Scientific Challenges to Common Sense Philosophy 1351064207, 9781351064200

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Introduction The Paradox of Science and Common Sense Rik Peels, Jeroen de Ridder, and René van Woudenberg

Common sense philosophy has a venerable tradition, tracing back all the way to Aristotle. But it is only since the 18th century that philosophers began to self-identify as common sense philosophers. Examples include Thomas Reid (1710–1796),1 Adam Ferguson (1723–1816), Dugald Stewart (1753–1828), who along with others, are often jointly referred to as the ‘Scottish school of common sense philosophy’.2 More recent examples include G. E. Moore (1873–1958),3 Roderick Chisholm (1916–1999),4 William G. Lycan (1945–),5 and Noah Lemos (1956–).6 Moreover, many philosophers who don’t self-identify as common sense philosophers, nonetheless avail themselves of ideas, concepts, and principles that those who do so self-identify have capitalized on. In this introduction, we provide a somewhat rough sketch of what common sense is supposed to be. We then consider what common sense philosophy amounts to. After that, we introduce a paradox that takes center stage in this volume. We spell out ways in which science can potentially debunk common sense. We also explain why this issue matters and then consider the alleged tensions between science and common sense in more detail for each of the book’s chapters.

1 What Is Common Sense?7 When one tries to pinpoint the referent of ‘common sense’ as the phrase is used in the philosophical literature, one is quickly struck by the fact that it refers to rather different kinds of things: to a particular collection of beliefs, a set of intuitions, a number of principles, a belief-forming faculty, or a loose array of methodological rules. The Greeks used the notion to refer to beliefs that are widely held. That Zeus is the highest god in the pantheon was widely believed in ancient Greece and hence qualified as a common sense belief.8 In later times, philosophers wielded a more restricted notion of common sense belief. Thomas Reid, for instance, delineated common sense beliefs as beliefs that are not only widely held but also have properties such as that their denials are absurd, that they are not believed on the basis of scientific

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investigation, and that they are foundational to practices that humans are ineluctably engaged in.9 Take the belief that there is life and intelligence in the people we converse with. This belief is widely shared, its denial is absurd, it is not based on scientific investigation, and it is foundational to practices such as buying and selling, education, and leading a social life. This notion of common sense is much more restricted than the notion that the Greeks used. That Zeus is the highest god of the pantheon was once widely believed. But its denial is not absurd, it is not based on scientific investigation, and it is not foundational to a practice that humans are ineluctably engaged in. Therefore, it is not a common sense belief in Reid’s sense. ‘Common sense’ is also often used to refer to certain intuitions that we have. If we think of intuitions as intellectual seemings, then the following sentences state intellectual seemings: that there presently is a body that is your body, to use an example from G. E. Moore, and that no proposition can be true and false at the same time. An intellectual seeming is not necessarily a belief, nor does it necessarily lead to one. It may intellectually seem to you that velocities are additive, but you might not believe it for reasons having to do with Einstein’s theory of special relativity. But often there is nothing wrong with believing what intellectually seems to be the case, for instance when we intuit and believe that the thoughts we are conscious of must have a subject. In cases like these, there is a common sense intuition of, as well as a common sense belief in, the same proposition. The phrase ‘common sense’ is sometimes also used to refer to principles of reasoning and inquiry that are widely held to be utterly plausible and wholly unproblematic. Examples include the following: •

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The Principle of Credulity (it is probable that what seems to be the case actually is the case)10 and the Principle of Epistemic Conservatism (it is unreasonable to revise or alter a belief that one has without good reason to do so)11—these are epistemological principles The Principle of Parsimony (Occam’s razor: entities should not be multiplied beyond necessity),12 the principle that every change has a cause, and the principle that everything that begins to exist must have a cause—these are metaphysical principles13 The Principle of Double Effect (there is a morally relevant difference between those consequences of our actions that we intend and those we do not intend but still foresee)14 as well as the principle that like cases should be treated equally—these are moral principles The Principle of Simplicity (Ceteris paribus: simpler explanations should be preferred over complex ones)15—this figures in the philosophy of science

Occasionally, although the idea never had many adherents, Thomas Reid spoke of a ‘faculty’ of common sense—a belief-forming faculty that operates in humans alongside perception, memory, and reason.16

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Finally, ‘common sense’ is used to refer to what could loosely be called a ‘method’—a method for doing philosophy.17 When that ‘method’ is used or applied in philosophy, the activity as well as its results could be called ‘common sense philosophy’.

2 What Is Common Sense Philosophy? In broad strokes, and in light of what we saw that ‘common sense’ can refer to, common sense philosophy is philosophy that is characterized by four methodological features.18 First, common sense beliefs, intuitions, and principles have a strong and privileged epistemic status: they have default authority, and they should only be given up, if that is possible at all, in the face of extraordinarily strong reasons. Moore held that no reason is strong enough to force us to give up a common sense belief: “The common sense view of the world”, he said, “is in certain fundamental features wholly true”.19 Other common sense philosophers hold common sense beliefs and intuitions to be defeasible. Second, common sense philosophy evaluates philosophical views by how well they square with common sense beliefs, common sense intuitions, and common sense principles. If a view denies, or entails the denial of, common sense beliefs, intuitions, or principles, then that is decidedly a strike against it. Third, if a philosophical view goes against common sense, then it must be rejected unless there is extraordinarily strong evidence in its favor. As noted, Moore thought this was never going to happen for some views. Fourth and finally, when common sense philosophy is not engaged in philosophical critique, but in constructive projects, it treats common sense beliefs, intuitions, and principles as data points that should be given their rightful place. For Thomas Reid, common sense is the soil on which the flower of philosophy should bloom: “Philosophy .  .  . has no other root but the principles of Common Sense: it grows out of them, and draws its nourishment from them: severed from this root, its honours wither, its sap is dried up, it dies and rots”.20 To further characterize common sense philosophy, something needs to be said about the content of common sense beliefs themselves. We have seen that common sense philosophers maintain that an important set of widely and deeply held beliefs has an epistemically strong status: in the absence of defeaters they are epistemically justified. Or, as it is sometimes put, common sense beliefs are innocent until proven guilty. But as we saw in the first section, modern common sense philosophers do not accord that status to just any widely and deeply held belief but only to those that have further features such as that their denials are absurd and that they are not believed on the basis of some kind of scientific investigation. Common sense philosophers also hold that many of these beliefs in fact face no defeaters. Although any particular list is bound to

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be controversial, the following items are putative examples of common sense beliefs: • • • • • • • • • •

There exists a mind-external material world. Our basic doxastic faculties are reliable. Some of our knowledge is a priori knowledge. If something seems to be so, it probably is so (the principle of credulity). Humans can be held responsible for their actions. Responsibility requires the ability to do otherwise. Time and space are real. External relations exist. Human beings have identity over time. Some things have intrinsic value.

These beliefs—or a selection of them or beliefs like them—thus form a crucial methodological bedrock and touchstone for common sense philosophy both in its constructive and critical guises.

3 The Paradox of Science and Common Sense Common sense philosophy has often been criticized by other philosophers as being unduly naïve and superficial or as not really being philosophy. David Hume is of course a prominent historical example and Immanuel Kant another. More recently Paul Moser and Richard Fumerton have joined the fold.21 Some of these critics have adopted some form of skepticism, others have embraced idealism, yet others have developed transcendental forms of philosophy. This goes to show that the debate about common sense philosophy among philosophers is still going on, even if it is mostly not explicitly framed as a discussion about common sense philosophy or about the role of common sense in philosophy. The present volume, however, is devoted not to philosophical challenges to common sense but to scientific ones. Science is often felt and claimed to be at odds with common sense.22 One classical example is the clash between our face-value ideas about medium-sized material objects and what contemporary physics tells us about the nature of such objects. Sir Arthur Eddington’s famous discussion of the two tables eloquently expresses the thought: Yes; there are duplicates of every object about me—two tables, two chairs, two pens. . . . One of them has been familiar to me from earliest years. It is a commonplace object of that environment which I call the world. . . . It has extension; it is comparatively permanent; it is colored; above all it is substantial. . . .

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Table No. 2 is my scientifc table. It is a more recent acquaintance and I do not feel so familiar with it. It does not belong to the world previously mentioned. .  .  . My scientifc table is mostly emptiness. Sparsely scattered in that emptiness are numerous electric charges rushing about with great speed; but their combined bulk amounts to less than a billionth of the bulk of the table itself.23 To use Wilfrid Sellars’s famous labels, the ‘scientifc image’ of the world is felt to be in tension with the ‘manifest image’ of the world.24 But whereas Sellars held that the two images have their own roles to play, recent developments seem to have put new science-based pressure on the value of common sense and by implication on common sense philosophy. The results of scientifc research, many now claim, debunk common sense beliefs: they show them to be false or at least to have dubious, untrustworthy origins. Debunking notwithstanding, it seems that we cannot do without common sense beliefs entirely. For arguably, science and the scientific method itself are built on, and continue to depend on, common sense.25 Science, as Susan Haack has reminded us, is itself “the long arm of common sense”.26 For example, we use common sense mathematical beliefs (2 +  1  = 3) and common sense logical beliefs (if A is incompatible with B, then B is incompatible with A) in construing arguments and in making calculations. Also, empirical science works with the common sense assumption that there is an external world. Many scientists regard evidence derived from their senses and their memory as innocent until proven guilty. And many contemporary psychologists and neuroscientists have the same attitude vis-à-vis introspective evidence. In the famous Libet experiments, experimenters take the introspective reports of test subjects about when they felt “the urge” or “decided” to move a finger or a wrist without much ado. Similarly, brain scientists studying which brain areas are connected with which mental functions, as in so-called location studies, rely on introspective reports of their test subjects. So we seem to be facing what may look like a paradox—let us call it ‘the paradox of science and common sense’. It consists of two claims that individually seem very plausible but cannot both be true. The first is that common sense must be relied on when we are doing science. The second is that science debunks common sense.

4 The Nature of Debunking Let us explain what debunking is supposed to be and how debunking arguments are thought to work. Debunking can be understood in terms of what many philosophers have called ‘defeaters’.27 Suppose you walk past your neighbor’s garden and see what you think is a dog. You know your neighbor owns a dog and accordingly form the belief that your

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neighbor’s dog is in your neighbor’s garden. The next day, however, your neighbor tells you that his dog has died a week ago. At that moment you obtain a defeater for your belief that yesterday you saw your neighbor’s dog in your neighbor’s garden. This is a rebutting defeater—what you learned from your neighbor (that her dog died a week ago) is inconsistent with the belief that you had formed the previous day. You should now deem that belief false as it is directly contradicted by what your neighbor has told you. Other defeaters work differently. Suppose you have learned how to use the Rohrschach test for measuring personality traits, and suppose you have put James to the test and have come to believe that James is an over-confident person. But later on, you figure out that psychometric researchers have strong evidence that the Rohrschach test is unreliable. Then your belief about James is not directly contradicted by what the psychometric researchers have found out. Your belief may still be true; James may indeed be over-confident. However, your belief is undercut by the psychometrics findings. You need not deem your belief false, but you now need to deem it to be without support, at least if your belief about James was exclusively based on the Rohrschach test. This is an undercutting defeater for your belief. Defeaters, then, are reasons for giving up a belief you hold. If you acquire a defeater, this puts you in a position in which you cannot rationally continue to hold your original belief—as long as that defeater is not itself defeated. Now, debunking arguments against common sense are arguments that present alleged defeaters for common sense beliefs—and these defeaters are either rebutting or undercutting. And science-based debunking arguments present common sense beliefs with defeaters that emerge from science: a scientific finding, for example, or a scientific theory. In general, such debunking arguments take the following form:28 (Causal premise) Common sense belief X is formed by process P. (Epistemic premise) Process P is off-track.29 Hence, belief X lacks positive epistemic status. Science can inform both the causal premise and the epistemic premise. For example, scientists have drawn on evolutionary theory and evolutionary psychology to propose explanations of our moral and religious beliefs (see Chapters 11 and 12 as well as 13 and 14). Similarly, they have drawn on neuroscience, cognitive science, or (evolutionary) psychology to explain why people believe they have free will (see Chapters 7 and 8). Such scientifc accounts lend support to specifc instances of the causal premise. It is the epistemic premise, however, that is supposed to do the real work of debunking. If a belief is formed by an off-track process, that

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means it’s either false (a rebutting defeater) or else unreliably formed and thus probably false and, if true, only luckily so (an undercutting defeater). Both options spell doom for the epistemic status of the belief in question. Different parts of science have given rise to both forms of the epistemic premise. For common sense beliefs that involve physics, free will, or introspection, science-based challenges typically seek to establish directly that these beliefs are false because they contradict presumed scientifically established truths. Psychological and neuroscientific experiments, for instance, suggest that allegedly free choices actually originate in brain activity that determines what choice will be made well before the agent becomes consciously aware of making a choice (cf. Pim Haselager’s contribution [Chapter 7]). The Eddington quote about the two tables can be read in the same way: physics directly shows our common sense beliefs to be false. For moral and religious beliefs, however, this direct route is unavailable because science is not in the business of directly disproving moral or religious beliefs. Hence, it is typically argued that science shows our moral and religious beliefs are unreliably formed: the belief-forming processes giving rise to moral and religious beliefs aren’t aimed at truth but at other goals, such as survival, self-preservation, or social cohesion. This is the sort of strategy we encounter in Chapters 9, 11, and 13. The two strategies can be combined, too: one can both argue that science gives us direct reason to think some common sense belief is false and supplement this with a scientific account of the process through which that belief is formed, which implies that the process is unreliable. This happens, for instance, when it is argued that neuroscience shows belief in free will to be false and that there is also an evolutionary explanation for why we nonetheless believe in free will (because, say, it’s an adaptive illusion or a by-product of other cognitive processes).30 Because the basic form of the debunking argument described here is logically valid, responses to it can contest either the causal premise or the epistemic premise or both. To undermine the causal premise, one can either propose alternative explanations of where a common sense belief comes from or point to shortcomings in the proposed scientific account of the origins of a common sense belief. Take the example of moral beliefs again: some people have responded to evolutionary explanations of moral beliefs by arguing that the influence of biological evolutionary processes on moral beliefs is negligible and that, instead, moral beliefs arise from cultural influences and conscious rational reflection on morality.31 These processes, it is then argued, are by no means off-track; or at least we lack reason to think so. Aku Visala (Chapter 14) takes a structurally similar approach in his response to Davis’s case against the epistemic rationality of religious beliefs. Others have leveled specifically scientific criticisms at the way evolutionary theory or evolutionary psychology is used to explain moral beliefs, thus undermining the causal premise.32 Similarly, the science behind free will denialism has been contested.33 Tim

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O’Connor’s contribution (Chapter 8) and Fleur Jongepier and Quassim Cassam’s contribution (Chapter 10) are examples of this strategy. What these authors in effect present are defeater defeaters. The epistemic premise, in turn, can be resisted in two ways—first, by arguing that the process responsible for a common sense belief is, perhaps despite first appearances, ontrack after all. For the case of religious beliefs, for instance, it has been argued that the fact that religious belief develops naturally and easily through processes shaped by evolutionary forces has no implications for the reliability of these processes. If God exists, it stands to reason that he would want people to form religious beliefs, and letting these beliefs develop by way of evolutionary processes seems as good a solution as any.34 For moral beliefs, so-called third-factor explanations propose that there is a common factor correlated with both our evolutionarily shaped moral beliefs and moral truths so that our moral beliefs are reliably formed after all.35 David Enoch,36 for example, has suggested that survival or reproductive success tends to be morally good so that evolutionary forces aimed at survival at the same time guide us toward moral truths. The second way to resist the epistemic premise is to cast doubt on the science that is supposed to show that the process is off-track or the relevant common sense belief is false. What distinguishes this strategy from resistance to the causal premise discussed is that, here, one would attempt to show that the scientific account of where a common sense belief comes from might be compelling as such but that it doesn’t entail that the common sense belief in question is false or unreliably formed. This can be done by making an argument that the process giving rise to the common sense belief is on track, as discussed in the previous paragraph, or, less ambitiously, by arguing that the relevant science doesn’t give us enough reason to think the process is off-track or the belief false.37 Finally, in some cases, common sense thinkers might be happy to accept a debunking argument but reply that the allegedly debunked common sense beliefs in question have been misconstrued so that the argument doesn’t really affect common sense on closer inspection. In the case of Eddington’s two tables, for instance, it wouldn’t seem far-fetched to propose that common sense was never committed to holding that the underlying physical nature of a table was massive and impermeable but that it looks that way to the human eye and behaves that way in the broad range of normal everyday interactions with it.38

5 Relevance Why does it matter what the challenges from science to common sense and common sense philosophy are and whether or not they can be overcome? First, science can sometimes debunk common sense, but as we have pointed out, it simultaneously cannot do without common sense. The

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paradox that this combination of observations gives rise to needs to be addressed if we want a clearheaded and rationally tenable view of the status and authority of both common sense and science. Second, common sense faculties might be more reliable in one area (say, morality) than in other areas (say, in physics). A defensible common sense philosophy thus requires a nuanced and textured account of the authority of common sense in different areas of thought and life. Thus, this volume will help fine-tune the common sense tradition by taking science seriously and exploring in which areas of thought and life common sense is reliable and in which not. This should strengthen the credentials of common sense philosophy. Third, we noted that common sense philosophy has a venerable tradition, but if it is to have a future as well, it needs to be revisited and, possibly, revised in light of contemporary questions and challenges. Because several of the scientific challenges that this volume discusses have only emerged in the past two to three decades, this is a good time to undertake the task of reevaluating the merits of common sense philosophy. It would be unfair to say this volume is the first to address these challenges, it is—as far as we know—this first that does so with an explicit eye on the viability of the common sense tradition in philosophy. Fourth, scrutinizing scientific challenges to common sense also has relevance outside academia. As one of us has documented previously,39 many bestselling popular science books propose grand debunking stories to the effect that contemporary science has shown some of our central, cherished common sense beliefs false. In previous work, we have laid bare and evaluated the often implicit scientistic epistemology behind such claims40 but without paying special attention to the foundations and status of common sense beliefs. By investigating scientific challenges to common sense head-on, the present volume also speaks to popular science books that allege that science has shown that we can no longer believe in free will, rationality, objective morality, or religion. Because we believe a well-informed and scientifically literate public is important to the well-being of liberal democracies, the task undertaken by the present volume matters.

6 Overview of the Book The book sets out with an exploratory essay by one of today’s leading common sense philosophers, Noah Lemos. The focus of the essay is on how science provides challenges to common sense philosophy. 6.1 Common Sense and Physics In their contribution to this book, Kelvin McQueen and Lev Vaidman explore the so-called many worlds interpretation of quantum

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mechanics—often held to be a paradigmatic anti-commonsensical view. The many worlds interpretation of quantum mechanics states that the world we live in is one among many parallel worlds. It is widely believed that because of this commitment to parallel worlds, the many worlds interpretation violates common sense. Some go so far as to reject the many worlds interpretation on this basis. This is despite its myriad of advantages to physics (e.g., consistency with relativity theory, mathematical simplicity, realism, determinism, etc.). Here, they make the case that common sense in fact favors the many worlds interpretation. They argue that causal explanations are commonsensical only when they are local causal explanations. They present several quantum mechanical experiments that seem to exhibit nonlocal ‘action at a distance’. Under the assumption that only one world exists, these experiments seem immune to local causal explanation. However, they show that the many worlds interpretation, by taking all worlds together, can provide local causal explanations of the experiments. The many worlds interpretation therefore restores common sense to physical explanation. In their reply to this essay, Meir Hemmo and Orly Shenker aim to show that in the many worlds interpretation, explanations of measurement outcomes are local in one world; they require causal influences that travel across different worlds. They take this conclusion to be one example of how this interpretation, if true, shutters our common sense intuitions about reality, like all other interpretations of quantum mechanics. They further argue that the local nature of our experience is not derivable in the many worlds interpretation from the Hilbert space structure but has to be added to it as an independent postulate. This is due to what they call the factorization symmetry and basis symmetry of Hilbert space. This need for additional structure or postulate makes the many worlds interpretation methodologically on a par with collapse and hidden variables interpretations of quantum mechanics. 6.2 Common Sense and Metaphysics According to Yuri Balashov, debates about material coincidence tend to start with common sense intuitions but quickly leave them behind, only to lead to highly problematic conclusions. Reconciling these conclusions with common sense is, according to him, the next stage in the process, which often requires revision of some of the initial beliefs. This procedure has been used to adjudicate many rather abstract and technical proposals in the metaphysics of composition and persistence, ranging from natural (constitutionalism) to radical (nihilism). Balashov does not disagree with this overall strategy: theories do need to turn abstract at some point, move beyond common sense, and eventually force upon us interesting, novel, and often counterintuitive revisions in our overall conceptual scheme. This applies to all theoretical areas, and contemporary

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metaphysics is no exception. But although the latter is widely regarded as being quite extreme in this respect, Balashov argues that in one sense, it is not extreme enough. He does so by developing a new case of material coincidence that is initially motivated not by common sense but by physical considerations and is not susceptible to any of the standard solutions. In response, Peter van Inwagen argues that the so-called problems of material coincidence can be framed and discussed without reference to the properties of the allegedly coincident things—and can a fortiori be framed and discussed without reference to the non-categorical properties of those things. For example, to deduce ‘~Lump = Vase’ from ‘Lump existed at noon yesterday’ and ‘~Vase existed at noon yesterday’, one need not suppose that there is a property such as ‘having existed at noon yesterday’. It suffices to point out that ‘xy (x existed at noon yesterday & ~y existed at noon yesterday .  ~x = y)’ comes from a theorem of quantifier logic with identity—‘xy (Fx & ~Fy.  ~x = y)’—by substitution of the one-place predicate ‘1 existed at noon yesterday’ for the one-place schematic predicate letter ‘F’. 6.3 Common Sense, Free Will, and Neuroscience In his essay, Pim Haselager investigates the possibilities of revising our understanding of free will and intentional action in the light of recent research in cognitive neuroscience. He investigates free will as intrinsically connected to responsibility for action rather than as the ability to do otherwise. A neurocentric approach, he argues, is to be rejected in favor of an embodied approach to free will. All the same cognitive neuroscience is important because it helps indicate how free will can be understood in a way that supports our social practice of attributing responsibility in a meaningful way. He explores the possibility that being free finds its basis in the possibility of flexible responses to internal and external stimuli, whereas intentions may find their most concrete implementations in socially relevant reports rather than in brain states. According to Haselager, common sense tells us that there is free will, but not exaclty what it amounts to, so that the common sense conception of free will is compatible both with libertarianism and compatibilism. Tim O’Connor takes on Haselager to argue that contemporary science and philosophical reflection together give us reason to revise our common sense experience and conception of human action as an exercise of autonomous, causally undetermined control. The aim of his response is to rebut this argument. He suggests that our common sense conception of action is internally coherent and can be comfortably integrated with the sciences of human action to date. The currently fragmentary findings of psychology and neuroscience reveal greater complexity to the processes constituting human action than the broad template that introspection indicates, but they can be smoothly mapped onto it. It would follow that

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the default status of common sense philosophy implies that we remain justified in our pre-theoretical understanding of ourselves as free and morally responsible agents. 6.4 Common Sense, Rational Action, and Psychology The chapter by Brett Pelham, Michael Harding, and Curtis Hardin focuses on what the authors take to be two surprising psychological truths. First, people often have little or no access to many of their own thought processes. Second, free will is a comforting illusion. They marshal both philosophical and psychological arguments in favor of these views. For example, they summarize Nietzsche’s arguments that people have limited access to their own inner lives as well as Hobbes’s critique of ‘deliberate desire’. Along more psychological lines, they summarize modern empirical work on topics as diverse as the phoneme restoration effect, automatic thinking, the preferences of split-brain patients, and implicit (unconscious) social cognition. From laboratory studies of walking speed to field studies of marriage and career choice, there is good evidence, they argue, to think that many of our decisions are driven by forces of which we are completely unaware. A large body of modern psychological research thus reveals sharp limits on how much freedom people have to make autonomous, self-directed choices. Research in this same tradition also reveals how prone people are to adopt the illusion of free will after the fact. They further suggest that people maintain a strong belief in free will (despite evidence to the contrary) because the belief in free will is highly comforting. In their reply, Fleur Jongepier and Quassim Cassam argue that the two main claims of Pelham and Hardis are independent of each other. They take these two claims to be that we don’t know our own mental states and that we don’t have free will. If one lacks free will because, say, all of one’s actions are controlled by an evil demon, it’s still possible for one to know that one believes it’s Friday or that one wants a cup of coffee. Conversely, it’s possible to have free will and to be radically self-deceived or ignorant about one’s mental states. They suggest that the authors take the two topics together because of their focus on (not) knowing why. If we don’t know why we think what we think, we lack self-knowledge; if we don’t know why we do what we do, we lack free will. In their reply, they argue that Pelham et al. fail to acknowledge that ‘knowing why’ one believes or does something is ambiguous between rationalizing and non-rationalizing explanations. As a result, the two dramatic claims do not follow in any straightforward sense once this ambiguity is properly recognized, or so they claim. 6.5 Common Sense Moral Belief and Evolutionary Explanations Michael Ruse explores whether Darwinian evolutionary explanations provide an undercutting defeater for moral common sense beliefs. He

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first points out that other than psychopaths and similar deviants, human beings, by and large, follow common sense morality. They are kind to children and help their neighbors in trouble. Darwinian evolutionary theory says that natural selection—survival of the fittest—is the reason why humans have evolved as they have, including their tendencies for behaving in accordance with common sense morality. That raises the issue of why common sense morality should have normative force. Ruse argues that there are good Darwinian reasons why common sense morality is, or perhaps we should say inevitably appears, binding. Humans are social animals, he says, and those who break the rules will be ostracized and pushed out of the group. Ruse acknowledges that the Darwinian does not think that there is any objective underpinning to morality but that it is binding nevertheless. If we did not ‘objectify’ morality, we would break the rules, and society would collapse in chaos. In reply, Regina Rini formulated the following worry: that Ruse’s position requires a form of existential bad faith, which is itself incompatible with our common sense self-conception. On Ruse’s view, morality appears to be an arational compulsion, overriding intelligible human motivations to advance the meaningless interests of genetic material. Even if this is an accurate description of morality, Rini argues, it is far from our common sense and requires a more substantive philosophical treatment than Ruse suggests. 6.6 Common Sense, Religious Belief, and Evolutionary Explanations In his chapter, Taylor Davis explores whether evolutionary explanations provide a defeater for common sense religious beliefs. Discussions of the epistemological consequences of the evolution of religion, he says, have been dominated by appeals to a branch of research known as the cognitive science of religion, which claims that religious beliefs have been directly favored by genetic selection and thus that cognitive biases for religious belief are universal features of human common sense. This has yielded a set of evolutionary-debunking arguments (EDAs) that seek to undermine the epistemic status of religious belief as well as responses to these arguments. However, the scientific study of religion has moved beyond the cognitive science of religion tradition. The most comprehensive and sophisticated theory of the evolution of religion available now, Davis suggests, is based on the dual-inheritance framework of human evolution, according to which the content of religious belief is primarily the result of cultural rather than genetic selection, and selection for theistic belief can be explained without appealing to genetic selection for such belief at all. As a result, the features of panhuman common sense responsible for producing religious beliefs may simply be capacities for cultural learning in general without any biases for theistic belief specifically. If so, says Davis, then the discussion of evolutionary-debunkding arguments

14 Rik Peels et al. needs to be revised. After first arguing that there is little evidence for specifically theistic cognitive biases, he discusses three responses to traditional, gene-based EDAs. In each case, he argues that once the relevant debunking argument is revised to appeal to cultural rather than genetic evolution, the reponses no longer succeed. Aku Visala’s response to Davis’s chapter has two parts. First, he voices his agreement with Davis’s assessment that cognitive science of religion has been too focused on biases that discriminate between representations on the basis of their content. The second part of the reply deals with debunking worries. Visala defends the evidentialist counterstrategy of Jong and Visala.41 He notes that Davis admits that the evidentialist strategy might work but only for a very small fraction of religious people— those who have access to relevant evidence. But according to Visala, the fraction might not be as small as Davis thinks because it may well be enough for religious people to have access to experts in possession of the relevant evidence. Because a principle of epistemic authority works for everyday scientific beliefs, it could work in the case of everyday religious beliefs as well. Finally, he suggests that Davis has not provided enough reasons to think that prosociality is the only possible selection factor in cultural evolution. That we discuss these scientific challenges—regarding quantum mechanics, metaphysics, free will, rational action, moral belief, and religious belief—is not to say that there are no further challenges from science to common sense and to common sense philosophy. First, for practical reasons (mainly having to do with brevity), certain areas of common sense are not covered in this book. For instance, we hold a variety of common sense beliefs that have to do with reading and interpretation: we believe that texts have meaning, that the primary meaning has to do with the author’s intention, and that we can know the meaning of many texts.42 Similarly, we have common sense beliefs about reliable access to some of our own mental states and about consciousness in general. For example, we take ourselves to reliably be able to identify what we believe, how we feel, and what our intentions are. We think we know that we are conscious and when we are. Yet, these beliefs are sometimes claimed to be false, typically with an appeal to science. Eric Schwitzgebel43 and Daniel Dennett44 argue that we are radically fallible and often misguided when it comes to our own phenomenal states.45 Others even go so far as to argue that consciousness is an illusion (Daniel Dennett,46 Alex Rosenberg,47 and Keith Frankish).48 Second, even within the areas that we do cover—physics, metaphysics, self-knowledge, morality, and religion—there are further challenges from science that we do not address. Thus, based on science, some have argued that rationality itself is an illusion, that the self is imaginary (there is no such thing as the self), that there are no spirits or souls (to the extent that that is part of common sense),49 that reality does not consist of physical

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stuff but of structures or quantum information (Erik Verlinde).50 Further exploration of these topics will have to wait until another occasion.51

Notes 1. See, for instance, Reid ([1764] 1997, [1785] 2002). 2. Accounts of Scottish common sense philosophy are provided by McCosh ([1875] 1990), Grave (1960), Broadie (2001), and McDermid (2018). 3. For example, Moore (1925, 1960, 1962a, 1962b). 4. For example, Chisholm (1977). 5. For example, Lycan (2001). 6. For example, Lemos (2004, 2008); see also his contribution to this volume. 7. This section and the next are lifted, with adjustments, from Van Woudenberg and Peels (2020). 8. See Richard Bett’s chapter in Peels and Van Woudenberg (2020). 9. For more on this, see Van Woudenberg (2020). 10. For example, Swinburne (2004, 293–327). 11. See McCain (2008). 12. Sober (2015). 13. Melamed and Lin (2018). 14. McIntyre (2019). 15. Sober (2015). 16. See Reid ([1785] 2002). 17. See Daley (2010, Chapter 1). 18. For further characterizations of common sense philosophy, see also Campbell (1988). Coady (2007), and Kelly (2008). 19. Moore (1925, 44). 20. Reid ([1764] 1997, 19). 21. Fumerton (1995) and Moser (1998); for a critical discussion of the objections, see Lemos (2004, 48–53, 122–128). 22. The following works argue that common sense and science are in tension with each other: Wolpert (1993), which bears the title The Unnatural Nature of Science; Cromer (1993), titled Uncommon Sense: The Heretical Nature of Science; and Watts (2011), titled Everything Is Obvious, Once You Know the Answer: How Common Sense Fails Us. 23. Eddington (1928, ix–x). 24. Sellars (1963). 25. The following authors argue for compatibility and continuity of science and common sense: Conant (1951), Oppenheimer (1963), Ziman (2000), and Peels (2018). 26. See Haack (2007). 27. See, for instance, Pollock (1984, 113). 28. Cf. Kahane (2011, 106). 29. A weaker version of the epistemic premise would be: ‘we lack non-questionbegging reason to believe process P is on-track’. As Vavova (2014) argues, however, that version of the premise quickly generalizes into a wide-ranging skeptical challenge. No doubt such a challenge, too, deserves a response, but it is not a distinctly science-based challenge to common sense and thus falls outside the scope of the present volume. 30. Wegner (2002) is an example of this two-barreled strategy. 31. FitzPatrick (2015). 32. Levy and Levy (2018). 33. Mele (2014).

16 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51.

Rik Peels et al. Clark and Barrett (2010) and Jong and Visala (2014). Copp (2008), Enoch (2010), and Wielenberg (2010). Enoch (2010). See Van Eyghen (2018). See Ranalli and De Ridder (2020) for further discussion of how ontologically committal common sense beliefs are. De Ridder (2014). De Ridder (2014) and De Ridder, Peels, and Van Woudenberg (2018). Jong and Visala (2014). See Van Woudenberg (2018). Schwitzgebel (2007, 2008). Dennett (2007). One of us has addressed this issue elsewhere; see Peels (2016). Dennett (1991). Rosenberg (2011). See Keith Frankish’s own contribution to Frankish (2017). Both claims are made in Rosenberg (2011). Verlinde (2017). We thank Alexandra Simmons for her helpful editorial assistance from the press. We also thank Mathanja Berger, Joris Koch, and Elisa Matse for taking care of all the practicalities of this volume, including composing the Index. We also thank various anonymous referees for commenting on one or more papers in this volume. This publication was made possible through the support of a grant from the Templeton World Charity Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the Templeton World Charity Foundation.

References Broadie, Alexander. 2001. The Scottish Enlightenment. Edinburgh: Birlinn. Campbell, Keith. 1988. “Philosophy and Common Sense.” Philosophy 63 (244): 161–174. Chisholm, Roderick M. 1977. Theory of Knowledge. 2nd ed. Englewood Cliffs: Prentice-Hall. Clark, Kelly James, and Justin L. Barrett. 2010. “Reformed Epistemology and the Cognitive Science of Religion.” Faith and Philosophy 27 (2): 174–189. Coady, C. A. J. 2007. “Moore’s Common Sense.” In Themes From G. E. Moore: New Essays in Epistemology and Ethics, edited by Susanna Nucetelli and Gary Seay, 100–118. Oxford: Oxford University Press. Conant, James. 1951. Science and Common Sense. New Haven: Yale University Press. Copp, David. 2008. “Darwinian Skepticism about Moral Realism.” Philosophical Issues 18: 184–204. Cromer, Alan. 1993. Uncommon Sense: The Heretical Nature of Science. New York and Oxford: Oxford University Press. Daley, Christopher. 2010. An Introduction to Philosophical Methods. Petersborough, ON: Broadview Press. Dennett, Daniel C. 1991. Consciousness Explained. Boston: Little, Brown. Dennett, Daniel C. 2007. “Heterophenomenology Reconsidered.” Phenomenology and the Cognitive Sciences 6 (1–2): 247–270. De Ridder, Jeroen. 2014. “Science and Scientism in Popular Science Writing.” Social Epistemology Review and Reply Collective 3 (12): 23–39.

