his textbooks on logic and metaphysics. In

258 Clinton Tolley and R. Brian Tracz his 1761 Acroasis logica, he translates cognitio as Erkenntnis (AL § 3). Using Erfahrung as the German correlate for experientia, he defnes “experience in the broad sense” as “clear cognition by sensations [clara cognitio per sensationem].” By contrast, “experience in the strict sense” is defned as “cognition by immediately acquired sensations” (AL § 163). In the ffth edition of Baumgarten’s Metaphysica (1763), we learn that sensation—rendered as Empfndung—is the mere “representation of my present state” (M § 534).21 It is contrasted with experience (experientia, Erfahrung), which consists of “clear cognition through sense” (M § 544). Here, the adjective ‘clear’ signals that consciousness accompanies the relevant representations in the form of “attention” (cf. M § 529). 22 In both the Metaphysica and the Acroasis logica, the term ‘perceptio’ is translated as ‘representation’ (Vorstellung). An apperceived perception (perceptio appercepta), by contrast, is called a thought (cogitatio, Gedanke) (cf. AL § 15). A constituent of a thought is not a mere representation but a concept (conceptus, Begriff) (AL §§ 16–17).23 Hence, insofar as experience itself involves apperceiving perceptions (sensations), it too will involve thoughts and concepts.

3 Tetens on the ‘Development’ of Experience from Sensation With this historical context in mind, we should be less surprised to fnd that Tetens himself couples his positive remarks about the contributions of the empiricists with a clear recognition of the importance of at least supplementing, if not correcting, their accounts with the more subtle analyses emerging from the Leibnizian school. This can be seen already in Tetens’s Preface to On Universal Speculative Philosophy. After applauding the observational method of the British philosophers, Tetens insists upon the need to complement their fndings with what can been learned from the rational (raisonnirende) method of the French (Bonnet, Condillac) and especially from “the geometrical genius of the Leibniz-Wolffans” (ASP 3–4, cf. 18). Tetens goes even further in this direction in the assessment he gives in the concluding section of the essay: As I see it, our Leibniz had a much deeper, sharper, and more correct insight into the nature of human understanding [and] its modes of thought […] than the more diligently observational Locke. He has seen farther than the sharp-sighted Hume, than Reid, Condillac, Beattie, Search, and Home. (ASP 91) As we will see in a moment, this prioritization of Leibniz over Locke and Hume manifests itself concretely in the body of Tetens’s Essays, insofar as Tetens models his core technical terminology not on that of Locke or Hume but on that of the Leibnizian-Wolffan tradition. This point

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has often been overlooked, which is likely due in large part to Tetens’s positive portrayal of Locke right at the start of the Preface. Here Tetens describes the method he means to pursue as nothing other than the “observational method that Locke pursued in relation to the understanding and that our psychologists pursued in the experiential doctrine of the soul [Erfahrungs-Seelenlehre]” (PV I, iii–iv). As Tetens puts it later in the Essays, “the soul is given to us not by hypotheses, but by observations” (PV I, 730). Accordingly, the powers of the human soul “can only be cognized through the effects that they bring about in us” (PV I, 730, cf. 733). Even so, once Tetens goes on in the Preface to elaborate upon the stages he takes to be involved in pursuing such a method, we can already notice the pervasive echoes of the Leibnizian terminology: To take the modifcations of the soul such as they are cognized through self-feeling [Selbstgefühl]; to take with awareness [gewahrnehmen] and observe [beobachten] these repeated modifcations with care and with alteration in circumstances, and notice [bemerken] their way of arising and the laws of effect of the powers that bring them forth; thereafter compare [vergleichen] the observations, analyze them and search out the simplest faculties and species [Arten] of effect and their relations to one another—these are the essential accomplishments of the psychological analysis of the soul, accomplishments which rest upon experiences [Erfahrungen]. (PV I, iv) In effect, Tetens is describing the observation to be performed by the philosopher as a process the stages of which parallel the Leibnizian ordering of the mind’s development of basic cognition that was sketched above. Yet now this observation is directed at the workings of the mind itself: frst, we have sensations of our mind’s activity (‘self-feeling’), then we take up these sensations with ‘awareness,’ after which we come to have ‘cognition’ of the mental activity itself by generating general concepts of the types (or ‘species’) of sensations as well as propositions which express their relations to one another. As we will see in the following section, the end of the Essays further confrms that Tetens applies Leibnizian distinctions to the stages of refective-philosophical cognition of the mind’s own workings. In the early parts, however, Tetens’s text primarily aims to give an account not of refective-philosophical cognition but of ordinary, day-to-day sensory cognition, including the kind that Tetens himself calls ‘experience.’ The fact that Tetens is Leibnizian rather than Lockean or Humean about the nature of experience becomes readily apparent in these early parts of the Essays as well. Tetens here proceeds to articulate a series of stages in the ‘development’ of what happens in the soul on the

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road to experience that parallels quite closely the one identifed by the Leibnizian-Wolffan system sketched above. In broad outlines: frst, Tetens takes up the general idea of a representation (Essay 1). He then focuses specifcally on how representations arise in relation to sensation (Essay 2). This leads to an analysis of what is further required for the consciousness or apperception of representations of sensation—in Tetens’s preferred terms, for becoming aware of them (Essay 3). Only at this point does Tetens introduce the topic of what it means to cognize something objectively on the basis of this awareness (Essay 4). And it is only much later, under the heading of “sensory cognition and the faculty of thinking active within it” (PV I, 426), that he fnally takes up the topic of experience itself. 24 While this account already places Tetens, on the whole, on the side of the Leibnizians, there is at least one point on which he might be thought to take up a more Humean position. This is because Tetens revises the Leibniz-Wolff scheme at its very frst stage by incorporating the distinction between sensation per se (qua mere impression) and its representation (viz., idea). This revision comes in two steps. First, whereas, for Leibniz and Wolff, the term ‘representation’ (as a correlate of perceptio) ranges over “every modifcation of our soul” (PV I, 8), Tetens thinks this usage stretches the term beyond its common signifcance. Accordingly, he restricts the use of the term to “those modifcations in us from which another thing can be immediately cognized by us” (PV I, 11). Even if the Leibnizians are correct in thinking that every single effect in us mirrors or corresponds to something real (namely, its cause), we humans are not immediately in a position to cognize every single thing (cause) that is so mirrored simply because of the presence in us of the relevant effect. 25 Some modifcations in us are nothing for us in the sense of meaning anything for us proto-cognitively but are simply that: modifcations. Second, Tetens insists that the frst genuine representations in us—the frst modifcations in us that mean something for us—are actually representations of other modifcations in us that have already occurred. When such modifcations leave traces (Spuren) in us, our soul is then able to take up these traces, or “drawings” (Zeichnungen) of the previous modifcations, so as to bring about representations of these earlier modifcations (PV I, 16). These “original basic representations” (ursprüngliche Grundvorstellungen) constitute the basis from which all other representations are developed (PV I, 17). More specifcally, Tetens thinks that these “original representations arise in us of our alterations and states, when the latter are presently occurrent in us, and become felt and sensed [gefühlt und empfunden]”; these felt or sensed alterations or modifcations are called ‘sensations’ (PV I, 22). The sensation itself (the modifcation that is sensed) is to be distinguished, however, from the representation which arises due to the sensing of the modifcation. That is, sensations

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themselves are thus not technically the frst original representations; rather, they are what is represented by these frst representations, which are accordingly called “representations of sensation” (Empfndungsvorstellungen) (PV I, 23). However, the capacity for producing representations, which Tetens, in accord with the Leibnizians, also names Perceptionsvermögen (PV I, 26), is not limited to the taking up or apprehending of sensations, 26 as it can also reproduce previous representations (PV I, 24) and “combine representations themselves into new wholes” (PV I, 127). The reproductive power is what Tetens calls ‘the power of imagination’ (Einbildungskraft), whereas the creative, self-active power is called ‘fantasy’ (Fantasie) or ‘fctive power’ (Dichtkraft). 27 Taking the foregoing together, then, we can see Tetens actually signaling a twofold appreciation of Hume’s attempt to take up a question that the Leibnizians seemed to take for granted. First, Tetens agrees with Hume on the necessity of accounting for the origin of representations themselves (that is, of ‘ideas’ understood as Leibnizian perceptiones), insofar as they seem to arise out of more elementary non-representational yet still mental occurrences. Second, Tetens also stands close to Hume in considering the imagination to be involved in the transformation of mere sensations into representations. 28 With this important clarifcation in hand, however, we can see that the remaining structural differentiation in Tetens’s account of the development from sensation to cognition remains quite close to the Leibnizian analysis discussed above. For even though Tetens insists that representation is something over and above mere sensation, he agrees with the Leibnizians that having a representation does not yet suffce for consciousness of this representation, let alone for any sort of cognition. As regards the frst point, Tetens criticizes Bonnet and Condillac for failing to recognize the important difference in kind between, on the one hand, mere sensing and feeling and, on the other, acts of the understanding (Verstand) such as becoming conscious (Bewußtwerden), apperception, and thinking (PV I, 7). It is only once we have consciousness of a representation—or take it up with awareness—that we have what Tetens refers to as an idea (Idee) or thought (Gedanke) (PV I, 26, 96). 29 According to Tetens, moreover, consciousness brings with it a “distinguishing of one image from another.”30 This act of distinguishing gives rise to concepts (Begriffe) (PV I, 135), takes the form of judgments (Urteile) (PV I, 26), and is a prerequisite for the most elementary form of cognizing (erkennen).31 Thus, Tetens agrees with the Leibnizians, against Hume and Locke insofar as their views are transmitted through the German translations, that it is only once all three powers of the soul (sensation, representation, and consciousness) are involved that the soul itself arrives at the threshold of experience (Erfahrung). Whereas Locke and Hume seemed

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willing to let ‘experience’ range over the mere having of a sensation, for Tetens, “the word ‘experience’, as it commonly occurs, is only used for the cognition of things (Erkenntnis der Sachen)” (PV I, 429). For this reason, neither sensation, nor the mere representation of sensation, nor even the conscious judging of representations (of sensations) themselves amounts to experience in the sense of the cognition of things distinct from one’s own mental events. To clarify this point, Tetens introduces the idea of pure experience (reine Erfahrung) (PV I, 429). Pure experience is ‘pure’ in the sense that it is elementary, i.e., does not involve any additional alteration by imagination, fantasy, or any further development through reasoning.32 More specifcally, pure experience is “the action of the power of thinking that judges on the basis of [durch] sensation, or rather, that determines something on the basis of the representation of sensation of the object that is presently there in us [gegenwärtig vorhanden]” and that “holds things to be as they are” rather than “as they appear to be in individual observations” (PV I, 429). It is these pure or elementary experiences—and not mere sensations or even representations of them—that, in turn, “constitute the pure and fxed material [Stoff] of all the cognitions [Kenntnisse] we can have of actual things [wirkliche Dingen]” (PV I, 430, our emphasis).

4 Tetens on ‘Observation’ as a Philosophical Methodology In the previous section, we saw that Tetens, largely drawing on his Wolffan predecessors, envisions a suite of mental activities that develop from sensation, through representation and consciousness, into experience as sensory cognition—thereby rejecting the tendency, present in the translations of Locke’s and Hume’s work, and perhaps in the originals themselves, to take sensation itself to be already a kind of experience. What we now want to turn to, however, is a key difference between Tetens and the Leibnizians as regards their method of presenting these distinctions and, correspondingly, a key continuity that Tetens sees between his own approach and the ‘observational’ method represented by Locke that he repeatedly praises. Tetens’s distance from the Leibnizian-Wolffan approach is of a piece with his post-Humean critique of the so-called mathematical or geometrical method of presentation favored by Wolff and Baumgarten, as can be seen already in his earlier On Universal Speculative Philosophy. With respect to psychology, Tetens thought that Hume had convincingly cast doubt on the idea that this putative science of the human understanding and the cognitions it produces was already anything like a genuinely established science that only required further systematization. For this reason, Tetens thinks that we need to complement, and

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ideally precede, any putative systematic presentation (via “synthetic speculations”) of such psychological concepts with a philosophical presentation of the source of these concepts in psychical realities themselves, according to what he calls “the analytical method” of Locke, Hume, and others (ASP 84-86). The latter procedure would demonstrate, by a kind of ostension within inner “observation,” how more complex kinds of psychical realities developmentally arise out of more elementary ones (ASP 84). 33 As regards its basic ambitions, if not in its ultimate execution, Tetens considered this synthetic method to be modeled not on Wolff or Baumgarten but on Locke’s Essay. In On Universal Speculative Philosophy, Tetens claims explicitly that, in order to provide the “proofs” of the objective validity of elementary concepts and propositions that is rightfully demanded by Hume, one must “go back along the path down which Locke has already traveled, namely, to the investigation of the understanding, its mode of acting, and its universal concepts” (ASP 35). What Tetens thinks has actually been provided by Locke, however, is not really the proofs themselves, but rather “the criteria [Kennzeichen] by which real representations, those that have objects corresponding to them, can be distinguished from what are merely appearances and so merely one-sided representations” (ASP 35). As he puts it later in this essay, Locke “has led the way, with the torch of observation in hand,” to the present project, which consists of “seeking out the sensations out of which the universal notions have been drawn” (ASP 72). Such a method contrasts with that of the textbooks of the Leibnizians, which, at least as Tetens reads them, usually presuppose or ignore the genesis of universal notions. Here again, however, Tetens takes the Locke-Hume model to call for some modifcations. More specifcally, he insists on the need to present the development from sensation to concepts in a way that “distinguishes these concepts more precisely than Locke had done from the effects of our creative power of fction [Dichtkraft]” (ASP 72). And though he notes that Hume had demonstrated the need for more precision on this point in his Enquiry, Tetens thinks that Hume was unable to “overcome the many diffculties that have been found” in Locke’s account (ASP 73; cf. 76).34 Regarding basic ontological concepts like ‘substance’ and ‘causality,’ Tetens agrees with Hume that their content could never be discovered merely by citing various sensations. Against Hume’s attempt to root such content in the workings of the imagination, however, Tetens takes the non-sensory content of these traditional ontological concepts to be supplied by the understanding itself, insofar as its activity consists in the processing (Verarbeitung) of sensations into something else, rather than merely abstracting contents from them (ASP 50).35 Concepts such as ‘actuality’ and ‘substance’ are instances of “the universal which, in separation from everything particular that our fantasy [Phantasie]

264 Clinton Tolley and R. Brian Tracz might make of it, contains nothing that depends on the properties of inner or outer sensations” (ASP 56; our emphasis). It is thus only “the understanding in its purity”—i.e., in its independence from sensation— that is capable of supplying the concepts and principles of ontology (ASP 57). This is because the fundamental science should contain the universal principles according to which we judge and infer about all things in general, about all genera of actual beings, about spirits and bodies, about the immaterial and the material, about the infnite and the fnite. (ASP 51)36 Strikingly, Tetens takes this also to rule out the idea that experience might serve as the source for these concepts. As he puts it in the Essays, “[w]e must frst of all discard the thought that the universal necessary principles are abstractions from experiences.” Whereas “individual examples can make such universal principles intelligible, and illuminate them, […] the insight that they are universal principles does not depend on induction” (PV I, 466) but on “the power of thought’s mode of operating” (PV I, 468–69). Hence, though Tetens agrees with Locke and especially Hume that, in order to clarify the genuine content of our fundamental concepts, we must attend to the way concepts or ideas arise from the way the mind “reworks [umarbeitet] sensations into representations” (ASP 38), he stridently denies that the content of concepts like that of causal connection ultimately depends on any particular sensation, act of imagination, or even experience. On his account, these concepts do not result from abstraction or induction but arise solely from “an inner self-activity of the understanding” (PV I, 320).37 Indeed, Tetens sees this unmooring of the  special contents generated by the understanding from any source in the senses as of a piece with Leibniz’s revision of the Aristotelian rule that “nothing is in the intellect which was not frst in the senses” by the addition of: “except the intellect itself” (cf. PV I, 336–37). Yet though Tetens shares this key commitment to an ultimately non-empirical source of the basic concepts of ontology with Leibniz, he thinks that even the latter failed to adequately justify his presumption of the objective validity of these concepts or suffciently demonstrate their applicability to our observations of the activities of the mind itself. In Tetens’s words, while Leibniz excels in “forming true and real concepts,” he does little to “prove their reality” (ASP 92; our emphasis). Similarly, he writes: When Clarke demanded a proof from him [Leibniz] of his principle of suffcient reason, he answered only that it is an axiom of reason [Axiom der Vernunft] to which no instance can be opposed, but that