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De Ridder, Jeroen, Rik Peels, and René van Woudenberg, eds. 2018. Scientism: Prospects and Problems. New York: Oxford University Press. Eddington, Arthur. 1928. The Nature of the Physical World. New York: MacMillan. Enoch, David. 2010. “The Epistemological Challenge to Metanormative Realism: How Best to Understand It, and How to Cope with It.” Philosophical Studies 148: 413–438. FitzPatrick, William. 2015. “Debunking Evolutionary Debunking of Ethical Realism.” Philosophical Studies 172 (4): 883–904. Frankish, Keith, ed. 2017. Illusionism as a Theory of Consciousness. Exeter: Imprint Academic. Fumerton, Richard. 1995. Metaepistemology and Skepticism. Lanham: Rowman and Littlefield. Grave, Selwyn A. 1960. The Scottish Philosophy of Common Sense. Oxford: Clarendon. Haack, Susan. 2007. Defending Science: Within Reason: Between Scientism and Cynicism. Amherst: Prometheus Books. Jong, Jonathan, and Aku Visala. 2014. “Evolutionary Debunking Arguments against Theism, Reconsidered.” International Journal for Philosophy of Religion 76 (3): 243–258. Kahane, Guy. 2011. “Evolutionary Debunking Arguments.” Noûs 45 (1): 103–125. Kelly, Thomas. 2008. “Common Sense as Evidence: Against Revisionary Ontology and Skepticism.” Midwest Studies in Philosophy 32 (1): 53–78. Lemos, Noah M. 2004. Common Sense: A Contemporary Defense. Cambridge: Cambridge University Press. Lemos, Noah M. 2008. “Moore and Skepticism.” In The Oxford Handbook of Skepticism, edited by John Greco, 330–347. New York: Oxford University Press. Levy, Arnon, and Yair Levy. 2018. “Evolutionary Debunking Arguments Meet Evolutionary Science.” Philosophy and Phenomenological Research. Published ahead of print, October 9. https://doi.org/10.1111/phpr.12554. Lycan, William. 2001. “Moore against the New Skeptics.” Philosophical Studies 103 (1): 35–53. McCain, Kevin. 2008. “The Virtues of Epistemic Conservatism.” Synthese 164 (2): 185–200. McCosh, James. (1875) 1990. The Scottish Philosophy, Biographical, Expository, Critical, from Hutcheson to Hamilton. Bristol: Thoemmes. McDermid, Douglas. 2018. The Rise and Fall of Scottish Common Sense Realism. Oxford: Oxford University Press. McIntyre, Alison. 2019. “Doctrine of Double Effect.” In The Stanford Encyclopedia of Philosophy (Spring), edited by Edward N. Zalta. https://plato.stanford. edu/archives/spr2019/entries/double-effect/. Melamed, Yitzhak Y., and Martin Lin. 2018. “Principle of Sufficient Reason.” In The Stanford Encyclopedia of Philosophy (Spring), edited by Edward N. Zalta. https://plato.stanford.edu/archives/spr2018/entries/sufficient-reason/. Mele, Alfred. 2014. Free: Why Science Hasn’t Disproven Free Will. New York: Oxford University Press. Moore, G. E. 1925. “A Defence of Common Sense.” In Selected Writings, edited by Thomas Baldwin, 106–133. London: Routledge. Moore, G. E. 1960. “Some Judgments of Perception.” In Philosophical Studies, by G. E. Moore. London: Routledge and Kegan Paul.

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Moore, G. E. 1962a. “Four Forms of Skepticism.” In Philosophical Papers, by G. E. Moore. London: Collier Books. Moore, G. E. 1962b. “Proof of an External World.” In Philosophical Papers, by G. E. Moore. London: Collier Books. Moser, Paul. 1998. “Epistemological Fission.” The Monist 81: 353–370. Oppenheimer, J. Robert. 1963. Science and the Common Understanding. New York: Simon and Schuster. Peels, Rik. 2016. “The Empirical Case against Introspection.” Philosophical Studies 173 (9): 2461–2485. Peels, Rik. 2018. “The Fundamental Argument against Scientism.” In Science Unlimited? The Challenges of Scientism, edited by Maarten Boudry and Massimo Pigliucci, 165–184. Chicago: University of Chicago Press. Pollock, John. 1984. “Reliability and Justified Belief.” Canadian Journal of Philosophy 14 (1): 103–114. Ranalli, Chris, and Jeroen de Ridder. 2020. “Common Sense and Ontological Commitment.” In The Cambridge Companion to Common-Sense Philosophy, edited by Rik Peels and René van Woudenberg. Cambridge: Cambridge University Press. Reid, Thomas. (1764) 1997. An Inquiry into the Human Mind on the Principles of Common Sense. Edited by Derek Brookes. Edinburgh: Edinburgh University Press. Reid, Thomas. (1785) 2002. Essays on the Intellectual Powers of Man. Edited by Derek Brookes. Edinburgh: Edinburgh University Press. Rosenberg, Alex. 2011. The Atheist Guide to Reality: Enjoying Life without Illusions. New York: W. W. Norton. Schwitzgebel, Eric. 2007. “No Unchallengeable Epistemic Authority, of Any Sort, Regarding Our Own Conscious Experience: Contra Dennett?” Phenomenology and the Cognitive Sciences 6 (1–2): 107–113. Schwitzgebel, Eric. 2008. “The Unreliability of Naive Introspection.” Philosophical Review 117 (2): 245–273. Sellars, Wilfrid. 1963. “Philosophy and the Scientific Image of Man.” In Science, Perception and Reality, by Wilfrid Sellars, 1–40. London: Routledge and Kegan Paul. Sober, Elliot. 2015. Ockham’s Razors: A User’s Manual. Cambridge: Cambridge University Press. Swinburne, Richard. 2004. The Existence of God. 2nd ed. Oxford: Clarendon Press. Van Eyghen, Hans. 2018. “Is Supernatural Belief Unreliably Formed?” International Journal for the Philosophy of Religion. Published ahead of print, May 5. https://doi.org/10.1007/s11153-018-9671-4. Van Woudenberg, René. 2018. “Reading as a Source of Knowledge.” Synthese. Published ahead of print, December 13. https://doi.org/10.1007/s11229-01802056-x. Van Woudenberg, René. 2020. “The Delineation of Common Sense.” In The Cambridge Companion to Common-Sense Philosophy, edited by Rik Peels and René van Woudenberg. Cambridge: Cambridge University Press. Van Woudenberg, René, and Rik Peels. 2020. “Introduction: Why Common Sense Matters.” In The Cambridge Companion to Common-Sense Philosophy, edited by Rik Peels and René van Woudenberg. Cambridge: Cambridge University Press.

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Vavova, Katia. 2014. “Debunking Evolutionary Debunking.” In Oxford Studies in Metaethics. Vol. 9, edited by Russ Shafer-Landau, 76–101. Oxford: Oxford University Press. Verlinde, Erik P. 2017. “Emergent Gravity and the Dark Universe.” SciPost Physics 2 (3): 16. Watts, Duncan. 2011. Everything Is Obvious, Once You Know the Answer: How Common Sense Fails Us. New York: Crown Business. Wegner, Daniel. 2002. The Illusion of Conscious Will. Cambridge: MIT Press. Wielenberg, Erik. 2010. “On the Evolutionary Debunking of Morality.” Ethics 120: 441–464. Wolpert, Lewis. 1993. The Unnatural Nature of Science. Cambridge: Harvard University Press. Ziman, John. 2000. Real Science: What It Is, and What It Means. Cambridge: Cambridge University Press.

2

Common Sense, Philosophy, and Science Noah Lemos

Some philosophers have held some rather startling views, views that run contrary to common sense. Among the ancients, for example, we find philosophers such as Zeno claiming that nothing moves, that all motion is an illusion. Other ancients declared that we do, in fact, know nothing. Perception, reason, and memory, they tell us, are simply incapable of yielding knowledge. In the modern age, we find Bishop Berkeley concluding from his philosophical principles that the only things that exist are immaterial minds and their ideas. Berkeley thus denies the existence of material objects and of a mind-independent reality. David Hume has followed Berkeley’s principles even further, arguing that we know nothing of material objects but also that we cannot know anything about the future or the past, other minds, or even that there is an enduring self, a thinking, perceiving self, that persists over time. For some philosophers, if their philosophical principles lead to a conflict with common sense, so much the worse for common sense. In opposition to this attitude, other philosophers have sided with common sense. The 18th-century philosopher Thomas Reid, a contemporary of Hume, held that that the conclusions of Berkeley and Reid were indeed contrary to our common sense beliefs, yet Reid held that these common sense beliefs were of greater weight and authority than the conclusions drawn by Berkeley and Hume and of greater weight and authority than the philosophical premises and assumptions from which they were drawn. Reid claimed that if their principles and conclusions were incompatible with these common sense beliefs, then we should abandon them in favor of our common sense beliefs. Reid is one of the earliest and most well-known members of what has become known as ‘the common sense tradition’ in philosophy, a tradition that includes the 20th-century philosophers, G. E. Moore and Roderick Chisholm. It is characteristic of the common sense tradition to take common sense beliefs as data for philosophical reflection and reject those philosophical views that conflict with them. A. C. Ewing was sympathetic to the common sense tradition in philosophy. Nevertheless, in a paper on common sense propositions, he asks

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why philosophers should be expected to pay so much respect to common sense. Why, he asks, should those who have studied philosophy alter their philosophical views because people who have never studied it think them wrong? What, he asks, would happen to the natural sciences if scientists had been forbidden to contradict the views that nonscientists held on scientific matters before they had studied science? He replies, “We should still be believing in a flat earth with the sun and all the stars going round it if people acted on those lines”.1 Essentially, the objection assumes that because it would be a mistake to reject scientific views that conflict with common sense beliefs, it would also be a mistake to reject philosophical views that do so. But is this so? What role should our common sense beliefs have in philosophical or scientific inquiry? Should they have any weight at all? And, if so, why? Moreover, what if scientific views do conflict with common sense beliefs? Suppose we concede that some common sense beliefs cannot be reasonably sustained in the face of scientific evidence; what are we to think when some scientists tell us that there are no publicaly observable objects or that given the theory of evolution we have no good reason to think that our moral beliefs or perceptual beliefs are likely to be true? Challenges to our common sense beliefs are not confined simply to philosophers. In this essay, I want to explain and defend the common sense tradition. I fear that much of what I say will be much too cursory, and I can only say in my defense that I have tried to address some of these issues at greater length elsewhere.2 In any event, I consider in the first section some main features of the common sense tradition. I consider briefly what it is for something to be a common sense belief and the scope of our common sense beliefs. I also note some views to which the common sense tradition is not committed. In the second section, I ask why any of our common sense beliefs should have the weight that members of the tradition take them to have. I will examine briefly three sorts of answers to this question. In the third section, I reply to some objections philosophers have raised against the appeal to our common sense beliefs. In the final section, I make some comments about the relationship between our scientific beliefs and some common sense beliefs. I note that some cases of apparent conflict between science and common sense are in fact conflicts between common sense beliefs and philosophical assumptions held by some philosophers and scientists.

1 Some Main Features of the Common Sense Tradition What is a common sense belief? I am not sure that there is any widely accepted answer to this question. I suspect the same is true for other sorts of beliefs, such as ‘scientific belief’ or ‘philosophical belief’. Others may

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understand the notion of a common sense belief differently, but I shall take a common sense belief to be either (i) a belief in a proposition that is deeply held by almost everyone or (ii) the self-attribution of a property that almost everyone attributes to him- or herself. Thus, the belief that there are other people is a common sense belief because it is the belief in a proposition that is deeply held by almost everyone. Similarly, my belief that I have a body is a common sense belief because it is the selfattribution of a property, the property of having a body, which almost everyone attributes to him- or herself. Other examples of common sense beliefs would be the belief that people think and feel, that they were born, and that they existed yesterday and my beliefs that I have hands, that I am alive, and that I was much smaller when I was born. What is the scope of our common sense beliefs? There are a great many common sense beliefs, and I am certain that I can’t list them all. Nevertheless, in addition to the examples just mentioned, they include epistemic claims. They include beliefs such as these: most people know that they have bodies, most people know that there are other people who think and feel, I know that I have body, I know that I have hands, and I know that I am alive. Almost everyone accepts the epistemic propositions that most people know they have bodies, and most people know that there are other people who think and feel. More generally, almost everyone accepts the proposition that people have knowledge. Similarly, almost everyone attributes to him- or herself the property of knowing that he or she has hands, knowing that he or she has a body, and knowing that he or she is alive. In addition to epistemic beliefs, there are also common sense beliefs about our own faculties. These include the beliefs that our memories, under certain conditions, are reliable; that perception, under certain conditions, is reliable; and that introspection, under certain conditions, is reliable. These principles about our faculties, or ones very similar to them, are what Reid calls ‘first principles of common sense’. They may not be consciously formulated, but they are accepted nonetheless. They guide our belief formation and the way we assess the testimony of others. I believe, then, that the scope of our common sense beliefs is quite large and includes epistemic beliefs and beliefs about our own faculties. I think it likely that it also includes some moral beliefs, perhaps the beliefs that some actions are right and some actions are wrong and that some things are good or bad or better than others. Perhaps it also includes beliefs that what we do is sometimes up to us, that sometimes we could have done otherwise, and that there is a God. In any event, we can distinguish two views concerning common sense beliefs an extreme view (EC) and a moderate view (MC): EC: All common sense beliefs are true. MC: Some common sense beliefs are true.

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I would say that some common sense beliefs are obviously true. Thus, it seems to me that MC is true. But what about EC? I, myself, see no reason to accept EC. EC seems to me no more reasonable than the claims that all scientifc beliefs are true or all philosophical beliefs are true. We know such claims about scientifc and philosophical beliefs are false, and there is no good reason to suppose that common sense beliefs fare any better in this regard than they do. Moreover, many philosophers in the common sense tradition who accept MC would not endorse EC. G. E. Moore, for example, in his “A Defense of Common Sense”, writes: [t]he phrases ‘Common Sense view of the world’ or ‘Common Sense beliefs’ (as used by philosophers) are, of course, extraordinarily vague; and for all I know, there may be many propositions which may be properly called features in ‘the Common Sense view of the world’ or ‘Common Sense beliefs’, which are not true, and which deserve to be mentioned with the contempt with which some philosophers speak of ‘Common Sense beliefs’. But to speak with contempt of ‘Common Sense beliefs’ which I have mentioned is quite certainly the height of absurdity. And there are, of course, enormous numbers of other features in ‘the Common Sense view of the world’ which, if these are true, are quite certainly true too: e.g. that there have lived on the surface of the earth not only human beings, but also many different species of plants and animals.3 Moore’s defense of common sense beliefs is clearly limited. Although he holds that some common sense beliefs are true and instances of knowledge, he is not committed to the view that all such beliefs are. If I am right about the scope of common sense beliefs, then to hold that no common sense beliefs are true, to accept not-MC, is to embrace a form of skepticism. This is because it is a common sense belief that people do, in fact, have knowledge. To hold that no common sense beliefs are true, and that this particular common sense belief is not true, is to accept the skeptical view that it is false that people know things. To hold that no common sense beliefs are true is to imply that there is no knowledge and, thus, no scientific knowledge. Moreover, to hold that no common sense beliefs are true is to deny that perception and memory are, under certain conditions, reliable. But if it were false that perception and memory are sometimes reliable, then it is hard to see how there could be any scientific knowledge at all. It seems to me, therefore, it is reasonable to hold that there is scientific knowledge only if one accepts MC, that some common sense beliefs are true. Furthermore, most of what anyone knows about science is based on the testimony of others. Scientific knowledge is the result of the collaborative efforts of large numbers of people who make use of the testimony

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of others. It is hard to see how one could coherently hold that we have scientific knowledge based on the testimony of others and deny the common sense claims that there are other people who think and know things. It would be like saying, “I know that Paris is in France because John told me so, but I have no idea whether John knows that, or anything at all, or even if he exists”. Philosophers in the common sense tradition accept not only MC, but they also accept this: MCK: Some common sense beliefs are instances of knowledge. Some common sense beliefs, such as the beliefs that there are other people, that they think and feel, that I have a body, and that I know that I am alive are instances of knowledge. Not only are they true, but we know them to be true. To accept MCK does not commit one to holding that there is a sui generis ‘faculty of common sense’ or that we know common sense propositions on the basis of such a faculty. Such a view is simply not to be found in Moore or Chisholm. Reid, of course, does refer to a faculty of common sense. It is not clear, however, that Reid considers it to be a sui generis faculty. Indeed, he suggests that “common sense” is “only another name for one branch or degree of reason”.4 Moreover, in holding that some common sense beliefs are instances of knowledge, we are not committed to the view that they are known in virtue of their being common sense beliefs or in virtue of their being deeply and widely held. We are not committed to the view that being deeply and widely held confers, or is a source of, any positive epistemic status on a proposition. But how do we know such things? What makes a common sense belief an instance of knowledge? Indeed, what makes any belief knowledge? Those, of course, are important epistemological questions. They are, however, far beyond the scope of this paper. I shall confine myself to making two general points. First, there are significant differences among the members of the common sense tradition such as Reid, Moore, and Chisholm concerning the nature of our knowledge of the external world, the past, and other minds. They have different epistemological views about how we know such things. But they would agree that one need not know how one knows such things to know them. They would say, for example, that I can know there are other people, and know that I do, without knowing how I do and certainly without having a well-developed theory about how such knowledge is to be had. Moore writes, “We are all, I think, in this strange position that we do know many things, with regard to which, we know further that we must have had evidence for them, and yet we do not know how we know them, i.e. we do not know what the evidence was”.5

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Second, the fact that some propositions are a matter of common knowledge is not without significance. If almost everyone has knowledge that there are other people, that they think and feel and know things, then there must be some way of knowing these things that does not rest on philosophical arguments or considerations grasped only by a handful of philosophers, and it can’t be the fruit of philosophical reasoning followed only by a philosophical elite. Whatever our account of knowledge, it must be adequate to the fact that such knowledge is widespread and common.

2 What Gives Some Common Sense Beliefs Their Weight? In describing the common sense tradition, Chisholm writes, “It is characteristic of ‘commonsensism’, as an alternative philosophical tradition, to assume that we do know, pretty much, those things we think we know, and having identified this knowledge, to trace it back to its sources and formulate criteria that will set it off from things we do not know”.6 We may say that the common sense tradition holds that we do know many of the things we ordinarily take ourselves to know, and our philosophical views should be adequate to the fact that we do know them. It holds that we may use much of what we take ourselves to know as data for developing and assessing philosophical theories and principles. Reid, too, takes such a stance. Reid took Hume’s empiricism to imply that we have no knowledge of the material world; no knowledge of the future, the past, or other minds; and no knowledge of ourselves as continuing subjects of experience. Reid took Hume to show that the wages of empiricism are a rather thoroughgoing skepticism. Reid writes: [a] traveller of good judgment may mistake his way, and be unawares led into a wrong track; and while the road is fair before him, he may go on without suspicion and be followed by others but, when it ends in a coal pit, it requires no great judgment to know he hath gone wrong, nor perhaps to find out what misled him.7 Reid held that because we do know many of the things that Hume’s empiricism would rule out, so much the worse for empiricism. We also find a similar theme throughout Moore’s writings. In his 1919 essay, “Some Judgments of Perception”, Moore begins by considering some views about perception and the possibility of perceptual knowledge. He rejects certain philosophical views because they imply that we cannot know facts about the external world: [b]ut it seems to me a sufficient refutation of such views as these, simply to point to cases in which we do know such things. This, after all, you know, really is a finger: there is no doubt about it: I know it, and you all know it. And I think we may safely challenge any

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Noah Lemos philosopher to bring forward any argument in favour either of the proposition that we do not know it, or of the proposition that it is not true, which does not at some point rest upon some premiss which is, beyond comparison, less certain, than is the proposition which it is designed to attack.8

Again, Chisholm takes a similar stance: [w]e reject the sceptical view according to which there is no reason to believe the premises of an inductive argument ever confer evidence upon the conclusion. If the skeptical view were true, then we would know next to nothing about the world around us.9 Chisholm holds that because we do know a lot about the world around us, so much the worse for skepticism about induction. But why should we take common sense beliefs as data and reject philosophical theories that clash with them? What gives these beliefs such weight? I would like to consider three sorts of answers defenders of common sense have sometimes offered. The first answer is suggested by Chisholm. He writes that in investigating the theory of knowledge from a philosophical point of view, we assume that what we know is pretty much that, which on reflection, we think we know. He goes on to say, “This might seem like the wrong place to start. But where else could we start”? As a defense of the common sense tradition, this does not seem compelling. Surely, there are alternatives one could adopt. One could, for example, follow a Cartesian model and confine one’s data to what is certain and indubitable, or one could confine one’s data to propositions about one’s own mental states. One cannot plausibly defend the common sense tradition on the grounds that it is the only approach available. A second answer can be found in the following striking passage from Reid’s Inquiry: [t]o what purpose is it for philosophy to decide against common sense in this or any other matter? The belief in a material world is older, and of more authority, than any of the principles of philosophy. It declines the tribunal of reason, and laughs at the artillery of the logician. It retains its sovereign authority in spite of all the edicts of philosophy, and reason itself must stoop to its orders. Even those philosophers who have disowned the authority of our notions of an external world, confess that they find themselves under a necessity of submitting to their power. Methinks, therefore, it were better to make a virtue of necessity; and, since we cannot get rid of the vulgar notion and belief of an external world, to reconcile our reason to it as well as we can; for, if

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Reason should stomach and fret ever so much at this yoke, she cannot throw it off; if she will not be the servant of Common Sense, she must be her slave.10 Reid claims that the belief in the material world is irresistible. He counsels us to “make a virtue of necessity”; because we can’t get rid of certain common sense beliefs, such as a belief in the existence of a material world, we should make our philosophical views ft these deeply held beliefs. Indeed, Reid often points to the diffculty of giving up certain sorts of beliefs and to the futility of skeptical arguments. In explaining why he does not ignore the testimony of his senses in the face of skeptical arguments, Reid says, “[B]ecause it is not in my power; why then should I make a vain attempt? . . . My belief is carried along by perception, as irresistibly as my body by the earth”.11 Here again Reid seems to be defending common sense beliefs on the basis of their irresistibility. The appeal to irresistibility, however, does not seem to be a satisfactory way of defending the common sense tradition. First, why would the irresistibility of such beliefs matter for assessing philosophical theories? The fact that a belief is irresistible might be an excuse for holding it, but it is not a good reason for holding it, and it would not be a good reason for rejecting other beliefs that conflict with it. Consider a bad habit that one cannot give up, such as smoking or overeating. Surely, one should not abandon one’s belief that such habits are unworthy of being indulged simply because one cannot give them up. It would be unreasonable to change one’s beliefs about the value of one’s habits simply because of a conflict between one’s beliefs and one’s deeply rooted habit. Why, then, should one abandon one’s philosophical beliefs simply because they conflict with beliefs that one cannot give up? Second, perhaps many common sense beliefs are irresistible. Perhaps this is true of beliefs such as there are bodies and there are other people, but as we have seen, the common sense philosopher also takes as data epistemic propositions, such as I know that I have a body and almost everyone knows that there are other people. But is it really clear that these epistemic propositions cannot be given up? Could one not hold, for example, “Yes, I have a body. I cannot give up that belief. But it isn’t something I know. Maybe it’s more likely than not, but I don’t know it”. It is not clear that all the propositions that common sense philosophers would take as data are irresistible. So, it is not clear that the common sense philosopher should point to irresistibility as what makes it reasonable for him or her to take common sense propositions as data.12 A third answer to the question “Why should some of our common sense beliefs have such weight?” is what I call the epistemic answer. According to this approach they have such weight because they are instances of knowledge and more reasonable to believe than the philosophical principles that conflict with them. The common sense philosopher may thus

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point to the positive epistemic status of the beliefs he or she takes as data. Reid, Moore, and Chisholm all hold that they know common sense propositions and that almost everyone knows them. Thus, Moore says he knows that this is a finger and that this proposition is more reasonable, and more certain, than the premises of skeptical arguments that imply that it is false. Similarly, Chisholm writes in defense of his theory of knowledge and his commonsensism, that “it corresponds with what we do know”.13 Reid, also, in the passage cited refers to the ‘authority’ of our belief in the material world. Indeed, he tells us that it has more authority than any of the principles of philosophy. The concept of ‘authority’ is a normative notion, and Reid is making a normative claim about such beliefs. He is not merely claiming that the belief in the material world is more firmly held, that it is irresistible, but that it is also worthy of being more firmly held, that it is more reasonable to believe. Here, then, we have a reply to Ewing’s question why philosophers should be expected to pay so much respect to common sense. It is because some common sense beliefs are instances of knowledge and they are more reasonable than the philosophical principles that compete with them. In his defense of Moore and the common sense tradition, William Lycan makes a similar point. Lycan claims that all skeptical arguments rest on some abstract metaphysical or epistemological principle that is doubtful: [j]ust as there is no such thing as an idealist argument that does not appeal to some metaphysical or epistemological principle that is simply assumed without defense, there is no such thing as a skeptical argument that does not do the same thing. Which is to say that there is no good reason to accept the argument; the unargued principle is only philosophy stuff.14 Lycan also claims, “No purely philosophical premise can ever (legitimately) have as strong a claim to our allegiance as can a humble common-sense proposition such as Moore’s autobiographical ones”.15 And again, “A metaphysician who claims to ‘just know’ that such an abstract principle is true (‘This is a deep intuition’) cannot be taken seriously”.16 Consider the following skeptical argument, one Moore himself entertained: 1 2 3

If I don’t know that I am not dreaming, then I don’t know that I have hands. I don’t know that I am not dreaming. Therefore, I do not know that I have hands.

Why should we think (1) is true? What supports that premise? Perhaps the skeptic will support (1) by appealing to some ‘principle of exclusion (PE)’, such as one of the following:

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(PE) One knows that p only if one can rule out (know to be false) any proposition q that one knows to be incompatible with one’s knowing that p. (PE’) One knows that p only if one can rule out (know to be false) any proposition q that is relevant to one’s knowing p and that one knows to be incompatible with one’s knowing that p. (PE’’) One knows that p only if one can show to be false any proposition one knows to be incompatible with one’s knowing that p. (PE’’’) One knows that p only if one can rule out (know to be false) any proposition one knows to be incompatible with p. Are any of these principles of exclusion as reasonable to believe as I know I am standing up or I know I have hands? Surely, the answer is no. Something similar may be said concerning the second premise of the argument. How might the skeptic support premise (2)? Skeptics have appealed to principles such as the following: (E1) One knows that p only if one’s evidence for p logically implies that p is true. (E2) If A’s evidence for p is not better than B’s evidence for q and A does not know p, then B does not know q. (E3) One knows that p only if one’s belief that p is sensitive. (One’s belief that p is sensitive just in case if p were false, one would not believe that p.) Again, are any of these principles as reasonable to believe as “I know have hands” or “I know that this is a fnger”? Again, the answer is surely no. Still, we must be careful not to overstate this position. Lycan says that no purely philosophical proposition can ever legitimately have as strong a claim to our allegiance as can a humble common sense proposition. But that does not seem quite right. The proposition that if S knows that p, then p, seems to be a philosophical proposition as reasonable to believe as many common sense propositions, including Moore’s autobiographical ones.17 Indeed, it might be more reasonable to believe than some common sense propositions. Philosophical propositions, like common sense propositions, can vary in their reasonableness. Moore need not claim that no philosophical proposition is as reasonable as his common sense claims. He need only hold that the common sense claims he appeals to are more reasonable than one or more of the philosophical propositions that underlie skeptical arguments. Still, we may wonder why the Moorean knowledge claims are more reasonable than the philosophical propositions. Of course, Moore might note that whereas it would be desirable to have an explanation for their greater reasonableness, we need not have such an explanation for them to be more reasonable or for us to know that they are. A satisfactory

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epistemological account of what makes one sort of belief more reasonable than another is not necessary for us to know, in some cases, that they are more reasonable. It is open, however, to Moore and other defenders of common sense to appeal to a familiar array of views to explain the greater reasonableness of his common sense claims over the competing philosophical principles. He might hold that we are more reliable about the former, that we are simply more reliable about whether we know that we have hands than we are about the sort of abstract philosophical principles to which the skeptic appeals. Alternatively, he may hold that the former cohere better with the rest of our beliefs. He might point to such factors or a combination of them to explain why his common sense beliefs are more reasonable. Consider coherence. Which coheres better with one’s total body of beliefs, the proposition that I know I have hands or some philosophical principle, such as PE’’ or E2? One’s total body of beliefs will include things such as I have hands, almost all human beings have hands, I am very good at identifying hands and other human appendages, almost everyone knows that he and others have hands, I see that I have hands, perception under the present conditions is highly reliable, and I and others know much about the world around us. If we wonder which coheres better with our total body of beliefs, can there be any serious doubt that it would be the Moorean common sense epistemic claims rather the philosophical propositions that underlie the skeptical argument? Of course, it might be held that reasonable belief requires more than coherence. Perhaps it will be urged that reasonable belief concerning p requires also that we be reliable with respect to p. But even if this were so, is there any good reason to think that the Moorean knowledge claims would fare worse? Moore may plausibly hold that we are far more reliable about humble epistemic propositions such as “I know this is a finger” than about the abstract philosophical principles underlying the skeptical arguments. About the former almost everyone is a competent judge, and there is much agreement. About the latter it is not clear that we are competent judges, and there is little agreement.

3 Philosophical Objections to the Common Sense Tradition The common sense tradition has faced a variety of objections. Sometimes it is objected that common sense beliefs can be false and unreasonable. Consider the following criticism: [i]ntuitive and common-sense judgments can be false, as a little reflection illustrates. Such judgments, furthermore, seem not always to be supported by the best available evidence. Consider, for instance, how various judgments of “common sense” are at odds with our

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best available evidence from the sciences or even from ordinary perception.18 Perhaps some common sense beliefs are epistemically shoddy, but there is no reason to think that is true of the particular common sense beliefs to which Moore, Chisholm, and Reid appeal. But as I have noted, philosophers in the common sense tradition need not endorse everything that might be properly called a common sense belief. As we have seen, Moore does not claim that all common sense beliefs are true or justifed. If there are good reasons for rejecting some common sense beliefs because they are ‘not supported by the best available evidence’ or at odds with ‘our best available evidence from the sciences or even from ordinary perception’, there is no reason whatsoever to reject Moore’s claims that I know this is a fnger or I know that there are other people on such grounds. Those particular claims don’t suffer from such defects. As we have seen, philosophers in the common sense tradition hold that they can pick out particular instances of knowledge and justification. Critics of commonsensism sometimes raise questions about the epistemic status of our particular epistemic judgments: [i]t is often left unclear what the epistemic status of the relevant preanalytic epistemic data is supposed to be. Such data, we hear, are accessed by “intuitions” or by “common sense”. We thus have some epistemologists talking as follows: “Intuitively (or commonsensically), justification resides in a particular case like this and does not reside in a case like that”. A statement of this sort aims to guide our formation of a notion of justification or at least a general explanatory principle concerning justification. A simple question arises: is such a statement self-justifying, with no need of independent epistemic support? If so, what notion of self-justification can sanction the deliverances of intuition or common sense, but exclude spontaneous judgments no better, epistemically, than mere prejudice or guesswork?19 This passage suggests that the common sense tradition holds that epistemic facts are accessed via ‘intuition’ or ‘common sense’. If this means that the common sense tradition holds that we know epistemic facts on the basis of a faculty of common sense or intuition, as we know about the past on the basis of memory, then there is no good reason to accept this claim. There is no good reason to think that Moore or Chisholm holds such a view. Although one might be able to make a stronger case that this is Reid’s view, it is not clear that this is his view either. Moreover, the commonsensist need not hold that particular epistemic judgments such as I know this is a fnger are self-justifying. He might hold that particular epistemic judgments are justifed in virtue of their cohering with

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one’s other beliefs, or because they are the product of a reliable cognitive faculty or intellectual virtue, or because they are appropriately related to what is given in experience. There are many candidates for sources of justifcation besides self-justifcation. Of course, what makes particular epistemic beliefs justified is an important problem for epistemology. But, as we have seen, Moore distinguishes knowing that some proposition is true from knowing how we know it or what makes it an instance of knowledge. Moore also holds that one can have the former sort of knowledge without the latter. Such a view seems plausible. Consider our knowledge of evaluative properties such as the beauty of a piece of music or the wrongness of an action. One might know that a particular piece of music is beautiful or that an act is wrong without knowing what makes it so. I might know, for example, that it would be wrong for me to kill my secretary now without knowing what makes it so. I might not know whether it is wrong because it fails to maximize utility or fails to treat her as an end or for some other reason. In any case, the common sense philosopher may agree that it is unclear what justifies our particular epistemic beliefs without denying that they are justified. Even if our particular epistemic judgments are problematic in the sense that we do not have a satisfactory explanation of what makes them justified, we need not deny that we know they are justified. Another objection often leveled against the common sense tradition is that it is question-begging. As we have seen, the common sense philosopher holds that skepticism implies that we know nothing about the external world, but because we know a great deal about the external world, for example, that this is a finger, skepticism is false. Such a reply is sometimes said to be question-begging insofar as it takes as a premise the very point that the skeptic is denying. When one takes as a premise a proposition that is denied by one’s philosophical opponent, one’s argument is not going to be persuasive. Indeed, one’s argument seems pointless. Again, consider the following objection by Moser: [q]uestions under dispute in a philosophical context cannot attract non-question-begging answers from the mere presumption of correctness of a disputed answer. If we allow such question-begging in general, we can support any disputed position we prefer. Simply beg the key question in any dispute regarding the preferred position. Given that strategy, argument becomes superfluous in the way circular argument is typically pointless. Question-begging strategies promote an undesirable arbitrariness in philosophical debate. They are thus rationally inconclusive relative to the questions under dispute.20 But here I think we should make three points. First, sometimes the point of an argument is not so much to persuade another person; it is rather to present (even if only to oneself) one’s reasons for believing something.

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The common sense philosopher might argue against the skeptic in his or characteristic way even if he or she knows that such reasoning will not settle the dispute or convince the skeptic to abandon his or her view. If this is so, then the common sense philosopher’s response to the skeptic is not pointless. It displays his or her reasons for rejecting skepticism. Second, even if an argument or a line of reasoning will not convince someone who doubts one of the premises, it might be nonetheless a cogent argument and one that provides one with reasons for believing the conclusion. Thus, if a detective asks suspect A why he or she believes that B is the killer, A might reply, “I know that the killer is either B or me. I know that I did not do it. Therefore, B is the killer”. Imagine that A knows every premise of his or her argument. A might know that B is the killer on the basis of such an argument. In presenting his or her argument, he or she displays sound cogent reasoning to the detective. Still, his or her argument might not convince the detective, who has no reason yet to exclude A. It might be rationally unpersuasive to the detective. Nevertheless, A’s argument is cogent and rationally conclusive in the sense that it gives him or her reason to accept the conclusion. Third, not to make use of what one knows in philosophical inquiries seems poor intellectual procedure. In trying to get to the truth in philosophical inquiry, one should use all one’s evidence. One’s evidence includes those things that we know, and this includes a great many common sense beliefs and humble Moorean propositions; for example, this is a finger, I know this is a finger, and so do others. Not to make use of one’s evidence is poor intellectual procedure and intellectually irresponsible. The common sense philosopher’s procedure in rejecting skeptical arguments because they conflict with what he or she knows is good intellectual procedure even if it begs the question against the skeptical or some other philosophical view.21 Of course, one might engage in some inquiry and confine one’s evidence to that which is certain and infallible. Perhaps such a restriction might be justified if one seeks truth and is especially averse to error. But we have seen how well that works out. Or perhaps one wants to pursue inquiry reasoning only from mutually accepted premises. Such a restriction might be justified on some grounds, perhaps a moral ground of conviviality or even mutual respect. What is admissible for evidence in inquiry can certainly be limited by moral or practical considerations, as in a trial where certain types of evidence are inadmissible. But it is not clear that that there are moral or practical reasons for not appealing to what we know in philosophical inquiries. One should search for the truth with both eyes open. Let us consider one further objection raised by Laurence BonJour: to accept commonsense convictions as Moore and other particularists do, does appear to rule out illegitimately even the possibility

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Noah Lemos that skepticism might in fact be true, that common sense might be mistaken. And, equally important, if this solution is taken at face value, it would have the effect of stifling or short-circuiting epistemological inquiry at least as effectively as would simply acquiescing to skepticism.22

Does the appeal to common sense as I have described it stife epistemological inquiry? That depends on what one takes to be involved in epistemological inquiry. It does not seem to stife the search for criteria of knowledge and justifcation. On the contrary, common sense philosophers such as Chisholm take the search for such criteria to be among the principle aims of epistemology. Even if we assume that we do know things about the world around us, we might wonder how we know them. We still might seek philosophical answers to that question. Furthermore, the common sense philosopher need not ignore skeptical arguments or consider them idle. He may take skeptical arguments seriously, attempting to identify what plausible, yet mistaken, assumptions yield skeptical conclusions. BonJour also objects that the appeal to common sense appears to rule out illegitimately the possibility that skepticism is true. But here we should be careful. Does it rule out the possibility that skepticism is true? Not if the relevant sense of possibility is that of ‘logical possibility’. Common sense philosophers such as Chisholm, Moore, and Reid grant that it is logically possible that skepticism is true. They grant that it is logically possible that we are deceived by evil demons or dream experiences and know next to nothing about the world around us. Still, they would deny that skepticism is ‘epistemically possible’ in the sense that, given what we know, it is reasonable to believe that skepticism is true. They would hold that because we do know much about the external world, it is not reasonable to accept skepticism about the external world. But they would deny that this is to rule out skepticism illegitimately.23

4 Common Sense and Science So far I have addressed the relationship between certain common sense beliefs and philosophical views. I turn now to consider briefly the relationship between scientific beliefs and certain common sense beliefs. Some scientific propositions are more reasonable to believe than some propositions that were once deeply and widely held. It is more reasonable to believe that the earth orbits the sun, that the earth spins, and that the sun is bigger than the earth. I assume the negations of these claims were once widely and deeply held. The scientific evidence against these views is overwhelming. At the same time there are a great many common sense beliefs that science has not shown to be false. These include many of the common sense

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beliefs mentioned above, for example, the beliefs that perception, memory, and introspection are, under certain conditions, reliable; that there are other people who think and feel; that we have bodies; and so forth. Not only has science not shown such beliefs to be false, but they are known to be true. We have a great deal of evidence for them. Furthermore, there is no good reason to think that there will be scientific evidence that shows that such beliefs are false. Indeed, it is hard to see how one could have good scientific evidence for denying that perception and memory are reliable under certain conditions. Indeed, what scientific experiments could provide sufficient evidence to show that it is now false that there are other people who think and feel and have bodies? Although science can show that certain deeply and widely held beliefs are mistaken, we must be on guard against claims that science conflicts with some common sense belief, when in reality, the conflict is actually between common sense and some philosophical view held by a scientist. To illustrate my point, imagine a philosopher or scientist who holds that all that really exists are only space-time points and, therefore, the common sense belief that there other people who think and feel is false. Would such a view be supported by purely scientific evidence? I don’t think so. It seems to me that such a view would depend crucially on certain metaphysical views, for example, about the ontological status of complexes and their constituents. Such a view might tell us that the only things that really exist are the fundamental entities of physics. It would imply not only that there are no people but that there are no stars or planets, or molecules or elements, or animals or plants. It would imply that the subject matters of astronomy, chemistry, and biology do not exist. I think such a metaphysical view is false. It is, as Lycan says, “only philosophy stuff”. If the common sense philosopher rejects the view that only space-time points exist, he is not really rejecting a scientific claim; he is rejecting a metaphysical thesis and one that it is far less reasonable to believe than the proposition that there are other people. Another sort of example involves not an imaginary philosopher but a real one. In an exchange with Ernest Nagel, Bertrand Russell writes, Mr. Nagel asserts with a passion that he has seen tables, but he adds that he means this in the sense in which we ordinarily use the words “see” and “table”. I might agree if we take the phrase “see a table” as a whole. . . . My objection is that the phrase, as commonly understood, involves false metaphysics. . . . . What I see has secondary properties recognized since Locke as not belonging to the physical object, and primary qualities concerning which the same has been recognized since Berkeley-or since Kant, by those who dislike Berkeley. Common sense says: “I see a brown table”. It will agree to both the statements: “I see a table” and “I see something brown”. Since, according to physics tables have no colour, we must either (a) deny

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Noah Lemos physics, or (b) deny that I see a table, or (c) deny that I see something brown. It is a painful choice; I have chosen (b), but (a) or (c) would lead to equal paradoxes”.24

Russell holds that the common sense view that one sees a brown table is mistaken, and he denies that he sees a table. We can take Russell to be arguing as follows: (1) I see something brown. (2) No table is brown. Therefore, (3) I do not see a table. Why does Russell accept (2)? He gives two reasons. First, he appeals to the metaphysical view that colors are secondary properties that do not belong to physical objects. According to his understanding of this metaphysical doctrine, colors are properties of sense data or sensations.25 They are mind dependent. Second, Russell appeals to physics. He says that according to physics, tables have no color. We have here an alleged example in which the common sense view that one sees brown tables conflicts with science. But is this really so? Russell appeals to the philosophical view that colors are properties of sense data or sensations to support his view that no table is brown. He also claims that this view is supported by physics. Here I would make four points. First, if the metaphysical view that Russell accepts is correct, then his premise that no table is brown is true. But, then, if the metaphysical thesis is true, his view does not need the support of physics. The metaphysical claim would suffice to support premise (2). Second, it is far from clear, however, that his metaphysical view is correct. One might hold, correctly I think, that colors are properties of physical objects. Such is Reid’s view, who writes, All people who have not been tutored by modern philosophy understand by color, not a sensation of the mind, which can have no existence when it is not perceived, but a quality or modification of bodies, which continues to be the same whether it is seen or not.26 On Reid’s view, the colors of things persist when they are not seen and do not go away when we turn out the lights. If this view of color is correct, and again, I believe it is, then Russell’s claim that no table is brown is false. Third, which of these two views about color is correct? If the matter is a clash between two philosophical views about the nature of color, then it seems to me that the Russell’s philosophical thesis is less reasonable to believe than the claim that I see a table. The philosophical thesis that no physical object has color is less reasonable to believe than the claim that I see a table. Finally, Russell claims that his view is supported by physics. I do not think that this is true. Does physics really support the claim that colors

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are properties of sense data or sensations over the claim that they are properties of physical objects? What experimental evidence from physics supports the one claim over the other? No doubt there are physicists and other scientists who have accepted the same metaphysical doctrine as Russell, but that does not show that there is scientific evidence that supports the one view over the other. The view is found, as Russell notes, in Locke, Berkeley, and Kant. But those illustrious thinkers present no evidence from physics or any actual scientific evidence that supports it. Even Homer nods, and Russell followed his premises intrepidly to the coal pit. However, it was not science that paved the way but bad philosophy, or mere philosophy stuff, cloaked as science. Science can tell us a lot about our world. It can expand our knowledge and explain many things that are matters of common sense knowledge. It can tell us more precisely under what conditions perception and memory are reliable. It can tell us what properties in bodies cause us to have the sensations of color that we do. It can overturn beliefs deeply and widely held. But when it purports to do so, the wise person will ask whether it does so on the basis of weighty evidence or not and whether it does so on the basis of claims less reasonable than the common sense beliefs they are designed to attack.

Notes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.

Ewing (1973, 367). Lemos (2004). Moore (1959, 33–34). Reid (1969, Essay VI, Chapter II, 567). Reid (1969, Essay VI, Chapter II, 45). Chisholm (1982, 113). Reid (1983, 11). Moore (1960, 228). Chisholm (1973, 232). Reid (1983, 4). Reid (1983, 85). For a more detailed discussion of the argument from irresistibility, Strawsonian ‘naturalism’, and Wittgensteinian ‘hinge propositions’, see my Common Sense (Lemos 2004, 13–23). Chisholm (1977, 121). Lycan (2001, 41). Lycan (2001, 41). Lycan (2001, 40). Earl Conee makes this point. See Conee (2001, 56). Moser (1998, 364). Moser (1998, 363). Moser and vander Nat (1995, 27). For an excellent discussion of these issues, see Kelly (2008). See also Lemos (2004, Chapter 1). BonJour (2002, 265).

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23. For sympathetic and more detailed treatments of the common sense tradition’s response to skepticism, see Sosa (1999), Lycan (2001, 41), Lemos (forthcoming), and Lemos (2004). 24. Russell (1973, 634–635). 25. Russell takes the claim that colors are secondary qualities to imply that physical objects do not have colors. It is not clear that secondary qualities should be understood this way, and it is not clear that this is how Descartes and Locke understood them. Barry Maund writes, “Descartes and Locke, for example, think that there are no colors in the physical world—no colors, as we ordinarily and naively understand them to be. But they are also widely interpreted as holding a secondary quality view of colors, i.e., holding the view that colors are powers or dispositions to cause experiences of a certain type”. If secondary properties are understood as powers or dispositions of physical objects to produce certain sensations, then they are properties of physical objects. See Maund (2012). 26. Reid (1983).

References BonJour, Laurence. 2002. Epistemology. Lanham: Rowman and Littlefield. Chisholm, Roderick M. 1973. “On the Nature of Empirical Evidence.” In Empirical Knowledge: Readings from Contemporary Sources, edited by Roderick M. Chisholm and Robert J. Swartz, 224–249. Englewood Cliffs: Prentice-Hall. Chisholm, Roderick M. 1977. Theory of Knowledge. 2nd ed. Englewood Cliffs: Prentice-Hall. Chisholm, Roderick M. 1982. The Foundations of Knowing. Minneapolis: The University of Minnesota Press. Conee, Earl. 2001. “Comments on Bill Lycan’s ‘Moore against the New Skeptics’.” Philosophical Studies 103 (1): 55–59. Ewing, A. C. 1973. “Common Sense Propositions.” Philosophy 48: 363–379. Kelly, Thomas. 2008. “Common Sense as Evidence: Against Revisionary Ontology and Skepticism.” Midwest Studies in Philosophy 32: 53–78. Lemos, Noah. 2004. Common Sense: A Contemporary Defense. Cambridge: Cambridge University Press. Lemos, Noah. Forthcoming. “Moore and Skepticism.” In The Oxford Handbook of Skepticism, edited by John Greco, 330–347. New York: Oxford University Press. Lycan, William. 2001. “Moore against the New Skeptics.” Philosophical Studies 103 (1): 35–53. Maund, Barry. 2012. “Color.” In The Stanford Encyclopedia of Philosophy (Winter), edited by Edward N. Zalta. https://plato.stanford.edu/archives/win2012/ entries/color/. Moore, G. E. 1959. “A Defence of Common Sense.” In Philosophical Papers, by G. E. Moore, 32–59. London: George Allen and Unwin. Moore, G. E. 1960. “Some Judgements of Perception.” In Philosophical Studies, by G. E. Moore, 220–252. London: Routledge and Kegan Paul. Moser, Paul K. 1998. “Epistemological Fission: On Unity and Diversity in Epistemology.” The Monist 81 (3): 353–370. Moser, Paul K., and Arnold vander Nat. 1995. Human Knowledge: Classical and Contemporary Approaches. Oxford: Oxford University Press.

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Reid, Thomas. 1969. Essays on the Intellectual Powers of Man. Cambridge: MIT Press. Reid, Thomas. 1983. Inquiry and Essays. Edited by Ronald E. Beanblossom and Keith Lehrer. Indianapolis: Hackett. Russell, Bertrand. 1973. “A Reply to Ernest Nagel.” In A Modern Introduction to Philosophy, edited by Paul Edwards and Arthur Pap. 3rd ed. New York: The Free Press. Sosa, Ernest. 1999. “How to Defeat Opposition to Moore.” In Philosophical Perspectives. Vol. 13, edited by James Tomberlin, 141–153. Cambridge: Blackwell.

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How the Many Worlds Interpretation Brings Common Sense to Paradoxical Quantum Experiments Kelvin J. McQueen and Lev Vaidman

1 Introduction The purpose of explanation is to help us understand why things happen as they do. Typically, one explains an event by citing the causes of that event. For example, to explain why the window broke, one might cite the throwing of a stone. A particularly compelling and natural type of causal explanation is local causal explanation. In a local causal explanation, there is spatiotemporal continuity between the cause and the explained effect. For example, the thrown stone explains the broken window in part because the stone traces out a continuous trajectory from the stone thrower’s hand to the window. In opposition to local explanations are nonlocal explanations. Nonlocal explanations involve ‘action at a distance’. Nonlocal explanations are rare in everyday life. Familiar cases are purported cases of psychokinesis, for example, when people claim to bend spoons with their minds. If one explains the bending of a spoon in terms of an individual’s mental effort, then one is offering a nonlocal explanation because there is no spatiotemporally continuous series of causes and effects connecting the mental effort and the spoon bending. Common sense rejects such nonlocal explanations and presumes a hidden local cause of the spoon bending. And there is a good reason for this. A nonlocal explanation of X in terms of Y only tells us that X happens given Y. But an explanation should enable us to understand why X happens given Y. This is what local causal explanations offer. We understand why the window broke given the stone throw because we understand the spatiotemporal continuity between the cause and the effect. Thus, if any type of explanation deserves to be called ‘common sense explanation’, it is local causal explanation. The point is a general one and is not specific to macroscopic objects. Whether we scale up to planets and galaxies or scale down to elementary particles, a causal explanation that leaves behind ‘gaps’ in spacetime will in turn leave behind gaps in our understanding. Presumably this is why Einstein famously referred to action at a distance as ‘spooky’ (Einstein, Podolsky, and Rosen (1935 ).

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In philosophy, there is an approach known as the common sense tradition. This approach takes common sense beliefs as data for philosophical reflection and rejects those philosophical views that conflict with them (Lemos, Chapter 2, this volume). Here, we employ a similar approach in the context of physics. In particular, we argue that locality is a necessary condition for causal explanations to be commonsensical. We then take it as a requirement on an adequate physical theory that it be able to offer local causal explanations of all experimental outcomes. In the next section, we discuss how the demand for local causal explanation shaped classical physics. In Section 3, we introduce quantum physics in the context of a simple experiment, which although strange, can be explained locally. We then specify three refined common sense principles of locality. These principles are satisfied by classical physics and by the simple quantum experiment. However, in Sections 4 and 5, we present several quantum experiments that do seem to violate the principles and therefore defy common sense. Finally, in Section 6, we show that common sense can be restored to quantum theory if we adopt the many worlds interpretation (MWI). We show how the MWI is capable of giving local causal explanations of all these experiments. We conclude by discussing the significance of our results to debates over the interpretation of quantum mechanics. In particular, many reject the MWI by an appeal to common sense. As one philosopher puts it, “The most obvious disadvantage is that its burgeoning world of duplicate histories seem repugnant to common sense” (Papineau, 1995, 239). We will argue that our results suggest the contrary, that the advantages to common sense that the MWI provides outweigh its disadvantages.

2 Common Sense Explanation in Classical Physics The philosopher of science W. V. O. Quine once said, “Science is not a substitute for common sense but an extension of it” (Quine, 1957, 229). Accordingly, physicists seek local causal explanations of the motions of physical objects. This is clear in classical physics. For example, in Newtonian mechanics a body’s motion in a given region and time is explained by a force applied at that region and time. The exception is Newton’s law of gravitation. According to this law, a planet’s motion at a time is explained by a force applied by a distant planet at that time. However, Newton himself described this action at a distance as an “absurdity” and proclaimed the source of gravitational forces to be “hitherto unknown”. In fact, Newton went so far as to say, Tis inconceivable that inanimate brute matter should (without the mediation of something else which is not material) operate upon and

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Kelvin J. McQueen and Lev Vaidman affect other matter without mutual contact. . . . [T]hat one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it (Newton, 2004, 102–103).

Newton’s appeal to “a competent faculty of thinking” is an appeal to common sense. Newton is then proclaiming that his theory of gravity cannot offer any commonsensical explanation of gravitational motion because it cannot offer a local causal explanation. (For recent debate over Newton’s views on action at a distance, see Ducheyne 2014). Later, Newton’s law was understood in local terms by adding the concept of a gravitational field created by massive bodies. Classical (i.e., non-quantum) physics, then, describes point particles (‘point-masses’) and fields spread out in spacetime. The point-masses create the fields that propagate with finite velocity. The motions of the point-masses are then affected locally by the fields of other point-masses. This physical ontology, together with Newton’s laws, Maxwell’s electromagnetic theory, and relativity theory, provides local explanations of many things we see around us. The common sense picture of classical physics ultimately consists of the motions of particles on continuous trajectories and the continuous propagation of waves with multiple trajectories, which includes the local phenomena of (constructive and destructive) interference. The motion of particles and the propagation of waves provide (common sense) causal connections. This includes continuous traces that moving particles and propagating waves leave behind in their local environments. The continuous propagation of waves and their local causal effects are illustrated by the Mach-Zehnder interferometer (MZI) (Zehnder, 1891; Mach, 1892); see Figure 3.1. The electromagnetic wave (i.e., the photon) splits at the beamsplitter, passes through two arms of the interferometer and reunites at the second beamsplitter. The reuniting of the waves creates interference, which leads to observable effects. When the interferometer is properly tuned, only detector D2 detects light. This is due to constructive interference toward D2 and destructive interference toward D1. If the distance of one path is lengthened by half of the wavelength of the electromagnetic wave, then only detector D1 receives light. Formally, classical physics places no constraints on interactions except that they be local. It is assumed that these local interactions never vanish completely and that the electromagnetic wave leaves some trace, for example, heating of the air in the arms of the interferometer. Any such trace can in principle be detected, so the interferometer tuned as in Figure 3.1a leaves an observable trace of the same form; see Figure 3.1b.

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Figure 3.1 Mach-Zehnder interferometer (MZI). A beam of light is sent toward a beamsplitter, resulting in two beams of light. Each beam is then deflected toward a second beamsplitter and then detected by one or both of the detectors. a) The interferometer is tuned so that the light comes only to detector D2. b) A trace is left by the light in the interferometer tuned as in a).

3 Common Sense Explanation in Quantum Physics In 1986 Grangier et al. showed that the MZI exhibits interference when we send single photons through the interferometer. MZI interference is also routinely observed with neutrons (Rauch, Treimer, and Bonse, 1974). But even before that, the double slit experiment with attenuated light, where single photons would one by one build up an interference pattern on the detection screen, led to the radical picture of quantum theory: in some sense particles are waves! Let us first discuss a quantum particle and a single beamsplitter; see Figure 3.2. We observe that sometimes the particle passes undisturbed and sometimes it bounces from the beamsplitter as if the beamsplitter was a mirror. The difficulty is that in standard quantum theory, there is no equation describing the motion of the particle to one direction or the other. The equation we have is the wave equation (the so-called Schrödinger equation), which splits the incoming wave to two waves, one reflected and one undisturbed, both propagating on a straight line; see Figure 3.2a. In quantum theory all couplings are local, and these local couplings never vanish. For example, when a particle passes by, it always leaves some trace in its surrounding environment. However, the trace, that is, the local

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Figure 3.2 A particle source, beam splitter, and two particle detectors. a) The quantum wave of the particle. b) The trace of particles sent through the beamsplitter, found by measuring the local environment of the two arms of the interferometer as a large ensemble of particles are sent through. c) The trace of a postselected ensemble of particles sent to the beamsplitter and detected by D1. Particles that reach D1 do not leave a trace on the path to D2.

change of the quantum state of the environment, is not always detected in a single system. In fact, in a well-performed interference experiment, the probability of finding the change due to the passage of a single particle is very small. We can convince ourselves that there is such a change only by performing the experiment on a large ensemble of identically prepared particles. The trace shows the splitting of the wave; see Figure 3.2b. The trace we obtain can vary depending upon postselection. For example, the trace in Figure 3.2c is obtained by examining only those particles that were found in D1. But a different trace is found if we postselect only those particles found in D2. In that case we would instead find a single continuous trace leading from the source to D2. Note that there is no classical wave analog for such behavior because there is no meaning for a classical postselected wave. Only in quantum mechanics are future measurement outcomes not fully specified by a complete description of the initial state. The trace of a postselected particle in Figure 3.2c is analogous to the trace of a classical particle reflected by the beamsplitter toward D1. In Figure 3.2b there is no postselection, and the trace corresponds to the quantum wave of each particle. This might conflict with common sense: for how can a single particle be in two places simultaneously? The lesson of quantum mechanics is that particles are waves, and thus they can be simultaneously in several places. It is strange and unusual, but because classical waves are well understood, the wave behavior of a quantum particle can be accepted as sensible. We can get used to it as we have gotten used to the idea that there is no observer-independent simultaneity of spatially remote events in special relativity. Consider again the MZI in Figure 3.1b, but this time with quantum particles instead of classical waves. We tune the MZI so that, due to

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constructive interference toward D2, all particles are found in D2. In that case, the trace is identical to the trace found in the MZI with classical waves, depicted in Figure 3.1b. When we detune the interferometer in a way that spoils the destructive interference toward D1, but postselect the particles detected in D2, the trace is again as in the tuned interferometer, Figure 3.1b. This is in contrast with the not-tuned classical wave interferometer, which leaves a trace also on the path leading toward D1. Of some interest is a sequence of two MZI interferometers both tuned so that the input from the left constructively interferes toward the right output port. Quantum calculations show that the postselected particles in detector D1 or D2 leave a single path trace; see Figure 3.3. The lack of a trace in the right (left) arm of the top MZI makes sense because the tuning of the bottom MZI prevents the particle in the right (left) arm of the top MZI from reaching detector D2 (D1). All of these cases of particles behaving like waves are strange, but they do not defy common sense explanation, understood as causal explanation in terms of continuous local trajectories/propagations through space. Let us recap our arguments so far, for our claim that locality is a necessary condition for causal explanations to be commonsensical. First, the locality condition is supported by layperson cases: the thrown stone is a common sense explanation of the window’s breaking, whereas mental effort is

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Figure 3.3 a) Quantum state of particle sent through a double MZI. Each MZI is tuned as in Figure 3.1. b,c). Traces of postselected particles detected in one of the detectors show a continuous path.

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not a common sense explanation of spoon bending. Second, it is possible to explain why the locality condition is commonsensical: nonlocal causal explanations do not perform a defining function of explanation; they tell us only that the effect occurs given the cause without telling us why the effect occurs given the cause. Third, the locality condition is not restricted to layperson cases because the reason for its applying to layperson cases (discussed in the second point) passes over naturally to any scale. Fourth, the scale-neutral generality of the condition is illustrated by the history of physics, which has consistently sought local explanations, gravity being a paradigmatic example. Fifth, it is widely accepted by physicists and philosophers of physics that the locality condition is commonsensical. We have illustrated this with quotes from Newton and Einstein, and it is not hard to find contemporaries describing the condition as ‘very commonsensical’ (Lange, 2002, 94). In what follows, we present interferometer experiments that seem to exhibit nonlocal action at a distance. If they intuitively violate common sense because they exhibit this feature, then they provide further support for the locality condition. The paradoxical experiments discussed in the next two sections concern the wave nature of quantum particles, traces left behind by such particles, and information carried by such particles. It will therefore be useful to define more specific principles for each of these, which follow from the locality condition: 1 2 3

Particles (which are waves in quantum mechanics) move on continuous trajectories (in some cases, multiple continuous trajectories). A trace is left behind in a region if and only if a particle went through that region. Information sent from one location to another always leaves a trace of some information carrier.

In the next section, we will present an example of an interferometer that apparently contradicts 1 and 2. Then in Section 5, we will present a more complex interferometer that apparently contradicts 3.

4 The Nested Interferometer Let us now consider an MZI in which one arm is replaced by a smaller MZI, which is tuned to create constructive interference toward the final beamsplitter of the external MZI; see Figure 3.4. When we also tune the external interferometer to create constructive interference toward D2, the situation seems very similar to a standard MZI. Indeed, the traces left behind are unsurprising as there is a set of continuous trajectories from the source to the detector. The surprising situation contradicting common sense happens when we tune the inner interferometer to create destructive interference toward the final beamsplitter of the external interferometer; see Figure 3.5. Now the external interferometer is not an interferometer any more. There is

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Figure 3.4 a) Nested MZI tuned to constructive interference toward D1. b) Traces of particles correspond to the locations with nonvanishing wave function.

only one possible trajectory from the source to the detector. If we get the click at D1, common sense tells us that the particle had a well-defined trajectory down arm C. The surprising feature is the trace left by the particle. It is not only on path C. Traces of similar strength also appear in the inner arms of the nested interferometer; see Figure 3.5b. The particles leave traces in places through which they could not pass! There is a large controversy about the nested MZI, which began with the analysis in Vaidman’s 2013 paper “Past of a Quantum Particle”. Experiments were done with continuous light (Danan et al., 2013), with single photons (Zhou, 2017), and even with neutrons (Geppert-kleinrath, 2018) showing (although somewhat indirectly) the trace in the isolated region. However, there is no agreement about the meaning of these readings (Vaidman, 2018), and the loudest criticism was by Englert et al. in a paper originally titled “Past of a Quantum Particle: Common Sense Prevails” (Englert et al., 2017). See the reply and multiple references to other discussions in Peleg and Vaidman (2019). Many aspects of the experiment were criticized. The main line of criticism was that the existence of the trace of the particle inside the inner interferometer invariably spoils the coherence of the photon wave function and thus invariably spoils exact destructive interference. So, it is not true that there is precisely zero trace on the way toward and on the way out of the inner interferometer. This, however, hardly resolves the problem. We can improve the fidelity of the interferometer by reducing the local coupling of the particle and its environment. This makes the trace outside

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Figure 3.5 a) Nested MZI with inner interferometer tuned to destructive interference toward the second beamsplitter of the large interferometer. b) Traces of particles detected at D1 appear on path C but also, surprisingly, inside the inner interferometer.

the inner interferometer arbitrarily small relative to the trace inside the interferometer, which is of the same order of magnitude as in the arm C, where everyone agrees that the particle was present. Because the interaction of the particle with the environment is the same inside and outside the interferometer, there is no explanation of the drastic difference in the trace. To summarize, common sense physics requires that (i) particles (waves) move on continuous (and sometimes multiple) trajectories and that (ii) a trace is left behind in a region if and only if a particle went through that region. The trace they leave is due to local interactions with the environment in the locations where they were present. The strength of the trace is a function of the interaction and the time the particle spent in a particular location. In the nested MZI, the trace on the continuous trajectory C is commonsensical because the particle can follow this (and only this) trajectory. However, there is also a trace of the same strength in the inner box, which has no common sense explanation given principles (i) and (ii). Vaidman defined the places with significant traces as places where the particle was (Vaidman, 2013). But we do not need this definition to obtain a contradiction with common sense: a significant trace in a location without a trace leading to that location is enough to contradict the common sense principles. This contradiction will be resolved, with the help of many worlds, in Section 6. But first, let us consider one more paradoxical quantum experiment.

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5 Counterfactual Communication Information (signals) cannot be sent faster than light. Common sense tells us that information can be transferred from one place to another with some carrier of information, particles. Because no particle can move faster than light, no signaling can happen faster than light. It seems obvious that to send information from one place to another, we need to send particles between these two places, for example, photons. However, as impossible as it might sound, quantum mechanics allows us to send signals, to communicate, without particles in the transmission channel. We do need a transmission channel. In the communication protocol, sometimes (rarely) the particles do pass through the channel, but these are (rare) events of communication failure. These events are discarded. The communication takes place only when particles are not in the transmission channel. It is enough that they could have been there: this is why these protocols are named ‘counterfactual’ communication protocols. Counterfactual communication protocols were inspired by interaction-free measurements (IFM) (Elitzur and Vaidman, 1993) and were first proposed and performed by Hosten et al. with the name ‘counterfactual computation (Hosten et al., 2006)’. They were rediscovered in 2013 (Salih et al., 2013) and were later upgraded to communicate quantum information (Salih, 2016; Li, Al-Amri, and Zubairy, 2015). The protocols are based on a complicated interferometer. Consider Alice and Bob, who are trying to communicate with each other. A major part of the interferometer is in Alice’s site, and some part of the interferometer is in Bob’s site; see Figure 3.6. The sites are separate, and between the sites there are numerous transmission channels. Alice sends a single photon into the interferometer. Bob sends a signal to Alice by blocking or not blocking the arms of his part of the interferometer. If he does not put the block up, the photon ends up in one port at Alice’s site, and if he blocks the arms, the photon ends up in another port of Alice. In rare cases, the photon is absorbed at Bob’s site, but those cases are discarded. In cases where Alice detects the photon (probability close to 1), the information is sent from Bob to Alice. What is the argument that the protocols are counterfactual? Standard quantum theory does not have a definition of when the particle is present in the channel. Except for cases of single localized wave packets, when it can be considered similar to a classical particle (or in some situations in the Bohmian interpretation) (Bohm, 1952), we do not know through which arm it passed in the MZI. This is similar to not knowing which slit the particle passes through in the famous double slit interference experiment. The counterfactuality of these protocols was based on a classical physics argument: the photon was not in the transmission channel during the communication because, if it were there, it could not end up in one of Alice’s detectors. This can be seen in Figure 3.6. If Bob does not put the block up, any photon that passes through the transmission channel will not reach the next beamsplitter that would take it to Alice (Figure 3.6a).

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Figure 3.6 Counterfactual communication protocols. The interferometer consisting of N external interferometers, each having a chain of M>>N inner interferometers, is mostly in Alice’s site separated from Bob’s site by two planes. Between the planes, there are numerous paths that photons might go through. In the protocol a single photon is sent by Alice into the interferometer. a) To send bit 0, Bob does nothing. In this case detector D1 clicks with probability close to 1. With probability of order 1/N2, there might be an error, and D2 clicks instead. With probability of order 1/N, the photon passes through the transmission channel to Bob’s site and is not detected by any of Alice’s detectors. b) To send bit 1, Bob blocks all arms of the interferometer in his site. In this case, detector D2 clicks with probability close to 1. With probability of order N/M, the photon passes through the transmission channel to Bob’s site and is not detected by any of the Alice’s detectors.