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he knew of nothing further that would furnish support for this last assertion. (ASP 92–93)38 What Tetens himself attempts to achieve in his Essays, then, is a twostep project. First, he takes up the prima facie insightful psychological distinctions he fnds in the Leibnizian-Wolffan school and then uses the Lockean developmental procedure to let his readers ‘observe’ for themselves that many of the concepts systematically presented in the Leibnizian metaphysics textbooks do in fact have their origin in the workings of the power of thought itself. Second, Tetens thinks he can use this genetic account to secure that these basic concepts do in fact correspond to some ‘reality’ (cf. ASP 27ff.). What the frst step in the ‘observational’ method presupposes, however, is that the psychological concepts that the Leibnizians make use of to articulate the nature of the soul and its powers—and in particular, the concept of power itself, in relation to the power of thought—are concepts that themselves have objective validity, at least within the reality of the mind. Thus, the primary ‘observations’ from which Tetens starts in the Essays concern the real unfolding of acts of the soul, which thereby have the function of making, e.g., the “nature of representation familiar.” On this basis, Tetens sets forth a “series of propositions from experience [Erfahrungs-Sätze]” that express “immediate observations and immediate consequences of these,” concerning what representations are like (PV I, 12). Though subject to certain deceptions (Blendwerke), this sort of observation is a kind of inner experience, based on “inner sense,” that can be honed and trained through the “repetition of the same observation” in “various circumstances” (PV I, xvii). When welltrained, a subject can distinguish an observation of “what is actually sensation” from a deception due to what is merely “invented” (PV I, xvii). Observation in this sense is Tetens’s name for the elementary access we have to representations merely insofar as they “are in us, in the thinking person.”39 With respect to the specifc mental act of judging, for example, Tetens acknowledges the need for (inner) observation on the part of the philosopher in order to form the very concept of judgment: If a concept of this act of understanding, or of its effect, is to be attained, then it must happen in the same way as those concepts of other accomplishments, alterations, activities, and powers of the soul. The act of thinking and of judging must be felt and sensed in its immediately suffered and persisting effects; and this felt modifcation has its residual sensation [Nachempfndung], and leaves behind its reproducible trace. Here is the representation, and therefore the material of the idea of the thought that, when isolated, perceived, and distinguished, becomes an idea of the relational thought [i.e.,

266 Clinton Tolley and R. Brian Tracz judgment]. […] Therefore, as experience teaches, it is also impossible to furnish someone with a concept of an actual connection of things who has never thought of such a connection beforehand, who has never sensed and reproduced this thought. (PV I, 339) On the one hand, the progression that Tetens telescopes in this paragraph broadly mirrors that of the Leibnizians: he moves from the sensation of a judging, to its representation, and eventually to the concept (‘idea’) of a judgment.40 On the other hand, his basic thesis about psychological concept formation ultimately bears much closer resemblance to a form of empiricism, insofar as he claims that the formation and possession of the real concept of judgment depends on having an inner sensation and, consequently, an inner experience or observation of an actual act of judging itself. Whether or not this seemingly sensation-based account of the origin of our psychological concept of judging can ultimately be made consistent with the earlier idea that refection on the activity of the power of thought itself will demonstrate the non-sensory origin of other ontological concepts, as arising from acts of judging, is something we take up in the concluding section below.

5 Conclusion: Tetens’s Proto-Kantian Synthesis of Empiricism and Rationalism In his attempt to synthesize the position represented by Locke and Hume with the one represented by Leibniz and Wolff, Tetens embraced a turn toward experience in several respects. First, Tetens accepted the importance of the distinction in Leibnizian-Wolffan Latin textbooks between sensation as mere representation or perception and, on the other hand, experience as involving both apperception and cognition. Accordingly, he contributed to the recognition of the complexity and the distinctiveness of experience within German philosophy. Along the same lines, we have seen that Tetens rejected the lack of this distinction in the British empiricists (at least as they were translated), according to which ‘experience’ can range over both mere sensations (impressions) and more complex acts that involve concepts, refection, and so on. Second, Tetens nevertheless sides with empiricism on the necessity to appeal to what can be ‘observed’ in the mind as arising through its own activities in relation to sensations, for only in this way can the validity or ‘reality’ of the fundamental principles and concepts employed in psychology, the science of human nature more generally, and ontology be justifed. To be sure, this alliance is complicated by the fact that Tetens also means to embrace a broadly Leibnizian account of the genesis of the contents of the elementary concepts and principles of ontology, according to which the content of such concepts and principles is, at least in principle, grounded only in the capacity for thinking itself, and not in the senses

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or even experiences. Furthermore, Tetens sides with the Leibnizians in denying that the power of thinking can be reduced to the senses, the power of representation, or, by extension, the power of imagination.41 How, then, are we to understand that basic psychological concepts, on the one hand, are acquired only through inner sensation and have objective validity only insofar as they can be applied in inner observation, but, on the other hand, do not depend for their content on sensation and experience but only on the power of thinking itself? At this point, of course, we have reached one of the central diffculties that is taken up in earnest a few years later in Kant’s frst Critique, namely, the claim that whereas all cognition might “begin with” experience, not all cognition ultimately “arises from” experience, as Kant puts it in the tantalizing frst sentence of the second edition (B1). In fact, a closer look at Kant’s own analysis of experience illuminates Tetens’s earlier attempted synthesis of Locke and Leibniz in several respects. Lewis White Beck has famously suggested that, in this frst sentence, Kant works with two conceptions of experience—one ‘Lockean’ (L-experience) and one ‘Kantian’ (K-experience): while L-experience is merely the “raw material of sensible impressions,” K-experience is “knowledge of objects” or whatever “coincide[s] with the phenomenally real.”42 We hold, by contrast, that experience for Kant has a quite uniform meaning, one that, in fact, mirrors fairly closely Tetens’s own account in the Essays. For Kant, too, experience is never a mere state of sensation but always involves a number of psychological components supplied by the understanding. What is more, for Kant experience always comes about in a number of stages very much akin to the ones distinguished in Tetens’s Leibnizian-inspired account: beyond (i) mere sensation, experience presupposes (ii) representation and imagination, (iii) consciousness, apperception, and perception, and ultimately (iv) concepts and cognition.43 Collectively, these different powers are responsible for “processing [verarbeiten] the raw material of sensible impressions” into experience—the frst (albeit cumulative) result of the “activity of our understanding” being “set into motion,” and the frst instance of cognition that we attain (B1).44 To be sure, Kant’s own solution to the problem as to how the insights of the Lockeans and the Leibnizians could be synthesized so as to make room for non-empirical cognition introduces further distinctions, ones that might only have been darkly glimpsed by Tetens, if he touched upon them at all. Most notably, perhaps, Tetens does not single out anything akin to Kant’s pure forms of sensibility or perhaps even more importantly, Kant’s account of pure consciousness (apperception). The latter point is particularly relevant insofar as pure consciousness promises to provide a specifcally non-empirical means by which to apprehend the activity of the power of thinking itself (B157) as well as the concepts that have this power as their “birthplace” (B90). Nevertheless, even the

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aforementioned points of overlap already testify to the signifcance of the fact that, as Johann Georg Hamann wrote to Herder in 1779, Kant had Tetens’s Essays open on his desk continuously during the fnal years of preparing of the Critique.45

Notes 1 See Stiening and Thiel (2014) for an overview; cf. Beck (1969), Kuehn (1985, 1989). 2 In 1756 Lessing also published a translation of Hutcheson’s System of Moral Philosophy (cf. Stiening and Thiel 2014: 14). 3 All translations of Tetens’s works are our own. The Versuche are cited by pagination to the frst volume, except for a few quotations from the second volume which are marked as ‘PV II.’ 4 See Thiel (2018: 61); cf. Beck (1969: 412). 5 Cf. Beck (1969: 412–25) and Allison (2015: 143–63). 6 For some helpful, if very brief, remarks on the reasons for resisting the common classifcation of Tetens as an empiricist, see Stiening and Thiel (2014: 21). 7 Indeed, as we will show below, Tetens actively took up Leibniz’s own then-recently published (1765) critical engagement with Locke’s views on the origins of concepts in the Nouveaux Essais. In fact, shortly after Tetens’s Essays, a German translation of the frst two books of Leibniz’s Essais was published in 1778 by Johann Ulrich under the title Neue Versuche über den menschlichen Verstand. 8 See Tetens, PV I, 466 and Section 4 below. 9 Poleyen (1757: 77). 10 Poleyen (1757: 77). 11 Poleyen (1757: 77–78). 12 Poleyen (1757: 76). 13 Sulzer (1755: 30). In fact, Sulzer uses Empfndung indifferently to render both ‘perception’ and ‘sensation.’ 14 Sulzer (1755: 30). 15 Sulzer (1755: 28). 16 Sulzer (1755: 32). 17 Sulzer (1755: 29–32). 18 Wolff, PE § 25. Wolff notes his debt to Leibniz’s terminology in this regard. 19 As Wolff puts it in his Latin Logic: “to experience [experiri] is to cognize something by attending to our perceptions [quicquid ad perceptiones nostras attenti cognoscimus]; that cognition itself which is given only through attention to our perceptions is called experience [experientia]” (LL § 664). 20 Once the perception is determined for thought, by the intellect, as to the “singular thing” that is responsible for bringing it about, it is called an ‘idea.’ Ideas are themselves eventually seen to “contain images and notions of what is universal in things” (LL § 52). For Wolff, then, cognition ranges over both the determination of the singular thing responsible for the perception qua change in the soul (the acquisition of an idea) and the determination of what is universal in the thing (the acquisition of a notion). 21 Baumgarten began adding German glosses on the Latin terms already in the 4th edition from 1757; we have chosen the 5th edition of 1763 to show the continuity with his near-contemporary Acroasis logica.

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22 Refection [refexio, Überlegung] is classifed by Baumgarten as a specifc form of attention (M § 626). 23 This, in turn, is consonant with Georg Meier’s complete German translation of Baumgarten’s Metaphysica (1766) and his earlier short text on logic entitled Auszug aus der Vernunftlehre (1752). 24 Tetens, Essay 6; cf. PV I, 429ff. 25 Tetens provides evidence from Wolff’s Psychologia rationalis (PR § 195) for the claim that Wolff implicitly concedes this very point, as the latter here introduces a further differentiation among representations, such that only those which “are related to their objects without requiring an intermediary inference” count as “immediately representing” objects, whereas others require “reasoning” to do so (cf. PV I, 10–11). 26 Tetens calls this power the facultas percipiendi (cf. PV I, 26) and considers it merely to consist in an initial ‘“taking up” (per-cipere) that does not imply any involvement of consciousness. We note this here to begin to head off a potential terminological confusion (see, e.g., Beck 1969: 422), given the now common practice of using ‘perception’ to translate Wahrnehmung (e.g., in the Cambridge edition of Kant’s works). For both Tetens and Kant, however, the latter term refers to the distinct act of “taking up with awareness” (Gewahrnehmen), and so is something which does involve consciousness. On this, see Tolley (2016). 27 Tetens, PV I, 24, 115, 154–61. 28 Some of Tetens’s attention to the level of mere impressions, prior even to representations (perceptio), is surely also motivated by his reading of the protophysiological psychology developed by Bonnet, an author who receives by far the most of Tetens’s attention in the Preface to the Essays. 29 Tetens considers this step to involve apperception (PV I, 97–98). His position implies that, along with Leibniz and others, Tetens accepts that there are representations (including sensations) in us “without consciousness” of them (PV I, 265). This lack of consciousness can obtain even of certain higher or more complicated acts of the imagination. 30 Tetens, PV I, 96, cf. 26, 273. 31 Tetens, PV I, 97–98, 295, 298. 32 To prevent misunderstanding: for Tetens, an experience is ‘pure’ not in Kant’s sense, i.e., devoid of sensation (cf. B74), but rather in the sense of being unmixed with any higher acts of the soul. For this reason, perhaps ‘mere experience’ would be a better rendering. 33 Compare Kant’s later remarks in the Prolegomena about the synthetic method of the frst Critique, according to which the science carried out in this work “places before the eyes [vor Augen stelle] all of its articulations, as the structure of the elements [Gliederbau] of a quite peculiar faculty of cognition, in their natural connection” (4:263). 34 Later on, Tetens adds Lambert to the list of those who failed to successfully demonstrate, in response to Hume, that the relevant concepts aren’t ultimately just “confused semblances of understanding [Verstandesscheine]” (ASP 83–84). 35 In fact, Tetens takes this intellectual content to be equally present in dreams as in “true thoughts,” due to how “the power of thought processes sensations into representations of objects” (ASP 50). Compare Essay 4 for Tetens’s rejection of Hume’s claim that concepts such as cause and effect arise merely through “connection […] in the association of the power of imagination” (PV I, 312–16).

270 Clinton Tolley and R. Brian Tracz 36 As Tetens understands it, what had gone under the name of ontology is actually the science of the most generic commonalities, which are represented through what Tetens calls “transcendent” concepts. Because these concepts are meant to be absolutely generic, ontology is not a theory about particular things or subsets of things but is rather “a general theory that in itself has no actual thing as an object.” In this respect, it is like the “analysis of the mathematician” (ASP 18, cf. 39–40). 37 This partially anticipates Kant’s later strategy in the so-called metaphysical deduction of the categories from acts of judgment by the understanding; on this, see Beck (1969: 420). 38 This sensitivity to the need for ‘proof’ of the ‘reality’ of ontological concepts partially anticipates Kant’s transcendental deduction of the objective validity of the pure concepts of the understanding. See De Vleeschauwer (1934) and Allison (2015: 145). 39 Since, on Tetens’s account, we can immediately become conscious of representations and learn to compare and distinguish them, observation does not rest on scientifc investigations of, e.g., our “nerve fbers,” which might also pertain to representations (PV I, 19). 40 Much later in the second volume of the Essays (Essay 13), we fnd further confrmation of the view that Tetens considers this higher-level or refective cognition on the part of the philosopher to itself take place according to a series that parallels that of ordinary experience. Here Tetens describes this refective process in a bit more detail. In general, he writes, “we cognize our sensing, our representing, our thinking, willing, and so on, insofar as we ourselves make ideas of these operations and compare and distinguish them by means of these ideas in the same way that we do so with the ideas of the effects and powers of physical things” (PV II, 152). The frst step in forming these ideas is for us to have “elementary modifcations” that our soul effects upon itself by its own acts; we then sense (empfnden) these modifcations by means of what Tetens calls ‘self-feeling’ (Selbst-Gefühl) (PV II, 154). As was seen above, it is only when suffciently “persisting traces” are left by sensations of these acts that we “take up representations of our soul’s accomplishments” from them (PV II, 154). In turn, these representations serve as the basis for the comparison, abstraction, and generalization by means of which we form concepts (Ideen) of these very same acts—and are thereby able to cognize them (PV II, 152). Strikingly, Tetens here draws the proto-Kantian inference that, just as in the case of outer cognition of bodies, so too our cognition of the soul’s acts is always mediated by sensations and representations of such acts, such that “our representations of the soul and its alterations […] are merely appearances [Scheine]” or “phenomena before us,” rather than identical with the acts themselves (PV II, 152). 41 Caimi (2008: 49) claims that Tetens “considered that understanding and imagination are identical or, at least […] can be transformed into the other,” and he sees this as an anticipation of Kant. This position seems hard to square with Tetens’s rejection (noted above) of Bonnet and Condillac’s commitment to just this kind of continuity. Moreover, we think that it misrepresents Kant’s own view on the relation of the imagination and the understanding (compare Tolley 2019). The centrality of images and the imagination to Kant’s account of perception is convincingly outlined in Matherne (2015); see Tracz (2020) for an account of the distinctive contribution to cognition made by images in Kant’s theory of representation. 42 See Beck (1978: 40–41).

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43 These parallels are perhaps most pronounced at the outset of Kant’s 1781 account of the transcendental deduction, i.e., in his identifcation of “sense, imagination, and apperception” as the “sources (capacities or faculties of the soul), which contain the conditions of the possibility of all experience” (A94). Experience itself is highlighted in the 1787 edition as that with which “all our cognition begins” (B1). For a complementary description of the progression from sense to cognition, compare A320f/B376f, and for an analysis of the place of this progression within Kant’s transcendental psychology, see Tolley (2017); see Watkins and Willaschek (2016) for additional discussion of Kant’s account of cognition itself. 44 As we see it, this is the sense in which Kant claims that cognition “begins with” experience: it is the frst instance of cognition in the developmental processing of the mind, not something that occurs prior to cognition. This interpretation also speaks against a neo-Kantian line of interpretation, according to which experience in Kant’s work is a far more epistemically demanding mental state, one that is roughly equivalent to the knowledge of nature provided in an ideal science, with there being ‘one’ complete experience in which all veridical perceptions are connected together according to empirical laws. For instance, Nick Stang claims that in Kant’s technical notion of the term, which he labels ‘Strong Experience,’ experience means “something stronger than just any perceptual episode with objective purport” (2012: 1130). See also Friedman (2001). According to Van Cleve (1999: 47), Kant did not make a consistent technical use of the term ‘experience.’ He proposes that Kant might have used the term ‘experience’ in as many as eight different senses. Beyond the overlap between Kant and Tetens’s conception of experience itself, Kant also can be seen as adopting key elements of Tetens’s methodology of ‘observation’ at several steps in his own system. For example, in his Anthropology, Kant claims that “[t]o observe [beobachten] the various acts of power of representation in myself, when I summon them, is indeed worth refection; it is necessary and useful for logic and metaphysics” (7:133). The Anthropology itself embraces this methodology explicitly, noting that it depends on not just the “consciousness of oneself” but on the “observation of oneself [das Beobachten seiner selbst]” (7:127, 132). 45 Cf. Kuehn (1989: 366).

Bibliography Primary Sources Baumgarten, Alexander Gottlieb (1761), Acroasis logica, Halle: Hemmerde (AL). ——— (2013), Metaphysics, transl. and ed. by C.D. Fugate and J. Hymers, London: Bloomsbury / Metaphysica, Halle: Hemmerde 1739; 5th edn. 1763 (M). Kant, Immanuel (1998), Critique of Pure Reason, transl. and ed. by P. Guyer and A.W. Wood, Cambridge: Cambridge University Press (CPR). ——— (2007) Anthropology from a Pragmatic Point of View (AA 7), in Anthropology, History, and Education, ed. by G. Zöller and R.B. Louden, transl. by R.B. Louden, Cambridge: Cambridge University Press (Anthr). Locke, John (1975), An Essay Concerning Human Understanding, ed. by P.H. Nidditch, Oxford: Clarendon (Essay).

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Poleyen, Heinrich Engelhard (1757), Herrn Johann Lockens Versuch vom menschlichen Verstande, Altenburg: Richter. Sulzer, Johann G. (1755), Philosophische Versuche über die menschliche Erkenntnis von David Hume, Hamburg: Grund und Holle. Tetens, Johann Nicolas (1775), Über die allgemeine speculativische Philosophie, Bützow/Wismar: Berger & Boedner; repr. in Neudrucke seltener philosophischer Werke, vol. 4, ed. by W. Uebele, Berlin: Reuther and Richard, 1913 (ASP). ——— (1777), Philosophische Versuche über die menschliche Natur und ihre Entwickelung, Leipzig: Weidmann (PV). Wolff, Christian (1728), Philosophia rationalis sive Logica, Frankfurt/Leipzig: Renger (LL). ——— (1732), Psychologia empirica, Frankfurt/Leipzig: Renger (PE). ——— (1734), Psychologia rationalis, Frankfurt/Leipzig: Renger (PR). Secondary Sources Allison, Henry (2015), Kant’s Transcendental Deduction, Oxford: Oxford University Press. Ameriks, Karl (1990), ‘Kant, Fichte, and Short Arguments for Idealism’, Archiv für Geschichte der Philosophie, 72/1, 63–85. Beck, Lewis White (1969), Early German Philosophy, Cambridge: Harvard University Press. ——— (1978), ‘Did the Sage of Königsberg have no Dreams?’, Essays on Kant and Hume, New Haven: Yale University Press. Caimi, Mario (2008), ‘Comments on the Conception of Imagination in the Critique of Pure Reason’, in V. Rohden, R. Terra, G. de Almeida, and M. Ruffng (eds.), Akten des X. Internationalen Kant-Kongresses, vol. 1, Berlin: De Gruyter, 39–50. De Vleeschauwer, Herman J. (1934), La déduction transcendantale dans l’œuvre de Kant, vol. 1, Antwerp: De Sikkel. Friedman, Michael (2001), ‘Kant on Science and Experience’, in V. Gerhardt, R.P. Horstmann, and R. Schumacher (eds.), Kant und die Berliner Aufklärung, Akten des IX. Internationalen Kant-Kongresses, Berlin: De Gruyter, 233–45. Kuehn, Manfred (1985), Scottish Common-Sense in Germany: 1768–1800, Queens: McGill University Press. ——— (1989), ‘Hume and Tetens, Hume Studies, 15/2, 365–76. Matherne, Samantha (2015), ‘Images and Kant’s Theory of Perception’, Ergo, 2/29, 737–77. Paton, Herbert J. (1936), Kant’s Metaphysic of Experience, London: George Allen & Unwin. Stang, Nicholas (2012), ‘Kant on Complete Determination and Infnite Judgement’, British Journal for the History of Philosophy, 20/6, 1117–39. Stiening, Gideon and Thiel, Udo (eds.) (2014), Johann Nikolaus Tetens (1736–1807). Philosophie in der Tradition des europäischen Empirismus, Berlin/Boston: De Gruyter. Thiel, Udo (2018), ‘Kant and Tetens on the Unity of the Self’, in C. Dyck and F. Wunderlich (eds.), Kant and his German Contemporaries, vol. 1, Cambridge: Cambridge University Press, 59–75.

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Tolley, Clinton (2016), ‘From “Perception” to Understanding, from Leibniz to Kant’, Estudos Kantianos, 4/2, 71–98. ——— (2017), ‘Kant on the Place of Cognition in the Progression of our Representations’, Synthese, 197, 3215–44. ——— (2019), ‘Kant on the Role of the Imagination (and Images) in the Transition from Intuition to Experience’, in G. Gentry and K. Pollok (eds.), The Imagination in German Idealism and Romanticism, Cambridge: Cambridge University Press, 27–47. Tracz, R. Brian (2020), ‘Imagination and the Distinction between Image and Intuition in Kant’, Ergo, 6/38, 1087–120. Van Cleve, James (1999), Problems from Kant, Oxford: Oxford University Press. Watkins, Eric and Willaschek, Marcus (2016), ‘Kant’s Account of Cognition’, Journal of the History of Philosophy, 55/1, 83–112.

13 Kant’s Inquiries into a New Touchstone for Metaphysical Truths Karin de Boer

1 Introduction Like many of his predecessors and contemporaries, Kant in the decades leading up to the Critique of Pure Reason (1781) struggled with the pressure the scientifc revolution put on German metaphysics. On the one hand, he embraced the scientifc model represented by Newtonian physics, since it provided a means to challenge the assumption on the part of Wolffan metaphysics that things could be known by the intellect alone. In this regard, Kant repeatedly defended the need to rely on indubitable experiences as an antidote to the reliance on defnitions, or the analysis of obscure concepts, of the Wolffans. On the other hand, Kant was not prepared to elevate experience into the absolute touchstone of metaphysics, for this would threaten the very possibility of purely intellectual notions such as that of an immaterial soul, freedom, and morality. Thus, at least from the 1760s onward, Kant faced the challenge of solving the tension between experience in its capacity as touchstone of truth and experience in its capacity as threat to the core assets of metaphysics. At frst sight, the Critique of Pure Reason seems to conceive of experience as a criterion that can be used to reject metaphysics as such. In the Introduction, Kant claims that the work aims at establishing the “touchstone of the worth and worthlessness of all cognitions a priori” (A12/B26). The frst Preface attributes the endless controversies that corrupted metaphysics to its failure to abide by the “touchstone of experience.” When relying on principles the use of which goes beyond all experience, Kant writes, human reason falls into obscurity and contradictions, from which it can indeed surmise that it must somewhere be proceeding on the ground of hidden errors; but it cannot discover them, for the principles on which it is proceeding, since they surpass the bounds of all experience, no longer recognize any touchstone of experience. (Aviii) Yet we should not take these references to experience at face value. They do not imply, at least, that metaphysics could remedy its defects

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by basing itself on empirical fndings. Kant rather argues in the Critique that the synthetic a priori cognitions to which metaphysics aspired are warranted only insofar as they pertain to possible objects of experience. This criterion allows Kant to preserve what he calls “principles of the pure understanding” (A148/B187) and to reject judgments that attribute, for instance, immortality to the soul. While this result is well known, I hope to shed new light on it by considering Kant’s searches for a touchstone that preceded the solution put forward in the Critique. Focusing in particular on the role Kant grants to experience in the Inquiry (1764) and Dreams (1766), my aim in this chapter is to argue that he came to solve the tension sketched above by conceiving of possible experience as the absolute touchstone for synthetic a priori cognitions and, thus, for any metaphysical truth whatsoever. Since Wolff was one of Kant’s most important interlocutors, I begin, in Section 2, by briefy examining Wolff’s understanding of the role experience ought to play in metaphysics. As we will see, the idea that experience ought to function as a touchstone for metaphysical truths can be found in Wolff’s works as well. This fact alone underscores the necessity to approach the Critique of Pure Reason and the debates from which it emerged without relying on the opposition between rationalism and empiricism.1 Sections 3 and 4 discuss Kant’s comments on the role of experience in the Inquiry and Dreams. Turning to the Critique of Pure Reason, Section 5 deals with Kant’s understanding of experience in this work. In Section 6, fnally, I argue that Kant in the Critique moves beyond his earlier attempts by identifying the relationship of synthetic a priori judgments to possible objects of experience as the touchstone by means of which the worthy and worthless elements of metaphysics can be separated once and for all.

2 Wolff on the Role of Inner Experience in Metaphysics In his so-called German Metaphysics, published in 1720, Wolff defnes experience as the “knowledge we obtain when we attend to our sensations and the modifcations of the soul” (GM § 325). 2 Distinguishing between common experiences and experiments, he urges that “we do not mingle experience with the products of our imagination and preconceived opinions and, thus, surreptitiously introduce grounds of cognition that are not grounded in the things” (GM § 326, cf. § 382). Evidently, this rule—which echoes Newton’s injunction to preclude unfounded assumptions—must be observed in experiments carried out on material things. 3 Given the purpose of this chapter, however, I will focus on Wolff’s remarks on the role of experience in psychology, which he considered to be part of metaphysics, and metaphysics as such.

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Wolff’s German Metaphysics consists of a brief introductory chapter, an ontology, empirical psychology, general cosmology, rational psychology, and natural theology. In empirical psychology, he explains, we attend to the modifcations of our own soul in order to produce clear concepts of those features of the soul that can be perceived (GM § 191). From these clear concepts, in turn, a number of truths can be drawn. Such inferred truths can subsequently be confrmed, Wolff writes, by “indubitable (untrügliche) experiences” (GM § 191). While he does not specify what these experiences are, he at the very outset of the German Metaphysics notes, along Cartesian lines, that “we experience irrefutably (unwidersprechlich) that we are conscious of ourselves and other things” and infers from this experience that we exist (GM § 5, cf. § 7).4 Clearly, the type of indubitable experience at stake in this context is inner rather than outer experience. In the context of Wolff’s empirical psychology, inner experience not only provides the metaphysician with the initial concepts to be clarifed but also serves as a means to check whether the results obtained by means of inferences are not contaminated by imagination and preconceived opinions. Indeed, Wolff considers the indubitable experiences that we can obtain by observing the modifcations of our own soul to constitute the “touchstone” of what rational psychology, for its part, teaches about the nature and essence of the soul: [W]hat was said earlier about the soul by drawing on experience is the touchstone (Probier-Stein) of that which is here taught about its nature and essence, as well as the effects grounded therein, but what we treat here is by no means the touchstone of what experience teaches us. (GM § 727, cf. DP § 112) According to this passage, rational psychology cannot dictate what empirical psychology needs to affrm as true, but must comply with the truths that the latter obtains by attending to the modifcations of the soul insofar as they can be perceived. Accordingly, Wolff can be said to conceive of inner experience as a touchstone to be applied to particular claims made in disciplines such as rational psychology. Wolff’s later Discursus praeliminaris (1728) suggests that he took his conception of the asymmetrical relationship between the empirical and rational branches of psychology to hold true of metaphysics as such. On his account, even in the case of frst philosophy, or ontology, the knowledge obtained by the intellect should be wedded to that obtained by observation, which he calls ‘historical’: Even in abstract disciplines such as frst philosophy, the foundational concepts must be derived from experience, which constitutes the ground of historical knowledge. […] Indeed, we should consider

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the marriage between [philosophical and historical] knowledge as something sacred. (DP § 12) While this passage does not entail that all metaphysical judgments can or must be kept in check by inner observation, it is clear that Wolff considered metaphysics as such to rest at least partly on concepts derived from experience. In the case of frst philosophy, the concepts at stake are the ones on which all sciences necessarily rely: It is certainly no small matter to obtain clarity in the frst general concepts, for in this way a light is cast that illuminates us in any knowledge we might obtain, whether we are concerned with the sciences or with human action. As regards these concepts I have done what I could to assume nothing without proof: my every assertion is either grounded on clear experiences (klare Erfahrungen) or demonstrated (erwiesen) by means of solid inferences. (GM, Preface) In order to clarify what it means, for Wolff, to generate ontological concepts by starting from clear experiences, his comments on the concept of space in the German Metaphysics can be used as an example. According to Wolff, we obtain the concept of space by paying attention to ourselves insofar as we are conscious of things as external to ourselves (GM § 45), that is, by focusing on the modifcations of our own mind from this particular angle. The act of representing things as external to ourselves as well as to one another gives rise to “a certain order among them,” and our representation of this order is what we call space. Following Leibniz, Wolff writes that “we must conceive of space as the order of things that exist simultaneously.” He then infers from this concept that there is no space apart from things that fll it (erfüllen), but that we must nevertheless distinguish space from the things contained in it (GM § 46). I take Wolff to hold, in short, that the metaphysician generates the concept of space by observing, from within, the act by means of which the mind conceives of something as spatial and, hence, by clarifying the various elements contained in this conception. This clarifcation constitutes the analytic element of Wolff’s method. 5 From the concept produced in this way, a number of truths can subsequently be inferred and presented in the form of propositions that clarify what we mean by the very concept of space. Evidently, doing so requires that one observe the principle of noncontradiction (GM § 10, cf. § 391). However, neither this principle nor experience reveal why something is the case. In order to understand why something possesses certain characteristics and how it relates to other things, the human mind must draw inferences that rely on the principle of suffcient reason, something which it does in both applied sciences

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such as physics and in purely rational disciplines such as mathematics.6 In the latter case, reason is said to establish the connection between truths independently of experience: If one grasps the connections between things by relating the truths without assuming propositions stemming from experience, then reason is pure (so ist die Vernunft lauter). […] The sciences provide us with suffcient evidence that our reason is not always pure, especially as regards our cognition of nature and ourselves. […] Arithmetic and geometry, as well as algebra, provide examples of pure reason. (GM § 382, cf. § 368) Given his comments on rational psychology, Wolff seems to hold that metaphysics cannot attain the same degree of purity as mathematics and, thus, will always need to take recourse to clear experiences. In any case, Wolff does not suggest that metaphysics can obtain new truths by means of the principle of non-contradiction alone. Perhaps Wolff drew criticisms to this effect—from Crusius and the early Kant, among others—because he especially in his Latin metaphysics gives more weight to the demonstrative method by means of which particular truths are derived from more basic ones rather than to the experiential origin of a number of basic concepts.7 Evidently, moreover, part of Wolff’s own inferences may well be less warranted than he took them to be. Yet I have wanted to stress that Wolff, frst, sought to establish metaphysics as a discipline anchored in a careful analysis of our own thoughts and, second, that he regarded this analysis as a type of experience analogous to outer experience. As I will argue in the next section, Kant’s position during the 1760s was closer to Wolff’s in this regard than appears at frst sight.