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If Bob does put the block up, then any photon that passes through the transmission channel is simply absorbed by his block. One of us criticized this counterfactuality argument on the basis that the particle in these protocols leaves a trace in the transmission channel, which is even stronger than the trace of a particle actually passing through this channel (Vaidman, 2007, 2014a, 2015b, 2016). This is the same type of trace as described in the previous section. The postselected particle could not pass through the inner interferometer, but it left a trace just as a particle actually present there would leave. The full counterfactual communication protocols that can reliably and efficiently transmit both classical bits are fairly complicated; see Figure 3.6. One of their crucial ingredients is the quantum Zeno effect, which requires numerous (counterfactual) passages of the photon between the parties. We refer the reader to the original papers for their descriptions. Here, following Aharonov and Vaidman (2019). We will only explain how to correct a simple protocol, which will be capable of transmitting in a counterfactual manner (without a trace of the particles in the transmission channel), the bit 0. The modification that makes full (i.e., transmitting both bit 0 and bit 1) counterfactual protocols counterfactual is essentially the same. The description of the protocols that separately transmit bits 0 and 1 in a counterfactual way will be enough to demonstrate the conflict between common sense and counterfactual communication. Let us start with IFM (Elitzur and Vaidman, 1993). The interferometer is tuned like the MZI from before; see Figure 3.7a. To send bit 1, Bob blocks his arm of the interferometer. Now detector D1 has probability 25% to click. When the click happens, Alice knows that Bob blocked the arm of the interferometer; that is, he transmitted bit 1. When the block is present, there is no trace in the right arm of the interferometer. Because there is no trace in the transmission channel, we can claim that the photon was not there, and therefore it is counterfactual communication. Given the criterion of the past of the particle, which states that the particle was where it left a trace Vaidman (2013), all full counterfactual communication protocols that have so far been proposed are actually not counterfactual. We can still argue that the counterfactual communication of even one of the bit values contradicts common sense, but there is no need to weaken the claim. Recently a simple modification of full communication protocols was proposed. It makes all protocols counterfactual (Aharonov and Vaidman, 2019). The next ingredient of the counterfactual protocols is the transmission of bit 0. Naively, it can be achieved using a properly tuned nested MZI; see Figure 3.8. On the one hand, it is tuned as in the interferometer in Figure 3.5a, such that the particle from the inner interferometer cannot reach detectors of the external interferometer; see Figure 3.8a. On the other hand, when the inner interferometer is blocked, we arrange destructive interference toward D1. Now, the click in D1 tells us that Bob did not use the block; that is, the value of the bit is 0. Naively it looks

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Figure 3.7 Counterfactual transmission of bit 1. a) MZI tuned to destructive interference toward D1. b) When Bob blocks his arm of the interferometer, detector D1 can click. This click is the transmission of bit 1 from Bob to Alice. c) When the photon is detected at D1, no trace is present in the transmission channel, which makes this communication counterfactual.

counterfactual because the photon in the arm of the external interferometer that enters the inner interferometer cannot reach D1. But, as can be seen from Figure 3.5b, the photon leaves a trace inside the inner interferometer, and thus it leaves a trace in the transmission channel. Fortunately, there is a simple modification of the protocol that makes it counterfactual (Aharonov and Vaidman, 2019). Two nested interferometers connected by a double-sided mirror with proper tuning achieves this task; see Figure 3.9. Detector D1 cannot click if Bob uses the block, so the click in the detector tells Alice that there is no block and that the bit is 0. And in this case there is no trace in the transmission channel. For an explanation for the absence of the trace, see Aharonov and Vaidman (2019). In Figure 3.7 we showed a counterfactual communication of bit 1 and in Figure 3.8a counterfactual communication of bit 0. This is not enough for two reasons. First, both protocols have a large probability to fail. Second, these are different devices, so we cannot really send different bits in a counterfactual manner; each bit requires a different device for counterfactual transmission. The quantum Zeno effect allows us to combine the two elements in a complicated interferometer, shown in Figure 3.6, to resolve the two problems together. The original solution falls short because it had a trace when bit 0 was communicated. But a simple modification shown in Figure 3.9 corrects this problem. Double each external interferometer, and connect it by a double-sided mirror (with appropriate tuning of the interferometer). (Note also a very recent simple, reliable, full

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Figure 3.8 Naïve counterfactual transmission of bit 0. The nested MZI is tuned with two requirements: a) without Bob’s block, there is destructive interference of the inner interferometer toward the beamsplitter of the external interferometer. b) When Bob blocks his arm of the interferometer, there is destructive interference toward detector D1.

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Figure 3.9 Counterfactual transmission of bit 0. Two nested interferometers connected by a double-sided mirror. (a–b) The quantum states with and without the block of Bob show the tuning of the interferometer. c) The trace in the interferometer when Bob does not block his arm. D1 can click only when there is no block, and then there is no trace in the transmission channel.

54 Kelvin J. McQueen and Lev Vaidman counterfactual protocol with this modification (Vaidman, 2019) which, however, is highly inefficient because 95% of the sent photons are lost.) The details can be seen in the physics references. The bottom line is that a full communication channel can be achieved with no trace left by the information carriers between Alice and Bob. And it is not by building a super-technology fiber in which photons leave no trace. The physics of the transmission channel is such that a photon, when present, would leave a trace. Still, in the communication, no trace is left. There is only a small probability for failure: then a trace is left (and no transmission happens). We therefore have a contradiction with our third principle of common sense physics, according to which information sent from one location to another always leaves a trace of some information carrier.

6 Common Sense Regained: The Many Worlds Interpretation The phenomena contradicting common sense are the phenomena violating our principles 1–3 from Section 3. This includes a trace left in a location without a trace that led to that location and information sent from one location to another without a trace of any information carriers. Such phenomena occur even when the environment is not a special one: if particles are certain to be in these locations, they invariably leave a trace. We know that these phenomena are caused by particles that are sent through the experimental setups because nothing happens when such particles are absent. In our world, we observe these phenomena. Therefore, in our world, common sense does not prevail. According to the MWI of quantum mechanics (Everett, 1957; Vaidman, 2014b), quantum experiments with several possible outcomes give rise to newly created worlds corresponding to those outcomes. These worlds are not fundamental objects in the theory: they are emergent patterns that help explain our experience. Experiences of distinct outcomes after a given measurement correspond to different worlds. These worlds have mathematical counterparts in the quantum wave function of the universe that correspond to well-localized macroscopic objects, such as measuring devices, people, planets, and so on. In the MWI, the laws of physics (in particular, the Schrödinger wave equation) describe all worlds together and do so in a way that restores common sense principles 1–3. The MWI resolves the contradictions with common sense in the examples described while retaining their surprising character. The MWI resolution is not that the examples somehow lose their paradoxical features in our world or in parallel worlds. Instead, common sense principles 1–3 are restored in the physical universe that incorporates all worlds together. Here is the MWI explanation of the nested interferometer. In our world, with detection of the photon by detector D1, there is a paradoxical trace in

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a separate island with no trace leading to it; see Figure 3.5b. However, we should understand that there are also two other parallel worlds where the photon is detected at other detectors; see Figure 3.10a and Figure 3.10b. The world with detection at D2 also has a paradoxical trace—see Figure 3.10a—whereas the world with detection at D3 has a continuous trace; see Figure 3.10b. Because physics describes all worlds together, the requirement of continuous trace is for all worlds together. The traces in all worlds together, that is, the places where the environment changed its quantum state in the world with a click in D1, in the world with a click in D2, and in the world with a click in D3, are shown on Figure 3.10c. There is no isolated island of trace created by the particle. Traces are created by particles (waves) moving on (multiple) continuous trajectories. Therefore, there is no contradiction with common sense principles 1–3. Let us now explain how the MWI brings common sense to counterfactual communication protocols. In the IFM in the presence of the block, that is, counterfactual communication of bit 1, presented in Figure 3.7, we find in our world that Bob’s arm of the interferometer is blocked without any trace near the block. In Figure 3.11, the traces in parallel worlds of this experiment are shown. Figure 3.11a describes traces in a world without any trace near the block, but the world is not problematic because the click in D2 provides no information about the presence of the block. Figure 3.11b shows the trace when the photon is absorbed by the block, and Figure 3.11c presents the traces in all worlds together. In the full physical universe, there is a continuous trace toward the block, and it is clear that it stops the photon from going toward Alice. In the counterfactual communication of bit 0, presented in Figure 3.9, we find that there is no block in Bob’s arms without leaving any trace at Bob’s site. In the parallel world with the click of detector D2—see

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D2

Figure 3.10 a) The trace in the world with the click at detector D2. b) The trace in the world with the click at detector D3. c) The trace in the physical universe, which includes all worlds together (Figure 3.5b and Figures 3.10a,b). There are no separate islands of trace and no contradiction with common sense.

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D1

Bob D2

Alice

(b)

D1

Transmission channel

(a)

Transmission channel

Transmission channel

Alice

Bob D2

Alice

(c)

D1

Bob D2

Figure 3.11 a) The trace in the world with the click at detector D2. b) The trace in the world without detector clicks in which the photon is absorbed by the block. c) The trace in the physical universe, which includes all worlds together (see Figure 3.7c and Figures 3.11a,b). The photon left a trace in the transmission channel.

Figure 3.12a—we also do not have any trace at Bob’s site. However, there is also a world without clicks of Alice’s detectors—see Figure 3.12b—in which the photon passes through one of Bob’s arms, leaving a trace there. Figure 3.12c shows traces in all worlds together. The physical laws applied to the physical universe incorporating all worlds together describe this experiment in terms of common sense continuous trajectories and local causality. The example is still very surprising because we need ingenuity to construct experiments whose results provide useful information in a particular world due to interaction in parallel worlds. In the full counterfactual communication protocol, the explanation is the same. We successfully communicate in our world because in parallel worlds the photons travel in the transmission channel between Alice and Bob and leave a trace there. What is even more surprising is that postselection here is almost not needed: with very high probability, the protocols work, and only very rarely does the photon fail to be detected by Alice. Although there is a very large number of these failure worlds with a particle in the transmission channel, we nevertheless have only a tiny probability to find ourselves in them. The meaning of self-location probability in the MWI is discussed in McQueen and Vaidman (2019). This is the paradoxical quantum Zeno effect. Still, the causality issue is resolved: in all worlds together the particle passes (leaves a trace) through the transmission channel. To summarize, the phenomena contradicting common sense are (i) trace in a location without a trace that led to that location and (ii) information being sent from one location to another without a trace of

Paradoxical Quantum Experiments

Alice

Bob

Transmission channel

Bob

Transmission channel

Transmission channel

Alice

Alice

57

Bob

D3

(a)

D1

D2

(b)

D1

D2

(c)

D1

D2

Figure 3.12 a) The trace in the world with the click at detector D2. b) The trace in the world without clicks of Alice’s detectors in which the photon is absorbed by a block inside the interferometer. c) The trace in the physical universe, which includes all worlds together (Figure 3.9c and Figures 3.12a,b). The photon left a trace in the transmission channel.

any information carriers. These phenomena are observed in our world. Hence, if one insists on a one-world interpretation of quantum mechanics, then one must concede that the laws of physics violate common sense explanation. We have argued that there is no need for such a concession. Common sense explanation can be restored by rejecting one-world interpretations and embracing the MWI. In the MWI, our world still contains the paradoxical phenomena of (i) and (ii). But those phenomena arise out of, and can be locally explained in terms of, (multiple) continuous trajectories in the full physical universe that includes all worlds together. This is how the MWI brings common sense to paradoxical quantum experiments. The MWI also brings common sense to other quantum experiments that if considered in a single world, deny the possibility of common sense explanation. Bell type correlation experiments suggest ‘spooky action at a distance’ (Vaidman, 2015a). Quantum teleportation in a single world transfers huge amounts of information by sending just a few bits (Vaidman, 1994). It is widely believed that the MWI violates common sense, and some researchers even reject the MWI on that basis. Our arguments challenge

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this sentiment. The parallel worlds of the MWI, when considered together, restore common sense causal explanation to physics. Perhaps one could still mount a common sense-based objection to the MWI, if one thought that the unintuitive features of the MWI outweigh its intuitive causal explanations. This is a big issue: a proper analysis of all unintuitive aspects of the MWI requires a paper in itself. However, we will conclude with some brief reasons for thinking that the unintuitive aspects of the MWI are of little theoretical consequence. There seem to be two main concerns. First, the human branch might seem unintuitive. Second, the sheer existence of parallel worlds might seem unintuitive. Regarding the first, it is well-known that some organisms—amoeba—routinely branch and leave behind multiple descendants. This can seem surprising until we understand the (biological) mechanism that gives rise to it (mitosis). We are organisms too, so provided we understand the (quantum) mechanism that gives rise to our branching (entanglement), then there should be no great reason for concern. Regarding the existence of parallel worlds, we can note that it was once deemed counterintuitive to entertain the thought of many parallel galaxies. Indeed, the astronomer Giordano Bruno was executed for making this suggestion. In hindsight, we now see that this hypothesis merely went against the widely held assumption that our solar system is special. Accordingly, there is no particular reason to consider our universe special by thinking it is the only one. And indeed, modern cosmology has gotten used to the idea of parallel worlds, for reasons independent of quantum mechanics, which have to do with cosmic inflation and the fine-tuning of the cosmological constants. Again, this is not to say that there is nothing unintuitive about the MWI. It is to say that in our view the unintuitive aspects are outweighed by what the MWI can offer common sense. (This work has been supported in part by the Israel Science Foundation Grant No. 2064/19).

References Aharonov, Yakir, and Lev Vaidman. 2019. “Modification of Counterfactual Communication Protocols That Eliminates Weak Particle Traces.” Physical Review A 99: 010103(R). Bohm, David (1952). “A Suggested Interpretation of the Quantum Theory in Terms of ‘Hidden Variables’ I”, Physical Review 85 (2): 166–179. Danan, Ariel, Demitry Farfurnik, Shimshon Bar-Ad, and Lev Vaidman. 2013. “Asking Photons Where Have They Been.” Physical Review Letters 111: 240402. Ducheyne, Steffen. 2014. “Newton on Action at a Distance.” Journal of the History of Philosophy 52 (4): 675–702. Einstein, Albert, Boris Podolsky, Nathan Rosen. 1935. “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” Physical Review 47 (10): 777–780.

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Elitzur, Avshalom C., and Lev Vaidman. 1993. “Quantum Mechanical Interaction-Free Measurements.” Foundations of Physics 23 (7): 987–997. Englert, Berthold-Georg, Kelvin Horia, Jibo Dai, Yink Loong Len, and Hui Khoon Ng. 2017.“Past of a Quantum Particle Revisited.” Physical Review A 96: 022126. Everett, Hugh, III. 1957. “Relative State Formulation of Quantum Mechanics.” Review of Modern Physics 29: 454. Geppert-Kleinrath, Hermann, Tobias Denkmayr, Stephan Sponar, Hartmut Lemmel, Tobias Jenke, and Yuji Hasegawa. 2018. “Multifold Paths of Neutrons in the Three-Beam Interferometer Detected by a Tiny Energy Kick.” Physical Review A 97: 052111. Grangier, Philippe, Gérard Roger, and Alain Aspect. 1986. “Experimental Evidence for a Photon Anticorrelation Effect on a Beam Splitter: A New Light on Single-Photon Interferences.” Europhysics Letters 1 (4): 173–179. Hosten, Onur, Matthew T. Rakher, Julio T. Barreiro, Nicholas A. Peters, and Paul G. Kwiat. 2006. “Counterfactual Quantum Computation through Quantum Interrogation.” Nature 439: 949–952. Janiak, Andrew, ed. 2004. Newton: Philosophical Writings. Cambridge: Cambridge University Press. Lange, Marc. 2002. An Introduction to the Philosophy of Physics: Locality, Fields, Energy, and Mass. Malden: Blackwell Publishing. Li, Zheng-Hong, Mohammad D. Al-Amri, and Muhammad S. Zubairy. 2015. “Direct Counterfactual Transmission of a Quantum State.” Physical Review A 92: 052315. Mach, Ludwig. 1892. “Ueber einen Interferenzrefraktor.” Zeitschrift für Instrumentenkunde 12: 89–93. McQueen, Kelvin J., and Lev Vaidman. 2019. “In Defence of the Self-Location Uncertainty Account of Probability in the Many-Worlds Interpretation.” Studies in History and Philosophy of Modern Physics 66: 14–23. Newton, Isaac. (2004). Isaac Newton: Philosophical Writings (Cambridge Texts in the History of Philosophy) (A. Janiak, Ed.). Cambridge: Cambridge University Press. Papineau, David. 1995. “Probabilities and the Many Minds Interpretation of Quantum Mechanics.” Analysis 55 (4): 239–246. Peleg, Uri, and Lev Vaidman. 2019. “Comment on ‘Past of a Quantum Particle Revisited’.” Physical Review A 99: 026103. Quine, Willard Van Orman. 1957. “The Scope and Language of Science.” British Journal for the Philosophy of Science 8: 1–17. Rauch, Helmut, Wolfgang Treimer, and Ulrich Bonse. 1974. “Test of a Single Crystal Neutron Interferometer.” Physics Letters A 47: 369. Salih, Hatim. 2016. “Protocol for Counterfactually Transporting an Unknown Qubit.” Frontiers in Physics 3: 94, arXiv:1404.2200 [quant-ph]. Salih, Hatim, Zheng-Hong Li, Mohammad D. Al-Amri, and M. Suhail Zubairy. 2013. “Protocol for Direct Counterfactual Quantum Communication.” Physical Review Letters 110: 170502. Vaidman, Lev. 1994. “On the Paradoxical Aspects of New Quantum Experiements.” In PSA 1994 Vol. 1, edited by D. Hull, M. Forbes and R.M. Burian. Philosophy of Science Association, 211–217. The University of Chicago Press https://doi.org/10.1086/psaprocbienmeetp.1994.1.193026

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Vaidman, Lev. 2007. “Impossibility of the Counterfactual Computation for All Possible Outcomes.” Physical Review Letters 98: 160403. Vaidman, Lev. 2013.“Past of a Quantum Particle.” Physical Review A 87: 052104. Vaidman, Lev. 2014a. “Comment on ‘Protocol for Direct Counterfactual Quantum Communication’.” Physical Review Letters 112: 208901. Vaidman, Lev. 2014b. “Many-Worlds Interpretation of Quantum Mechanics.” In The Stanford Encyclopedia of Philosophy (Fall), edited by Edward N. Zalta. https://plato.stanford.edu/entries/qm-manyworlds/. Vaidman, Lev. 2015a. “The Bell Inequality and the Many-Worlds Interpretation.” In Quantum Nonlocality and Reality, edited by Mary Bell and Gao Shan. Oxford: Oxford University Press. Vaidman, Lev. 2015b. “Counterfactuality of ‘Counterfactual’ Communication.” Journal of Physics A: Mathematical and Theoretical 48: 465303. Vaidman, Lev. 2016. “Comment on ‘Direct Counterfactual Transmission of a Quantum State’.” Physical Review A 93: 066301. Vaidman, Lev. 2018. “Comment on ‘Multifold Paths of Neutrons in the ThreeBeam Interferometer Detected by a Tiny Energy Kick’.” arXiv:1806.01774 [quant-ph]. Vaidman, Lev. 2019. “Analysis of Counterfactuality of Counterfactual Communication Protocols.” Physical Review A 99: 052127. Zehnder, Lev. 1891. “Ein neuer Interferenzrefraktor.” Zeitschrift für Instrumentenkunde 11: 275–285. Zhou, Zong-Quan, Xiao Liu, Yaron Kedem, Jin-Min Cui, Zong-Feng Li, Yi-Lin Hua, Chuan-Feng Li, and Guang-Can Guo. 2017. “Experimental Observation of Anomalous Trajectories of Single Photons.” Physical Review A 95: 042121.

4

Why the Many Worlds Interpretation of Quantum Mechanics Needs More Than Hilbert Space Structure Meir Hemmo and Orly Shenker

1 Introduction In their contribution to this volume, McQueen and Vaidman argue that common sense requires that explanations in physics be not only causal1 but also local (they give some necessary conditions for what counts as ‘local’; see end of Section 3 in their paper). Their main claim is that the MWI of quantum mechanics (originally due to Everett)2 provides local explanations of the outcomes of experiments that in other interpretations of quantum mechanics seem to require (some sort of) nonlocality. In this sense, they argue, the MWI restores common sense to quantum mechanics.

2 The Causal Role of the Worlds We accept here the necessary conditions assumed by McQueen and Vaidman on what counts as local, and we grant (for the sake of the argument) their position that fundamental physics describes causal processes. To see what is at stake here, consider, for example, what happens in the experiment of the nested MZI (Figure 3.5 in McQueen and Vaidman, Chapter 3). They admit that the locality of the explanation is restored not by looking at what happens in one or another ‘parallel’ world but rather in all parallel worlds taken together. But what does this exactly mean? In the MWI it turns out that physical facts in one world depend not only on whatever happens in that world but rather on interactions literally occurring in other parallel worlds so that causation might be spatio-temporally local but only in virtue of these otherworldly interactions. Let us see how this idea plays out. Take, for example, the world in which the particle is detected by D2 (in the nested MZI, see Figures 3.5 and 3.10 in McQueen and Vaidman, Chapter 3). Call this world, our world. The explanation McQueen and Vaidman suggest of what causes D2 to click in our world is that there is a continuous trace of the motion of the particle in our world from the origin of the experiment along path C up to D2. However, in our

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world there is also a trace in the inner box, which cannot be explained locally by the motion of our particle through the inner box because no trace in our world leads to our particle passing through the inner box (see McQueen and Vaidman, Chapter 3, Figure 3.5). Here the intuition is that a local explanation of the trace in the inner box (which appears as strong as the trace along path C) based on physical matters of fact in our world requires that there are traces of the particle in our world that lead to the inner box. But there are no such traces in our world. According to McQueen and Vaidman the physical facts that explain this inner trace occur in another world. In that other world, there is a continuous trace of the motion of a copy of our particle from the origin through the inner box up to detector D3 (see Figure 3.10c, McQueen and Vaidman, Chapter 3). And their point about local causation is that this motion of the copy particle in the other world leaves a trace in the inner box also in our world. So the situation is this: (i) a copy of our particle is detected by (a copy of detector) D3 in some other world, but not in ours, and therefore this copy particle might be said to exist in that world; (ii) this copy particle leaves a continuous trace in the other world from the origin of the experiment via the (copy) inner box up to D3 (we shall omit from now on the term ‘copy’ unless it is needed); (iii) our particle does not leave a trace that leads to the inner box, so if its motion were the cause of the trace we see in the inner box, this trace would be created either by some sort of a nonlocal influence in our world (from path C to the inner box) or else by some sort of a nonlocal motion in which our particle travels along both path C and the inner box (without leaving a trace that leads to or from the inner box; (iv) to avoid this sort of nonlocality, the claim (on this proposal) is that it is the copy particle in the other world that causes (or creates or what have you) the trace in the inner box also in our world. We grant that in the MWI, one might take the trace in the inner box in our world to be some sort of a ‘photograph’ of the other ‘parallel’ world, where in the ‘photograph’ we have a ‘record’ of a segment of the trace left locally by the copy particle in the (copy) inner box of the other world. But we don’t see that this local behavior in the other world leads to some sort of a local picture of how things play out causally in our world, even on this way of looking at the trace (i.e., as a ‘photograph’ in our world of segments of the motion of the copy particle in the other world) because also on this way of thinking we have a cross-world causation by which the ‘record’ of the trace is formed. The same points (mutatis mutandis) arise with respect to the other experiments described by McQueen and Vaidman. The upshot is that particles in the MWI leave traces both in the world where they exist but also in other worlds in which they don’t exist. So the explanation is said to be local because spacetime splits together with the particles so that there is no influence at space-like separation within

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a world, but the causal influence literally travels across ‘parallel’ worlds. This seems to us to stretch the concept of locality beyond common sense, if not beyond breaking point, even if one understands causation weakly in terms of counterfactual dependence rather than by straightforward physical interaction. This leads to the more general question of how precisely one should understand the concept of ‘worlds’ in the MWI, which is indispensable but quite tricky. In this context it seems to us that an old problem that has been mounted against the MWI3 (called the ‘preferred basis problem’), which is believed by many to have been solved by decoherence,4 is still open for reasons that have escaped the literature up to now.

3 Consequences of the Preferred Basis Problem in the MWI The problem of the preferred basis stems from the mathematical fact that the quantum state is symmetric (or invariant) under the (infinitely many) choices of basis of Hilbert space in which it can be written. By this we mean that given the Hilbert space structure, a choice of basis in which the quantum state is described makes no difference with respect to the physical state and the facts obtained in the universe when it is in this state, it makes no difference with respect to the time evolution of the quantum state, and it makes no difference with respect to the predictions of future facts. Moreover, the standard description of local interactions (as well as the decoherence interaction) presupposes a factorization of the set of all degrees of freedom of the universe into subsets (which are the subsystems), for example, a measured system (say the spin + position of an electron in a Stern-Gerlach device), a photographic screen, an observer, and environment. This standard factorization is intuitive and justified by our experience. However, there are theoretically other factorizations: for example, into the electron, the left hemisphere of the observer’s brain + one cubic meter of air molecules in the laboratory, and the rest of the degrees of freedom of the universe. We call this the factorization-symmetry of Hilbert space, by which we mean the following: there are many (possibly an infinite number of) factorizations of the universal Hilbert space into sets of degrees of freedom (or subsystems), such that given the quantum state of the universe, all the factorizations are on equal footing; in other words, there are no facts determining a preferred factorization. But our experience corresponds (by and large) to the standard factorization and in addition also to certain local states of macroscopic systems given the standard factorization. In this sense the standard factorization and the local basis of states are preferred, but there is no deeper account of why they are preferred. In particular, the structure of the interactions does not explain this preference because it presupposes it. When one appeals to the structure of the interactions in the universe, say the decoherence interaction, or the fact that the interactions between macroscopic systems are local, one presupposes the factorization that features in our experience of the total set

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of degrees of freedom. This is acceptable, but we should note already at this stage that it does not explain our experience. In other factorizations, the structure of the interactions among the subsystems, induced by the same total Hamiltonian, is different. Let us illustrate this idea by the following figure:

Figure 4.1 Branching and other structures.

On the left side of Figure 4.1 we depict the branching structure that matches our classical-like experience as described by the psi-basis, which is the basis of localized states, and the same structure as it is described by another basis, which we call the phi-basis. In these two bases, the interference terms (denoted by the thin, black lines on the left side of the figure) between the branches are small and the interaction Hamiltonian picks out the psi-basis as dynamically preferred in the sense that the interference terms in this basis are small and the states match our experience. Formally, in the phi-description of the branching on the left side, we do not add up the similar terms in the different branches. It is a fact that under the time evolution of the universal state, the interference between the branches in the psi-basis are very small; this fact is common to the two descriptions of the branching structure on the left side in terms of the psi-basis and the phi-basis. By contrast, on the right side of the figure, we depicted a different structure that (by the symmetry of bases in Hilbert space) equally exists in the same quantum state when it is written in the phi-basis. In this structure (on the left side of the figure), the interference terms (denoted by the thick, black lines) between the branches are large. Vaidman5 and McQueen6 acknowledge the factorization-symmetry and the symmetry of bases in Hilbert space as well as the preferred basis problem that follows from these symmetries for the MWI: [m]athematically, one can decompose the wave function of the universe into a superposition of orthogonal components… in many

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other ways that will not provide a familiar world’s picture in every branch. So, critics might say that the proposal is circular: I define by fiat what I want to explain. First, a simple definition that is confirmed by observation sounds to me like a legitimate strategy. But there is also a more specific answer. The basis of the decomposition is indeed preferred.7 But the question is: which facts make the decomposition corresponding to our experience preferred? Or what makes it the case that our experience is described by components of the state in the preferred (psi-)basis (and factorization)? According to Vaidman and McQueen, the local structure of the interactions singles out the decomposition of states such as state 5 in terms of the psi-states in which macroscopic systems are in localized states (see the left side of Figure 4.1). But as we have argued, this claim already presupposes our experience; it does not follow from the structure of the universal Hilbert space alone. In measurements, for example, the interaction Hamiltonian depends on the position of a macroscopic pointer, or the position of ink marks on a piece of paper, or the position of neurons in our brains, and so on, and even if one disregards the decoherence interaction with the environment, the position basis, or more generally the expansion of the state in terms of narrowly peaked Gaussians in position, are preferred in the sense that these states match our experience. In our example of Figure 4.1, the psi-states (corresponding to the branch structure on the left side of the fgure) are the localized states that match our experience, whereas the phi-states (depicted on the right side of the fgure) are delocalized superpositions of the psi-states and do not match our experience. But what in the Hilbert space structure accounts for this asymmetry between the psi-states and the phi-states? Vaidman8 argues, in a way that might seem to undermine this point, that the localized states are preferred because they are stable over time: [u]ntil now I have not mentioned time evolution. Everything was considered at a particular moment. But we cannot experience anything at zero time. We need an order of 0.1 seconds to identify our experience. Thus, the world needs some finite time to be defined. The world has to be stable, at least on the scale of seconds. Locality of interactions in nature ensures that only the decomposition of wave functions corresponding to well-localized macroscopic objects can be stable. A quantum state describing the superposition of a macroscopic object in separate locations with a particular phase evolves almost immediately into a mixture that has a large component with a different phase. This obvious fact is analyzed in numerous papers using the buzzword ‘decoherence’.9 This goes along the tradition of Everett’s original argument from 1957. But why, for example, does the world or our experience have to be stable,

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as Vaidman and McQueen require? Of course, as a matter of empirical fact, the world as we experience it is stable (or at least has been stable up to now). But the MWI should derive this fact from its fundamental postulates and laws, not assume it. Here, as we mentioned earlier, evolutionary arguments to the effect that stability of the preferred states is essential for survival come in.10 The idea is that because our experience is associated with components of the universal state, the components need be stable over time for biological systems to evolve and survive along the branch structure defned by these components. It is true that in biology the standard description of evolutionary survival is in terms of adaptive systems that are immersed in some environment that survive stably over time. But how does this condition become a constraint on fundamental physics, which is compatible also with universes in which there are no biological systems at all? After all, whether or not there is experience of our kind that is stable over time or, for that matter, whether or not certain biological kinds survive need not be a factor that determines whether or not something is real. If it is true that a stable basis is a condition for survival, this fact should be accounted for by fundamental physics, or else it should be added to the Hilbert space structure. Let us suppose (for the sake of the argument) that stability of components of the universal state in some basis is indeed a condition for survival. But given the MWI the universal state now, in the present moment, is some superposition in the psi-basis: why do we not experience now the unstable phi-basis in each component of which we are in superpositions of localized states? In this case, if we grant the evolutionary argument, we would presumably cease to evolve as experiencing agents, and we would not be around to ask questions about our experience. But this is just bad luck for us. Why should the laws of physics care about our luck or our evolution in the first place? Again, perhaps it is true that a stable basis is a condition for survival, but if so, some additional structure backing this up and breaking the basis-symmetry of Hilbert space is needed. Note that the situation here is essentially the same as in the standard view about classical statistical mechanics, according to which, the past hypothesis of low entropy is added in order to break the time symmetry of the equations of motion and account for the increase of entropy only toward the future.11 Our conclusion applies also to the versions of the MWI that rely on decoherence to define the preferred basis.12 One might say that the most obvious justification of choosing the decoherence basis (or the localized states basis) as preferred (as well as the corresponding factorization) to define the worlds or the branching is that in this basis the on-diagonal elements of the reduced states of the macroscopic systems that appear in our experience can be directly interpreted as the relative frequencies of the states of these systems in our experience. Of course, this can be done (and this is what is usually done)! But our point is that this ‘obvious’ addition requires adding structure to Hilbert space beyond the structure

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given by the quantum state. That is, one must add structure to Hilbert space that will underlie the facts that make it the case that we have this experience. In particular, Wallace13 introduces a high-level law (he calls Dennett’s criterion) for the emergence of the worlds (or our experience), the role of which is to make some patterns in the quantum state real. This high-level criterion is based on functionalist ideas in the foundations of the special sciences. However, in his influential paper on the functionalstate hypothesis, Putnam has already noted that “the functional-state hypothesis is not incompatible with dualism!”14 Moreover, it is provable (regardless of quantum mechanics) that if a functionally defined property is not identical to a micro-physical property (i.e., in quantum mechanics, of the quantum state), then the functional-state hypothesis implies that any token of the quantum state from which the functional property emerges must itself have some nonphysical property.15 So functionalism is not only compatible with dualism; it entails additional nonphysical structure. Vaidman and McQueen are aware of the crucial difference with respect to the preferred basis problem and the account of our experience that holds between, on the one hand, the MWI and, on the other hand, collapse and hidden variable theories (like, respectively, the GRW theory and Bohm’s theory16) in which the additional laws that are added to the Hilbert space structure (respectively, GRW collapses or flashes, Bohmian trajectories) account for our familiar macroscopic experience. In the GRW theory the states that we experience are singled out by the flashes or the collapses of the wave function and in Bohm’s theory by the trajectories in 3-D space (or perhaps in 3N space; this is debated in the literature).17 But in the MWI if one only presupposes the Hilbert space structure, there is no account for why in the first place we experience the components of the universal state in the preferred basis rather than in some other (stable or not) basis or why we do not experience the entire superposition despite the fact that our brain states are superposed in the way depicted in Figure 4.1. One has to accept that our experience corresponds to the localized psi-states familiar from classical mechanics as a brute fact. It seems to us that Vaidman acknowledges this point when he says, “In quantum mechanics without collapse we must add a postulate to connect to our experience, because mathematics does not provide a (unique) picture corresponding to what we see around us.”18 Perhaps for Vaidman and McQueen adding a postulate, such as the locality of the interactions in our universe, which as we argued presupposes our experience, is nevertheless more justified than the GRW collapses or Bohm’s trajectories. However, it follows from our argument that contrary to the received wisdom, the MWI is not more parsimonious, and therefore it has no advantage over other theories that solve the measurement problem (such as Bohm’s theory; or the collapse theory by Ghirardi, Rimini, and Weber; or the many minds theory of Albert and

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Loewer.19 All these theories introduce additional laws or structure and additional elements of reality over and above the Schrödinger equation for the quantum state, and as we argued in this paper, the MWI is no exception in this regard. They all solve the measurement problem by changing drastically quantum mechanics, for good or for worse. Here, obviously, different questions may come up, such as the compatibility of the extra laws with relativity theory. But Ockham’s razor does not cut in favor of the MWI. Many often reject the MWI on the grounds that the multiplicity of the worlds is extravagant. This does not strike us as a good argument; it seems to us that none of the interpretations of quantum mechanics is commonsensical. Although the set of common sense beliefs is not uniquely and sharply delineated and is often given by examples that appear to be psychologically irresistible and intuitively true, each and every interpretation of quantum mechanics is strongly incompatible with some of the most central common sense beliefs. In this sense quantum mechanics in all its interpretations shutters our common sense, if one takes it to be true. The result is that naïve realism leads to physics and physics, if true, shows that naïve realism is false. Therefore, naïve realism, if true, is false; therefore, it is false.20 The question arises: how do the common sense beliefs come about in a quantum-mechanical world and what justifies relying on empirical evidence that we understand commonsensically as conforming quantum mechanics to begin with? This question is addressed and answered by Shenker.21

Acknowledgment We thank Lev Vaidman, Kelvin McQueen, Christoph Lehner, and Guy Hetzroni for discussions of the MWI. We also thank an anonymous reviewer for helpful comments. The research on which this paper is supported by the Israel Science Foundation (ISF), grant number 1148/2018.