3 Kant’s Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality Kant wrote the Inquiry, published in 1764, in response to the question announced by the Prussian Royal Academy in 1761, namely, whether metaphysical truths, in particular those that concern natural theology and morality, are capable of the same degree of certainty as those in geometry. Since the debates among the members of the Academy centered on the tension between the movements represented by Wolff and Newton, everyone knew that the contest was intended to gauge the viability of these movements. Kant presents the text, also called Prize Essay, as “a treatise in which metaphysics is to be shown the true degree of certainty of which it is capable, as well as the path by which this certainty may be attained” (Inq,

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2:275). Insofar as Kant explicitly steps back from frst-order metaphysics so as to investigate its very possibility as a science, the text foreshadows the second-order inquiry carried out in the Critique of Pure Reason (cf. A3–4/B7–8). In line with the question of the Academy, Kant couches many of his methodological refections in a comparison between geometry and philosophy, a theme that recurs in the Critique of Pure Reason as well.8 In what follows I abstract from this much-discussed comparison in order to focus on the role Kant grants to experience in the acquisition of frst-order metaphysical truths.9 As regards this class of truths, Kant proposes at the very outset of the text that metaphysics follow the example of Newton, whose “method transformed the chaos of physical hypotheses into a secure procedure based on experience and geometry” (Inq, 2:275). If metaphysics were to follow in his tracks, he writes, the endless instability of opinions and dogmatic sects (Schulsecten) will be replaced by an immutable rule which will govern the method (Lehrart) and unite refective minds in a single effort. (Inq, 2:275) But what does it actually mean to follow Newton’s example in metaphysics? Since metaphysics does not start out from empirical fndings, Kant’s reference to Newton seems to be intended as an analogy: just like physics, metaphysics ought to preclude vacuous speculations by means of careful observations of what is given. Yet whereas physics proceeds by analyzing empirical fndings, metaphysics must proceed by analyzing given cognitions, that is, the thoughts we have about space, substance, or causality. Thus, Kant writes that in metaphysics “one must proceed analytically throughout, for the business of metaphysics is actually the analysis of confused cognitions.”10 This analysis ought to result in a determinate number of indemonstrable truths, or material principles, that are comparable to mathematical axioms (Inq, 2:281, cf. 295) and cannot be derived from the principle of non-contradiction.11 Kant’s account of these principles is clearly indebted to Crusius’s critique of the Wolffans and corresponding account of material frst principles in his treatise on logic titled Path to the Certainty and Reliability of Human Cognition (Weg zur Gewißheit und Zuverläßigkeit der menschlichen Erkenntnis, 1747), something he explicitly acknowledges.12 However, he seems to depart from Crusius by suggesting that the material principles be ordered in the form of a table. With regard to philosophy in general and metaphysics in particular, Kant envisions a table of the indemonstrable propositions that lie at the foundation of these sciences from beginning to end (durch ihre ganze Strecke). […] The most important business of higher philosophy consists

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Karin de Boer exclusively in seeking out (aufsuchen) these indemonstrable fundamental truths.13

According to Kant, these material principles can be identifed by analyzing the marks that one “primarily and immediately” perceives (wahrnimmt) in whatever object one considers (Inq, 2:281, cf. 2:295). Thus, if one wants to know what space is, one should single out the marks that are “primarily and immediately thought in the concept of space,” such as being a manifold of which the parts are external to one another and possessing three dimensions (Inq, 2:281). Such marks constitute “the frst and most simple thoughts I can have of my object” and “the data (Data) for exactly the same number of indemonstrable propositions” (Inq, 2:281). In this context, the term ‘datum’ clearly refers to a class of thoughts, namely, those thoughts that are ‘given’ to the metaphysician who analyzes a certain concept. Regardless of Kant’s explicit appeal to Newton, his account of the way in which metaphysics ought to establish basic concepts and principles clearly echoes Wolff’s own remarks on the subject in the German Metaphysics and the Discursus discussed above. It is hard to tell whether Kant was aware of the discrepancy between the analytic element of Wolff’s own method and the reputation of later Wolffanism, which is a problem I will not try to solve. Kant’s position in the Inquiry is also similar to Wolff’s as regards the role he assigns to experience in metaphysics. Like Wolff, Kant maintains that we must identify the marks that are necessarily thought in a concept such as space by means of a careful analysis of the latter, and, like Wolff, he conceives of this act as a type of indubitable inner experience. However, Kant in this case as well discusses the issue not by referring to Wolff but by drawing an analogy with the method Newton employed in physics: The true method of metaphysics is basically the same as that introduced by Newton into natural science and which has been of such beneft to it. Newton’s method maintains that one ought, on the basis of indubitable experiences (sichere Erfahrungen), albeit with the help of geometry, to seek out the rules according to which certain (gewisse) phenomena of nature occur. […] Likewise in metaphysics: by means of indubitable inner experience (sichere innere Erfahrung), that is to say, an immediate and self-evident consciousness, seek out those marks that are certainly to be found in the concept of any general property (Beschaffenheit). And even if you are not acquainted with the complete essence of the thing, you can still safely employ those marks to infer a great deal from them about the thing in question. (Inq, 2:286)

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Kant considers the rules of which this method consists to be “quite different from those which have hitherto been followed” in metaphysics. Yet apart from the fact that he is skeptical about the possibility of obtaining proper defnitions of metaphysical concepts, his method seems to be very similar to the type of analysis advocated by Wolff. However, Kant may well have held that Wolff or his followers failed to live up to this methodological principle by either ignoring relevant marks or importing marks into concepts from without. Thus, he writes, in a passage partly quoted above, that the manifold we immediately think in the concept of space should not be mistaken for a manifold of substances, which is to say that the concept of substance should not be imported from without into the concept of space: Before I set out to defne what space is, I clearly see that, since this concept is given to me, I must frst of all, by analysing it, seek out those marks (Merkmale) that are initially and immediately thought in that concept. Doing so, I notice that the many elements that are in space are external to each other, that this manifold is not a manifold of substances, […] that space can only have three dimensions, etc. (Inq, 2:281, translation modifed) Kant’s very sketchy remarks on the method to be employed in metaphysics do not discuss the criterion—or touchstone—by means of which indubitable truths can be distinguished from judgments that surreptitiously infuse metaphysical concepts with marks they do not contain. While Kant does not explicitly address this problem in the Inquiry, his comments in this work on Crusius’s Path to the Certainty and Reliability of Human Cognition, suggests that he was well aware of it. As was mentioned above, Kant in the Inquiry endorses Crusius’s view that metaphysics rests on indubitable material principles that cannot be obtained by means of the principle of non-contradiction. But what about Crusius’s claim, quoted by Kant, that the ontological principle ‘all things must be somewhere and somewhen’ belongs to this class of indubitable principles as well? (Inq, 2:294). Does it follow from our analysis of the concept of a thing that it has spatiotemporal properties? In his treatise on metaphysics, titled Outline of the Necessary Truths of Reason (Entwurf der nothwendigen Vernunft-Wahrheiten, 1745), Crusius’s defends this principle by appealing to the essence of the understanding: If we represent something as existing, then the essence of our understanding requires us […] to think […] that it exists somewhere and at some time, and thus we must also add in thought, beyond the metaphysical essence of the thing, an ubi and quando that belongs to it. For that reason ‘existence’ is the predicate of a thing due

282 Karin de Boer to which it can also be found outside of thought somewhere and at some time. […] It is impossible for us to think something other than this.14 Evidently, affrming Crusius’s principle would amount to either denying the existence of God and the spiritual nature of the soul or steering metaphysics into extremely murky waters. As Kant puts it: [S]trictly speaking, God does not exist in any place, although he is present in all things (allen Dingen gegenwärtig) in all the places in which things exist. (Inq, 2:297) Seen from Kant’s perspective, Crusius infused the notion of space and time into the purely intellectual concept of a thing. Accordingly, he writes that Crusius’s principle—and the alleged type of certainty on which it is based—cannot hold unconditionally: [A] number of the principles adduced by Crusius are open to doubt, and, indeed, to serious doubt. […] [T]he feeling of conviction that we have with respect to these cognitions is merely an avowal (Geständniß), not an argument establishing that they are true.15 Thus, while Kant in the Inquiry and related texts agrees with Crusius that Wolff gave too much weight to the formal principle of noncontradiction, it is clear that he also rejected Crusius’s alternative, namely, the claim that the truth of a judgment depends on the mere feeling that concepts must be connected in a certain way. Possibly, Kant’s refection on the arbitrariness that Crusius’s method invites led him to the conviction that analyzing the content of given concepts along the lines of Wolff suffers from the same defect. Why should we trust that metaphysics can be built on allegedly indubitable experiences gained by observing the acts carried out by the human mind? How can we know for sure we do not infuse our concepts with determinations not originally contained in them?16 If appeals to inner experience cannot be trusted, then neither Wolff nor Crusius can be said to have established a touchstone by means of which true metaphysical judgments can be distinguished from false ones. Moreover, since the method that according to Kant ought to be employed in metaphysics is akin to the analytic element of Wolff’s method, Kant’s criticism of Crusius seems applicable to his own view of the role to be granted to inner experience as well. Admittedly, it is hard to tell whether Kant actually drew this conclusion at the time he was working on the Inquiry. Yet it is clear, at the very least, that the treatise does not yet provide an answer to the question as

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to the touchstone by means of which all metaphysical judgments can be assessed.

4 Dreams of a Spirit-Seer Elucidated by Dreams of Metaphysics In Dreams of a Spirit-Seer, published in 1766, Kant no longer seems to hold that metaphysics can be purged of surreptitious judgments by carefully examining the concepts on which they rely. At frst sight, he in this text resorts to a very different touchstone, namely, experience as understood in the empiricist tradition. Frederick Beiser, for example, considers Dreams to represent “the height of Kant’s growing disaffection with metaphysics” and to use an “empiricist criterion of knowledge” as the main weapon of his “new skepticism.”17 But is this really the case? As was seen above, appealing to experience in an eighteenth-century treatise did not necessarily imply adhering to the methods advocated by Locke, Hume, or Newton. Bypassing Kant’s critique of former metaphysics and his baffing engagement with Swedenborg’s speculations, this section seeks to show that Kant’s remarks on the role of experience in metaphysics do not necessarily qualify his position as empiricist. In accordance with the opening page of the Inquiry, the fnal pages of Dreams distinguish a type of metaphysics concerned with “the hidden properties of things” from a type of metaphysics that passes “judgment on its own activity” (Dreams, 2:369). Thus, Kant here as well distinguishes between the frst-order metaphysics elaborated by his predecessors and a second-order critical investigation into this metaphysics—itself also called metaphysics in this context—that has not yet been properly elaborated.18 Kant clarifes the task of the latter by comparing it to the act of returning a butterfy—i.e., frst-order metaphysics—to “the terrain (Boden) of experience and common sense.”19 This means, he explains, that his projected “science of the limits of human reason” ought to determine the relation between the questions raised in frst-order metaphysics to “the concepts of experience on which our judgments must at all times rely” (Dreams, 2:367–68). To illustrate this point, Kant refers to concepts such as causality, substance, and action. Such concepts, he writes, represent basic relations that allow us to reduce a manifold of appearances to more simple representations (Dreams, 2:370). This reduction is carried out, I take him to imply, by means of judgments. However, metaphysics would be wrong to assume, Kant adds, that one can determine by reason alone how a thing can be the cause of something else. Echoing Hume and Crusius, he maintains that the relationship between cause and effect is not analogous to

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the logical relationship between subject and predicate: whereas we can know a priori that the predicate ‘round’ can be connected with the subject ‘sun,’ we must rely on experience in order to determine that the sun causes the stone to become warm. As Kant puts it: It is impossible for reason ever to understand how something can be a cause, or have a force; such relations can only be derived from experience. For our rule of reason only governs the drawing of comparisons in respect of identity and contradiction. If something is a cause, then something is posited by something else; there is not, however, any connection between the two things here which is based on agreement.20 Evidently, this Humean insight puts limits on metaphysics: it entails, as Kant notes, that judgments “concerning the way in which my soul moves my body, or the way in which the soul is now or may in the future be related to similar beings” are nothing but fctions (Dreams, 2:371). Yet can it be inferred from this critique that Kant, at this stage, adopted an empiricist position? In my opinion, this is true only up to a point. Kant claims indeed that “if the basic concepts of things as causes, of powers and of actions are not derived from experience, then they are wholly arbitrary and admit of neither proof nor refutation.”21 However, this remark concerns the origin of basic concepts rather than the problem of the touchstone discussed above. Leaving the former issue aside, I propose to examine some examples of what Kant in Dreams actually takes to be unjustifed and justifed metaphysical propositions. In the following lines, which seem to target Crusius, Kant indeed appeals to experience as a criterion: Now, suppose that it has been proved that the human soul was a spirit […], the next question to which we might then proceed would perhaps be the following: where is the place of this human soul in the world of bodies? […]. [I]t is easy to see that the question already presupposes something with which we are not acquainted through experience, though it may perhaps be based on imaginary inferences. The question presupposes, namely, that my thinking ‘I’ is in a place which is distinct from the places of the other parts of that body which belongs to my self. But no one is immediately conscious of a particular place in his body; one is only immediately conscious of the space which one occupies relatively to the world around. I would therefore rely on ordinary experience and say, for the time being: where I feel, it is there that I am. (Dreams, 2:324, my emphasis) Kant here denounces the metaphysical judgment “The soul occupies a different space than the body” by appealing to a type of experience

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that any human being is capable of. However, I maintain that Kant uses this weapon only to target inferences that surreptitiously move from experience to that which can only be thought, i.e., that do not heed the difference between the sensible and the intelligible realms. Nothing indicates that Kant wanted to abolish the very idea of the human soul as an immaterial, simple, and indivisible substance, or of immaterial monads as such. As regards these metaphysical ideas, Kant does not appeal to the touchstone of experience but adopts a properly skeptical stance: We may […] accept the possibility of immaterial beings without any fear that we shall be refuted, though there is no hope either of our ever being able to prove their possibility by means of rational argument.22 Kant’s appeal to experience in Dreams is very different from his appeal to inner experience in the Inquiry because the essay deals with experiences any human being is capable of rather than a type of refection carried out by philosophers alone. He must have realized, moreover, that the use of ordinary experience as a touchstone to assess metaphysical claims is limited for at least two reasons. First, as seen, he is not prepared to use it with regard to purely intellectual determinations of things such as the soul and God. Kant was defnitely not prepared to follow Hume in this regard. Second, the touchstone does not seem to be useful with regard to ontological principles such as Crusius’s principle that ‘all things must be somewhere and somewhen.’ In sum, Kant’s call upon metaphysics to return to the “terrain of experience” (Dreams, 2:368) appears to come down to the view, frst, that the discipline should identify basic concepts by starting from experience and, second, that one’s immediate consciousness of one’s own body can be used as a touchstone to preclude judgments about the soul that mix in sensible determinations. As we have seen, if we take Kant to use the term ‘experience’ in a broad sense, the former view can be traced back to Wolff. In fact, Kant in Dreams does not go beyond the use of experience as a touchstone to reject particular metaphysical judgments, which is the use that Wolff recommended as well. Yet this is not the end of the story. I hold that Kant at least from the late 1760s onward breached the Wolffan framework by searching for a touchstone by means of which metaphysics as such could be subjected to a critique. As I see it, the Inaugural Dissertation (1770) represents a crucial moment in Kant’s quest.23 Yet, for reasons of space, the next two sections turn immediately to Kant’s account of experience in the Critique of Pure Reason and the touchstone for metaphysics he introduces and employs in this work.