Notes 1. McQueen and Vaidman’s argument is meant to be independent of any specific view about causation; see Ben-Menahem (2018) for the linkage between causation and locality (and other related concepts, e.g., determinism). 2. Everett (1957). 3. There are many versions of the MWI: see Everett’s (1957) ‘relative-state’ formulation and later versions, for example: DeWitt (1970), Zeh (1973, 2001), Deutsch (1985), Zurek (1993), Saunders (1995), Vaidman (1998, 2014), and Wallace (2012). Our argument applies to all the versions. 4. For decoherence, see Zurek (1993) and Joos et al. (2003). 5. Vaidman (2014, 2019). 6. Private correspondence. 7. Vaidman (2019, 100). 8. Vaidman (2019). 9. Vaidman (2019, 100).

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10. Vaidman, McQueen, private correspondence; it seems to us that this is also Zurek’s (1993) view. 11. See, for example, Feynman (1965). 12. See Zurek (1993) and Zeh (2001). 13. Wallace (2012). 14. Putnam (1975, 436). 15. See Hemmo and Shenker (2019, Forthcoming). 16. See, respectively, Ghirardi, Rimini, and Weber (1986) and Bohm (1952). 17. See Ney and Albert (2013). 18. Vaidman (2019, 98). 19. Bohm (1952), Ghirardi, Rimini, and Weber (1986), see Bell (1987), and Albert and Loewer (1988). 20. Russell (1940, 15). 21. Shenker (2020).

References Albert, David, and Barry Loewer. 1988. “Interpreting the Many Worlds Interpretation.” Synthese 77: 195–213. Bell, John S. (1987) “Are There Quantum Jumps.” In Speakable and Unspeakable in Quantum Mechanics, edited by J.S. Bell, 201–212. Cambridge: Cambridge University Press. Ben-Menahem, Yemima. 2018. Causation in Science. Princeton: Princeton University Press. Bohm, David. 1952. “A Suggested Interpretation of the Quantum Theory in Terms of ‘Hidden Variables’, I and II.” Physical Review 85: 166–179;180–193. Deutsch, David. 1985. “Quantum Theory as a Universal Physical Theory.” International Journal of Theoretical Physics 24: 1–41. DeWitt, Bryce S. 1970. “Quantum Mechanics and Reality.” Physics Today 23 (9): 30–35. Everett, Hugh, III. 1957. “‘Relative State’ Formulation of Quantum Mechanics.” Reviews of Modern Physics 29: 454–462. Feynman, Richard. 1965. The Character of Physical Law. Cambridge: MIT Press. Ghirardi, G., A. Rimini, and T. Weber. 1986. “Unified Dynamics for Microscopic and Macroscopic Systems.” Physical Review D 34: 470–479. Hemmo, Meir, and Orly Shenker. 2019. “Two Kinds of High-Level Probability.” The Monist 102: 458–477. Hemmo, Meir, and Orly Shenker. Forthcoming. “Why Quantum Mechanics Is Not Enough to Set the Framework for the Many-Worlds Interpretation.” Joos, Erich, H. Dieter Zeh, Claus Kiefer, Domenico Giulini, Joachim Kupsch, and Ion-Olimpiu Stamatescu. 2003. Decoherence and the Appearance of a Classical World in Quantum Theory. Heidelberg: Springer. Ney, A., and Albert, D. 2013. The Wave Function: Essays in the Metaphysics of Quantum Mechanics. Oxford: Oxford University Press. Putnam, Hilary. 1975. “The Nature of Mental States.” In Mind, Language and Reality, by Hilary Putnam, 429–440. Cambridge: Cambridge University Press. Originally published as “Psychological Predicates.” In Art, Mind and Religion, edited by William H. Capitan and Daniel D. Merrill, 37–48. Pittsburgh: University of Pittsburgh Press (1967). Russell, Bertrand. 1940. An Inquiry into Meaning and Truth. London: Allen and Unwin.

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Saunders, Simon. 1995. “Time, Decoherence and Quantum Mechanics.” Synthese 102: 235–266. Shenker, Orly. 2020. “A Scientific Realist Account of Common Sense.” In The Cambridge Companion to Common Sense Philosophy, edited by Jeroen de Ridder, René van Woudenberg, and Rik Peels. Cambridge: Cambridge University Press. Vaidman, L. (1998) “On schizophrenic Experiences of the Neutron or Why We Should Believe in the Many-Worlds Interpretation of Quantum Theory.” International Studies in the Philosophy of Science 12: 245–261. Vaidman, L. 2014. “Many-Worlds Interpretation of Quantum Mechanics.” In The Stanford Encyclopedia of Philosophy (Fall), edited by Edward N. Zalta. https://plato.stanford.edu/archives/fall2018/entries/qm-manyworlds/. Vaidman, L. 2019. “Ontology of the Wave Function and the Many-Worlds Interpretation.” In Quantum Worlds: Perspectives on the Ontology of Quantum Mechanics, edited by Olimpia Lombardi, Sebastian Fortin, Cristian López, and Federico Holik, 93–106. Cambridge: Cambridge University Press. Wallace, David M. 2012. The Emergent Multiverse. Oxford: Oxford University Press. Zeh, H. Dieter. 1973. “Towards a Quantum Theory of Observation.” Foundations of Physics 3: 109–116. Zeh, H. Dieter. 2001. The Physical Basis of the Direction of Time. 4th ed. Berlin: Springer. Zurek, Wojciech H. 1993. “Preferred States, Predictability, Classicality and the Environment-Induced Decoherence.” Progress in Theoretical Physics 89: 281–312.

5

Common Sense and Relativistic Supercoincidence Yuri Balashov

1 Traditional Puzzles of Material Coincidence Debates about material coincidence have a long and venerable history and tend to rely on common sense intuitions. For example, no two things can occupy the same place at the same time; a part cannot be identical to the whole; things can survive the loss and addition of small parts; nothing can have incompatible properties at a single moment of time. But starting with these common sense beliefs, the debates leave them behind rather early in the process, leading to highly problematic consequences. The next stage in the process involves revision of one or more initial assumptions to accommodate as many of the common sense intuitions as possible. Although some trade-offs are inevitable, our theoretical schemes must eventually remain anchored in common sense beliefs. This is how it always works in theoretical domains. We begin by accepting two or more individually plausible beliefs—for example, belief in free will and in determinism—without realizing that they are incompatible. Sometimes it takes quite a bit of theoretical work to put two and two together, but this is also what makes it so interesting and exciting. And when this finally happens we face a difficult choice: reject one of the initial beliefs, or refine them to make them compatible after all. Each of these options, in turn, leads to important theoretical developments. Metaphysical debates about material coincidence are very similar. Suppose a potter takes a lump of clay (‘Lump’) at t1 and shapes it into a vase (‘Vase’) at t2. One may feel under some pressure to say that there are two distinct objects at t2, Lump and Vase, which occupy exactly the same region of space and are composed of exactly the same matter. The pressure comes from the observation that Lump and Vase differ at t2 in that the former, but not the latter, has the historical property having existed at t1 and, therefore, Lump and Vase cannot be identical. Or consider Tibbles the cat who, as a result of some accident, loses its tail and Tib, a part of Tibbles including everything but the tail. Before the accident, Tibbles and Tib are distinct (a part cannot be the whole), so they must continue to be distinct even thereafter (two things cannot become one),

72 Yuri Balashov thus producing another famous example of coincident material entities. All along, we rely on the indubitable principles stated two paragraphs previously. But when we put them together in a manner suggested in the scenarios, they clash, forcing us to reject or modify at least one of the initial common sense assumptions.1 Doing exactly that has generated a major industry in contemporary analytic metaphysics and has been used to adjudicate many proposals in the ontology of composition and persistence, ranging from natural to radical, and sometimes grouped2 into two categories, pluralist and monist, depending on whether the existence of two (or more) coincident entities is embraced or resisted.3 The most natural pluralist proposal is probably constitutionalism: acknowledge that Lump and Vase are distinct but fully coincident entities and try to eliminate or downplay the worry about their locational and mereological coincidence by saying that the former constitutes the latter without being identical to it.4 The most radical proposal is nihilism: deny the existence of any composite objects, such as Lump, Vase, Tibbles, Tib, and Lumpl,5 altogether (‘no objects— no problem’).6 Other interesting proposals include mereological essentialism, the dominant kinds view, the rejection of the doctrine of arbitrary undetached parts, relativizing approaches, four-dimensionalism (the doctrine of temporal parts), as well as more recent hylomorphic, bundle, and constituent ontologies.7 It is instructive to highlight an interesting difference between the traditional puzzles of coincidence and exotic cases that figure prominently in the metaphysical debates in close proximity. The latter include discussions of extended simples and gunk, objects with nonstandard topology, sophisticated time travel scenarios, and proposals to cut the intuitive links between the mereological structure of material objects and the mereological structure of the regions of space or spacetime in which the former are located.8 The combinatorial inspiration behind such cases tends to move the discussion beyond the boundaries of physical possibility, often landing one in uncharted waters. One may feel uncertain about the significance of such cases precisely for that reason. The putative cases of material coincidence, on the other hand, are quite different. They portray situations that are familiar, nonexotic, indeed highly realistic: cats, unfortunately, do lose tails, and potters create vases every day. The facts about them lie in plain view. The recherché part comes from the subsequent theorizing about such cases. Ordinary folk may be initially sensitive to the principle that no two things can occupy the same place at the same time (“Can I walk through a wall?”) but are taken by complete surprise when the principle is applied to an object and the matter that makes it up; that is clearly not the kind of case they had in the back of their minds when they wanted to accept the principle.9

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It is fair to say that the proverbial person in the street fnds nothing problematic in the stories about Tib and Tibbles, and Lump and Vase, until he or she is brainwashed by the philosopher into being serious about noncategorical properties—the “various ways that a thing was, will, would, could, or must be”.10 One could argue that such features—temporal and historical properties, kind properties, persistence conditions, and other modal properties—are not robust enough to generate widespread ontological anxiety or confict with Leibniz’s Law. It is relatively easy to set them aside. Why should we worry about such allegedly incompatible pairs of properties as will exist tomorrow and will not exist tomorrow or had a tail and did not have a tail to the extent that we do about being square versus being round, hot versus cold, or moving right versus moving left (at the same time)? The worry, known as the ‘grounding problem’,11 can be put as follows: what is the current (or occurrent) property of x in virtue of which x will not exist tomorrow?12 To a considerable extent, it is this decidedly bleak appearance of ungrounded, free-floating, non-categorical properties that makes them highly susceptible to vicarious treatment generously offered by the counterpart analyses of modal and temporal predication and by relativizing strategies.13 Vicarious problems naturally call for, and may be adequately resolved by, vicarious treatment. In this chapter I present a new case of material coincidence that is non-vicarious, robust, categorical, non-modal, non-relational, and striking. It is motivated by physical considerations and is not susceptible to any traditional solutions. Thus, in one sense, it is more disciplined than the traditional cases already mentioned—precisely because of its reliance on robust physical properties actually possessed by the objects to which they are attributed. But in another sense, it is more radical in being not susceptible to any traditional solutions. Because of these features I call it supercoincidence. I will conclude, however, by raising some caveats about the case. One underappreciated lesson of science is its ability to expand our theoretical imagination. This may be important for the metaphysics of material constitution and for metaphysics more generally. It also raises interesting questions about the relationships among science, philosophy, and common sense. I discuss such questions at various junctures in the development of my case by comparing and contrasting it with the traditional material coincidence puzzles.

2 MultiLife Consider MultiLife (see Figure 5.1; the reason for the name will become clear shortly), an object composed of two oscillating point particles of equal mass, moving uniformly toward and away from each other in frame (x, t).14

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Figure 5.1 MultiLife.

Figure 5.2 is a spacetime diagram of the situation. Which line in Minkowski spacetime15 represents the history of MultiLife? The only physically meaningful candidate would be a line connecting the locations of MultiLife’s center of mass at different moments of its career. More carefully, such a line must connect the locations of the center of mass of MultiLife determined in a series of reference frames in which MultiLife is ‘instantaneously at rest’. In general, the instantaneous-center-of-mass trajectory of a composite object whose particles are in complex relative motion to each other in a relativistic setting will be rather convoluted, and the procedure for its calculation is far from trivial.16 Here we can focus on a partial and simplified description of the case. It is obvious that the symmetry line of the whole diagram—the boldfaced vertical line L in Figure 5.2—is a good candidate for the trajectory of MultiLife (i.e., its instantaneous-center-of-mass trajectory). Indeed, MultiLife is instantaneously at rest at any moment in the reference frame (x,t); for example, at t1, t2, t3, and so on. Notice, however, that MultiLife is also periodically at rest in two other reference frames (x', t') and (x", t"), co-moving with each of the particles and, hence, moving relative to each other and relative to (x, t). At t1' and t2', for example, both MultiLife’s constituent particles are instantaneously at rest in (x', t') and, therefore, are moving with the same speed and in the same direction in (x, t). This happens over the stretches of time in (x', t') between the two ‘turning points’ on the worldlines of

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Figure 5.2 MultiLife is moving left, moving right, and staying at rest at p1 and p2. Consider, first, the reference frame (x, t). In this frame, the motion of the two particles is perfectly symmetrical (as in Figure 5.1), so the central boldface line, representing the trajectory of the MultiLife’s center of mass, is ‘vertical’: MultiLife remains at rest in this frame throughout the whole scenario. Consider, next, the reference frame (x', t'), which is co-moving with both particles over the stretches of time in this frame between the two ‘turning points’ on the worldlines of MultiLife’s constituents, shown as the shaded areas. A brief explanation is in order. In a typical Minkowski spacetime diagram, a pair of coordinate axes, such as (x', t'), may not look orthogonal to each other, even though they are in a strict mathematical sense. This has to do with the need to represent nonEuclidean relations characteristic of relativistic spacetime in a Euclidean drawing, such as Figure 5.2. In this diagram, moments of time in (x', t') are ‘at an angle’ to moments of time in (x, t); think of such ‘cross-crossing’ of time instants in different frames of reference as a geometrical image of the relativity of simultaneity. Now consider t1', a moment of time in (x', t'). At that moment (focus on the shaded rectangle), both particles are instantaneously at rest in (x', t'): their worldlines are parallel to the t' axis! Consequently, L' represents their common state of motion at p1, according to (x', t'). Similarly, L" represents the common state of motion of the particles at the same point p1, according to (x", t"). The same analysis applies to p2 and other similar points on MultiLife’s trajectory.

76 Yuri Balashov MultiLife’s constituents, shown as the shaded areas in Figure 5.2. During such a stretch, MultiLife is at rest in (x', t'), and therefore, a line including ‘oblique’ boldfaced fragments (such as L' in Figure 5.2), along with some later and earlier fragments of the symmetry line, would also be a suitable candidate for the trajectory of MultiLife. For the same reason, a line including the oppositely oriented ‘oblique’ fragments (such as L" in Figure 5.2) would also be a viable candidate.17 Charting a full trajectory of MultiLife comprising the oblique portions need not detract us at this point; we shall return to this task later. For now, we can focus on a simpler question: what is the instantaneous velocity of MultiLife at a single point p1, which definitely belongs to its life career?18 Is MultiLife moving ‘right’ or ‘left’ or staying at rest at p1? It seems that it is doing all three things. But a single object cannot be involved in three incompatible states of motion19 at any moment of its career. Should we say that we are dealing here with three coincident objects (call them MovingRight, MovingLeft, and AtRest) composed of the same particles? This result (which will be further developed in Section 5) appears troubling. The trouble at this point may be summarized by saying that on the face of it, MultiLife has three incompatible properties (i.e., instantaneous velocities) at p1 that are: (i) robust, (ii) non-modal, and (iii) prima facie non-relational. This brings out a striking contrast between MultiLife and the traditional cases of alleged material coincidence. MultiLife’s properties at p1—moving left, moving right, and staying at rest—are robust because they are not merely historical, ‘free-floating’, or otherwise vicariously grounded properties. Instead they are respectable physical properties. They are non-modal for obvious reasons. And they are prima facie non-relational in the sense that the conflict between them cannot be easily resolved by relativizing them to different indices. The three mutually incompatible states of motion of MultiLife at p1 are represented in a single reference frame (x, t) in Figure 5.2. Perhaps one could say that they are relativized to the same index, that is, (x, t). This makes them as troubling as tall for a basketball player and short for a basketball player and very different from tall for a philosopher and short for a basketball player, or being well made for a lump and not being well made for a vase.20

3 Some Details Let us pause and reflect on several important aspects of the MultiLife case. The problem with it arose essentially from our desire to draw a spacetime trajectory of a simple composite object taken as a whole. We know everything there is to know about the motion of the object’s constituent particles over its lifetime (let us assume). We want to know what the whole object does at various moments of its lifetime. Surprisingly, there is no

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unique answer to this question because more than one spacetime trajectory is eligible to represent the career of our composite system in spacetime. This result is grounded in rather peculiar properties of relativistic spacetime. The following remarks are intended to put the result in sharper focus and highlight the factors primarily responsible for it. In classical physics, the trajectory of a composite system is determined by following its center of mass. This is a straightforward task, for the location of the center of mass at any moment of time is determined by the locations of the system’s smallest parts at that time via a simple formula.21 But in special relativity, there is no such notion as ‘a moment of time’; there are only moments of time in particular frames of reference. What frame should be used in calculating an instantaneous location of the center of mass? Presumably, the instantaneous rest frame of the whole body. But to know in which frame the body is ‘instantaneously at rest’ when its constituent particles move relative to each other in complicated ways, one apparently needs to know what trajectory in spacetime represents the motion of the ‘body as a whole’,22 and it is unclear that this could be known without knowing the trajectory of the composite body’s center of mass. We seem to be in a circle. To make things worse, one cannot simply assume, as is done in classical mechanics, that the frame in which the whole body is at rest automatically coincides with the frame in which the total momentum of the body is zero.23 Can the circle be broken in a principled and physically motivated way? Yes. The basic idea in the idealized case of an object such as MultiLife, composed of n non-interacting particles, is to chart the trajectory of the whole object by connecting the locations of its center of mass determined in instantaneous frames, in which the total relativistic momentum is zero, and then translate the result to an arbitrary frame by a Lorentz transformation. The circle could thus be broken by identifying an instantaneous zero-momentum frame first. This way of doing it is motivated by the physical significance of zero total momentum frames and their uncontested eligibility to serve as instantaneous rest frames of composite bodies.24 But as Figure 5.2 clearly shows, a procedure of this sort may fail to yield a unique trajectory of the body. The vertical boldfaced line as well as both oblique lines, all intersecting at p1 and p2, are equally eligible to represent fragments of such trajectories. Hence a problem.25 Confronted with this problem one might attempt to dismiss it as follows. What is the big deal about the state of motion of MultiLife represented by the trajectory of its center of mass? And what does it have to do with material coincidence anyway? The traditional coincidence puzzles originate in, and get their bite from, not only the sameness of matter but the alleged colocation of two objects: their exact location at the same region of space or spacetime. We wonder, for example, how Lump and Vase can have incompatible (historical or modal) properties at their

78 Yuri Balashov common location. There appears to be no similar worry about MultiLife, where the alleged incompatible properties (viz. moving right vs. staying at rest) seem to be attributed not to the ‘real stuff’ (i.e., the scattered quantity of matter) of which MultiLife is composed but to an empty point of spacetime representing its center of mass. This empty point simply does not deserve the title of a location of MultiLife in difference from the Lump and Vase case, where a particular matter-filled region of space is a bona fide location of both objects (if there are two) or a single object (if there is only one). If asked to identify a location of MultiLife, one could perhaps refer to a pair of separated, matter-filled points but not to an empty point. Because the incompatible instantaneous velocities are attributed to the latter, but the object is actually located at the former, there is no problem of colocation and hence no puzzle of material coincidence. Indeed, one could make an excellent tu quoque retort to an earlier note about the ‘vicarious’ or ‘merely relational’ nature of the allegedly non-categorical and ungrounded historical and modal properties doing the heavy lifting in the traditional puzzles. The kinematic properties of the center of mass, which do the heavy lifting in the MultiLife case are, if anything, worse and should not be taken seriously. My response to this is that the kinematic properties—such as moving right and staying at rest—are the real properties of the composite object(s) in question26 and that they should be taken seriously. Although such properties are best represented by assigning velocities to the objects’ centers of mass, the properties so represented are the actual properties of the composite material objects located at the corresponding matterfilled regions and not the properties of empty spacetime points. And they should be taken seriously because they play important roles in physics. Take the classical laws of motion. Their application to objects consisting of several massive parts crucially involves the notion of the center of force (which, of course, is none other than the center of mass) whose kinematics and dynamics embody important physical properties of an object as a whole, for example, acceleration arising in response to a net external force. It is with respect to the center of balance (which, again, is none other than the center of mass) that the rotation of a body in a complex state of motion is best described in terms of angular momentum, torque, and other such parameters. Any textbook in mechanics is filled with problems featuring multiple bodies on inclined and rotating planes, arms, levers and beams, connected by ropes, springs and other links restricting their degrees of freedom in various ways and often requiring the application of Newton’s second law, or the conservation of momentum law, to the connected system as a whole, which in turn, requires the identification of the center of mass of the entire connected system and also requires working in its rest frame. Indeed, for any realistic object larger than an idealized material point, the ‘F’ of the ‘F = ma’ refers to the net force acting on the object’s center of mass and the ‘a’ to the latter’s acceleration. The same holds true,

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mutatis mutandis, for relativistic mechanics. The concept of the center of mass is central and indispensable to physics. With such credentials, denying it a robust metaphysical status would be inappropriate.27 And this status is also needed for other theoretical purposes. If we want to be able to talk meaningfully about composite objects’ persistence over time, we need a way of tracking their momentary locations—the 3-D slices of the objects’ paths in spacetime. And the only way to track them is to have a spacetime trajectory representing the composite object’s career. If we want to label such locations—for example, by the age of the object— we need the notion of proper time for the whole object, and it is not possible to define it without drawing the object’s worldline in spacetime.28 The center of mass trajectory is the best, indeed the only, notion capable of playing these important roles. Going back to MultiLife, it is, of course, a very simple object consisting of two particles. One might think it is too ‘thin’ to deserve so much attention. But other more complex symmetric configurations,29 shown in Figure 5.3, generate similar results. For simplicity, I continue focusing on MultiLife in the sequel.

Figure 5.3 MultiLife variations.

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4 Implications MultiLife is not easily amenable to any of the traditional non-radical treatments of alleged material coincidence.30 Let us begin by setting aside mereological essentialism and the dominant kinds view. These remedies are ineffective because the case of MultiLife does not involve mereological change or kind change. Consider constitutionalism. The constitutionalist has two options. She could say that there are three objects in the situation—MovingRight, MovingLeft, and AtRest, which are, respectively, moving right, moving left, and staying at rest at p1. The constitutionalist could insist that one of them constitutes another without being identical to it. But it seems grossly implausible to suggest that something that is moving left or staying at rest can in any way constitute anything moving right. The instantaneous properties of the constitution base and constitution product cannot be so drastically incompatible. The situation here is very different from the sorts of situations that are used by constitutionalists in their support, where the relevant properties of a complex aggregate of matter make it highly eligible to constitute a certain vase, or an animal, or a human person. MovingRight or AtRest, in contrast, are simply ineligible to constitute MovingLeft. But there is a better constitutionalist response. Let us return to Figure 5.2. Intuitively, MultiLife is staying at rest at p1 because of what its constituent particles are doing at t1; for it is their states of rest at t1 that are relevant to calculating the instantaneous velocity (i.e., zero) of MultiLife’s center of mass at p1. Similarly, we are led to conclude that MultiLife is moving to the right at p1 when we focus on what its particles are doing at t1': both are moving to the right at that moment (look again at the shaded portion of the diagram in Figure 5.2); and similarly for moving to the left. Depending on what portions of the constituent particles’ trajectories we focus on, we attribute different velocities to MultiLife at p1. And we focus on different portions of those trajectories because they are cut out by different time hyperplanes in different frames of reference. This suggests that the constitutionalist should concentrate not on the relation between MovingLeft and AtRest but on the relation between each of the three composite objects and their common constituent matter—the two particles, considered at various times in various frames. The constitutionalist could say that the particles constitute AtRest at t1 and that the very same particles constitute MovingRight at t1' and also constitute MovingLeft at t1". All three composite objects are constituted by the same matter at different times in different frames, and it is those relations of constitution that account for what the three composite objects are doing at the respective times in frames. This is different from what most constitutionalists normally say when dealing with the traditional puzzles of material coincidence. Most of them

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do not say that the same matter constitutes both Lump and Vase; instead they say that Lump constitutes Vase. But some authors do emphasize the availability of three entities involved in the situation—Lump, Vase, and their common underlying matter—and the need to keep track of them in resolving the puzzles.31 Far from being implausible then, this proposal—to say that three differently moving objects are constituted by their common underlying matter at different times in frames, without being identical to the matter—looks very reasonable. But when the case is looked upon this way, it becomes clear that one need not be a constitutionalist to avail him- or herself of this obvious relativizing strategy. All one needs to do is relativize composition to times in frames. One could say that the two particles compose AtRest at t1, MovingRight at t1', and MovingLeft at t1". There is no need to wheel in constitution. And the motivation for relativizing composition to times in frames is quite straightforward. In the classical setting, we routinely relativize composition to different moments of absolute time, common to all frames; we say, for example, that certain particles compose Vase at one time and the bust of Napoleon at another. Special relativity brings new and unexpected features to the situation: times are no longer common to frames, and time hyperplanes corresponding to different frames may crisscross, as t1, t1', and t1" do in Figure 5.2. Having appreciated the significance of these new features we may feel the need to adjust our relativization schemes accordingly. And they provide the pluralist with a desired and perhaps non-puzzling strategy in the case of MultiLife. Could the monist avail oneself of a similar relativization strategy? The monist must deny the existence of three objects in the situation; instead he or she should say that a single object has three compatible properties relativized to different indices. Could he or she put this by saying that MultiLife is moving to the left qua MovingLeft but not qua MovingRight and then point out that the velocity properties expressed by such sortrelative predicates are not incompatible? For this proposal to work in a way it is expected to work in other cases of material coincidence,32 MovingLeft and MovingRight must delineate separate kinds in the way lump, vase, animal, and human person do. But there is every reason to think that if MovingLeft and MovingRight (and AtRest) demarcate any physically interesting kinds at all, they demarcate the same kind of uniformly moving object. So, relativizing velocity properties to kinds of moving objects will not help. But relativization to kinds is not the only available option. Indeed, it may be as ill-conceived as imposing on the constitutionalist an implausible view (briefly considered and rejected above) that MovingLeft may constitute AtRest. And as the constitutionalist could, in principle, relativize constitution to times in frames,33 the monist could make similar use of relativizing the state of motion of a single object (i.e., MultiLife) at an otherwise eligible point to reference frames. In our case this yields

82 Yuri Balashov an apparently unproblematic verdict that MultiLife at p1 is at rest relative to (x, t), moving right relative to (x', t'), and moving left relative to (x", t"). However, things are not as simple as they might appear. The first point to note is that the procedure underlying the current approach is very different from, and much more complicated than, a trivial relativization of velocities to frames of reference. The latter is involved in saying, for example, that a car is moving straight ahead according to one observer, moving left according to another, and moving right according to yet another observer. One could well imagine this sort of situation when approaching a road intersection. Similarly, MovingRight (let us assume, for a moment, that there is such a distinct object) can be said to be moving to the right at p1 in reference frame (x, t) but to be at rest at the same point in frame (x', t'). Figure 5.2, showing a single fragment of the boldfaced line L' at different angles at p1 in two different frames, provides a good illustration of this trivial relativity of motion known from elementary physics and common sense. In contrast, the other—peculiar and nontrivial—relativization recipe suggested as a monist treatment for the MultiLife case requires us to consider not one but all three boldfaced lines, L, L', and L", which intersect at p1 and represent three incompatible states of motion of MultiLife at that point. We want to say that all three intersecting lines represent actual states of motion of MultiLife at p1, but we now want to relativize them to three different reference frames. In other words, we want to say that at p1, MultiLife is: (i) at rest in (x, t) relative to (x, t), (ii) moving right in (x, t) relative to (x', t'), and (iii) moving left in (x, t) relative to (x", t"). That would be similar to saying that the very same car is moving straight ahead according to a given observer but also moving to the left (and moving to the right) at the very same point according to the very same observer. The second point to note is that the frames of reference to which the state of motion of MultiLife at p1 is thus relativized—that is, (x, t), (x', t'), and (x", t")—are not chosen arbitrarily by us (as is done in illustrations of the trivial relativity of velocity) but are determined by the actual kinematic histories of the constituents of MultiLife according to a somewhat complicated procedure for identifying the latter’s instantaneous rest frames.34 Figure 5.2 suggests that this procedure fails to yield a unique trajectory of MultiLife at p1; that is why we end up having three intersecting boldfaced lines at this point. The lines, in turn, determine three instantaneous rest frames (i.e., [x, t], [x', t'], and [x", t"]), to which the instantaneous state of motion of MultiLife at p1 is then relativized. The overall result may be summarized as follows: given the full trajectories (and nothing else) of the constituents of MultiLife in relativistic spacetime, three intersecting lines turn out to be equally eligible to represent the state of motion of this composite object at their common point

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of intersection (to repeat, in a single frame of reference). In an important sense, the orientation of these three lines (in any single frame of reference) supervenes on the kinematic histories of the constituent particles and is intrinsic to the composite system. But it is the orientation of a particular boldfaced line at p1 that itself determines a corresponding instantaneous rest frame that serves as a relatum in the suggested relativization strategy. In fact, such a reference frame could be strictly defined in terms of the tangent to the respective boldfaced line at p1. The net result of the relativizing approach currently under discussion is then somewhat as follows: given the actual motion of MultiLife’s constituent particles (and nothing else), the instantaneous state of motion of MultiLife at p1 is represented by line L relative to L, by line L' relative to L', and by line L" relative to L". In other words, MultiLife at p1 is staying at rest according to L, is moving to the right according to L', and moving to the left according to L". This may be what it is in fact doing. But the real worry is how it manages to do all three things. I am not sure this worry is fully addressed by the relativization strategy developed here. Although the whole triple of the intersecting lines supervenes on (is wholly determined by) the kinematic histories of MultiLife’s constituent particles, it remains troubling to realize that the whole composite object is doing three things at once: moving right, left, and staying at rest. And it does not immediately help to be told that it is moving right relative to the intrinsically determined direction representing its motion to the right, and is staying at rest relative to another intrinsically determined direction representing its state of rest. I think it is fair to say that common sense, even when extended by traditional metaphysical theorizing, is simply blind to such a possibility. Again, drawing a contrast with the relativization approaches typically deployed to resolve ordinary cases of material coincidence may be helpful here. One could maintain that there is a single material object o at t2, variously referred to as ‘Lump’ and ‘Vase’, which survives flattening qua Lump but not qua Vase, is valuable or beautiful qua Vase but not qua Lump, and so forth.35 This monistic resolution of the Lump/Vase quandary may or may not be eventually acceptable,36 but here the allegedly conflicting historical, modal, or aesthetic properties are relativized to different kinds grounded, at least in part, in the extrinsic relations o bears to other members of the corresponding kinds, to communities or social conventions, and so on. Quite apart from the contrast37 between the controversial status of the historical, modal, or aesthetic properties involved in such cases and the robust physical properties at work in the MultiLife case, the items responsible for relativizing away the allegedly incompatible properties in the Lump/Vase case (e.g., future histories, possible histories, or social communities) do not emerge from the structure of the composite object in question (i.e., o) in a way they do in the MultiLife

84 Yuri Balashov case; instead they must be brought from without. In other words, they are extrinsic, not intrinsic. In these two respects—the non-categorical nature of the apparently conflicting properties and the extrinsic nature of the relata invoked to explain away the apparent conflict—other popular cases of material coincidence are no different from the Lump/Vase scenario. A curious case that may bear more resemblance to the MultiLife situation was mentioned by Simons and developed by Varzi.38 Consider two English words, ‘fallout’ and ‘outfall’, made up of the same letters arranged in a circle. This circular inscription can be read as two different words depending on where one starts. For that matter, consider the famous rabbit/duck drawing or the letter ‘p’ drawn on a glass door. The letter could also be taken to read ‘q’ or ‘b’ or ‘d’ instead, depending on the direction from which one looks at it.39 In these examples, a natural inclination is to deny any puzzling coincidence (of two words or pictures or of four letters) and to assert that there is one inscription, or a single line drawing, that is read differently from different perspectives or from different gestalt states of perception. The respect in which these examples are closer to the MultiLife case and different from the standard coincidence cases has to do with the more straightforward nature of the apparently incompatible features of the mereologically and locationally coincident entities: the difference between ‘fallout’ and ‘outfall’, and between the rabbit and the duck, stares us in the face. But the extrinsic nature of the relata called upon to resolve the apparent puzzles in the inscription and drawing cases is even more pronounced than in the Lump/Vase case and their likes: visual perspectives and gestalt states of perception are clearly external to the inscriptions and drawings and are grounded in factors (psychology of perception, evolutionary history, and language learning) that have nothing to do with the internal structure of the coincident entities in question. As noted, in the MultiLife case the relevant perspectives are, on the contrary, determined by the physical history of the constituents, and the resulting ‘lines of internal relativization’ (to different instantaneous rest frames) are drawn by nature itself. In other words, the three apparently incompatible states of motion are handed to us by the physical world and are not simply brought by different ways of ‘reading’ the situation, as in the ‘fallout’/‘outfall’ or rabbit/duck cases. Despite these differences, it would be wrong not to emphasize one special aspect of the MultiLife case that could make the relativizing approach attractive, at least initially. It may be true that the three relevant perspectives on the motion of MultiLife emerge ‘from within’—from the kinematic history of its constituent particles. But once the perspectives have emerged, in the manner depicted in Figure 5.2, it becomes clear that the three apparently incompatible local states of motion of MultiLife (represented by the intersection of the three boldfaced lines at p1) are determined by what its constituents do at three different stages of

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their histories, cut out by the crisscrossing time hyperplanes: t1, t1', and t1". These hyperplanes may be drawn through p1 ‘by nature’ (i.e., solely determined by the trajectories of the constituent particles and not by any extrinsic factors). But this does not detract from the fact that the three allegedly incompatible states of motion of MultiLife at a certain single moment of its career are fully grounded in what its constituents do at different moments of their careers. If so, then relativizing MultiLife’s state of motion to such different ‘doings’ might not seem so implausible after all. On the other hand, this nonlocal40 determination of a local state of motion of MultiLife makes the approach that turns on relativizing this state itself inferior to relativizing composition or constitution, considered previously on behalf of the pluralist. The point could be supported by putting it in terms of temporal parts. Suppose the three pairs of sections of the trajectories of MultiLife’s constituent particles, cut out by t1, t1', and t1", represent not three different stages of motion of these particles but the states of motion of numerically distinct entities. This would considerably enhance the plausibility of relativizing composition (or constitution). It seems rather natural to say that one pair of temporal parts of the two particles compose AtRest, whereas another, numerically distinct pair of their temporal parts compose MovingRight. In a familiar derivative sense, central to the doctrine of temporal parts, the particles themselves (i.e., the long temporally extended things) could then be said to compose AtRest at t1, in virtue of having the corresponding temporal parts, and to compose MovingRight at t1', in virtue of having different temporal parts. It seems much less natural to say that the particles compose one thing whose states of motion at various times in frames must be relativized to complicated items eventually emerging from the extended stretches of the histories of the particles. To sum up the discussion so far, MultiLife seems to have three incompatible local states of motion at select points of its history. The best pluralist response to a potential coincidence worry is to relativize instantaneous composition to times in frames and thus to different stages (or temporal parts) of the constituent particles. The best monist response (which seems inferior to the pluralist’s) is to relativize in a similar way the instantaneous state of motion of a single composite object. These treatments may be adequate for the initial problem about the local states of motion of MultiLife at several discrete points of its history. But there is more to the case.