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5 Kant’s Conception of Experience in the Critique of Pure Reason The Critique of Pure Reason presents its ultimate subject matter—pure reason—as a mode of thought that “contains the principles by means of which something can be known a priori in an absolute sense,” that is to say, in which “no experience or sensation is mixed in at all” (A11, cf. B24–25). On Kant’s account, metaphysics is the discipline that treats these principles in a systematic fashion (A841/B869). The passage just quoted suggests that Kant was not opposed to the idea of purely intellectual principles per se. Rather, in accordance with an idea already put forward in the Inquiry and Dreams, the Critique aims to separate the warranted core of metaphysics, qua purely intellectual discipline, from the unwarranted speculations that had tarnished its reputation. Put differently, Kant here carries out a second-order investigation into the viability of a discipline said to elevate itself “entirely above all instruction from experience, and that through mere concepts” (Bxiv). What is at stake in the Critique, Kant writes, is a critique of the faculty of reason as such, in respect of all the cognitions after which reason might strive independently of all experience, and hence the decision about the possibility or impossibility of a metaphysics as such, and the determination of its sources, as well as its extent and boundaries. (Axii) As was mentioned in the introduction to this chapter, Kant blames the “obscurity and contradictions” perverting metaphysics on its disavowal of the “touchstone of experience” (Aviii, cf. A3/B6). We have seen, however, that Kant from at least the late 1760s onward considered neither the careful observation of one’s own thoughts (Wolff and Crusius) nor ordinary experience (Hume) to constitute ftting touchstones for metaphysics as such. If this is the case, then why does he in the context of the Critique continue to appeal to experience as a touchstone of metaphysical truths? Before addressing this issue, it is necessary to briefy examine Kant’s scattered remarks on the notion of experience in both the Critique and the Prolegomena. Following his Wolffan predecessors, Kant clearly distinguishes between sensation and experience: on his account, sensations are nothing but modifcations undergone by the human mind, whereas experiences are instances of empirical cognition that presuppose the unifying activity carried out by the understanding. 24 In the well-known frst section of the Introduction, Kant writes: Experience is without doubt the frst product that our understanding brings forth as it processes (bearbeitet) the raw material of

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sensible sensations. […] Nevertheless, experience is far from the only feld to which our understanding can be restricted. It tells us, to be sure, what is, but never that it must necessarily be thus and not otherwise. 25 Yet according to the Prolegomena not every empirical judgment counts as an instance of empirical cognition or experience. The latter must not only unify various perceptions but also determine their relationship in a way that lays claim to necessity.26 Kant famously maintains that this is the case in judgments such as ‘the sun warms the stone.’27 Since even empirical cognitions in this sense merely deal with facts, however, they can never lay claim to the absolute necessity and universality that Kant attributes to a priori judgments alone: the heat could after all have been caused by something else. For this reason, he notes in the Critique that experience does not provide us with “true universality” (A1). On Kant’s account, a careful analysis of an empirical judgment like ‘the sun warms the stone’ reveals that it relies on the pure concept of causality and, more generally, that “among our experiences cognitions are mixed in that must have their origin a priori and that perhaps serve only to establish connections among our sensible representations” (A2). According to Kant, only synthetic a priori cognitions such as ‘every event has a cause,’ which function as principles of other cognitions, possess the “true universality and strict necessity” (A2) mentioned above, since the judgment holds true of any possible object of experience. I take Kant to hold that metaphysics, qua frst-order discipline, must isolate these a priori principles and establish the sum total of pure concepts on which they rely. This task is carried out, to some extent, in the Critique of Pure Reason, but was also pursued, one way or another, in the metaphysical tradition that goes back to Aristotle. 28 By contrast, the second-order investigation that is carried out in the Critique alone seeks to determine the limits within which such a priori cognitions can actually be used to determine objects and, hence, the limits within which metaphysics can achieve this aim. A further relevant element of Kant’s account of experience does not come to the fore until the Transcendental Deduction. By making the judgment ‘the sun warms the stone,’ to use the example of the Prolegomena, we implicitly conceive of the content of the judgment as element of an encompassing whole. For Kant, a single empirical judgment cannot lay claim to objectivity unless the sum total of possible empirical judgments is conceived as a unity, which is to say that the latter must be subjected to a single set of a priori principles. Evidently, Kant in this way seeks to account for the unity established in sciences such as Newtonian physics. Deviating from the tradition, Kant proposes to use the term ‘experience’ to denote the sum total of possible empirical judgments presupposed in the natural sciences:

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Karin de Boer There is only one experience, in which all perceptions are represented as in thoroughgoing and lawlike connection. […] If one speaks of different experiences, they are only so many perceptions insofar as they belong to one and the same universal experience. The thoroughgoing and synthetic unity of perceptions is precisely what constitutes the form of experience, and this unity is nothing other than the synthetic unity of the appearances in accordance with concepts. 29

Kant’s idea of experience as an all-encompassing system is relevant not only to his account of the sciences but also to the role he grants to experience in the context of his critique of Wolffan and post-Wolffan metaphysics. Focusing on its 1781 version, the following and fnal section examines the transcendental deduction in this light.

6 Possible Experience as Touchstone Briefy put, the transcendental deduction seeks to determine under which conditions the categories—qua purely intellectual concepts—can be used to produce a priori cognitions of objects (cf. A85/B117). Kant undertakes this task, I have argued elsewhere, in order to determine to what extent the a priori cognitions to which metaphysics aspired are warranted.30 Evidently, it is impossible to do justice to the complexities of the text here. In this section I limit myself to Kant’s effort to identify a touchstone for metaphysical cognitions that involves experience but does not entail the impossibility of metaphysics per se. As we will see, Kant establishes this touchstone by offering a nuanced response to the positions represented by Hume and Wolff. Against Hume, to begin with, Kant defends the very capacity of the human mind to produce a priori cognitions of objects. He does so by maintaining that “the objective validity of the categories […] rests on the fact that through them alone experience is possible (as far as the form of thinking is concerned)” (A93/B126, my emphasis, cf. B5). As I see it, Kant here conceives of experience as the sum total of empirical cognitions presupposed in the sciences. According to him, we cannot account for the objectivity achieved in Newtonian physics, for instance, unless we assume that the human understanding generates a number of a priori principles—based on categories—that determine how our perceptions can be unifed in a law-like manner. Absent such principles, it would be impossible to conceive of empirical cognitions as elements of a thoroughgoing unity of which any human being can conceive as such: [W]ithout that sort of unity, which has its rule a priori, and which subjects the appearances to itself, thoroughgoing and universal, hence necessary unity of consciousness would not be encountered in the manifold perceptions. […] All attempts to derive

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these pure concepts of the understanding from experience and to ascribe to them a merely empirical origin are therefore entirely vain and futile.31 Similarly, Kant concludes the A-Deduction by arguing that the rulebound ways in which the human mind unifes its successive representations “must precede all experience and frst make it possible as far as its form is concerned” (A130). Arguably, Kant in this context uses his account of experience as a weapon to defend the necessity of a priori principles against skeptical attacks rather than as a touchstone (cf. A766–67/B794–95). However, Kant’s analysis of pure concepts in their capacity of rules for the unifcation of successive representations has implications that go beyond his response to Hume’s skepticism regarding the possibility of a priori cognition of objects. Challenging the Wolffans, conversely, Kant draws on this analysis to demonstrate that pure concepts, or categories, are nothing but “a priori conditions for a possible experience, as that alone on which their objective reality can rest” (A95, emphasis mine, cf. A156/B195). If pure concepts are nothing but rules that allow the human mind to unify its successive representations (cf. A121–22) and if, consequently, these concepts can generate a priori cognitions of objects only insofar as they are involved in this unifcation, then they cannot be used to achieve a priori cognitions of quasi-objects such as the soul, the world as such, and God.32 In this regard, Kant sides with Hume against the Wolffans. Seen in this way, Kant’s analysis of the condition under which categories can be employed is intended to determine to what extent their role in the constitution of objects of cognition as such is justifed. The following passage clearly articulates this key element of his argument: The transcendental deduction of all a priori concepts […] has a principle toward which the entire investigation must be directed, namely, that they must be conceived as a priori conditions of the possibility of experience. […] Without this original relation to possible experience, in which all objects of cognition are found, their relation to any object whatsoever (irgendein Objekt) could not be comprehended at all. (A94/B126–27, my emphasis) Similarly, Kant claims in the B-Deduction that categories do not afford us cognition of things […] except through their possible application to empirical intuition. […] [They] consequently have no other use for the cognition of things except insofar as the latter are taken as objects of possible experience. […] The above proposition is of the greatest importance, for it determines

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Karin de Boer the boundaries of the use of the pure concepts of the understanding in regard to objects.33

There can be no doubt, it seems to me, that these and similar passages target the assumption on the part of the Wolffans that the human mind can turn the soul and God into objects of cognition by means of pure reason alone. What emerges from these passages, accordingly, is that Kant’s transcendental deduction is intended to establish ‘possible experience’ as a universal touchstone for metaphysical truths.34 Evidently, to reject speculations about the existence of God or the way in which the soul moves the body, one might as well appeal to the empiricist claim that all valid cognitions must be based on inner or outer sensations. Yet Kant’s touchstone has a great advantage—seen from his perspective—for it can be used to reject any such speculations without thereby undermining the possibility of a priori cognitions of objects per se. Contrary to the touchstone of common experience, this touchstone does not rule out the very enactment of synthetic a priori judgments such as ‘all events have a cause’ as long as this enactment is geared toward possible objects of experience. Moreover, it does not rule out the possibility of a metaphysical discipline devoted to the systematic treatment of the categories and principles that allow the human mind to generate the system of empirical cognitions Kant calls experience. Kant was convinced that the problems afficting the theoretical part of metaphysics could be solved by assessing its synthetic a priori cognitions in view of their bearing on possible objects of experience. However, the Doctrine of Method makes clear he was aware of the peculiarity of his argument. According to the most well-known strand of the Critique, an empirical judgment concerning two colliding billiard balls—strictly speaking, an element of experience—is made possible by the principle of causality and, ultimately, by the category it expresses. Yet we can also turn our attention to the validity of the principle itself. In this regard, the Doctrine of Method states that the proposition ‘everything that happens has its cause’ can be “proved apodictically” only insofar as it is related to “the sole feld of its possible use, i.e., experience.”35 For Kant, the principle of causality is valid because we can demonstrate, in transcendental philosophy, that something does not amount to an object of experience unless it is considered to be causally determined by a preceding event. The same applies to the a priori rules contained in the other categories. Since the validity of the principle of causality depends on its use with regard to “possible experience,” Kant notes that this principle “has the special character of frst making possible the ground of its proof (Beweisgrund), namely experience” (A737/B765). In other words, experience

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rests on the principle of causality, but the validity of the principle of causality depends on its use with regard to experience. While this conclusion suggests the argument is circular, 36 I do not think this is the case: Kant’s point is rather that [1] actual experience rests on a priori principles, whereas [2] the validity of these principles themselves rests on their use with regard to possible experience, that is, with regard to any appearance that the mind can set out to unify. Accordingly, Kant’s argument hinges not on the actuality of experience but simply on the striving of the human mind to unify and objectify the content of its successive representations to the largest possible extent.37 Categories are valid insofar as they are being used for this purpose alone. On this account, Kant conceives of possible experience as a touchstone, not as a ground or starting point, which is to say that his remarks to this effect only make sense in light of his attempt to exclude purported a priori cognitions of the world as such, the soul, and God. Thus, depending on whether one focuses on one element of the argument or the other, the transcendental deduction—and the Transcendental Analytic as such—appears to be devoted either [1] to the conditions of possibility of empirical cognition or [2] to the touchstone for the type of synthetic a priori cognitions at stake in metaphysics. I have argued that, from the late 1760s onward, establishing the latter touchstone was Kant’s main concern.

Conclusion In this chapter I have considered the Critique of Pure Reason in view of Kant’s successive efforts to identify a touchstone by means of which the validity of the synthetic a priori cognitions pursued in metaphysics can be assessed. The touchstone put forward in the Critique consists not in inner experiences allegedly obtained by the metaphysician or in the outer sensations obtained by everyone, but in the requirement that pure concepts be employed to generate objects of experience alone. This new touchstone can be said to move beyond the two classical touchstones available prior to Kant, namely, sensations and the principle of noncontradiction. Seen from Kant’s mature perspective, actual sensations can merely be used to assess the truth of synthetic a posteriori judgment such as ‘the ball is red.’ The principle of non-contradiction, on the other hand, is a suffcient criterion for the validity of analytic judgments but merely a necessary criterion for that of synthetic judgments (cf. A151– 52/B191). The class of judgments that Kant calls ‘synthetic a priori’ calls for a criterion that cannot be established by either logic or metaphysics in the pre-Kantian sense but requires the “as yet little attempted analysis of the faculty of the understanding” (A65/B90) carried out in the Critique of Pure Reason.38

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Notes 1 In line with Engfer (1996), my account does not view Kant’s trajectory through the lens of the historiographical categories of rationalism and empiricism. As Engfer explains, apart from the fact that authors assigned to the two approaches may hold overlapping views on one or more of the elements of cognition, terms such as cognition, experience, and reason can acquire very different meanings depending on the context (14). He also shows that these terms gained traction only after Kant (19–20). Accordingly, I do not share the view of commentators who consider Kant’s Dreams of a Spirit-Seer (1776) to testify to an empiricist phase in his development (see Section 4 of this chapter). 2 The translations of Wolff’s texts are my own. I will disregard Wolff’s later and much more detailed four-volumed Latin Metaphysics. 3 On Wolff’s account of experimentation in physics, see Leduc’s contribution to this volume. 4 On this, see Dyck (2014: 176–79). Apart from Dyck, a number of commentators have challenged the prevailing view of Wolff by emphasizing the role he grants to experience. See Wundt (1924), Arndt (1983), Engfer (1996: 268–83), and Kreimendahl (2007). 5 On this element, see Prunea-Bretonnet (2009: 139–41). 6 Wolff, GM §§ 29–30, cf. §§ 370–72, DP §§ 7–10. Wolff maintains, for example, that the principle of suffcient reason allows us to posit the existence of simple things, since otherwise we could not account for given manifolds (GM § 77). Once we know the reason of things, he writes, we can achieve insight “into the interconnection of truths” and infer unknown truths from those we already know, that is, “invent new truths” (GM § 378). 7 I briefy deal with Crusius’s philosophy and Kant’s assessment of Crusius in Section 3 of this chapter. 8 See Kant, CPR, A712–38/B740–66. 9 Kant also alludes to the role of experience in his own second-order assessment of metaphysics. As regards the method he himself adopts, he writes at the beginning of the Inquiry that “the complete content” of his treatise will be made up of “indubitable judgments of experience (sichere Erfahrungssätze) and inferences that are immediately drawn from the latter” (Inq, 2:275, translation modifed). An analysis of this issue falls outside the scope of this chapter. 10 Kant, Inq, 2:289, cf. 278. A bit later on, Kant seems to mitigate his claim: if metaphysics would achieve the analysis of its concepts, he writes, it could go on to proceed synthetically, namely, by subsuming “compound cognitions under the most simple ones” (Inq, 2:290). 11 Kant, Inq, 2:294. Kant also opposes the Wolffans by claiming that metaphysics need not start from defnitions to attain the sought-for indemonstrable truths: he considers the effort to imitate mathematics in this regard to be misguided as well (Inq, 2:284, cf. 292–93). 12 Kant, Inq, 2:295. Principles Kant himself considers principia materialia indemonstrabilia include “space is three-dimensional” (2:281) and “a body is a composite” (2:295). See Herder’s transcripts of Kant’s lectures from the same period (1762–64), where Kant also endorses Crusius’s view that these material principles must be derived “from the nature of the soul” (28:10). The examples of “real principles” Crusius himself offers in Path to the Certainty and Reliability of Human Cognition include “any power is in a subject” and “any substance is somewhere” (§ 259). On Kant’s relation to

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13 14

15

16 17

18 19 20 21 22 23

24 25

26

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Crusius’s during this formative period, see Kanzian (1993). See Heimsoeth (1926/1956) for a very good overview of Crusius’s logic and metaphysics. Kant, Inq, 2:281, translation modifed. In this regard, the Inquiry clearly bears witness to the birth of Kant’s table of the categories. Crusius, Entwurf § 46, frst emphasis mine, cf. § 54, § 59 and Weg § 53. I follow the translation of the excerpts of Crusius’s Outline in Watkins (2009). Note that Crusius considers his principle to rest on the addition, in thought, of two determinations—space and time—to the concept of existence that are not contained in the concept, but that we allegedly cannot but attribute to the latter. Possibly, Kant’s refections on Crusius’s philosophy during the 1760s fed into his framing of the problem in terms of the possibility of synthetic a priori judgments in the Critique of Pure Reason (cf. A6–10/B10–14). Kant, Inq, 2:295. In Path to the Certainty and Reliability of Human Cognition, Crusius considers the principle according to which “that which cannot be thought otherwise than as true, is true” to be “the highest ground of our cognition” (§ 261). Cf. Wolff, GM § 326, quoted in Section 2 above. Beiser (1992: 45). Similarly, Clewis (2014) asserts that Kant around the time he published Dreams “thought that philosophy should be grounded in empirical propositions” (182). My own reading is in line with Heymans (1889), who also defends the non-empiricist thrust of Kant’s early works and, thus, challenges the view that Kant’s thoughts during the late 1760s testify to inexplicable shifts. Laywine (1993) rightly points out, in my view, that “Kant uses the example of Swedenborg […] to warn metaphysicians against the danger of subjecting immaterial substances to spatio-temporal conditions” (24, cf. 54). I discuss Dreams, and Kant’s response to Wolff and Crusius in this text, in more detail in De Boer (2019). See Kant’s letter to Herz, dated May 11, 1781 (Corr, 10:269). Kant, Inq, 2:368. Kant uses a similar image, of a dove, in the Critique of Pure Reason (A5/B8). 2: 370. See Crusius, Weg § 260. Kant, Dreams, 2:370, cf. 320n, 322. Kant, Dreams, 2:323; cf. LM Herder, 28:114. I argue in De Boer (2020) that the Inaugural Dissertation establishes intellectual purity as a criterion by means of which the validity of any metaphysical judgment can be assessed. I here further defend the claim that Kant does not abandon this criterion in the Critique of Pure Reason but complements it by the requirement that the actual use of synthetic a priori principles necessarily rests on time qua form of intuition and, consequently, is warranted with regard to the realm of experience alone. See Fugate (2014: 120–42) for an illuminating account of Kant’s indebtedness to Wolff and Crusius’s conceptions of experience. Kant, CPR, A1, translation modifed, my emphasis, cf. Bxvii, A124, B147; Prol, 4:299. Contrary to Beck (1978: 40–41), among others, I do not assume that Kant in the 1787 version of this passage initially uses the term ‘experience’ to denote the mere reception of sensible impressions. He might as well have meant that experience qua empirical cognition—itself already the result of a cognitive process—necessarily precedes the efforts of the human mind to produce explicit a priori cognitions. Experience, Kant writes in the Prolegomena, is not to be confused with a merely subjective set of perceptions, but is that which “provides empirical judgments with universal validity” and, thus, rests on “a pure unity of the understanding that precedes a priori” (4:310).

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27 “But if I say: the sun warms the stone, then beyond the perception is added the understanding’s concept of cause, which connects necessarily the concept of sunshine with that of heat, and the synthetic judgment becomes necessarily universally valid, hence objective, and changes from a perception into experience” (Prol, 4:301n). 28 See Kant, CPR, A13–14/B27–28. Kant affrms the proximity of his own account of the categories to Aristotle’s at A81/B107. 29 Kant, CPR, A110, cf. A217/B264. See Stang (2018) for a helpful analysis of the various senses of the term ‘experience’ in the Critique of Pure Reason, including the universal experience Kant considers to be presupposed in any actual scientifc system. 30 The present section draws on Chapter 5 of De Boer (2020). 31 Kant, CPR, A112, cf. A111, B127–28. According to the title of § 22, “[t]he category has no other use for the cognition of things than its application to objects of experience” (B146). 32 This strand of the transcendental deduction is highlighted by Kuehn (1988) and Hatfeld (2003). Evidently, the argument according to which any cognition of objects rests on the conditions required for the unifcation of a series of successive representations does not prevent the human mind from conceiving of the soul, the world as such, and God in a determinate manner. The distinction between thought (involving reason and the understanding) and cognition (involving the understanding and sensibility) allows Kant to secure the ideas of reason as concepts that both allow us to establish the highest possible unity among our sensible cognitions and provide moral guidance. 33 B147–48, my emphasis, cf. B166, B288–89, B294. See also A139/B178, where Kant maintains that pure concepts, in their capacity of “conditions of a possible experience, relate a priori solely to appearances” and, hence, cannot be “extended to objects in themselves.” This is also the thrust of what Kant calls the “highest principle of all synthetic judgments” and, thus, of all synthetic a priori judgments (A158/B197). 34 The scope of this chapter does not allow me to elaborate on the various steps Kant takes in order to support this point, including the view that the mind produces synthetic unity of apperception by objectifying the content of its successive representations in a rule-bound manner (cf. A217/B264). 35 Kant, CPR, A737/B765, cf. A94/B126–27, A217/B264, A259/B314–15, A766/B794, A783/B811. 36 This criticism was put forward by, among others, Maimon and Reinhold. See Baum (2004/2019) for a reconstruction of Reinhold’s position in this regard. In a more recent article, Baum addresses the seemingly circular argument at A737/B765. He defends Kant’s position by arguing that Kant does not presuppose experience as a fact but provides a proof of the possibility of experience in the transcendental deduction (Baum 2015/2019: 389). However, it is hard to see how his further analysis, focused on the question concerning the objective validity of the categories, offers a solution to the seeming circularity of Kant’s position he started out from. Unlike Baum, as seen, I do not consider the transcendental deduction to prove the possibility of experience but hold, rather, that the notion of possible experience is an element of Kant’s argument against Wolffan special metaphysics. 37 Thus, Kant posits not so much that we actually possess empirical knowledge as that it must be possible to subsume the “swarm of appearances” (A111) by which the mind is confronted under a limited set of basic rules. He seems

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to hold that this premise suffces to prove the objective validity of the categories, which on his account are nothing but such rules (cf. A121–22). 38 Thanks are due to Stephen Howard for his comments on an earlier version of this paper.

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——— (2015/2019), ‘Kant’s “Möglichkeit der Erfahrung”’, in M. Heinz (ed.), Kleine Schriften 1. Arbeiten zur Kants Theoretischer Philosophie, Berlin: De Gruyter, 385–401. Beck, Lewis White (1978), ‘Did the Sage of Königsberg Have No Dreams?’, Essays on Kant and Hume, New Haven: Yale University Press, 38–60. Beiser, Frederick (1992), ‘Kant’s Intellectual Development: 1746–1781’, in P. Guyer (ed.), Cambridge Companion to Kant, Cambridge: Cambridge University Press, 26–61. De Boer, Karin (2019), ‘Staking out the Terrain of Pure Reason: Kant’s Critique of Wolffan Metaphysics in Dreams of a Spirit-Seer’, Internationales Jahrbuch des Deutschen Idealismus / International Yearbook of German Idealism, 14, 3–24. ——— (2020), Kant’s Reform of Metaphysics: The Critique of Pure Reason Reconsidered, Cambridge: Cambridge University Press. Clewis, Robert R. (2014), ‘Kant’s Empiricist Rationalism of the Mid-1760s’, Eighteenth-Century Thought, 5, 179–225. Dyck, Corey (2014), Kant and Rational Psychology, Oxford: Oxford University Press. Engfer, Hans-Jürgen (1996), Empirismus versus Rationalismus? Kritik eines philosophie-historischen Schemas, Paderborn: Schöningh. Fugate, Courtney D. (2014), The Teleology of Reason: A Study of the Structure of Kant’s Critical Philosophy, Berlin: De Gruyter. Hatfeld, Gary (2003), ‘What were Kant’s Aims in the Deduction?’, Philosophical Topics, 31/1–2, 165–98. Heimsoeth (1926/1956), ‘Metaphysik und Kritik bei Chr. A. Crusius. Ein Beitrag zur ontologischen Vorgeschichte der Kritik der reinen Vernunft im 18. Jahrhundert’, Studien zur Philosophie Immanuel Kants. Metaphysische Ursprünge und ontologische Grundlagen, Köln: Kölner Universitäts-Verlag, 125–88. Heymans, Gerard (1889), ‘Einige Bemerkungen über die sogenannte empiristische Periode Kants’, Archiv für Geschichte der Philosophie, 2, 572–91. Kanzian, Christian (1993), ‘Kant und Crusius 1763’, Kant-Studien, 84/4, 399–407. Kreimendahl, Lothar (2007), ‘Empiristische Elemente im Denken Christian Wolffs’, in J. Stolzenberg and O.-P. Rudolph (eds.), Christian Wolff und die europäische Aufklärung, vol. 1, Hildesheim: Olms, 95–112. Kuehn, Manfred (1988), ‘Kant’s Transcendental Deduction: A Limited Defense of Hume’, in B. den Ouden (ed.), New Essays on Kant, Bern: Lang, 47–72. Laywine, Alison (1993), Kant’s Early Metaphysics and the Origins of the Critical Philosophy, Atascadero: Ridgeview Publishing Company. Prunea-Bretonnet, Tinca (2009), ‘La question de l’analyse et l’héritage wolffen dans la Preisschrift de 1762 (1764)’, in L. Langlois (ed.), Les années 1747–1781: Kant avant la Critique de la raison pure, Paris: Vrin, 137–44. Stang, Nicolas (2018), ‘Hermann Cohen and Kant’s Concept of Experience’, in C. Damböck (ed.), Philosophy and Science in Hermann Cohen / Philosophie und Wissenschaft bei Hermann Cohen, Berlin: Springer Verlag, 13–40. Watkins, Eric (2009), Kant’s Critique of Pure Reason: Background Source Materials, Cambridge: Cambridge University Press. Wundt, Max (1924), Kant als Metaphysiker: Ein Beitrag zur Geschichte der deutschen Philosophie im achtzehnten Jahrhundert, Stuttgart: Enke.

Contributors

Paola Basso  has held a postdoctoral position at the University of Milan (2002–2006), teaching positions at the SILSIS (2005–2008) and the IUSS of Pavia (2013–2014), and a research position at the University of Bucharest (2017). Her current research focuses on the foundation of philosophy as a science in the eighteenth century. Her publications include Lambert interprete di Euclide (La Nuova Italia, 1999), Il secolo geometrico (Le Lettere 2004), and The Other Side of Euclid. Lambert’s Epistemology of Constructive and Visual Strategies (Ledizioni 2012). Karin de Boer is professor of philosophy at the University of Leuven. She is the author of Thinking in the Light of Time: Heidegger’s Encounter with Hegel (SUNY 2000), On Hegel: The Sway of the Negative (Palgrave 2010), and Kant’s Reform of Metaphysics: The Critique of Pure Reason Reconsidered (CUP 2020) as well as of numerous articles on Kant, Hegel, and contemporary continental philosophy in journals such as Journal of the History of Philosophy, Kant-Studien, and Inquiry. She also coedited (with Ruth Sonderegger) the volume Conceptions of Critique in Modern and Contemporary Philosophy (Palgrave 2011). Corey W. Dyck  is professor of philosophy and faculty scholar for arts and humanities at the University of Western Ontario. He is the author of Kant and Rational Psychology (Oxford 2014) and has published numerous articles on Kant’s philosophy and its history in journals such as the Journal of the History of Philosophy, British Journal for the History of Philosophy, Kant-Studien, and Kantian Review. He is also the translator and editor of Early Modern German Philosophy (1690–1750) (OUP 2019), coeditor (with Falk Wunderlich) of the collection Kant and his German Contemporaries (CUP 2017), and co-translator (with Daniel O. Dahlstrom) of Moses Mendelssohn’s Morning Hours: Lectures on God’s Existence (Springer 2011). Courtney D. Fugate  is associate professor of philosophy and civilization studies at the American University of Beirut, Lebanon. He is

298 Contributors co-translator (with John Hymers) of A. G. Baumgarten’s Metaphysics: A Critical Translation with Kant’s Elucidations, Selected Notes, and Related Materials (Bloomsbury 2013) and Baumgarten’s Elements of First Practical Philosophy: A Critical Translation with Kant’s Refections on Moral Philosophy (Bloomsbury 2020). He is also the author of The Teleology of Reason: A Study of the Structure of Kant’s Critical Philosophy (De Gruyter 2014), editor of Kant’s Lectures on Metaphysics: A Critical Guide (CUP 2019), and executive editor (with Anne Pollok) of the Bloomsbury Series in Modern German Philosophy. His articles on Kant and pre-Kantian philosophy have appeared in journals such as European Journal of Philosophy, Canadian Journal of Philosophy, History of Philosophy Quarterly, and Archiv für Geschichte der Philosophie. Annelie Grosse  is a postdoctoral researcher at the Berlin-Brandenburg Academy of Sciences and Humanities. She received her PhD in eighteenth-century intellectual history from the European University Institute in Florence in 2018. Her research interests lie in eighteenthcentury religious and moral philosophical thinking with a particular focus on philosophical debates at the Berlin Academy. She is preparing a monograph on Jean Henri Samuel Formey as advocate of the religious Enlightenment. Stefan Heßbrüggen-Walter  is associate professor of philosophy at HSE University, Moscow. His research interests mainly concern the history of early modern German philosophy between Melanchthon and Kant. His articles, published in journals such as Kant Yearbook, Archiv für Begriffsgeschichte, and Journal of Early Modern Studies, treat subjects such as the role of experience in natural philosophy (Zabarella), the philosophy of history (Keckermann), and Wolff’s conception of philosophy and its historical context. He is the author of Die Seele und ihre Vermögen: Kants Metaphysik des Mentalen in der “Kritik der reinen Vernunft” (Mentis 2004) and coeditor of Departure for Modern Europe: A Handbook of Early Modern Philosophy (Meiner 2011). Christian Leduc  is associate professor of philosophy at the University of Montreal. His research focuses on Leibniz and the German and French Enlightenment. He has published Substance, individu et connaissance chez Leibniz (PUM/Vrin 2009) and coedited (with P. Rateau and J.-L. Solère) Leibniz et Bayle: Confrontation et dialogue (Steiner 2015) and (with P. Girard and M. Rioux-Beaulne) Les Métaphysiques des Lumières (Garnier 2016). His articles appeared in journals such as British Journal for the History of Philosophy, Foundations of Science, and Studia Leibnitiana. His recent work focuses on speculative philosophy at the Berlin Academy and eighteenthcentury natural teleology.

Contributors

299

Alessandro Nannini  was a research fellow at several universities and research centers, among them the University of Jena (2016–2017) and the University of Bucharest (2018–2020). His research focuses on intellectual history and aesthetics in the Early Modern Age, with particular regard to Baumgarten and the German Enlightenment. He edited the frst Italian anthology of Sulzer’s Allgemeine Theorie der Schönen Künste (CLUEB 2011) and published in journals such as Archiv für Geschichte der Philosophie, Journal of Early Modern Studies, and Journal of the History of Ideas. Tinca Prunea-Bretonnet  held postdoctoral positions at the Institute for Advanced Studies New Europe College, Bucharest (2014) and IZEA Halle (Saale) (2015). She is a researcher at the Research Institute of the University of Bucharest (Humanities Division) and affliated researcher at the Institut d’Histoire des Représentations et des Idées dans les Modernités, ENS Lyon. Her research focuses on Kant and the German Enlightenment (in particular Wolff, Crusius, Reimarus, and the Berlin Academy) as well as on the twentieth-century reception of Kant’s philosophy. She is the coeditor (with Sophie Grapotte) of Kant et Wolff: Héritages et Ruptures (Vrin 2011) and the author of L’avènement de la métaphysique kantienne. Prémisses et enjeux d’une réception au XXe siècle (Garnier 2021). Anne-Lise Rey is professor of philosophy of science at the University of Paris Nanterre. She was a member of the School of Historical Studies at the Institute for Advanced Study (Princeton) in 2012–2013 and Marie Curie Fellow at VUB (Brussels) in 2017–2018. She published numerous articles on Leibniz and eighteenth-century natural philosophy. She edited a volume entitled Méthode et histoire: Quelle histoire font les historiens des sciences et des techniques? (Garnier 2014), published a French translation of the correspondence between Leibniz and De Volder (Vrin 2016) and (with Siegfried Bodenmann) coedited the volume What Does It Mean to be an Empiricist? Empiricisms in Eighteenth-Century Sciences (Springer 2018). She is one of the coinvestigators of an international partnership “Extending New Narratives in the History of Philosophy” fnanced by SSHRC (2020–2027). Udo Thiel is emeritus professor at the Department of Philosophy at the University of Graz, Austria. He held positions at the University of Sydney and the Australian National University in Canberra and is an elected member of the Austrian Academy of Sciences. His research focuses on early modern epistemology, metaphysics, and philosophy of mind. He is the author of many articles on these subjects as well as the editor and coeditor of several collection of essays, including (with Giuseppa Motta) Immanuel Kant: Die Einheit des Bewußtseins (De Gruyter 2017). Thiel’s monographs include The Early Modern

300 Contributors Subject. Self-Consciousness and Personal Identity from Descartes to Hume (OUP 2011, 2nd ed. 2014). Clinton Tolley  is professor of philosophy at the University of California, San Diego. His work focuses on Kant’s idealism and its infuence on later developments in modern philosophy. He is the coeditor and co-translator (with S. Lapointe) of The New Anti-Kant (Palgrave 2014) and has published in journals such as Journal of the History of Philosophy, European Journal of Philosophy, and International Yearbook for German Idealism. He is currently working on a book on Kant’s transcendental idealism. R. Brian Tracz  is a PhD candidate at the University of California, San Diego. His dissertation on Kant’s theory of mental imagery received DAAD fellowship support for the 2018–2019 academic year. His work focuses on the history of philosophy of mind as well as historical approaches to the study of perception and imagination. Some of his recent work was published in Ergo and the Journal for the History of Analytical Philosophy. Falk Wunderlich teaches philosophy at Martin-Luther-Universität HalleWittenberg, having previously held positions at Johannes GutenbergUniversität Mainz, University of Notre Dame, and Max Planck Institute for the History of Science, Berlin. His publications include many articles on Kant and German and British Enlightenment philosophy, as well as the monograph Kant und die Bewußtseinstheorien des 18. Jahrhunderts (De Gruyter 2005). He coedited (with Patricia Springborg) a special issue of the British Journal for the History of Philosophy on Varieties of Early Modern Materialism (De Gruyter 2016) and (with Charles T. Wolfe) a special issue of Intellectual History Review on Joseph Priestley: Materialism and the Science of the Mind (2020). He is also the coeditor (with Hans-Peter Nowitzki et al.) of Michael Hißmann: Briefwechsel (2016) and (with Corey W. Dyck) of Kant and His German Contemporaries (CUP 2018).