5 Calm and Hectic Lives We began by raising this question: what is MultiLife doing at a single point p1 that belongs to its life career? We noted that on the face of it, it is doing three incompatible things there: moving right, moving left, and staying at rest (see Figure 5.2 reproduced in Figure 5.4 with

86 Yuri Balashov

Figure 5.4 MultiLife is moving left, moving right, and staying at rest at p1 and p2.

some simplifications). We concluded that this raises a prima facie coincidence problem, to which the pluralist could respond by relativizing instantaneous composition (or constitution) of a composite object to several different stretches of the trajectories of its constituent particles (or to their temporal parts). The monist could respond, less plausibly, by relativizing in the same way the instantaneous state of motion of a single object. But eventually we must confront a more intriguing question: what is MultiLife doing throughout its entire life? To address this question, we need to connect the stretches of the boldfaced lines intersecting at p1, p2, and so on, to obtain complete continuous trajectories representing MultiLife’s total history. One such trajectory is the symmetry line of the whole diagram (Figure 5.5a). Other trajectories will include one or more ‘oblique’ boldfaced fragments at p1, p2, and so on, continuously merging with the symmetry line (Figures 5.5b and c). Each continuous selection of vertical and oblique fragments will constitute a possible total history of MultiLife.41 Every such history is determined by the total histories of MultiLife’s constituent particles; just not uniquely.

Figure 5.5 (a) Calm life, (b) and (c) hectic lives.

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88 Yuri Balashov The pluralist could try to summarize the situation by saying that we are dealing here with multiple (infinitely many!) composite objects completely coinciding throughout their entire histories, one of them living a very calm life, the others more or less hectic lives. It is not immediately clear what the monist could say. So let us focus on the pluralist options first. They are not very many, and none of them seems very promising. Contrast the ‘global question’ (about entire lives) with the earlier ‘local question’ about the state of motion at a single time. The pluralist response to the local question turned on relativizing instantaneous composition or constitution to different times in frames. In other words, it turned on relativizing what happens at one point to what happens at more than one point. Now that the question is about entire histories, this relativizing strategy is unavailable. Intuitively, the total history of a composite object must be determined (supervene on) the histories of its parts and the total history of their relations to each other. But in this case, it simply is not (does not). The parts do what they do throughout the lifetime. But there seems to be no fact of the matter about what the whole does throughout its lifetime. Again, it is useful to compare and contrast the situation with other coincidence puzzles. At this juncture, a good contrast case is that of Lumpl.42 Lumpl and Goliath are composed of the very same particles throughout their lifetimes. The total physical histories of both composite objects are fully determined by the physical histories of their constituent matter; we know what Lumpl and Goliath are doing—sitting there, in the sculptor’s studio. Arguably, their modal properties are not so determined. They could be taken to be ungrounded primitives or grounded in multiple de re representations, such as possibilia, or in different ways of conceptualizing a single object.43 This may give the pluralist the requisite resources to distinguish Lumpl and Goliath and to the monist the resources to resolve the apparent incompatibility of their modal profiles. But one may simply dig in one’s heels and refuse to grant a robust status to the non-categorical modal properties in the first place (see Section 1). One cannot do so in the MultiLife case. Physical states of motion underwriting the many histories of MultiLife are categorical, non-modal, and robust. This makes the case insusceptible to any of the traditional remedies. One might feel that the potential of the relativizing strategies is not yet exhausted. Couldn’t the diehard pluralist relativizer say that the particles, considered throughout their histories, compose (or constitute, if one prefers) CalmLife relative to a particular sequence of times in frames associated with the vertical boldfaced line in Figure 5.5a and that the very same particles compose a certain HecticLife (one of the infinitely many) relative to another such sequence associated with one of the zigzagging boldfaced lines (Figures 5.5b and c)? For that matter, couldn’t the diehard monist relativizer say that the particles considered

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throughout their histories compose a single object, MultiLife, which has one total physical history relative to a corresponding sequence of times in frames and many other histories associated with other such sequences? Perhaps they could say this. (What else could they say?) But what is ‘a particular sequence of times in frames’, which is required to do the heavy lifting in such relativizing strategies? In essence, it is a sequence of time hyperplanes through the consecutive points on a chosen boldfaced trajectory drawn at each point orthogonally to the tangent of the trajectory. Any such sequence of hyperplanes is fully determined (in a strict mathematical sense) by the corresponding boldfaced line and vice versa (modulo parallel transport). The net result of this relativizing approach for the pluralist is then as follows: throughout their total histories, the particles compose (or constitute) the history of CalmLife relative to the history of CalmLife, and they compose the history of a given HecticLife relative to that history, and so forth. The corresponding net result for the monist is this: MultiLife leads a calm life relative to the calm life history (i.e., the vertical line), and it also leads multiple hectic lives relative to the corresponding hectic life histories. This may be what it is in fact doing. But apart from being dangerously close to circular,44 this relativizing proposal does not get at the real worry about the case: how do the particles taken together manage to do all these things at once? Why does the system have these multiple, equally eligible histories in the first place? The many boldfaced lines keep staring us in the face even after the relativization. This leaves us with an option of saying that nothing lives any of these drastically different lives, calm or hectic. There are just two particles doing what they do. This amounts to denying metaphysical significance to the boldfaced lines in Figures 5.2, 5.4, and 5.5.45 Maybe they do not represent the trajectories of anything. Perhaps this is the most reasonable thing to say in the circumstances. But this is, of course, good old nihilism.46

6 Conclusion I conclude tentatively that the case of MultiLife is curious and resistant to the standard non-radical treatments of material coincidence.47 And to return to the point made at the beginning, we do not encounter anything similar of MultiLife in our ordinary reflections on material coincidence. Common sense, even when extended with the traditional metaphysical tools, seems to be blind to the sheer possibility of MultiLife. It is the physics of the case that opens a rather unexpected dimension in logical space. Consider this contrast: we often say of someone that he or she has lived many different lives at once: the life of a teacher as well as

90 Yuri Balashov that of a student, the life of a giver and the life of a taker. One can also be said to have lived both a good and a bad life. But one cannot be said to have spent his or her entire life in Europe and also in frequent trips between the Old and the New Worlds. Reconciling this new possibility with common sense may require a more drastic revision in our overall conceptual scheme than those that have been forced upon us by the traditional puzzles of material coincidence.48

Notes 1. For more details on how it happens in this case, see a very helpful introduction to a volume of classical readings on material constitution (Rea 1997). 2. Following Fine (2003). 3. The literature on material coincidence is large. For a collection of earlier classical readings, see Rea (1997). For an illuminating survey and useful bibliography, see Wasserman (2017). Recent developments are also discussed in some detail in Paul (2010) and Sattig (2015, Chapter 3). 4. The constitution view has been defended, among others, by Wiggins (2001), Johnston (1992), Baker (2000), and Thomson (1998). 5. Lumpl is a lump of clay created at t1 in the shape of Goliath (say, by putting two pre-carved pieces of clay together) and destroyed at t2 (Gibbard 1975). Lumpl and Goliath coexist over the same period of time and share all their historical as well as momentary properties. In fact, they share all their non-modal properties, differing only in such properties as possibly surviving flattening. This makes the case different from Lump and Vase and raises additional problems for some popular solutions to the latter. 6. For an earlier defense of mereological nihilism inspired by the ‘problem of the many’, see Unger (1979). 7. On mereological essentialism, see Chisholm (1976) and Van Cleve (1986). On the dominant kinds view, see Burke (1994). On the rejection of the doctrine of arbitrary undetached parts, see van Inwagen (1981). On four-dimensionalism, see Lewis (1983) and Sider (2001). On hylomorphic, bundle, and constituent ontologies, see Fine (2008), Paul (2006), and Sattig (2015). Each of these views is motivated by separate considerations, and none was intended to deal exclusively with the coincidence puzzles. In the discussion that follows I abstract from the more recent developments and focus instead on the earlier approaches, as my primary concern is not to adjudicate among the many currently available solutions to the familiar puzzles but to emphasize the unique nature of the new puzzle developed in Sections 2–5 and its resistance to any of the traditional approaches. 8. For surveys of the debates on simples and gunk, see Hudson (2007) and Gilmore (2018). On extended simples, gunk, and objects with nonstandard topology, see Hudson (2006) and Parsons (2007). On an interesting use of sophisticated time travel scenarios, see Gilmore (2007). On cutting the intuitive links between the mereological structure of objects and the mereological structure of regions in which they are located, see Saucedo (2011). 9. Hirsch (2008, 372). 10. Wasserman (2017, § 1). 11. On the grounding problem see Bennett (2004). 12. Should ‘the person in the street’ be worried about apparently incompatible aesthetic properties such as being defective that could be attributed to Vase but denied to Lump (see Fine 2003)? For the most part I will set the aesthetic

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14.

15. 16. 17.

18. 19. 20.

21. 22. 23. 24.

25.

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properties aside because the new case of coincidence I wish to develop involves only physical properties. According to the counterpart analysis of modality, Hubert Humphrey has the modal property of possibly winning the US presidential election in 1968 because of the full-blooded existence of someone else—his counterpart in a different possible world—who wins the election there. See Lewis (1971) and Sider (2001, Chapter 5). On the relativizing strategies, see Gibbard (1975), Noonan (1993), and King (2006). I learned of MultiLife (but not under this name) from Ian Gibson and Oliver Pooley (2006, 194n29). A useful way to think of MultiLife is to imagine the particles to be connected by a very light spring and the whole system to be floating freely in space. Note, however, that the springs should be specially designed to ensure the kind of motion depicted in a spacetime diagram in Figure 5.2, where the straight boldface line segments represent portions of uniform motion. A normal spring would turn both boldface lines into sine curves—which is not what is intended here. That is, special relativistic spacetime, which does not support the notion of absolute simultaneity and embodies, instead, an absolute metrical relation between events known as the interval, which imposes partial ordering on them. For a recent philosophically motivated discussion of such a procedure, see Balashov (2012). An even more striking two-particle case was briefly discussed by Maudlin (2002, 203–204). If the particles have suitably scaled hyperbolic trajectories in Minkowski spacetime, then their center of mass at the common focal point of these trajectories is instantaneously at rest in all inertial frames of reference. Thanks to Gordon Belot for pointing me to this discussion. It belongs to all three different trajectories of MultiLife’s center of mass, described previously. In the spirit of mechanics we treat the state of rest as a state of motion with zero velocity. The last two are modeled after paradigm aesthetic properties whose importance for the coincidence problems was emphasized by Kit Fine (2003). For further discussion, see King (2006) and Fine (2006). I hasten to note that the unsophisticated and unsuccessful relativization of the state of motion of MultiLife to reference frames mentioned in the text does not exhaust all the relativizing options available to those (i.e., the monists) who wish to deny coincidence in this case. I consider a more sophisticated and promising (but still unsuccessful) strategy in Section 4. If the system’s smallest parts are discrete masses, the radius vector of the center of mass r at any given time is simply the weighted sum of the radius vectors of the components: r = ∑miri / ∑mi. Then the instantaneous frame of the whole body would be defined by the tangent to this trajectory at a given point. See, in this connection, Pryce (1948), who mentions six different methods for defining the center of mass of a system of free particles in special relativity. For details of this procedure, see Balashov (2012). This procedure is similar to Pryce’s ‘proposal (d)’ (1948, 63 and § 3) developed in a much more technical environment of his article. More recent articles refer to Pryce’s ‘proposal (d)’ as the prescription for calculating the location of the “covariant noncanonical Fokker-Pryce center of inertia”. See, in this connection, Alba, Lusanna, and Pauri (2002), Alba, Crater, and Lusanna (2007), and Lusanna (2013), and references therein. The problem is not the existence of three different reference frames—(x, t), (x', t'), and (x", t"). The real problem is the existence of three intersecting

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26. 27.

28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46.

47.

boldfaced lines representing the intuitively incompatible states of motion of a single object in any chosen frame. I thank the referee for pressing me to highlight this important difference. I revisit this point in Section 4. That is, of MultiLife, if one denies material coincidence, or of MovingRight and AtRest, if one allows coincidence. To be sure, not everything that plays an important role in physics is real. For example, the ether and phlogiston, which played important roles in the development of classical electrodynamics and thermodynamics, respectively, are not real. This raises a host of hotly contested issues that are beyond the scope of my discussion here. I will say this much: the metaphysical status of the central concepts of mechanics, such as mass and force, is much more secure than the status of the ether and phlogiston was in their heyday. See Balashov (2012) for a recent discussion of these issues. Possibly connected by light springs and floating freely in space. The discussion that follows is not intended to favor any of the traditional treatments of material coincidence. For example, Gibbard (1975, 188–189) is careful to distinguish among a portion of clay (which may continue to exist when scattered), the lump of clay (which cannot survive breaking into pieces), and the statue. See, for example, Noonan (1993) who invokes an ‘Abelardian’ approach on which the properties expressed by certain predicates vary according to how the subject is conceptualized. Even if this gives him or her no advantage over the foe of constitution who is free to relativize composition to times in frames; see the preceding discussion. As described in Balashov (2012). Proposals along these lines have been developed, among others, by Gibbard (1975), Noonan (1993), and King (2006). See, in this connection, Fine’s (2006) response to King (2006). Noted in Sections 1 and 2 above. Simons (1987, 113–114) and Varzi (2008, § 6.2). See Varzi (2008, § 6.2). But still internal to the composite system; see above. Although the diagrams in Figure 5.5 are rather crude sketches and not exact calculations, they are intended to be faithful to the essential features of the case. See Gibbard (1975). These strategies have been developed, in rather different ways, by Lewis (1971), Gibbard (1975), Noonan (1993), and Paul (2006). Where the circle is very small: the relata (i.e., entire histories) to which the relevant properties are relativized are identical with the properties themselves (i.e., entire histories). See Section 3 for the physical considerations against such denial. Some of the referee’s comments suggest to me that a version of the problem would arise even if nihilism were true. Even the nihilist would have to say that the particles perform, collectively, three incompatible activities throughout their lifetime. The qualification is due to residual uncertainty about the status of the simple diagrams, such as Figures 5.2 and 5.4, and of the procedure for calculating the trajectories of discrete composite systems from the trajectories of their constituent particles, described in Balashov (2012). Both are rather sketchy, involve idealizations, and their relation to each other is not so clear. When fully developed, the procedure may establish the existence of an instantaneous center of mass trajectory. But the case of MultiLife also hinges on the non-uniqueness of such a trajectory, which cannot be established by the

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simple procedure. It is strongly suggested by the physical description of the case in Section 2 and by Figures 5.2 and 5.4. But the description and the figures may mask further details. The case may eventually be decided by physics (‘empirical metaphysics’ at work?). But its very possibility would remain striking even then. Interestingly, the notion of the center of mass of composite bodies in special and general relativity has rarely been discussed by physicists (cf. Pryce 1948). See, however, Alba, Lusanna, and Pauri (2002), Alba, Crater, and Lusanna (2007), and Lusanna (2013) for recent discussions and further references. 48. Versions of this chapter were presented at the annual meeting of the Society for Exact Philosophy at the California Institute of Technology in Pasadena, CA (June 2014) and at the Eidos Centre for Metaphysics, University of Geneva (December 2015). My thanks to these audiences for stimulating questions. I am indebted to Ant Eagle, Luca Lusanna, Graham Nerlich, Kent Peacock, and Tom Sattig for discussion of physical and metaphysical issues raised here. Special thanks are due to Rik Peels, Jeroen de Ridder, and a referee for their detailed comments on a draft. They have helped me better understand what I want to say in this chapter. The result may or may not be up to their full expectations. And needless to say, none of them is responsible for any remaining defects.

References Alba, David, Horace W. Crater, and Luca Lusanna. 2007. “Hamiltonian Relativistic Two-Body Problem: Center of Mass and Orbit Reconstruction.” Journal of Physics A: Mathematical and Theoretical 40: 9585–9607. Alba, David, Luca Lusanna, and Massimo Pauri. 2002. “Centers of Mass and Rotational Kinematics for the Relativistic N-body Problem in the Rest-Frame Instant Form.” Journal of Mathematical Physics 43: 1677–1727. Baker, Lynne Rudder. 2000. Persons and Bodies: A Constitution View. Cambridge: Cambridge University Press. Balashov, Yuri. 2012. “Do Composite Objects Have an Age in Relativistic Spacetime?” Philosophia Naturalis 49: 9–23. Bennett, Karen. 2004. “Spatio-Temporal Coincidence and the Grounding Problem.” Philosophical Studies 118: 339–371. Burke, Michael. 1994. “Preserving the Principle of One Object to a Place: A Novel Account of the Relations among Objects, Sorts, Sortals, and Persistence Conditions.” Philosophy and Phenomenological Research 54: 591–624. Chisholm, Roderick. 1976. Person and Object. London: Allen and Unwin. Fine, Kit. 2003. “The Non-identity of a Thing and Its Matter.” Mind 112: 195–234. Fine, Kit. 2006. “Arguing for Non-Identity: A Response to King and Frances.” Mind 115: 1059–1082. Fine, Kit. 2008. “Coincidence and Form.” Proceedings of the Aristotelian Society 82: 101–118. Gibbard, Alan. 1975. “Contingent Identity.” Journal of Philosophical Logic 4: 187–221. Gibson, Ian, and Oliver Pooley. 2006. “Relativistic Persistence.” In Philosophical Perspectives. Volume 20, Metaphysics, edited by John Hawthorne, 157–198. Oxford: Blackwell.

94 Yuri Balashov Gilmore, Cody. 2007. “Time Travel, Coinciding Objects, and Persistence.” In Oxford Studies in Metaphysics. Vol. 3, edited by Dean W. Zimmerman, 177– 198. Oxford: Clarendon Press. Gilmore, Cody. 2018. “Location and Mereology.” In The Stanford Encyclopedia of Philosophy (Spring), edited by Edward N. Zalta. https://plato.stanford.edu/ archives/spr2018/entries/location-mereology/. Hirsch, Eli. 2008. “Ontological Arguments: Interpretive Charity and Quantifier Variance.” In Contemporary Debates in Metaphysics, edited by Theodore Sider, John Hawthorne, and Dean Zimmerman, 367–381. Oxford: Blackwell. Hudson, Hud. 2006. The Metaphysics of Hyperspace. Oxford: Oxford University Press. Hudson, Hud. 2007. “Simples and Gunk.” Philosophy Compass 2 (2): 291–302. Johnston, Mark. 1992. “Constitution Is Not Identity.” Mind 101: 89–105. King, Jeffrey. 2006. “Semantics for Monists.” Mind 115: 1023–1058. Lewis, David. 1971. “Counterparts of Persons and Their Bodies.” Journal of Philosophy 68: 203–211. Lewis, David. 1983. “Survival and Identity.” In Philosophical Papers. Vol. 1, by David Lewis, 55–77. Oxford: Oxford University Press. Lusanna, Luca. 2013. “On Relativistic Quantum Mechanics in the Rest-Frame Instant Form of Dynamics.” Journal of Physics: Conference Series 437: 1–9. Maudlin, Tim. 2002. Quantum Non-Locality and Relativity. 2nd ed. Oxford: Blackwell. Noonan, Harold. 1993. “Constitution Is Identity.” Mind 102: 133–146. Parsons, Josh. 2007. “Theories of Location.” In Oxford Studies in Metaphysics. Vol. 3, edited by Dean W. Zimmerman, 201–232. Oxford: Oxford University Press. Paul, L. A. 2006. “Coincidence as Overlap.” Noûs 40: 623–659. Paul, L. A. 2010. “The Puzzles of Material Constitution.” Philosophy Compass 5 (7): 579–590. Pryce, Maurice H. L. 1948. “The Mass-Centre in the Restricted Theory of Relativity and Its Connexion with the Quantum Theory of Elementary Particles.” Proceedings of the Royal Society of London 195A: 62–81. Rea, Michael, ed. 1997. Material Constitution. Lanham: Rowman and Littlefield. Sattig, Thomas. 2015. The Double Lives of Objects. Oxford: Oxford University Press. Saucedo, Raul. 2011. “Parthood and Location.” In Oxford Studies in Metaphysics. Vol. 6, edited by Karen Bennett and Dean W. Zimmerman, 223–284. Oxford: Oxford University Press. Sider, Theodore. 2001. Four-Dimensionalism: An Ontology of Persistence and Time. Oxford: Clarendon Press. Simons, Peter. 1987. Parts: A Study in Ontology. Oxford: Clarendon Press. Thomson, Judith Jarvis. 1998. “The Statue and the Clay.” Noûs 32: 149–173. Unger, Peter. 1979. “There Are No Ordinary Things.” Synthese 41: 117–154. Van Cleve, James. 1986. “Mereological Essentialism, Mereological Conjunctivism, and Identity Through Time.” Midwest Studies in Philosophy 11: 141–156. Van Inwagen, Peter. 1981. “The Doctrine of Arbitrary Undetached Parts.” Pacific Philosophical Quarterly 62: 123–137.

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Varzi, Achille. 2008. “The Extensionality of Parthood and Composition.” Philosophical Quarterly 58: 108–133. Wasserman, Ryan. 2017. “Material Constitution.” In The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta. https://plato.stanford.edu/archives/ fall2017/entries/material-constitution/. Wiggins, David. 2001. Sameness and Substance Renewed. Cambridge: Cambridge University Press.

6

Coincidence Problems Without Properties Peter van Inwagen

Professor Balashov maintains that—so far—statements of the so-called problems of material coincidence (‘Lump and Vase’, ‘Tibs and Tibbles’.) have been framed in ways that require appeals to ‘non-categorical properties’—modal properties like ‘could survive radical deformation’, for example, or temporally indexed properties like ‘having existed at noon yesterday’, ‘having once been vase-shaped’, and ‘being a thing that will at some point lose its present shape and will, at some later point, acquire that shape a second time’. In the following passage, he suggests that such properties are insufficiently ‘robust’ to pose real, substantive problems about the identities of material things. It is fair to say that the proverbial man in the street finds nothing problematic in the stories about Tib and Tibbles, and Lump and Vase, until he is brainwashed by the philosopher into being serious about non-categorical properties—[in Ryan Wasserman’s words] the ‘various ways that a thing was, will, would, could, or must be’. One could argue that such features—temporal and historical properties, kind properties, persistence conditions, and other modal properties—are not robust enough to generate widespread ontological anxiety or conflict with Leibniz’s Law. It is relatively easy to set them aside. Why should we worry about such allegedly incompatible pairs of properties as will exist tomorrow and will not exist tomorrow or had a tail and did not have a tail to the extent that we do about being square versus being round, hot versus cold, or moving right versus moving left (at the same time)? (Balashov, Chapter 5, 74) He proceeds to show how—by a clever application of the special theory of relativity—one may describe a case of materially coincident bodies that differ in respect of their possession of a certain robust property. And he defends the thesis that the solutions to the (supposed) problems of material coincidence that philosophers have proposed1 (formulated as they have been in terms of Leibniz’s law and non-categorical properties) cannot be applied to the problem he has posed.

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If the theses affirmed in the offset passage are correct, the problems of material coincidence (as they have so far been stated by analytical metaphysicians) rest on three assumptions: (i) that there are properties such as ‘temporal and historical properties, kind properties, persistence conditions, and other modal properties’, and (ii) that these properties are among the properties ‘quantified over’ in the principle (commonly called ‘Leibniz’s law’), ∀x∀y∀z (z is a property & x = y . → . x has z ↔ y has z),

and (iii) that Leibniz’s law is true. I will contend, however, that the so-called puzzles of material coincidence can be stated without any appeal to properties of any sort. I will confine my remarks to ‘the problem of Lump and Vase’. I begin by asking whether the following argument (‘Argument A’) is formally valid. 1. Lump existed at noon yesterday 2. ~Vase existed at noon yesterday 3. ~Lump = Vase

Premise Premise 1,2

I maintain that Argument A is indeed formally valid—and not because it is an enthymematic abbreviation of the argument (suppressed premises in boldface). 1. Lump existed at noon yesterday Premise 1a. Lump has the property ‘having existed at noon yesterday’ ↔ Lump existed at noon yesterday Premise 2. ~Vase existed at noon yesterday Premise 2a. Vase has the property ‘having existed at noon yesterday’ ↔ Vase existed at noon yesterday Premise 2b. ∀x∀y∀z (z is a property & x = y . → . x has z ↔ y has z ) Premise 3. ~Lump = Vase 1, 1a, 2, 2a, 2b This second argument (‘Argument B’) is, of course, formally valid. But is it sound (given the truth of (1) and (2)? It is only if the three premises it does not share with Argument A—(1a), (2a), and (2b)—are true. (If Argument A is valid, its validity obviously cannot be accounted for by saying that it is an ‘enthymematic abbreviation’ of Argument B if any of those three premises is false.) And are they true? We need not address this question— I maintain—because Argument A is formally valid just as it stands. Its validity—I maintain—is endorsed by frst-order quantifer logic with identity2 (hereinafter, QL=). To see this, consider the schematic sentence: ∀x∀y (x = y → . Fx ↔ Fy).

98 Peter van Inwagen This sentence is a theorem of QL=. Let us say that a theorem of QL= endorses (or guarantees the truth of) a semantically complete or truthevaluable sentence if that sentence comes from that theorem by proper substitution of extensional predicates for the predicate-letters (‘F’, ‘G’, ‘H’, etc.) that occur in that schematic sentence. I offer the following twoclause defnition of ‘predicate’. (The frst clause is a recursive defnition of infnite length. An equivalent fnite defnition is easy enough to state, but I think that what I have provided is easier to grasp intuitively.) (i) All declarative sentences are 0-place predicates; nothing else is a 0-place predicate The result of replacing some of the nominal phrases in any 0-place predicate with ‘1’ is a 1-place predicate; nothing else is a 1-place predicate The result of replacing some of the nominal phrases in any 1-place predicate with ‘2’ is a 2-place predicate; nothing else is a 2-place predicate The result of replacing some of the nominal phrases in any 2-place predicate with ‘3’ is a 3-place predicate; nothing else is a 3-place predicate. (ii) A predicate is an expression that, for some n, is an n-place predicate. Thus, ‘Miami is north of Boston’ is a 0-place predicate; ‘1 is north of Boston’, ‘Miami is north of 1’, and ‘1 is north of 1’ are 1-place predicates; ‘1 is north of 2’ and ‘2 is north of 1’ are 2-place predicates; ‘4 and 1 are more distant from each other than 3 is from any of 1, 2, and 4’ is a 4-place predicate.3 A predicate is non-extensional just in the case that sentences with different truth values can be obtained by replacing the boldface numerals it contains with referring phrases that have the same referent. (And a predicate is extensional if it is not non-extensional.) So, for example, ‘1 is north of 1’ is extensional; if ‘Boston’ and ‘the hub of the universe’ designate the same object, ‘Boston is north of Boston’ and ‘The hub of the universe is north of the hub of the universe’ cannot have different truth values. But ‘Mayor Walsh believes that 1 is beautiful’ is not an extensional predicate, owing to the fact that it could be that Mayor Walsh believes that Boston is beautiful and does not believe that the hub of the universe is beautiful. Consider now the sentence ‘This lump of clay existed at noon yesterday’. Since there is such a sentence, there is such a predicate as ‘1 existed at noon yesterday’. Proper substitution of this predicate for the predicate letter ‘F’ in ‘∀x∀y (x = y → . Fx ↔ Fy)’ yields:

4. ∀x∀y (x = y → . 1 existed at noon yesterday x ↔ 1 existed at noon yesterday y).

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This substitution is ‘proper’ owing to the fact that ‘F’ is a 1-place predicate letter (in the expression we are considering) and ‘1 existed at noon yesterday’ is a 1-place predicate. ‘F’ is a 1-place predicate letter because, at each of its occurrences, it is followed by a single occurrence of a variable—by a 1-term left-to-right sequence of occurrences of variables, so to speak. (In the expression ‘Gxxyxyz’, ‘G’ is a 6-place predicate letter. A sentence-letter like ‘q’ is a 0-place predicate letter.) Having made this substitution, we proceed to translate (4) into a sentence in standard logical notation—thus: 4’. ∀x∀y (x = y → . x existed at noon yesterday ↔ y existed at noon yesterday). Sentence (4’) comes from sentence (4) by a trivial application of what might be called a translation algorithm—an algorithm whose full statement you will, I hope, be able to ‘read off’ the following nontrivial application: applied to ∀x∀y∀z∀w (z = y → . 3 and 1 are north of 2 ywx ↔ 3 and 1 are north of 2 zwx), the algorithm yields: ∀x∀y∀z∀w (z = y → . x and y are north of w ↔ x and z are north of w). Sentence (4’) therefore comes from ‘∀x∀y (x = y → . Fx ↔ Fy)’ (a theorem of QL=) by proper substitution of the 1-place predicate ‘1 existed at noon yesterday’ for the 1-place predicate letter ‘F’.4 It is, moreover, evident that ‘1 existed at noon yesterday’ is an extensional predicate: substituting co-referring terms for ‘1’ in this predicate cannot yield sentences with differing truth values. So, fnally, sentence (4’) is a truth-evaluable sentence that comes from a theorem of QL= by proper substitution of an extensional predicate for the predicate letter ‘F’ in that theorem. We may therefore say: Sentence (4’) is a truth of formal logic—that is, it is ‘endorsed’ by a theorem of QL= (to wit: ‘∀x∀y (x = y → . Fx ↔ Fy)’). And we may therefore further say that Argument A is formally valid in the following sense: the argument 5. Lump existed at noon yesterday Premise 6. ~Vase existed at noon yesterday Premise 7. ∀x∀y (x = y → . x existed at noon yesterday ↔ y existed at noon yesterday) Premise 8. ~Lump = Vase. 5, 6, 7

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is formally valid, and the ‘new’ premise (line [7]) is a truth of formal logic. Note that no premise of this argument involves quantification over properties—properties of any sort. ‘But what about that theorem of QL= —‘∀x∀y (x = y → . Fx ↔ Fy)? Doesn’t it presuppose Leibniz’s law’? Well, that depends on what you mean by ‘presuppose’ and on what you mean by ‘Leibniz’s law’. Two things are certainly true: (i) In no sense of ‘presuppose’ does that theorem (or the fact of its theoremhood) presuppose the truth of the statement ∀x∀y∀z (z is a property & x = y . → . x has z ↔ y has z),

a statement that (like ‘∀x∀y (x is a property → y has x)’) is vacuously true if Platonic Realism is false and there are no properties—and interesting only if Platonic Realism is true.5 (ii) The inference rules of QL= are those of quantifier logic simpliciter supplemented by two rules that define the logical properties of the identity sign. One of these is sometimes called Leibniz’s law, but to avoid calling that rule and the preceding statement (or sentence or proposition) by the same name, I’ll call it the rule of the indiscernibility of identicals or I=. The following statement of I= is as good as any: For any variables α and β, and any sentences p and q, if β does not occur in p and q is like p except for containing occurrences of β at some or all places at which p has free occurrences of α, then ⌜α = β → (p ↔ q)⌝ may occur as a line at any point in a derivation. (Annotation: I=.)6 (By a ‘sentence’ we understand a well-formed formula of QL=. For example: ‘p’, ‘yFx’, ‘x = z’, ‘∀y (Fzyz → . q ~Gyz)’, . . .) One proof of ‘∀x∀y (x = y → . Fx ↔ Fy)7 looks like this: 1 2

∀x∀y (x = y → . Fx ↔ Fy) x = y → . Fx ↔ Fy

I=

The application of I= in line 2 is correct because ‘y’ does not occur in ‘Fx’, and ‘Fy’ is like ‘Fx’ except for containing occurrences of ‘y’ at some or all places at which ‘Fx’ has free occurrences of ‘x’. I contend that these remarks demonstrate that ‘~Lump = Vase’ may be deduced from ‘Lump existed at noon yesterday’ and ‘~Vase existed at noon yesterday’ using techniques equivalent to those that can be found

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in any logic text. I have not supposed that there is such a property as ‘having existed at noon yesterday’. I have not supposed that there are properties of any description. The following statement therefore rests on a false assumption: [i]t is fair to say that the proverbial man in the street finds nothing problematic in [the story of] Lump and Vase, until he is brainwashed by the philosopher into being serious about non-categorical properties . . . the ‘various ways that a thing was, will, would, could, or must be’. One could argue that such features—temporal and historical properties, kind properties, persistence conditions, and other modal properties—are not robust enough to generate widespread ontological anxiety or conflict with Leibniz’s Law. (Balashov, Chapter 5, 74) For philosophers have misled that proverbial creature—I myself generally refer to him by his postwar Oxonian designation, the man on the Clapham omnibus—if they have led him to suppose that the problems of material coincidence cannot be stated without an appeal to non-categorical or non-robust properties. If some philosophers have appealed to such properties in their statements of those problems, well, they needn’t have. If my deduction of the nonidentity of Lump and Vase did not involve reference to any property or quantification over properties, it certainly involved reference to a predicate, to wit, the predicate ‘1 existed at noon yesterday’. But there is such a predicate—for there is something that is common to the sentences ‘The Taj Mahal existed at noon yesterday’, ‘It existed at noon yesterday’, ‘God existed at noon yesterday’, and ‘z existed at noon yesterday’. And there is such a predicate whether or not there are properties (or qualities, attributes, characteristics, or features). The predicate ‘1 existed at noon yesterday’ therefore exists even if it ‘has no associated property’ or ‘fails to express a property’—that is, even if someone who says, for example, ‘The Taj Mahal existed at noon yesterday’ does not thereby ascribe or attribute any property to the Taj. And, a fortiori, that predicate exists even if it does express a property and that property is a non-categorical property. And if that predicate exists, it is an extensional predicate and may be substituted for ‘F’ in the theorem ‘∀x∀y (x = y → . Fx ↔ Fy)’. And, really, is what I have been saying not extremely intuitive? If you think it is not, perhaps I can convince you that it is by asking you to reflect on the argument I attribute to ‘Bill’ in the following exchange. Your theory is crazy, Bill. Lady Anne Clifford can’t have been the author of Hamlet. We know that the play was written within a year or two of 1600. Anne Clifford was ten years old in 1600.