Index

Note: Page numbers followed by “n” refer to end notes. action at a distance see attraction aesthetics 55–68 Ahnert T. 94n, 175n Albrecht, M. 51n, 91n Allison, H. 268n, 270n analysis: of concepts 23, 28, 206, 236, 240–41, 244; vs. synthesis 198n, 235, 236–39; see also method, analytic Ancillon, F. 204, 225n Anderson, L. 51n, 232, 251n Angelelli, I. 52n Anstey, P.R. 10n–11n, 174n, 224n–25n apperception: empirical vs. pure 110–11, 116n; in Kant 108–12, 267, 271n, 294n; in Merian 115–16n, 203–10, 212, 214–17, 222n; in Tetens 260–61, 266–67; transcendental 110, 116n Aristotle 3, 11n, 219, 234, 287; and Lambert 182, 195n; and Kant 294n Arndt, H.W. 34n, 175n, 292n Arnold, G. 62, 70n, 94n Arnsperger, W. 34n astronomy 41–42, 52n, 146, 193 attraction 44, 48, 143, 145–46, 209 axiomatics 192, 194 axioms 115n, 225n; in Bacon 234–36; in Crusius 86, 90–91, 93n; in Kant 279; in Lambert 181–82, 184–85, 188–89, 191, 196–97n; in Newton 237; in Tschirnhaus 19–21; in Wolff 21, 28–29, 34n, 38, 46–47, 189 Ayers, M. 197n Bacon, F. 11n, 59, 61, 70n, 82–83, 233, 250–51; on method 219,

235–36, 240, 251n; and Newton 237–39; on philosophy 234–35; see also method, Baconian Baertschi, B. 222n Basedow, J.B. 102–3, 109, 113n Baum, M. 115n, 294n Baumgarten, A.G. 38; aesthetic art of experience 57–61, 72n; on aesthetic experiments 65–67, 69n; on aesthetics 56–57; on conceptual analysis 241; on sensation 69n, 257–58; on spiritual experiments 61–65, 71n Beck, L.W. 33n, 91n, 182, 195n, 197–98n, 267–68n Beiser, F. 283, 293n Bilfnger, G.B. 210 Bodenmann, S. 10–11n, 155n Bodin, J. 174 Boerhaave, H. 158 Bonnet, C. 122, 124, 133n, 258, 261, 269–70n Boran, E. 10n Boyle, R. 44, 59, 69n, 72n, 225n Bronisch, J. 174–75n Brown, A. 155n Brucker, J.J. 234–35, 251n Budde(us), J.F. 81; on historical cognition 69n; on sensation 82, 89–90, 94n; on sensible cognition 64, 68n; on spiritual experience 64, 72n, 82, 89 Bullynck, M. 198n Buschmann, C. 69n, 134n, 223n Caimi, M. 270n Calinger, R.S. 175n Campe, R. 69n

302 Index Canz, I.G. 63, 71n Carboncini–Gavanelli, S. 176n Cartesianism, experimental 18 Cassirer, E. 141–43, 155n, 187, 197n Casula, M. 176n Cataldi Madona, L. 69n, 93n causality 94n, 126, 130, 134n, 212–13, 215, 224n, 263, 279, 283, 287, 290–91 cause: effcient 44, 235; fnal 155n, 235; mechanical 43–45, 48, 132, 172 certainty see probability vs. certainty Charles, S. 223–24n Charrak, A. 141, 148, 151, 154, 155–56n Chladenius, J.M. 69n chronometry 186 Clark, W. 175n Clarke, S. 17, 264 Clauberg, J. 82, 92n Clewis, R. 251n, 293n Cochius, L. 126, 134n cogito 207 cognition: beautiful 67–68; clear 258; empirical 3–4, 37–38, 45–47, 51, 98–100, 103, 108, 160, 163–65, 168–70, 185, 286–90, 293n; experimental 45, 49, 51, 55; historical 37, 45–47, 51, 69n, 164–65, 276–77; limitation of 121, 125, 151–54, 205, 211, 213, 220–22, 224n, 283; philosophical 37, 46–47, 51, 88, 90; a priori 18, 129, 161, 185, 190, 193–94, 198n, 275, 287–91, 293–94n; a priori vs. a posteriori 37, 46, 162, 182, 185, 190–91, 194, 198n; scientifc 3–4, 45, 87, 181, 186, 191–94, 219, 231; sensible 25, 55–58, 64–65, 68, 70n, 72, 164–65, 167, 169, 259–60, 262; spiritual 62–64, 82, 89 Collins A. 17 concepts: anatomy of 182, 184, 187, 195–96n; clear 28, 240, 245, 276; distinct 24, 28, 30, 32, 58, 120, 240; empirical 243, 246; a priori 289, 293; probable 83–84; pure 287, 289–91, 294n Condillac, E.B. de 122; on force (power) 126; on method 225n, 258; and Tetens 261, 270n

connubium rationis et experientiae (Wolff) see marriage between reason and experience conscium sui 207–8 contingency 39, 147, 151, 187 Copernicus, 83 cosmology 37–51; experimental 48–50; general 41–42, 44–49; transcendental 41, 47 critical philosophy 112, 115n, 233 Crousaz, J.–P. 223n Crusius, C.A. 81–82, 217, 286; on causality 283–84; on inner experience 89–91, 94n; on method 278, 282; theory of principles 94n, 198n, 251n, 279, 281–82, 285, 292–93n; theory of proposition 86–89, 91, 93n Cyprian, J. 69n, 83, 92n D’Alembert, 162, 181; on attraction 145; on metaphysics 10–11n, 155n, 225n D’Holbach, P.T. 132, 135n De Boer, K. 293–94n De Felice, F. 69n, 176n De Raey, J. 92n De Vleeschauwer, H.J. 33n, 232–33, 240, 251n, 270n Dear, P. 10n deceptions of the senses (fallaciae sensuum) 60 deduction: in Formey 161, 163, 168; in Kant 270–71n; in Lambert 182–83, 185, 190–92; in Maupertuis 141, 151–53; see also transcendental deduction defnition 19–23, 27–32, 34n, 50, 58, 84–85, 91, 183, 189, 196n, 217, 236–37, 240–41, 248–50, 274, 281, 292n Demeter, T. 196n demonstration 24, 92, 190, 193, 206; and certainty 153–54, 208; in cosmology 37–40, 43, 46, 49–51, 52n; and defnitions 28–29, 31; in empirical psychology 38, 122; of the existence of God 24, 147–51; principles of 30, 32 Descartes, R. 2–3, 44, 150, 154, 231, 233; on the cogito 207, 222n; on dualism 158; and Maupertuis 141– 42, 150; on method 183–84, 198n,

Index 303 236, 247; and skepticism 210, 212; theory of cognition 23; and Wolff 23, 183, 222n, 231 Deutsch, M.F. 71n Diderot, D. 155n, 176n, 225n Dilthey, W. 195n, 199n, 205, 222n dreams, theory of 158–60, 160–74 dogmatism 1, 122, 205, 222 Du Châtelet, É. 145–46, 155n, 175n dualism 119, 125, 127, 158 Dumouchel, D. 174n Duncan, S. 134n Dunlop, K. 197n Dyck, C. 11n, 51n, 165, 174–76n, 198n, 292n dynamics 65–66, 142, 155n, 186, 192–93 eclecticism 106, 203; see also philosophy, eclectic École, J. 51n, 174–76n Edwards, J. 71–72n Empfndung 27, 101, 254, 256–58, 268n; see also sensation empirical sciences 234–36, 244, 250, 251n empiricism 5, 33, 100, 132, 148, 155n, 203, 210, 222, 254–55, 257, 266; vs. rationalism 1–2, 11n, 158, 165, 163, 195n, 222, 232–33, 250, 251n, 266, 275, 292n empiricist: accounts of cognition 33, 106–7, 165, 170, 173, 203, 205, 208, 218, 222n, 235, 255, 283–84, 290, 292n; philosophers 10–11n, 32, 119–20, 122, 126, 160, 176n, 233, 241, 250, 254–55, 266, 268n empirics, aesthetic 58–68 Engfer, H.J. 1–2, 10–11n, 19n, 292n enthusiasm 64 epistemology 91n, 151, 154, 159, 160, 165, 192 Euclid 182–86, 189, 192, 194, 196n, 198n Euler, L. 162–63, 169, 175n, 231, 244–46, 250–51, 251n experience: defnitions of 2–4, 56–58, 69n, 72n, 82–84, 89, 92n, 99, 262, 266, 275, 286–88; clear 29–30, 32, 34n, 176n, 277–78; indubitable 189, 274, 276, 280–82; outer 3–4, 98–99, 101, 107–8, 173, 276, 278; see also inner experience

experimental philosophy see philosophy, experimental experimentalism 56, 62, 64–68, 69n, 72n, 160, 169, 173 faculties (powers): mental 121, 158–59, 173, 206–7, 211–12, 217, 219; of the soul 38, 57, 72n, 90, 109, 121, 158–59, 164, 173, 176n, 206–7, 211–12, 217, 259, 271n; see also forces Fechner, G.T. 68, 72n Feder, J.G.H. 98, 100–5, 112, 113n, 120, 132, 133n; and Basedow 102–3; and Lossius 106–8, 112; and Kant 109–11, 115n feeling of the self see Selbstgefühl Feger, H.D. 68n Feingold, M. 10n Fischer, K.P. 11n Fogelin, R. 223–24n Fontius, M. 174n forces: inertial 43–44, 48–49, 128; living 66; passive vs. active 43–44, 48–49, 126, 176; in physics 26, 43–44, 46, 48–49, 126, 128, 154, 186–87, 192, 232, 238, 242, 284; in psychology 109, 125, 176, 209, 265; supernatural 162; see also faculties Formey, J.H.S. 158–73, 210, 234, 174–76n Francke, A.H. 56, 68n, 70n Frank, M. 116n Frederick II (the Great) 4, 155, 161–62, 204 Frederick William II 204 Frey, C. 72n Friedman, M. 233, 244, 250, 251n, 271n Fugate, C. 94n, 293n Gadamer, H.G. 11n Gantet, C. 174n Garve, C. 101, 204 Gawlick, G. 223n geometry 19, 181, 183–84, 186–87, 192, 194–97n, 245–46, 278–80 Gerhardt, C.I. 34 Geulincx, A. 18 God 62–64, 89, 72n, 144, 146–49, 155n; divine choice 144, 146–49, 155n; existence of 24, 142, 147–48,

304

Index

150–51, 153–54, 156n, 161, 243, 282, 290; see also experience, spiritual; wisdom, divine Gottsched, J.C. 173 Gracián, B. 57, 68n Graf, M. 195n gravity 46, 107, 155, 189, 192, 238, 250 Greenberg, J.L. 155n Griffng, H. 195n Grote, S. 70n Hagen, G.F. 62, 65, 71–72n, 159 Haller, A. von 124, 133–34n Hamann, J.G. 268 Hanov, M.C. 59, 61–63, 70n, 72n harmony, pre–established 23, 126, 131, 134n, 141, 160, 171–73 Harnack, A. von 175n Harrison, P. 71n Hartley, D. 124, 133–34n Harvey, W. 55, 68n Häseler, J. 174n Hatfeld, G. 294n Heßbrüggen-Walter, S. 92n, 95n Hegel, G.W.F. 57, 182, 195n, 233, 254 Heimsoeth, H. 92n, 94–95n, 293n Heller-Roazen, D. 112n Herder, J.G. 195n, 268, 292n Hernandez Marcos, M. 70n Heymans, G. 293n Hißmann, M. 105, 113, 119–34 Hinske, N. 52n Hofmann, A.F. 81–82, 88–91, 92–94n Holland, G.J. 187–88 Holzhey, H. 10–11n, 68–70n, 91–94n Honnefelder, L. 33n Hooke, R. 69n Hume, D. 1–2, 4, 11n, 128, 203, 220, 254, 259–60, 283–85; analysis of the mind 196n, 219, 223n, 256–58, 260–64, 266, 269n, 286, 288–89; on causality 94n, 129–30, 134n; and empiricism 254–56; and phenomenalism 206, 214–17, 224n; and skepticism 204, 210–13, 221–22, 223n Hupel, A.W. 119, 133n, 135n idealism 188, 214, 222n identity, personal 208, 216, 222n, 224n

imagination 20–21, 33n, 40, 62, 64, 68n, 71n, 124, 159–60, 165–67, 169–70, 172, 176, 205, 207, 257, 261–64, 267, 269–71n, 275–76; and memory 68n, 124, 256–57 Indregard, J.J. 95n induction 49–50, 83, 163, 166, 181–82, 190, 198n, 224n, 236, 238–39, 246, 264 inertia 43–44, 48, 51, 52n, 128, 155n inference 25, 34n, 85–88, 90–91, 93–94n, 105, 190, 198, 231, 237, 276–78, 284–85, 292n innate ideas 121, 232, 255 inner experience 3–5, 11n; in Feder 105; in Hißmann 119, 132; in Kant 100, 108, 112n, 233, 241, 247, 265–66, 282, 285; in Locke 98–99; in Lossius 107–8; in Merian 210; in the Thomasian school 82, 89–91, 94n; in Wolff 37, 275–76, 280; see also experience inner sense 105–6, 110; in Baumgarten 56, 61, 70n; in Basedow 102; in Feder 100–5, 113n; in Hißmann 121, 129; in Kant 98–100, 108–12, 115–16n; in Locke 98–100; in Merian 206–8; vs. outer sense 56, 98–103, 129; in Tetens 265 intuition 100, 206–8; empirical 111–12, 289; inner 110–11, 132; intellectual 116n Isler, H. 174n judgments 60, 72n, 83, 111, 113n, 115n, 125, 198, 207, 265–66, 270n, 282–84; empirical 287, 290; intuitive 63; synthetic a priori 275, 290, 293–94n Kaitaro, T. 133n Kames, H.H. 129, 134n Kant, I. 1–2, 5, 10n, 37, 105–6, 181–82, 194, 203, 221, 254, 271; on apperception 108–12, 115–16n, 206, 208, 267; on inner sense 98–101, 115n; and metaphysics 38, 52n, 274, 283–86; on method in philosophy 183, 231–34, 236, 239– 51, 278–83, 292n; and Newton 236, 239; theory of cognition 198n,

Index 305 233, 267–68, 269–71n, 274–75, 286–91, 292n Kanzian, C. 293n Keding V. 70n, 94n Kepler, J. 41, 52n Kettel, S.F. 71n Klemme, H.F. 115n, 133n Knoblauch, K. von 119 knowledge see cognition Knutzen, M. 173, 236, 251n Koch, C.H. 198–99n Kollving, U. 155n Kreimendahl, L. 176n, 223n, 292n Krüger, J.G. 159 Kuehn, M. 91n, 94n, 114n–15n, 268n, 271n, 294n Kurz, G. 113n Lagrange, J.-L. 181, 194–95n Lambert, J.H. 181, 204, 269n; on method 182–84, 186–90, 194n, 196n; on a priori cognition 190–94, 197–98n; theory of concepts 185, 187–88, 195–96n Lange, F.A. 133n Lange, J. 70n, 89, 94n Laursen, J.C. 223n laws: of experience 26; of inertia 43; mechanical 44–45, 48, 156n, 191; of motion 40, 43–46, 48–51, 141, 149–50, 152, 155n, 237; Newtonian 143, 147, 237 Laywine, A. 293n Leduc, C. 33n, 51–52n, 156n, 175n, 292n Leibniz 1–4, 126, 163; on apperception 109; on certainty 154; on cosmology 142; dynamics 66, 255n; and empiricism 71; on forces (powers) 43–44, 52n, 126, 265; on innate ideas 252, 255; on method 23–24, 27, 34n, 163, 195n, 198n, 237–38, 247, 262, 264; and metaphysics 106, 135n, 144, 219, 231; on monads 130–32, 134n, 163, 242; Nouveaux Essais 256, 268n; on perception 209–10; and physical theology 141–42, 150; on pre-established harmony 131, 141, 171; and rationalism 165, 266; on syllogism 23; theory of concepts 27–28, 183, 191, 255, 258–61, 264, 266–67; theory of principles 44, 48,

142–43, 152, 155n, 161, 238; and Wolff 17–23, 33 Leibnizian school 255, 257–58, 260–63, 265–67 Leibnizian-Wolffan 204, 210, 258, 260, 262, 265–66 Leinsle U.G. 91n Lepsius, J. 195n Licoppe, C. 155n Locke J. 1–4, 27, 82, 92n, 119, 129, 148, 165, 203, 210, 214, 254; on inner sense 98–100, 103–4, 114n, 121, 122; and method 120–21, 182–83, 195n, 259, 262–3, 265, 283; theory of concepts 183–86, 196n, 221, 254–59, 261, 263–67, 268n; and personal identity 208 logic 26, 31, 57, 81–82, 86, 257, 271n, 279, 291; empirical 58; esoteric 58; practical 91n; and psychology 120–21 Lossius, J.C. 98, 106–9, 111–12, 114–15n, 122; and Kant 109–11, 115n Lyon, W. 133n Luther, M. 62 Malebranche, N. 59 Mandelbrote, S. 10n Manteuffel, E.C. 161–63, 168, 174–75n marriage between reason and experience (Wolff) 38, 46, 50–51, 175n, 193 Mariotte, E. 44, 48, 52n materialism 108, 119–32, 133–35n mathematics 3–4, 19, 34n, 146, 153, 163, 181, 194n, 196n, 198–99n, 218–19, 233–34, 236, 239–40, 244–45, 278; see also geometry; method, mathematical Matherne, S. 270n matter 40, 43–46, 49, 51, 114n, 142–46, 154, 218, 235, 238; and thought 122, 125, 128, 132, 133n Maupertuis, P.-L.M. de 4, 141–42, 147–48, 162, 169, 204–5, 208–9; on attraction 143–46; on God 146–54; on the laws of nature 143, 150–52, 156n; on the limitation of cognition 151–54, 208; phenomenalism 203, 208–9; physical theology 141, 147, 150,

306 Index 153–54, 156n; principle of least action 142, 146, 149, 155n McNiven Hine, E. 146, 156n mechanics 141, 145, 152, 156n, 186, 192–93, 244 mechanism 44–45, 48, 51, 124, 132, 188, 194 medicine 119, 123, 132, 156, 166 Meier, G.F. 60–61, 70n, 113n, 269n Meiners, C. 105, 119–21, 132, 133n memory 92n, 101, 124, 207–8, 256 Mencke, O. 22, 34n Mendelssohn M. 204 Mercer C. 11n Merian, J.-B. 1, 126, 203–4; on apperception 205–10, 216–17; and eclectic philosophy 203, 211–12, 220–22; and Hume 210–17; on metaphysics 217–20; and skepticism 205, 210–14 metaphysics: division of 38–39, 120, 217–20; experimental 187, 193; general (metaphysica generalis) 38, 42, 133n, 219, 255 (see also ontology); of nature 43, 141; and physics 141–42, 144–46, 149, 153– 54; as a science of principles 45, 161, 219–20, 225n, 232–35; scope of 120–21; special (metaphysica specialis) 37–38, 40, 42, 50, 133n, 219, 255, 294n method: analytic 28, 47, 198, 233, 235–50, 251n, 275, 278–82, 287, 289; analytic vs. synthetic 47, 50–51, 198n, 233, 235–41; Baconian 219; demonstrative 39, 46–48, 50, 50, 52n, 220, 278; eclectic 81, 203, 221–22; empiricist 18, 142, 160, 206, 208–9, 218, 221, 222n; experimental 4, 44, 123; Lockean 121, 126, 182, 255, 265; mathematical (scientifc) 17–32, 34n, 48; Newtonian 189, 198n, 203, 233, 236, 239, 246–7; rationalist 18, 32, 240, 246, 250; synthetic 47, 198n, 233, 235–50, 251n, 255, 263, 269n Mohr, G. 112n monad 131–32, 141, 242, 285 monadology 120, 130–2, 134n, 163, 169 motion 149, 218, 237–38 Motta, G. 115n Müller, A.F. 57, 82, 94n

Nannini A. 68n natural philosophy 3, 10n, 42, 81, 83, 146, 158–60, 163, 166, 171, 218–20, 234–36, 238 Neveu, S. 174n Newton, I. 1, 4, 10–11n, 17, 148, 169, 186, 191, 203–4, 278, 283; on attraction (action at a distance) 142–46, 155n, 243; empiricism 232–33; laws of nature 44, 49, 129, 150, 237; and method 2, 165, 188–89, 192, 198n, 221, 236–39, 246–50, 251n, 275, 279–80; natural philosophy 42, 44, 141–42, 145–47, 156n, 158, 161–62, 173, 181, 232, 246, 274, 287–88 Newtonian philosophers 162, 165, 169, 173, 175n, 231–32, 250 Neyden, T. 92n ontology 38–39, 41–42, 45–51, 121, 132, 187, 218–19, 255, 264, 266, 270n, 276; experimental 37; see also metaphysics, general Paccioni, J.–P. 51n, 175n Pasini E. 10–11n Paul, F. 176n Pelletier, A. 34n perception: in Baumgarten 257–58; and causation 26, 129–30; of corporeal substances 124; vs. experience 82–88, 92n, 163; in Hume 215, 256, 224n; and inner sense 92n, 100, 102, 106–7, 169; in Kant 287–88; in Merian 205–6, 209–10, 215; in Tetens 261, 269n; in Wolff 21, 25–26, 31, 159, 257–58, 268n Peres, C. 70n, 72n Perin, A. 195n Peters, W.S. 195n phenomenalism 203–5, 209–10, 214–16, 222, 224n phenomenon: in Hume 214–16; mental 108, 121, 124, 132, 255, 270n; in Merian 205, 209, 215, 224n; in Newton 236–37 philosophy: eclectic 106, 203, 211–12, 221–22; experimental 62, 72n, 142, 148, 198n, 225n, 236, 238; popular 6, 159; school 160 phoronomy 186 physical infux 126, 131, 172–73

Index 307 physical theology see theology, physical physics 38–42, 40–46; dogmatic 40, 43, 50; experimental 40, 44, 46, 48, 50, 61–62, 69n, 70n; general 39–41 physiology 8, 39, 41, 119, 123, 132, 158, 171, 173 phytology 39, 41 Pietism 1, 4, 62, 70n, 81, 89, 94n Pimpinella, P. 69–70n, 72n pneumatology 105 Poleyen, H.E. 254, 256 Popkin, R.H. 223n Poser, H. 69n, 176n Potterfeld, W. 133n powers see faculties; forces Priestley, J. 122, 132, 133–35n principles: of the best 149; of conservation 150, 152; of continuity 127, 142; cosmological 38, 40, 46–48, 50, 52n; experimental 40; of least action 143–43, 146, 148–49, 151–53, 155n; mathematical 44, 48; mechanical 44, 48; metaphysical 18, 41, 44–46, 51, 141–42, 146, 155n, 221, 248; ontological 38–39, 42, 45–46, 47–48, 50–51, 285; of non-contradiction 39–40, 50, 232, 278–79, 281–82, 291; of suffcient reason 37–38, 43–44, 48–50, 84, 141, 143, 155n, 161, 238, 264, 277, 292n probability vs. certainty 92n, 123, 142, 151, 153–54, 213 Protestantism 62 prudence 57, 92n Prunea-Bretonnet, T. 11n, 155n, 224n, 292n psychology: empirical 38, 112n, 121–22, 159–66, 170, 173, 174–76n, 257, 276; physiological 269; rational 38–39, 41, 92n, 121, 164–65, 168, 173, 174–76n, 276, 278 Puech, M. 10n Pulte, H. 10n rationalism 17, 26, 162–63, 165, 195n, 275 rationalist: account of cognition 6, 33, 189, 208, 239; philosophers 1–2, 37, 160–63, 165, 176n, 205, 233, 235, 239–40, 247; see also method, rationalist

Reid, T. 114n, 130 Reinhold, K.L. 10n, 195n, 294n Reusch, J.P. 69n, 173n Rey, A.-L. 10–11n Richards, R.J. 175n Riehl, A. 195n Risse, W. 197n Ritter, J. 11n Rogers, M. 11n Rohr, J.B. von 70n Rüdiger, A. 217; and apperception 207; and metaphysics 81, 92n; on philosophical cognition 88–90; on sensation 82–84, 90 Rumore, P. 10–11n, 114n, 133n, 174–76n Rüping, H. 91n Rydberg, A. 5, 11n, 70n Saunderson, N. 188, 198n Schenk, G. 196n Schliesser, E. 10n Schneiders, W. 68n, 91n Scholz, O. 92n Schönfeld, M. 33–34n Schulting, D. 115n Schwaiger, C. 68–72n Schwarte, L. 55, 68n Seifert, A. 69n Selbstgefühl 100–12, 113–15n, 259, 270n self-consciousness 108–11, 115n, 222n; see also apperception; Selbstgefühl Selle, C. 119 Sellhof, M. 114n sensation: in Baumgarten 55, 58, 60–64, 69–71n, 258; and the brain 123–24, 130, 165, 170–71; in Hume 256; and imagination 165–67, 170; and inner sense 101–4, 106–7, 109, 123–24, 130, 165, 170–71; in Kant 28–87, 290–91; in Locke 99, 256; in Tetens 254–55, 257–67, 269–70n; in the Thomasian school 82–91, 92–93n; in Wolff 24–25, 26, 257, 275 Serjeantson, R. 174n Shapin, S. 11n skepticism 1, 19, 104, 203–6, 208, 210–16, 221, 223–24n, 283, 289 Smith, P.J. 223n Soboth, C. 71n

308

Index

soul 23, 158–59; and the brain 123– 25; doctrine of the 104–5, 122; and inner sense 104, 106–7, 113n, 208– 10, 259 (see also apperception); faculties / forces of 23, 38, 65, 101, 159, 259–61, 271n; immateriality of 104–5, 113n, 124–25, 127, 159, 169, 172, 176n, 204, 208, 274, 282, 285; immortality of 275; simplicity of 105, 114, 122, 176n, 285; substantiality of 122, 124, 204, 208, 285; in Wolffan psychology 25, 163–66, 168–69, 171–73, 176n Spinoza B. 18, 34n, 119, 207 spontaneity 110–11 Société des Aléthophiles 161–62 Stang, N. 271n, 294n Stiening, G. 268n Sträter, U. 71n Sturm T. 11n subreption 60–61, 63–64, 69n substance: as aggregate 131; concept of 21, 104, 173, 206, 208, 214–16, 224n, 225, 263, 281, 283, 285, 292–93n; corporeal 89, 122, 124–25, 153; immaterial 104–6, 108, 114n, 122, 125, 293n; as simple 122–23, 197n, 285; spiritual 89; thinking 104–6, 114n, 208 substantial forms 43 Sulzer, J.G. 126, 174n, 184, 210, 254, 256 syllogism 18, 23, 28, 32 Syrbius, J.J. 64, 68n, 72n, 81–82, 84, 89–90, 92n tabula rasa 205 teleology 142 Tetens, J.N. 5, 105, 206; and empiricism 254–57; and method 255, 258–59, 262–63, 267, 271n; on representation 260–62, 269n; theory of concepts 263–67, 269– 71n; see also perception, sensation Theis, R. 91n Tennemann, W.G. 10n Terrall, M. 141, 155n, 175n theology 62–63; experimental 62, 71n; Lutheran 62, 70n, 94n; natural 26, 38, 41, 121, 133n, 161, 219, 234, 276, 278; physical 141–42, 147, 151, 153–54, 155n, 161; rational 121

Thiel, U. 112–15n, 133n, 222n, 268n Thomas, prejudice of 60, 64, 71n Thomasius, C. 5, 81–83; on causation 87, 89, 93n Thompson, A. 133–34n Tittel, G.A. 105, 114n Toland, J. 132, 134n Tolley, C. 269–71n Tommasi, F.V. 11n, 52n Tonelli, G. 222–23n Torra-Mattenklott, C. 72n Tracz, R.B. 270n transcendental deduction 270–71n, 287–91, 294n Tschirnhaus, E.W. von 4–5; on method 17–23, 33n, 196n; and Wolff 26–33, 34n Unzer, J.A. 159, 174n Van Cleve, J. 271n Van Musschenbroek, P. 59, 69–70n Van Peursen, C.A. 33n Vanzo, A. 10–11n, 51n Vartanian, A. 135n Verweyen, J. 33n Vidal, F. 158–59, 173, 174n Vollhardt, F. 92n Vollrath, E. 51n Walch, J.G. 68n Warda, A. 115n Watkins, E. 11n, 176n, 271n, 293n Wepfer, J.J. 55, 68n Widmaier, R. 92n Wiedemann, R.E. 56 Willis, T. 56, 68n, 158 Wilson, C. 133n Winter, E. 33n wisdom 1, 92n; divine 141, 147, 150–51, 153–54 Wolf, R. 195n Wolfe, C. 133–35n Wolff, C. 1, 4–5, 37, 106, 126, 141, 147, 203, 210, 221, 233, 266; on apperception 109, 207, 210, 222n; and Baumgarten 65, 72n; and the Berlin Academy 161–63, 175n, 204, 231; cognition of singulars 68–69n, 268n; and Crusius 81–82; division of philosophy 38–41, 121, 133n, 219; on dreaming 170–71, 176n; empirical psychology 69n,

Index 309 158–60, 164–70, 173, 175–76n, 276; experimental cosmology 48–5; experimental theology 62; and Formey 158–74; general cosmology 41–47, 50–51, 52n; and Hißmann 131; on inner sense 70n; and Kant 232, 243, 278–88; and Lambert 182–87, 189–90, 193; and Leibniz 17, 22–24; and Meiners 120–21; and metaphysics 120, 131, 161, 205, 274–75, 278, 285–86, 288; on method 21, 26–33, 121, 182–85, 193, 196n, 232, 236–38, 241, 243, 246–47, 249, 262–63, 274, 282; and Newton 237–38, 247; on perceptions 58, 84–85, 87, 257, 260, 266, 268n; on a priori cognition 186–87, 189, 198n; on representation 260, 262; and Tetens 260, 262–63, 266, 269n; theory of concepts 24–26, 196n, 198n, 276– 81; theory of principles 84, 232,

282, 292n; theory of proposition 85–88, 92n; and Tschirnhaus 17–18, 20–22, 34n; see also marriage of reason and experience; cosmology; psychology Wollgast, S. 33n Wolters, G. 184, 194, 195–96n, 198–99n Wood, P. 174n Wübben, Y. 70n Wunderlich, F. 11n, 115n, 133–35n, 176n Wundt, M. 35n, 292n Wurtz, J.-P. 33n Yolton, J.W. 133n Zart, G. 91n, 114n Zedler, J.H. 171, 176n Zelle, C. 55, 68n, 174n Zeno 187, 199n Zimmermann, R. 195n