BETSY:

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Peter van Inwagen Betsy, you’ve been brainwashed by philosophers into supposing that there are historical properties—properties like ‘having been ten years old in 1600’. And there aren’t any such properties. What’s more, your reasoning is flawed even if there are. You’re in effect appealing to Leibniz’s law. That is, a hidden premise of your argument is

BILL:

Lady Anne Clifford = the author of Hamlet → . Lady Anne Clifford has ‘having been ten years old in 1600’ ↔ the author of Hamlet has ‘having been ten years old in 1600’. And even if non-categorical properties like ‘having been ten years old in 1600’ do exist, they’re not robust enough to conflict with Leibniz’s law. Perhaps the reader will agree with me when I say—as I do—that Bill’s critique of Betsy’s reasoning makes no sense. Now consider the exactly parallel critique (by ‘Will’) of the argument of ‘Bess’, who has deduced ‘~Lump = Vase’ from ‘Lump existed at noon yesterday’ and ‘~Vase existed at noon yesterday’: substitute ‘Bess’ for ‘Betsy’; substitute ‘having existed at noon yesterday’ for ‘having been ten years old in 1600’; substitute ‘Lump’ for ‘Lady Anne Clifford’; substitute ‘Vase’ for ‘the author of Hamlet’. I would ask this: if Bill’s critique of Betsy’s reasoning makes no sense, can it be that Will’s critique of Bess’s reasoning does make sense?

Notes 1. Other than the solution that affirms nihilism, the thesis is that there are no composite objects. And that solution is a solution to the problems of material coincidence only in the sense in which atheism is a solution to the problem of evil. That is, according to the nihilist solution, there are no such things as Lump, Vase, Tib, and Tibbles. And, therefore, the propositions ‘Lump and Vase are distinct material objects that at some times occupy the same region of space and have the same proper parts’ and ‘Tib and Tibbles are distinct material objects that at some times occupy the same region of space and have the same proper parts’ raise no philosophical problems—for the very good reason that they are false. 2. So-called—I dislike the term ‘order’ (as it is used in phrases such as ‘secondorder logic’ and ‘variable of higher order’, because I believe that the only true variables are nominal variables—and therefore believe, like Quine, my master in matters pertaining to the philosophy of logic, that higher-order logic is ‘set theory in sheep’s clothing’. See Quine (1970, 66). The phrase ‘Set Theory in Sheep’s Clothing’ is a section heading in Chapter 5. 3. Note that, for example, ‘1 is north of 3’ and ‘2 is north of 2’ and ‘3 is north of 2’ are not predicates. A predicate must either contain no occurrences of boldface numerals or contain occurrences of ‘1’ and of no other boldface numerals or contain occurrences of each of ‘1’ and ‘2’ and of no other boldface numerals or contain occurrences of each of ‘1’ and ‘2’and ‘3’ and of no other boldface numerals or . . . 4. Similarly, ‘∀x∀y∀z∀w (z = y → . x and y are north of w ↔ x and z are north of w)’ comes from the theorem ‘∀x∀y∀z∀w (z = y → . Fxyw ↔ Fxzw)’ by proper

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substitution of the 3-place predicate ‘3 and 1 are north of 2’ for the 3-place predicate letter ‘F’. 5. Here is an exercise for the reader: show that the offset sentence is ‘endorsed’ by the theorem ‘∀x∀y∀z (Fz & x = y . → . Gxz ↔ Gyz)’. 6. The other rule is reflexivity: for any variable a, ⌜a = a⌝ may occur at any point in a derivation. 7. The ‘apparatus’ of the proof—I have not used the symbol they use for the universal quantifier—is that of Donald Kalish and Richard Montague (1964). That apparatus (‘boxing and canceling’, ‘universal proof’) is rather different from the apparatus of most systems of natural deduction, but it of course generates the same theorems (defective systems like that of Copi [1965] aside). A completeness proof by the authors is cited on page 264.

References Copi, Irving M. 1965. Symbolic Logic. 2nd ed. New York: Macmillan. Kalish, Donald, and Richard Montague. 1964. Logic: Techniques of Formal Reasoning. New York: Harcourt, Brace & World. Quine, W. V. 1970. Philosophy of Logic. Englewood Cliffs: Prentice Hall.

7

Conceptual Revisions Intentions and Free Will in the Light of Cognitive Neuroscience Pim Haselager

1 Introduction Under normal circumstances, we experience a freedom to engage in or refrain from specific actions: we feel free to do or don’t as we like. From relatively simple choices (tea or coffee), to complex decisions (buy that house or not), to potentially life determining steps (marry him/her or not), we appear to decide and act freely. Barring exceptional situations, we are free to determine our own goals; form our behavioral intentions on the basis of what we perceive, know, believe, feel and desire; and then act upon them. Concepts such as identity, autonomy, and responsibility are interwoven with this everyday image of ourselves and others. For instance, my selection of goals (‘this is what I find important; that’s what I want’) demonstrates aspects of my autonomy, and reveals who I am, by showing what I find important to achieve and what I am prepared to do to pull it off.1 I normally also accept responsibility for my thoughts and actions. I myself chose to do something, and I view the results as consequences of my thoughts and deeds. Sometimes that makes me proud, sometimes ashamed, and at times I may even have to pay for it. There is a lot to be said for this common sense perspective on ourselves, perhaps first and foremost that we live by it. And, as one great philosopher of common sense, Thomas Reid has said: [i]f there are certain principles, as I think there are, which the constitution of our nature leads us to believe, and which we are under a necessity to take for granted in the common concerns of life, without being able to give a reason for them—these are what we call the principles of common sense; and what is manifestly contrary to them, is what we call absurd.2 Therefore, it seems reasonable to take such a common sense perspective as seriously as possible for as long as possible. At the same time, several of our most widespread views on ourselves and the world around us, for example, the earth’s relation to the sun, our rationality, the nature of

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matter, and so on have been challenged by science. And, in such cases, as Sellars has put it: in the dimension of describing and explaining the world, science is the measure of all things, of what is that it is, and of what is not that it is not.3 Hence, the common sense perspective on free will is not and should not be immune to scientifc challenges. Free will has been debated and challenged for centuries (from, e.g., the time of Pelagius and St. Augustine via Luther, Erasmus, Spinoza, and LaMettrie up to our current times). Recently, the discussion about the (im)possibility of free will has left the perhaps less visible corners of philosophy and theology as a result of neuroscientifc research that demonstrates, sometimes dramatically so, the extent to which our thoughts and actions depend on matter, specifcally neuronal matter. Whatever kind of media one may want to consult (TV, radio, newspapers, YouTube, Facebook, Twitter, etc.), one is bombarded by reports about the latest results of cognitive neuroscience, often related to how our intentions can cause actions, accompanied by vivid demonstrations about what can be achieved via neurotechnology (brain imaging or brain stimulation). This had led to, what could perhaps be called, a popular debate about the nonexistence of free will.4 As is often the case in popular debates, extreme positions tend to capture the headlines and the imagination and tend to dominate the discussion. This can easily lead to situations in which only two options seem to remain: either free will exists or it doesn’t. I have briefly indicated elsewhere5 why I find the question of whether free will exists or not a misguided and badly formulated one. Briefly put, it is far from clear to me whether considering free will as a unitary phenomenon, something amenable to a classical style of definition specifying necessary and sufficient conditions, makes much sense. Rather, I suggest to see free will as a hypothetical construct:6 a hypothesized capacity that we need to further investigate to establish whether it is meaningful, existing, and if so, what its properties are. Positing such a hypothetical construct makes sense, as a first approximation, because of an experience of free will we sometimes have and because of the social practices of holding each other responsible or accountable for our thoughts, desires, and actions (as well as their consequences).7 It is not immediately obvious, nor required for the construct to be useful, that such a hypothetical construct will always map neatly to a mental and/or neurophysiological reality. Moreover, free will, insofar as it may turn out to be applicable, could turn out to do so only to a certain and perhaps even variable extent. Hence, here I will make a plea to use the current neuroscientific investigations not as an arbitrator for yes/no decisions. Instead, I will suggest that we should take the research of cognitive neuroscience (CNS) on intentions and free will as providing

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opportunities for better informed self-reflection and investigations of how we could revise that notion to expand our self-understanding. This also involves a consideration of how certain folk psychological notions, such as intention, may have been too uncritically accepted in CNS.8 In a way, CNS research may be seen as a snake biting its own tail: to the extent that it starts out from traditional concepts such as intention and free will, the results of CNS may help underscore not that the phenomena as such don’t exist at all, but that our way of conceptualizing them is in need of revision. Finally, I will briefly consider what implications revisions in the notion of free will might have for current or potentially future societal practices related to the attribution of responsibility. In all, conceptual revision in the light of neuroscientific progress may improve our understanding of intention and free will, which may benefit both societal practice and stimulate more adequate research in cognitive neuroscience.

2 Preliminaries As the topic of free will has been extensively debated in a variety of ways, from popular media to arcane academics, and many different perspectives, concepts and positions can be taken, it is perhaps useful to briefly indicate my general outlook before going into details. Free will, for me, has little to do with the ability to do otherwise. If everything in a situation, our brains, bodies and environments, down to the molecular level, would be 100 percent similar to an earlier situation, we would do exactly the same. I have not seen any explanation that indicates how it could be otherwise, except by introducing an element of chance, and I don’t see what we would gain in terms of meaningful free will if that would be the case. That said, I don’t know whether determinism is true in the sense of the universe being a deterministic system. It might turn out to be; it might also be that quantum mechanistic indeterminacy might be more accurate. But at least temporarily and for the sake of the argument, I’m willing to work on the hypothesis that determinism is true. Determinism, in any case, is for me not the essence of the free will debate. Responsibility is. Attributing, accepting, or rejecting responsibility is a crucial ingredient of our social practices. I am interested in examining whether, and if so how, in the light of scientific discoveries about ourselves (body, brain, and environment) a notion of free will can be developed that supports this social practice of attributing responsibility in a meaningful, not merely metaphorical, way. The question is not about what kind of free will we would like to have but rather what kind of free will we can have, given what we know about the world and ourselves. Amidst so much that we should improve about ourselves, one of the more beautiful aspects of the human species is the capacity for and willingness to engage in an exploration of ourselves and our surroundings. We may not always immediately like what we discover, but as has happened

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before (e.g., the earth not being the unmoving center of the universe, the ancestry we have in common with apes, and our irrationality), we can learn to live with it and perhaps even use the newly acquired knowledge to improve ourselves. One of the most crucial questions regarding free will is: how, in virtue of what, can free will exist and have the consequences it is claimed to have? How can I be free to form an intention to act in a certain way and then act it? Without an answer to this question, any theory or perspective regarding free will is based on a promissory note. Note that this question is not sufficiently answered by, for instance, acknowledging that, for example, the brain plays an important role as that would be too vague and potentially incomplete (what is the role precisely, how does it work, and if there are other elements that play a role, what are those and how do they work?). I don’t think science currently has an answer, in part because the evidence is incomplete and in part because the notion of free will needs to be clarified and revised for the question to be answerable. But I do think that the framework of scientific materialism is the most promising candidate to present an answer in terms of the physical law-abiding interaction of material elements. I am not an epistemological reductionist because higher level concepts are necessary to identify and explain the overall patterns we see in reality. However, although I’ve tried hard, I have been unable to see exactly how concepts like ‘emergence’, ‘collective variables’, and ‘downward causation’ could be understood in an ontological, causally efficacious way. That is, at least upon my own closer analyses, higher-order phenomena, essential from an epistemological perspective, derive their explanatory powers from lower-level physical-causal interactions. Hence, I can’t be an ontological non-reductionist. I would like to remain a realist for as long as possible, in the sense that the answers to our questions to nature (investigations and experiments) display features of something that exists even if no observers would exist. Although these answers unavoidably reflect the questions as well, they not only reflect the questions. Something bites back, and that I call ‘reality’. I am a scientific realist in the sense that I believe that systematic and prolonged scientific investigation does converge, in the long run, toward a more veridical description and explanation of that reality. I am not suggesting that human beings, as a species, have an unlimited capacity to understand everything, and hence it is entirely possible that because of our species’s related limitations, we may not find the answers to certain questions, even though such answers might exist. I also do not think that science, currently, has already conclusively proven that, for example, souls, or nonmaterial causally efficacious phenomena, do not exist. I do think that such phenomena, given what we know, are highly unlikely to exist and that a materialist explanation of the mental is much more likely to capture ‘all there is’. I think this in part because of the converging

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evidence that science produces in relation to psychological phenomena, its empirical progress and because no alternative, as far as I can see, comes even remotely close to the descriptive, explanatory, and predictive powers of a materialist science. Materialist science, especially in relation to mental phenomena such as free will, encompasses much more than merely neuronal phenomena. I reject a neurocentric approach because I think cognition and behavior are essentially and continuously embodied and embedded. Our physiological bodies and our social environments are crucial in shaping our thoughts, feelings, and behaviors. We can’t develop a full understanding of ourselves by focusing only on the brain. In this chapter, I will focus on neuroscientific data and theories, but I’d much prefer to replace every mention of brain by body–brain–environment, if that wouldn’t be so cumbersome.

3 What Cognitive Neuroscience Does (Not) Show in Relation to Free Will In a series of experiments,9 Libet et al. identified a brain signal in the supplementary motor cortex, the readiness potential (RP), that appears to reliably precede, by a few hundred milliseconds, the experience of wanting to move. The experimental setup is so famous that it makes little sense to repeat it here. Hence the question arises: if subconscious brain processes precede the intention and/or the action, what does that imply for free will? The awareness of the intention appears after the measured brain signals, so how could intentions be the true initiators of action? According to some, Libet’s experiments are the ‘final death blow’ to the idea that thoughts determine our behavior.10 But having participated in replications and extensions of Libet-style studies, I think any such claim is highly premature. There are many questions one can ask about Libetstyle studies, and as these are extensively discussed as well, I will only mention the main categories here. First, there is the question regarding the operationalization of ‘intention’ or ‘will’. What mental process exactly is being measured?11 A decision, wish, intention, volition, or urge? What do participants in experiments think they are being asked to report about their awareness of what is leading up to their finger movements? And how accurate and reliable is their capacity to report such events? Second, what is the ecological validity of performing unprompted, meaningless finger movements for no reason in particular that have no discernible consequences in the real world? The Libet-style experiments have been criticized for lacking ecological validity.12 In these experiments the focus is on self-initiated voluntary actions, where participants engage in actions without being prompted. Yet, societally speaking, the importance of free will seems to lie rather in deliberative action, where someone pursues goals of one’s liking and,

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on the basis of arguments that one considers to be persuasive, engages in specific actions. Third, one may question the clarity of the data. Here it is important to realize that generally the time differences between RP and intention awareness are averages, not individual case-by-case differences.13 Fourth, the significance of the temporal relation between RP and awareness (and movement) is under debate. Most importantly, one cannot derive a causal relationship between the RP, the awareness of the intention, and the act from the mere observation that brain signals can be measured prior to intention reports and finger movements.14 Finally, the exact nature and role of the RP continues to be discussed. What exactly does the RP represent? How likely is it, for instance, that a brain signal in the supplementary motor cortex is correlated with an intention? Rather, the supplementary motor cortex is a brain area the activity of which is correlated with direct control of body movement and coordination. Hence, activity there may be predictive of, for example, a finger movement rather than a decision or intention to move. As Soon et al. say, it is “unclear whether the Supplementary Motor Area is indeed the cortical site where the decision for a movement originates or whether high-level planning stages might be involved”.15 Given such questions, any claim about a ‘final death blow’ would be, in the words of Mark Twain, ‘an exaggeration’.16 Rather, I suggest such experiments could be taken as illustrations of, instead of proofs for, scientific materialism. The Libet studies, as they currently stand, do not debunk the existence of free will. However, it is also important to realize that absence of proof is not proof of absence. The fact that there are many issues remaining to be solved or even appropriately addressed only serves as a reminder that any conclusions about the nonexistence of free will would be premature. I think that attempts to use these questions as grounds for an argument that free will does exist would be ill-advised. The questions raised by critical reflection on Libet-style studies are being addressed by different setups,17 and the converging evidence for brain processes being detectable prior to subjective awareness of intention is substantial. More importantly, there is a more general argument that strikes me as crucial: if it is not in virtue of the body–brain–environment, then how do we make decisions, have intentions, and engage in action? In other words, to reject a neuroscientific perspective on how cognition leads to action, one needs an alternative paradigm that is, from its perspective, empirically and logically reasonably well grounded as well. I do not see such an alternative. If intentions wouldn’t derive their causal powers from material (body–brain–environment) states, how would they have causal effects? In relation to this question I am committed to the working hypothesis that in as far as our behavior is caused, this will be in virtue of the physical law abiding causal interaction of material parts (body–brain–environment). Hence, despite the scientific relevance of the

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remaining questions, any attempt to ‘save’ free will based on the current lack of complete and fully demonstrative evidence seems as unsatisfactory as claims that it is beyond saving on the basis of the currently available evidence. All the same, our everyday, folk psychology way of talking about it need not map onto the underlying causal-material processes. As an alternative, I suggest to move away from such a forced binary choice and to refocus on our common sense perspective on what intentions do and what free will is. As indicated in the introduction, the common sense perspective suggests that under normal circumstances, I am free to make up my mind about what goals to pursue and what actions to perform to achieve them. My goals, intentions, and actions are up to me. I propose to examine more closely the notions of ‘intention’ and ‘free’ to see what possibilities a conceptual revision might offer as an escape from a forced binary choice.

4 Intentions and the Brain It may be useful to consider the notion of intention as a first target for revision. From a common sense perspective, the idea is that agents, on the basis of what they perceive, know, believe, feel, and desire are free to develop specific intentions to act, which then, under normal circumstances (unless vetoed, etc.), are put into action. Of course, this need not imply that everything we do is based on an explicit conscious decision as much of our behavior can be automatic, unreflective, or subconscious. It merely means that to the extent that we engage in the practice of describing, explaining, and predicting behavior, we tend do so in terms of beliefs, desires, and intentions. This daily folk psychological framework or craft18 demonstrates its usability on a continuing basis. It is, by now, a long-standing debate whether this everyday perspective on the role of intentions in action provides an adequate conceptual framework for the study of cognition.19 Traditionally, it has been tempting to take intentions literally, as representations in the brain that play a causal role in the production of behavior. In artificial intelligence (AI), physical symbol models were developed that attempted to capture the role of knowledge, beliefs, desires (goals), and intentions in terms of symbolic representations to be processed according to specific rules.20 In CNS, it is still common for researchers to explore the ‘neural correlates’ of mental phenomena.21 To be sure, this could very well turn out to be a useful, productive way of creating computational models and doing empirical research. However, it could be worthwhile to consider intentions as ‘hypothetical constructs’—that is, postulated unobserved entities or processes.22 As Dennett suggests, it is useful to engage in an ontologically neutral heterophenomenology, in that we take the reports about the experience of intentions seriously, without thereby committing to the claim that

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intentions are present in the brain.23 After all, in Libet-style experiments, it may seem that we already know that the intentions are there, and we are ‘merely’ attempting to find their neural correlates (e.g., the RP), but as far as empirical observation goes, it might actually be the opposite. In addition to the finger movements, in terms of hard observables, the RP is more concretely measurable (although see my previous reservations) than the intention, of which only the participants’ reports are empirically available. In “Why We May Not Find Intentions in the Brain” we argued that “intention may not be the most fruitful theoretical construct for investigation into the neural processes underlying action generation and control”.24 Details aside, the basic argument is that in their everyday practical use, intentions play an identifiable, concrete explanatory role. When someone asks me why I’m putting on my coat, my answer is that I intend to go out for a walk and that I believe it to be cold outside. Beliefs, desires, and intentions can be distinguished and identified in their everyday descriptive, explanatory, and predictive usage (this is sometimes referred to as the ‘functional discreteness’ of mental states).25 It may very well be, however, that this functional discreteness of intentions is more a consequence of our everyday explanatory usage than a consequence of its neuronal interpretation. The underlying neural activity is continuous and dynamically complex rather than discrete. In addition, the study of intention has led to a move away from the idea of an intention as a unitary state, moment, or step in the cognitive processes toward action. Instead, different phases of the process of intending now form the leading model. Verbaarschot, Haselager, and Farquhar distinguish between five different phases involved in Libet-style intentional action (see Figure 7.1).26 When subjects decide to participate in an experiment, this reflects a ‘global whether’ decision: once participating in the experiment, there is a general willingness to engage in actions conforming to the experimental instructions. A second phase consists of waiting (e.g., for a signal or for the moment of acting) during which random fluctuations in neural activity can be found.27 A third phase that can be distinguished is a ‘deciding what’ phase, when a particular type of action (e.g., moving left or right finger) is prepared. This can evolve into a fourth phase of deciding when to move, for example, when the neural fluctuations pass a certain threshold. Finally, a possibility of vetoing the intended act constitutes a potential fifth phase. Different models are obviously possible and may help explain the occurrence of differentially timed reports and brain signals. In any case, it is clear that an intention as a particular mental state occurring at a particular point in time is, at best, a huge oversimplification, and, at worst, a thoroughly misleading assumption for neuroscientific research. It might simply be that during the process of acting, when probed for experiencing or explaining, reports about intentions can be generated without there being intentions identifiable as such getting caused by brain processes.

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Figure 7.128 The process of intending consists of five phases (top box): (i) global whether decision, (ii) waiting, (iii) deciding what, (iv) deciding when, and (v) local whether decision. The phases in the process of intending run from abstract (global agreement to participate) to specific (knowing which action to perform and when to perform it). The middle box shows the reported onsets of intending. Phases in the process of intending can be suggested to be linked to distinct neural correlates in the brain (bottom box). The neural preparatory processes for action run from activity in higher cognitive areas to lower cognitive areas. dMPFC: dorsomedial prefrontal cortex, RCZ: rostral cingulate zone, SMA: supplementary motor area, RP: readiness potential, ERD: event related desynchronization.

Schurger, Sitt, and Dehaene have sketched an alternative where random fluctuations in brain activity may pass a threshold, leading to an action.29 It is, in fact, precisely the completely open, reason-less nature of Libet-style actions (‘when you feel like it’) that may make the system very sensitive to noise and random fluctuations. Actions might take place, and explanations invoking intentions provided, while neuronally speaking, there was nothing more than noise. In another way of making the same point, Schmidt et al. suggest that acts are more likely to take place during the negative phase of slow, ongoing oscillations.30 The implication here again is that it is not a meaningful identifiable intention that makes the difference but simple threshold passing influenced by nonmeaningful neural activity fluctuations. Indeed, Verbaarschot, Haselager, and Farquhar31 suggest that the RP, in the final analysis, may be identical to the contingent negative variation (CNV) occurring prior to an expected

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stimulus.32 As time passes during an experimental condition, the chance of moving increases, and the RP might merely reflect the neuronal anticipation of the upcoming movement. The point here is not to claim that these alternative perspectives are true and the traditional views on intentions and RPs are false. These issues are far from being decided yet. The point is rather to open the possibility of revising our notion of intention and examining the implications for the search of neural correlates. Mainly, intentions could be viewed as hypothetical constructs, postulated on the basis of a conceptual framework applied in daily practice but not necessarily referring or relatable to internal structures or processes that can be identified precisely by neuroscience. Before considering the implications of such a revision in our understanding of intention, I now would like to consider a second revision, namely, that of ‘free’, as in ‘free will’.

5 Free From What and to Do What With? Regarding the everyday usage of ‘free’, it needs to be asked ‘free from what?’ and ‘to do what with that freedom?’ Here an important but often neglected difference can be made between freedom from the environment and freedom from the brain. It is the latter, I suggest, that is the main intuition underlying everyday interpretations of free will. This is sometimes expressed in phrases such as ‘I use my brain’ in the sense of an ‘I’ that initiates a thought, desire, or action that then gets prepared and executed by the brain and body. ‘I’ (in some unspecified way of being me) wants or intends something, and then my brain enables me to do it. Everyday interpretations of having free will in this sense mean that ‘I’ think, intend, decide, and act not depending on but, at crucial points or moments, independently of the brain. In everyday contexts (and sometimes in neuroscientific debates as well), the freedom involved seems to be intended as ‘free from the brain’. That, at least, would explain why so many people are interested in (or shocked by) the possibility that Libetstyle experiments indicate that intentions and volitions seem to follow, instead of direct, brain processes. One example is presented by Lamme: The prefrontal cortex makes the behavior much less directly environmentally driven. Apparently also more free, at least for the one who perceives the behaviour from the outside. In reality it remains a matter of balance between different brain structures that work mainly at different temporary scale. That doesn’t make them less determined.33 Apparently, it is the freedom from the brain that is important, not the freedom from the environment. Yet, despite the perhaps intuitive attractiveness of interpreting free will as being free from the brain, I suggest precisely that this makes a good candidate for revision. Upon refection

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it turns out to be hard to understand: as my brain is a part of me, how could I be free from it? Just like I can’t breathe without my lungs, or pump blood without my heart, how would I intend, decide, or act without my brain? Indeed, why would I want to be free from my brain? What could I do with that kind of freedom? If it would lead to different decisions, volitions, or intentions than I currently make, in what sense would they be ‘mine’? Who would ‘I’ be if not constituted by my life experiences and personality features as stored or implemented in my brain? Rather, it is my brain, and my body, that enable me to make the choices, select the goals, and act the way I want. Together they constitute me. Together, my body and brain enable my freedom with respect to the environment. It provides me with experience-enriched evaluations of environmental stimulation and action possibilities. Of course, sometimes we regret what we chose, intended, or did. We feel we should have acted differently. But such evaluations and insights are made possible by the brain as the brain enables us to respond differently to similar stimulation. In short, brains allow a relative freedom from the environment both in time and space in that they make it possible to let the past influence the present and future or allow non-present stimuli (via internal representations, such as memories or imaginings) to shape our thoughts and actions. This creates the possibility to distance ourselves from the immediate push and pull of environmental stimuli or internal drives. It allows us to say no to our first behavioral impulses, and it is there that the origin of responsibility and moral assessment of behavior lies. In a very interesting paper,34 Brembs points out that instead of searching for a metaphysical or theological interpretation of free will, we may do well to focus on a scientific one, starting with the observation that complete predictability would be evolutionary disadvantageous. Organisms without ways of varying their first reflexes would be extremely predictable, making relatively easy targets for predators. Although reflexes are efficient and fast, lack of flexibility constitutes an evolutionary weakness. When brains grow in complexity, a more subtle balance becomes possible between behavior that is determined completely by the environment and internal sources and/or modulators of behavior. Initially, mere random fluctuations help achieve evolutionarily useful types of unpredictability, enabling organisms to not blindly repeat the same response. Further developed brains allow experience-based variability (‘learning’), adding goal-efficiency to mere flexibility. With Brembs, I’m suggesting to locate the origin of free will in this internal, brain-based capacity to initiate or vary behavior, going beyond mere randomness. Unlike systems that are completely driven by impending physical forces (such as stones), or purely reflex-based organisms (one may think of ‘simple’ insects perhaps), organisms with a reasonably developed central nervous system could be more or less ‘free’ from their environment.

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This is an appropriate point, I hope, to make a more general point regarding the primary focus on the brain that is so characteristic for many recent debates on intentions and free will. I think this seriously underestimates the contributions of the body and the environment to cognition and behavior. Although the brain is of crucial importance, it is far from being the only factor. My body provides me with a repertoire of sensory and motor capacities that are coupled in various configurations and operate in response to a variety of environmental and bodily input (e.g., presence of food or hunger). It is out of that dynamic interplay that mediated by my brain, my behavior emerges. Behavior and thought originate out of the complex interplay of body, brain, and environment, and focusing solely on the brain, excluding the contributions of the latter two, strikes me as a form of neurocentrism that I reject, as already indicated.35

6 Revisions and Responsibility A crucial question, of course, is what such revisions might imply for our notions of morality and responsibility. I do not see why a brain-based relative form of freedom from the environment, and intentions as claims to authorship of action would render responsibility attributions, either by oneself or by others, obsolete. Rather, such a view might make the main motivation for ethical judgments more clearly visible. It is precisely because human beings are capable of distancing themselves from the immediate forces of their biological and environmental stimuli and requirements that it becomes possible to create standards for the evaluation of behavior. Brains play a crucial role in making that possible by adding experience-based variation to more random forms of variation. Embodied embedded brains also enable authorship claims in the form of intention reports that summarize the main cognitive (interpretations, reasons, and feelings) and environmental (events) factors that present the agent as socially acceptable as possible. It is also in virtue of some specific features of their brains that humans can apply such standards to assess concrete actions and their consequences as well as the reasons provided for them in intention reports. Such a revision might imply that evaluative standards are better understandable in terms of healthy brains rather than in terms of absolute norms or natural or divine laws. Healthy body– brain–environment systems have a certain capacity for experience and education-based self-control that liberates them from mere instinctual or reflex behaviors. It is for this reason that we normally wait a substantial amount of years before considering individuals as ‘adults’, with the particular rights and duties that come with that label. To put it (perhaps overly) simply: societies consist of networks of interacting individuals, embodied embedded persons, that on the basis of culturally developed standards, expect a certain amount of self-control, enabled by their body-brain-environment constellations, that come with the attribution

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of responsibility. When such self-control is not properly demonstrated, societally accepted forms of blame can be admonished, together with the imposition of societally accepted behavioral restrictions or cognitive reeducation practices. When the required self-control turns out not to have been possible, for example, due to physical or experiential damage, this can be taken into account in the implementation of behavioral restrictions or clinical or educational steps. Of course, there is a bullet to be bitten here. If this brief and incomplete sketch is in the right direction, and freedom from the brain is not only unlikely to be possible but also not required, and assuming that the brain is a deterministic system (which it may very well not be,36 but I’m assuming it here momentarily for the sake of argument), then we also have to revise a traditionally important aspect of free will, namely, that we could have done otherwise. Here too I admit to having difficulties in understanding exactly what ‘could have done otherwise’ might mean or why it is considered to be so valuable. Of course I understand (and regularly experience) the thoughts and feelings of regret after I have done something. I should have done that differently, and given my capacities for reflection and self-control, in principle I could have acted differently. However, I do not see how it would be possible, or even desirable, to be in that exact 100 percent similar type of situation (down to the molecular level, body, brain, and all relevant aspects of the environment) and then still having had the possibility of performing a different action. If it would be by chance, by random fluctuations (as the work quoted previously suggests), then what value would it have for a form of free will that can support genuine self-determination or responsibility attributions? If it would not be by chance, then how, in virtue of what, would that have been possible? Rejecting freedom from the brain implies that if I would be exactly (but genuinely exactly, down to the level of molecules) the same in exactly the same condition and circumstances, I would have done the same. Otherwise, how would I have been me?

7 Conclusion Conceptual revisions, especially in relation to concepts that we hold dear, both individually and as a society, are not necessarily easy. The scientific picture, incomplete as it may be, indicates that we are bipedal great apes, possessing linguistic skills often used for confabulating societally acceptable reasons for actions that are generally driven by subconscious processes on a small planet circling around an insignificant sun in a remote area of the universe. The revisions of intentions and free will examined in this chapter may undermine other aspects of a cherished human self-perspective. It is conceivable that being free comes down to possessing a certain amount of flexibility in relation to internal and external stimuli and that intentions find their most concrete and identifiable

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implementations in socially relevant reports rather than in brain states. Such revisions may carry the promise to gain better insights in who or what we are and how we function, but they also come at the price of showing us in a less favorable light than perhaps we would like. Societally speaking, such revisions might lead to a reevaluation of certain practices that may not be accomplished without certain forms of unrest or even upheaval. That is not necessarily a bad thing, although it does require caution, carefulness, and consideration with alternative possibilities and perspectives. Above all, it requires an avoidance of overly simple answers or premature claims of proof.

Notes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

Haselager (2005). Reid (1764, section VI); see also Moore (1925). Sellars (1963, 173). Dennett (2003), Soon et al. (2008), Swaab (2014), Filevich, Kühn, and Haggard (2013), and Harris (2012). Haselager (2013). Dennett (1991b) and MacCorquodale and Meehl (1948). Mecacci and Haselager (2015). Haselager (1997), Uithol, Burnston, and Haselager (2014), andVerbaarschot, Haselager, and Farquhar (2016). Libet et al. (1983). Lamme (2010, 211). Mele (2010). Mecacci and Haselager (2015). See Verbaarschot, Farquhar, and Haselager (2015) and Verbaarschot, Haselager, and Farquhar (2016) for detailed discussion. Radder and Meynen (2013), Khalighinejad et al. (2018), and Schurger (2018). Soon et al. (2008, 543). Twain (1879). https://www.mentalfloss.com/article/562400/reports-marktwains-quote-about-mark-twains-death-are-greatly-exaggerated. For example, Verbaarschot, Farquhar, and Haselager (2019) and Verbaarschot, Haselager, and Farquhar (2019). Dennett (1991b, 135). See Sellars (1963), Feyerabend (1963), and Churchland (1979, 1981) for some early inputs. For example, Newell (1980). For example, Wairagkar, Hayashi, and Nasuto (2018) and Pereira et al. (2017). MacCorquodale and Meehl (1948). Dennett (1991a). Uithol, Burnston, and Haselager (2014). See Stich (1983), Haselager (1997), and Uithol, Burnston, and Haselager (2014). Verbaarschot, Haselager, and Farquhar (2016), based on Brass and Haggard (2008), and Brass et al. (2013). Schurger, Sitt, and Dehaene (2012). Verbaarschot, Haselager, and Farquhar (2016). Schurger, Sitt, and Dehaene (2012). Schmidt et al. (2016).

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31. Verbaarschot, Farquhar, and Haselager (2019) and Verbaarschot, Haselager, and Farquhar (2019). 32. Alexander et al. (2016). 33. Lamme (2010, 119, my translation). 34. Brembs (2011). 35. Haselager et al. (2008) and Van Dijk et al. (2008). 36. See, for example, Khalighinejad et al. (2018) and Schurger (2018).

References Alexander, Prescott, Alexander Schlegel, Walter Sinnott-Armstrong, Adina L. Roskies, Thalia Wheatley, and Peter Ulric Tse. 2016. “Readiness Potentials Driven by Non-Motoric Processes.” Consciousness and Cognition 39: 38–47. Brass, Marcel, and Patrick Haggard. 2008. “The What, When, Whether Model of Intentional Action.” The Neuroscientist 14 (4): 319–325. Brass, Marcel, Margaret T. Lynn, Jelle Demanet, and Davide Rigoni. 2013. “Imaging Volition: What the Brain Can Tell Us about the Will.” Experimental Brain Research 229 (3): 301–312. Brembs, Björn. 2011. “Towards a Scientific Concept of Free Will as a Biological Trait: Spontaneous Actions and Decision-Making in Invertebrates.” Proceedings of the Royal Society B 278 (1707): 930–939. https://doi:10.1098/ rspb.2010.2325. Churchland, Paul M. 1979. Scientific Realism and the Plasticity of Mind. Cambridge: Cambridge University Press. Churchland, Paul M. 1981. “Eliminative Materialism and the Propositional Attitudes.” The Journal of Philosophy 78 (2): 67–90. https://doi:10.2307/2025900. Dennett, Daniel C. 1991a. Consciousness Explained. London: Allen Lane. Dennett, Daniel C. 1991b. “Two Contrasts.” In The Future of Folk Psychology, edited by John D. Greenwood, 135–148. Cambridge: Cambridge University Press. Dennett, Daniel C. 2003. Freedom Evolves. New York: Viking Press. Feyerabend, Paul K. 1963. “Materialism and the Mind-Body Problem.” In The Mind/Brain Identity Theory, edited by Clive V. Borst, 142–156. London: Macmillan. Filevich, Elisa, Simone Kühn, and Patrick Haggard. 2013. “There Is No Free Won’t: Antecedent Brain Activity Predicts Decisions to Inhibit.” PLoS One 8 (2): 1–11. https://doi.org/10.1371/journal.pone.0053053. Harris, Sam. 2012. Free Will. New York: Free Press. Haselager, Pim. 1997. Cognitive Science and Folk Psychology: The Right Frame of Mind. Thousand Oaks: Sage Press. Haselager, Pim. 2005. “Robotics, Philosophy and the Problems of Autonomy.” Pragmatics & Cognition 13 (3): 515–532. https://doi: 10.1075/pc.13.3.07has. Haselager, Pim. 2013. “De vrije will wordt mede mogelijk gemaakt door de hersenen (Free will is made possible in part by the brain. Text in Dutch).” In Vrije wil: Een hersenkronkel?, edited by Palmyre Oomen, 45–61. Zoetermeer: Klement. Haselager, Pim, Jelle van Dijk, and Iris van Rooij. 2008. “A Lazy Brain? Embodied Embedded Cognition and Cognitive Neuroscience.” In Handbook of

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Cognitive Science, edited by Paco Calvo and Antoni Gomila, 273–290. Oxford: Elsevier. Khalighinejad, Nima, Aaron Schurger, Andrea Desantis, Leor Zmigrod, and Patrick Haggard. 2018. “Precursor Processes of Human Self-Initiated Action.” NeuroImage 165: 35–47. Lamme, Victor. 2010. De vrije wil bestaat niet [Free Will Doesn’t Exist]. Amsterdam: Uitgeverij Bert Bakker. Libet, Benjamin, Curtis A. Gleason, Elwood W. Wright, and Dennis K. Pearl. 1983. “Time of Conscious Intention to Act in Relation to Onset of Cerebral Activity (Readiness-Potential).” Brain 106 (3): 623–642. https://doi:10.1093/ brain/106.3.623. MacCorquodale, Kenneth, and Paul E. Meehl. 1948. “On a Distinction between Hypothetical Constructs and Intervening Variables.” Psychological Review 55 (2): 95–107. Mecacci, Giulio, and Pim Haselager. 2015. “A Reason to Be Free.” Neuroethics 8 (3): 327–334. Mele, Alfred R. 2010. “Testing Free Will.” Neuroethics 3 (2): 161–172. Moore, Gerald E. 1925. “A Defence of Common Sense.” In Contemporary British Philosophy, edited by J. H. Muirhead. 2nd series. Reprinted in Philosophical Papers, by G. E. Moore (1959). www.ditext.com/moore/common-sense.html. Newell, Herbert. 1980. “Physical Symbol Systems.” Cognition 4 (2): 135–183. https://doi.org/10.1207/s15516709cog0402_2. Pereira, Joana, Patrick Ofner, Andreas Schwarz, Andreea Ioana Sburlea, and Gernot R. Müller-Putz. 2017. “EEG Neural Correlates of Goal-Directed Movement Intention.” NeuroImage 149: 129–140. https://doi.org/10.1016/j. neuroimage.2017.01.030. Radder, Hans, and Gerben Meynen. 2013. “Does the Brain ‘Initiate’ Freely Willed Processes? A Philosophy of Science Critique of Libet-Type Experiments and Their Interpretation.” Theory & Psychology 23 (1): 3–21. Reid, Thomas. 1764. An Inquiry into the Human Mind: On the Principles of Common Sense. Charleston: Etheridge. https://en.wikisource.org/wiki/An_Inquiry_ into_the_Human_Mind. Schmidt, Stefan, Han-Gue Jo, Marc Wittmann, and Thilo Hinterberger. 2016. “‘Catching the Waves’ – Slow Cortical Potentials as Moderator of Voluntary Action.” Neuroscience and Biobehavioral Reviews 68: 639–650. https://dx.doi. org/10.1016/j.neubiorev.2016.06.023. Schurger, Aaron. 2018. “Specific Relationship between the Shape of the Readiness Potential, Subjective Decision Time, and Waiting Time Predicted by an Accumulator Model with Temporally Autocorrelated Input Noise.” eNeuro 5 (1): e0302–17.2018. https://doi:10.1523/ENEURO.0302-17.2018. Schurger, Aaron, Jacobo Sitt, and Stanislas Dehaene. 2012. “An Accumulator Model for Spontaneous Neural Activity Prior to Self-Initiated Movement.” Proceedings of the National Academy of Sciences of the United States of America 109 (42): E2904–2913. https://doi:10.1073/pnas.1210467109. Sellars, Wilfrid. 1963. Science, Perception and Reality. London: Routledge and Kegan Paul. Soon, Chun Siong, Marcel Brass, Hans-Jochen Heinze, and John-Dylan Haynes. 2008. “Unconscious Determinants of Free Decisions in the Human Brain.” Nature Neuroscience 11 (5): 543–545. https://doi:10.1038/nn.2112:543.

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Stich, Stephen. 1983. From Folk Psychology to Cognitive Science. Cambridge: MIT Press. Swaab, Dick. 2014. We Are Our Brains: A Neurobiography of the Brain, from the Womb to Alzheimer’s. New York: Random House. Twain, Mark. 1897. https://www.mentalfloss.com/article/562400/reports-marktwains-quote-about-mark-twains-death-are-greatly-exaggerated. The New York Journal, June 2, 1897. In Emily Petsko. 2018. “Reports of Mark Twain’s Quote About His Own Death Are Greatly Exaggerated.” Mental Floss. https://www. mentalfloss.com/article/562400/reports-mark-twains-quote-about-mark-twainsdeath-are-greatly-exaggerated. Uithol, Sebo, Daniel C. Burnston, and Pim Haselager. 2014. “Why We May Not Find Intentions in the Brain.” Neuropsychologia 56: 129–139. Van Dijk, Jelle, Roel Kerkhofs, Iris van Rooij, and Pim Haselager. 2008. “Can There Be Such a Thing as Embodied Embedded Cognitive Neuroscience?” Theory & Psychology 13 (3): 297–316. Verbaarschot, Ceci, Jason Farquhar, and Pim Haselager. 2015. “Lost in Time . . .: The Search for Intentions and Readiness Potentials.” Consciousness and Cognition 33: 300–315. Verbaarschot, Ceci, Jason Farquhar, and Pim Haselager. 2019. “Free Wally: Where Motor Intentions Meet Reason and Consequence.” Neuropsychologia 133. https://doi.org/10.1016/j.neuropsychologia.2019.107156. Verbaarschot, Ceci, Pim Haselager, and Jason Farquhar. 2016. “Detecting Traces of Consciousness in the Process of Intending to Act.” Experimental Brain Research 234 (7): 1945–1956. Verbaarschot, Ceci, Pim Haselager, and Jason Farquhar. 2019. “Probing for Intentions: Why Clocks Do Not Provide the Only Measurement of Time.” Frontiers in Human Neuroscience 13. https://doi.org/10.3389/fnhum.2019.00068. Wairagkar, Maitreyee, Yoshikatsu Hayashi, and Slawomir J. Nasuto. 2018. “Exploration of Neural Correlates of Movement Intention Based on Characterisation of Temporal Dependencies in Electroencephalography.” PLoS One 13 (3): 1–23. https://doi.org/10.1371/journal.pone.0193722.

8

The Emergence of Free, Intentional Control Reply to Haselager Timothy O’Connor

Pim Haselager (Chapter 7, this volume) explores the question of how we should think about free will and more generally human intention in action in light of tentative and slowly developing frameworks in neuroscience and embodied cognition. He starts with a note of sympathy for Reidian ‘common sense’ epistemology, which contends that we are rationally entitled without independent evidence or argument to certain general beliefs about the world and the cognitive tools that we bring to our encounter with it. We have to start somewhere in coming to learn things about the world and ourselves. The reasonable starting points are, roughly, those that we find ourselves accepting instinctively and that appear to be essential to our ability to engage in critical inquiry and action. Among these instinctive beliefs is our self-conception as purposive agents: confronted by more than one option that we have reason to pursue, and being uncertain about what to do, we deliberate and choose. Choice is a kind of uncertainty-resolving intention to act that—so it seems—initiates and (in complex cases) guides the completion of the action. It seems to us, then, that we are effective, purpose-driven choosers. But further, it seems that our choosing is free: having chosen one option, it was open to us to have chosen differently. Nothing necessitated that particular option, and partly for that reason, we are responsible for having chosen as we did. Haselager allows that this description captures our instinctive conception and experience of deliberate agency and that it is prima facie reasonable to accept it. However, he adds that epistemic starting points may be overturned by empirical evidence, and he quickly proceeds to suggest that our common sense conception of agency is in need of significant revision. Why, exactly? It is not that our well-confirmed sciences pertaining to the human mind demonstrate its falsity. Haselager (correctly) acknowledges that they are too immature to have done that. Instead, he thinks, there is a broad metaphysics of nature that is more promising than any alternative. This framework is ‘scientific materialism’, which sees all of nature as constituted by ‘physical-law abiding interactions of material elements’ (Haselager, Chapter 7, 3). High-level organized phenomena are one and

122 Timothy O’Connor all determined from the bottom up, even though scientific practice necessarily starts from our macroscopic perceptual level and tries to burrow down. Furthermore, in thinking about human choice and action, Haselager has ‘not seen’ any explanation of how macroscopically significant indeterminism might be anything other than mere ‘chance’ (Haselager, Chapter 7, 3), and so he struggles to understand “what ‘could have done otherwise’ might mean, or why it is considered to be so valuable” (Haselager, Chapter 7, 9). So in theorizing about human freedom and moral responsibility, we should discard this naive but possibly incoherent notion of an ‘open future’ that we partly determine and instead focus on the undoubted flexibility of our responses to stimuli over time, that is, on the fact that we learn from experience and often adapt our responses to similar future circumstances. It should be very puzzling that we are naturally disposed to think of our own agency in profoundly confused ways. Indeed, I do not think that we are. Causal indeterminism is a merely negative condition on our freedom. It is the precondition on something positive: the exercise of a two- (or multi-) way power of choice that is guided but not determined by reasons we have (from our subjective perspective, however misguided) to act in particular ways. We humans are psychologically complex creatures, and we often enough have competing motivations that point toward different courses of action. These motivations are causal as well as rational influences, and so they make us more or less likely to choose one way rather than the other. Even so, we must choose. In choosing one way (and in experiencing the consequences), we influence incrementally the probabilities pertaining to future choices; over time, we typically come to have fairly settled dispositions concerning certain types of goals and outcomes. I take the previous paragraph to be consistent with a reflective common sense perspective. Contra Haselager, I think it is readily understandable from a broadly scientific perspective, although it requires abandoning the ontologically reductionist straitjacket that he builds into ‘scientific materialism’ and seeing greater complexity in the relationship of the differently leveled structures studied by our successful sciences. First, it should be noted that probabilistic causal influence is now a firmly-established part of science. Sometimes, of course, this merely reflects relative frequencies of common variables over ensembles of processes that are similar in coarse-grained ways but whose fine-grained conditions on the underlying driving mechanisms differ. But we can also understand probabilities as reflecting stochastic propensities—individual-case, weighted tendencies of causal agents toward possible outcomes. Certain quantum phenomena such as radioactive decay are naturally understood in this way. Whatever the facts turn out to be, we can certainly conceive choice in a similar way. Haselager says that if actual, this would be mere chance and so of no help in understanding how we might control our actions in a way that grounds moral responsibility. However, we have to ask what ‘chance’

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means, something that he nowhere defines. I suggest that our ordinary notion of a chance occurrence is of one that is causally undetermined and not intentionally controlled. By that definition, a motivated forming of an intention to act is hardly something that comes about by chance. Perhaps Haselager is supposing that chance occurrence may be defined more simply as anything that is causally undetermined for the reason that control over an outcome is necessarily exercised antecedently. So any causal conditions that fail to determine an outcome thereby fail to (fully) control it. But choice is not a mere outcome; it is an exercise of control. It is something we do, not something that happens to us. Or, again, so it naturally seems. So when Haselager asks, prior to the consideration of scientific evidence, what could have done otherwise ‘means’, and why it might be valuable, the common sense answer is quite simple: it means that we exercised a power to settle which course of action we would follow among a plurality of alternatives, and it is valuable because it constitutes a form of limited autonomy. We are not merely complex and changing conduits of causal influences from the past, flexible decisionmakers over time, but always pre-determined in how we decide on any occasion. We are fundamental difference makers—in the necessarily constrained manner of conditioned creatures rather than in godlike, ex nihilo fashion—yet still freely and creatively responding at a time. Let us turn from Haselager’s conceptual misgivings to the more empirical question of whether the totality of present evidence from a range of sciences supports a reductionist conception of physical reality as wholly fixed from below by basic and impersonal physical forces. On this vision, all the structures and activity of chemistry, biology, neuroscience and psychology, sociology, and ecology are but the outworkings of a 21st-century version of Democritus’s atoms in the void. The descriptive concepts and principles of these restricted-domain sciences are not derivable from physical theory, Haslager allows, but the structural and dynamical realities they describe are wholly derivative: they are as they are in all respects because the basic physical realities are as they are. Physics is a complete and autonomous domain, determining but not determined by the structured realities. There is much to say about this reductionist vision, but here I can only comment briefly. This vision dominated scientific thinking in the first part of the 20th century between the breakthroughs of quantum mechanical explanations for chemical structure and the uncovering of the biochemical basis of life. However, developments in the second half of the last century strongly challenged it, as the power of complementary, top-down powers of organized structures to constrain and channel the behavior of their elements became clear in a variety of domains. Robert Laughlin (solid-state physics), Denis Noble (systems biology), and George Ellis (cosmology) are among the prominent voices articulating an alternative vision on which complex systems of many kinds exhibit reciprocal and inter-dependent bottom-up and top-down behavior in their

124 Timothy O’Connor evolving trajectories over time.1 Although neither vision is conclusively demonstrable, and (given measurement and computational constraints) likely never will be, the ‘emergentist’ vision is arguably a more natural fit with our evidential reality: profound successes in fundamental physics in describing artificially isolated interactions of small numbers of particles; equal success in delineating and confirming top-down explanations in many complex domains; and little prospect of ever being able to directly apply quantum theory to the entirety of large-scale composed systems involving billions or trillions of interacting particles. Certainly the emergentist vision is a more natural fit with available evidence if one gives any significant credence to our common sense perspective. Our encounter with the world begins with our conscious experiences, thoughts, emotions, and other intentional states. All of these present themselves to us as having distinctive intrinsic character that is quite unlike the character of our nonconscious environment and as continuously affecting our behavior and other, subsequent conscious states. To take them at face value is to implicitly endorse an ontologically emergentist understanding of their place alongside the subconscious neural machinery that sustains and modifies them in turn. To endorse, alternatively, a reductionist thesis regarding conscious states is to implicitly endorse a kind of illusionism, according to which our pervasive impression of directly apprehending the intrinsic character of conscious states is simply an illusion for future cognitive science to explain. (On such a view, conscious states are neural, which fact is not given to us in conscious experience. Our awareness of such states and ability reliably to compare them with previous such states is wholly constituted by subconscious mechanisms, as is the pervasive illusion of our grasping a distinctive qualitative and subjective character.) A serious problem for the scientist who would endorse the reductionist’s rejection of our common sense perspective on conscious experience and agency is that this perspective is quite fundamental to the epistemology of science itself. Scientific theories, models, and results are themselves the products of scientific activity: of human persons acting in certain coordinated, purposive ways and communicating their activities and results to one another. The nature of this activity is not part of the content of such theories as the theories are not (in most cases) about such activity. However, we who embrace the theories and conclusions drawn in any scientific domain must tacitly accept that the theorists and experimenters were guided by purposes known to themselves and successfully carried out those purposes by intending a variety of specific behaviors thought to advance those purposes, where again they were aware of those intentions. Absent reasonable belief in their reliably self-aware agency, our confidence in what took place and what it resulted in would be undermined: we would have words on a page or a screen, but we would not be in a position to assess what they were indicative of. Or, this would be our predicament absent some alternative account that insured the reliability

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of the products, despite the unwitting behavior of the scientists yielding them. No such alternative account readily suggests itself, and any candidate that might be presented for our consideration would require us to trust the one providing it, raising the same problem all over again. Haselager seems dimly aware of the problem here when he likens the revisionist perspective that he envisions cognitive neuroscience as possibly producing to “a snake biting its own tail” (Haselager, Chapter 7, 2). But it would more accurately be characterized as the paradox of a snake swallowing its own tail. Or, to switch the metaphor, a scientist who comes to reject our fundamental self-understanding as agents who are regularly consciously aware of efficaciously intending actions is sawing off the branch on which he sits. Now, affirming that we form conscious intentions that are efficacious in initiating and guiding action is not to affirm that we ever do so freely. But the sciences of brain and behavior do not (yet) pose serious challenges to our freedom. At any rate, no such challenge endures from the one set of studies that Haselager discusses, viz, those pioneered by Benjamin Libet and refined by many others on the timing of conscious intention or will. Haselager appears to agree up to a point. However, it is unclear how widely he would apply the conjecture of Schurger, Sitt, and Dehaene that the timing of action initiation may result from the passing of a threshold in random neural activity.2 This conjecture has some intuitive as well as experimental plausibility in Libet-style experimental scenarios where agents are asked to ‘spontaneously’ make arbitrary decisions, but no good basis has been given to generalize this to the seemingly very different, nonarbitrary, and deliberate choices that are better exemplars of our common sense understanding of free will. Haselager closes his discussion by reciting in compact form the familiar scientific ‘creation myth’ that is the credo of many would-be deflaters of the human pretension to which prescientific people are supposedly naturally inclined: The scientific picture, incomplete as it may be, indicates that we are bipedal great apes, possessing linguistic skills often used for confabulating societally acceptable reasons for actions that are generally driven by subconscious processes, on a small planet circling around an insignificant sun in a remote area of the universe. The revisions of intentions and free will examined in this chapter may undermine other aspects of a cherished human self-perspective. (Haselager, Chapter 7, 9) What is true within this myth is that an important aspect of the advance of scientifc understanding, especially in physics, has come from learning to prescind our view of the cosmos from our perspectival limitations with respect to time, space, and history. However, the resulting advance

126 Timothy O’Connor in knowledge concerning the cosmos and its (and our) history does not overturn our basic self-understanding or speak one way or another concerning our fundamental signifcance. An alternative framing of the story of the appearance of human beings on this planet that is at least as consonant with the established facts and well-confrmed theories in 2020 as Haselager’s is this: Sundry basic features at the origin of our cosmos were exquisitely finetuned for the building blocks necessary for the subsequent appearance of life on our planet and its slow evolution toward greater complexity. Along one branch of that fecund biological bush there emerged a variety of complex creatures unified by the striking new feature of conscious awareness and culminating in ourselves: purposive, flexibly intelligent, self- and other-aware creatures. Our nature contains strata of our many precursors, such that we are curious hybrids governed by a patchwork of mammalian machinery and drives interacting with our distinctively personal capacities and attitudes. Curious but also wondrous, we are planetbound, bipedal great apes by heritage yet, astonishingly, also capable of contemplating, probing, and coming to understand the entirety of the vast cosmos whose elemental traces our bodies bear—and capable, too, of contemplating and debating the possible purposes that may govern our remarkable species.3

Notes 1. See Laughlin (2005), Noble (2006), and Ellis (2016), as well as the multiauthored volume edited by Murphy, Ellis, and O’Connor (2009), and the special journal issue edited by Ellis, Noble, and O’Connor (2012). For systematic analysis of the concept of emergence and its possible scientific applications, see O’Connor (2020). 2. Schurger, Sitt, and Dehaene (2012). 3. This publication was made possible through the support of a joint grant from the John Templeton Foundation and the Fetzer Institute. The opinions expressed in this publication are those of the author and do not necessarily reflect the views of the John Templeton Foundation or the Fetzer Institute.

References Ellis, George F. R. 2016. How Can Physics Underlie the Mind? Top-Down Causation in the Human Context. Berlin: Springer-Verlag. Ellis, George F. R., Denis Noble, and Timothy O’Connor, eds. 2012. “Top-Down Causation: An Integrating Theme within and across the Sciences?” Themed Issue of Interface Focus: A Journal of the Royal Society 2 (February): 1–140. Laughlin, Robert. 2005. A Different Universe: Reinventing Physics from the Bottom Down. New York: Basic Books. Murphy, Nancey, George Ellis, and Timothy O’Connor, eds. 2009. Downward Causation and the Neurobiology of Free Will. New York: Springer Publications. Noble, Denis. 2006. The Music of Life. Oxford: Oxford University Press.

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O’Connor, T. 2020. “Emergent Properties.” In The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta. Schurger, Aaron, Jacobo Sitt, and Stanislas Dehaene. 2012. “An Accumulator Model for Spontaneous Neural Activity Prior to Self-Initiated Movement.” Proceedings of the National Academy of Sciences 109 (42): E2904–2913. https://doi:10.1073/pnas.1210467109.

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Psychological Challenges to Common Sense Philosophy Illusions of Introspection and Free Will Brett W. Pelham, Michael Harding, and Curtis Hardin

Human enlightenment has been tightly linked to scientific discovery. Just as Darwin and Mendel helped us understand human origins, Pasteur and Koch helped us understand disease. Newton and Leibniz invented calculus. Einstein used it to help us understand time and space. Further, just as physics has uncovered surprising truths about physical reality, psychological science has uncovered surprising truths about psychological reality. Such truths often defy common sense. As physicists argue that all the matter in the earth could be squeezed into the space of a matchbox,1 psychologists argue that many common sense beliefs are illusory. This chapter focuses on two surprising psychological truths. First, people often have little or no access to their own thought processes. Second, free will is probably a comforting illusion.

1 Philosophical Arguments Against Introspection Beginning with the first of these points, how well do we know our own thoughts? In Beyond Good and Evil,2 Nietzsche writes of the “harmless self-observers who believe in the existence of ‘immediate certainties’, such as ‘I think’ or ‘I will’”. Nietzsche characterizes such claims as being grounded in “the seduction of words” rather than true self-insight. Arguing against our common sense faith in our own self-knowledge, Nietzsche writes: Let the people believe that knowing means knowing to the very end; the philosopher has to say: “When I dissect the process expressed in the proposition ‘I think’, I get a whole set of bold claims that are difficult, perhaps impossible, to establish,—for instance, that I am the one who is thinking, that there must be something that is thinking in the first place, that thinking is an activity and the effect of a being who is considered the cause, that there is an ‘I’, and finally, that it has already been determined what is meant by thinking. . . . [T]his ‘I

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think’ presupposes that I compare my present state with other states that I have seen in myself, in order to determine what it is.3 In Nietzsche’s view, any privileged access to our own inner lives is, at best, debatable. It is implicit in Nietzsche’s arguments that very few people, whether philosopher or fle clerk, have the courage to face “a whole assortment of metaphysical questions”. Part of what makes Nietzsche an existential philosopher is his argument that for most people, acknowledging the absence of self-insight or personal agency would have deeply troubling psychic consequences.4 In Nietzsche’s view, it is mainly the seduction of grammar that creates the illusion of self-understanding. Thoughts, he suggests, do not come when we want them to come but when they, metaphorically, wish to come. Specifically, Nietzsche writes, It is, therefore, a falsification of the facts to say that the subject “I” is the condition of the predicate “think”. It thinks: but to say the “it” is just that famous old “I”—well that is just an assumption or opinion, to put it mildly, and by no means an “immediate certainty”.5 In Nietzsche’s view, we assume that we are the architects of our thoughts because language suggests so. This ‘seduction of grammar’ causes us to make many assumptions about self-knowledge that are not borne out by experience. Nietzsche was not the frst to recognize a disconnect between reality and perception. Plato’s tripartite division of the soul—as presented by Socrates in both the Phaedrus and the Republic—is a good example. Socrates described the soul as a multiplicity of competing forces disguised as a unity. In one metaphor, the soul is a chariot drawn by two horses of different temperaments. In another, it is a “many colored, many headed beast” that is at once both “tame” and “savage”. This beast, Socrates reports, has an “outer shell” that merely “looks like one animal” when it is really many.6 In Nietzsche’s presentation, the soul is more like a many-headed monster than a charioteer pulled by a pair of discordant horses. If introspection were valid, it would thus reveal a roiling mass of different drives. In fact, Nietzsche suggests an even more colorful metaphor for the self that many view as a fee and autonomous agent. He claims that the “I” is akin to “a ball of snakes that never have peace from each other”.7 Each snake in this metaphor is a drive that wants to be tyrant. The self, soul, or will is thus an unhappy confederacy of competing passions. In Beyond Good and Evil,8 Nietzsche further argues that the unified will is purely epiphenomenal. It is one of the “illusions or phantasms” of the inner world.9 As we will see, psychological science strongly supports Nietzsche’s idea that

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(i) introspection is seriously flawed and (ii) much of what we think we choose is grounded in forces other than free will.

2 Psychological Evidence Against Introspection In their classic studies of introspection, Nisbett and Wilson10 raise serious questions about self-insight. In one study, they asked female shoppers to evaluate four pairs of pantyhose. To make the test blind, they arbitrarily labeled the four pairs of hose A–D. Four times as many shoppers preferred the fourth pair as the first. When asked to explain the reasons for their choices, the shoppers offered a wide range of explanations. Some preferred the subtle shading of their favorite pair; others said their favorite pair felt smoother or seemed more durable. None of these shoppers had any difficulty answering this question. But none answered it correctly. This is because the four pairs of panty hose were identical. The 4:1 preference shoppers showed for pair D over pair A was a ‘shopping around effect’ (an order effect). Nisbett and Wilson refer to such failures of introspection as “telling more than we can know”.11 They argue that when people explain why they have made decisions, they often fall back on lay theories about human preferences—because they have little direct access to their own thought processes. Failures of introspection have now been documented for a wide range of decisions.12 More recently, Johansson, Hall, Sikström, and Olsson13 studied failures of introspection using the choice blindness paradigm. In this paradigm, participants must quickly and repeatedly choose between pairs of similar stimuli (e.g., deciding which of two female faces is more physically attractive). Occasionally during these repeated judgments, participants are asked to explain their most recent preference. Typically, each stimulus is presented for four seconds on a card. This, and some sleight of hand, makes it easy for the experimenters to dupe participants by occasionally asking them to justify a decision they did not make. On some trials, that is, participants see the card they did not choose from a pair, and the experimenter asks them why they preferred it. On any given trial, about three-quarters of participants fail to notice this switch (thus the name choice blindness). When people have been duped this way, they readily explain choices that are the opposite of the choice they just made. To further explore this, Johansson et al. asked blind raters to code participants’ explanations for their preferences on three dimensions—emotionality, specificity, and certainty. They reasoned that if people have any awareness that they are confabulating, those reporting on false choices rather than true choices should express less emotion, should be less specific, and should express less self-certainty. No such differences emerged. In a follow-up study, Johansson, Hall, Sikström, Tärning, and Lind14 coded people’s explanations using linguistic coding software rather than blind

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judgments. They found virtually no evidence that participants were aware that they were confabulating. In a classic study that preceded Nisbett and Wilson, Warren and Sherman15 showed that the tendency to edit recent experience affects speech perception. In their work on the phoneme restoration effect, their participants listened to sentences in which a small part of a word was replaced by a short cough. But instead of saying they heard ‘orange–eel’, for example, participants almost always reported having heard ‘orange peel’. But almost no participants could report which exact phoneme was replaced by the cough. Remarkably, this was true when the crucial word that disambiguated the damaged word came several words after the damaged word. The crucial sentences reported in Warren and Warren’s study16 appear as follows. It was found that the–eel was on the axle. It was found that the–eel was on the orange. It was found that the–eel was on the shoe. It was found that the–eel was on the table. A variation on this phenomenon happens every time you turn on your car’s radio to listen to National Public Radio. When you do so, you hear things such as “Nonetheless, most Trump supporters say they still believe him”. What you do not ever hear is what frst comes out of your radio, which is more likely to be “less, most Trump . . .” “theless, most Trump . . .” or “s most Trump”. Human beings are masters at reconstruction. Even many fans of introspection concede that introspection has its limits. Hixon and Swann17 showed that when people are asked what is true (“What kind of person are you”?) rather than why it is true (“Why are you the kind of person you are””), introspection may promote predictable decision-making. Nisbett and Wilson18 would presumably agree. They argued that people usually have access to the products of judgment (What did I prefer?) but have little or no access to the judgmental process (Why did I prefer it?). Bem’s self-perception theory19 is built on a similar assumption: People often figure out their own attitudes not via introspection but by observing their own behavior in context. If I told a stranger that a boring task was interesting, and if I was paid very little to do this, I will conclude, as participants in numerous experiments have, that I think the task was not so boring. Self-perception is a route to attitude formation that requires no direct self-insight. In fact, people with severe memory impairments can develop self-views in the absence of any memories for any information that supports their self-views. This means that people who can’t recall a single introverted thing they have ever done might still be able to tell you that they are highly introverted.20

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Research in many other areas of psychology reveals sharp limitations on how much conscious access people have to their own thoughts.21 For decades, researchers have distinguished between two different kinds of thinking. As Shiffrin and Schneider noted,22 controlled processes are slow, conscious, optional, and cognitively taxing. But after people have practiced a judgment or skill for a long time, thought processes that were once controlled become automatic—meaning they are fast, unconscious, mandatory, and effortless. The point of a lot of research in social cognition is that many human judgments and preferences are grounded heavily in automatic processes.23 To the degree that any judgment has automatic components, people are likely to have little or no access to the thoughts that led to the judgment. Some of the most dramatic examples of the disconnect between what people do and why they think they do it comes from work with ‘splitbrain’ patients. In most people, the corpus callosum allows continuous communication between the right and left hemispheres of the brain. A few decades ago, surgeons learned that they could sometimes stop dangerous and debilitating seizures in epileptic patients by severing the corpus callosum. Such split-brain patients possess two independently operating brains, each of which typically directs different cognitive functions. In most right-handed people (split-brain patients included), parts of the left hemisphere are responsible for speech production. In experiments with split-brain patients, one can send a pictorial signal directly to the nonverbal right hemisphere to get patients to engage in a behavior. When asked why they engaged in the behavior, such patients unknowingly concoct false, after-the-fact justifications.24 Critics of studies such as these are quick to note that split-brain patients and patients with severe amnesia are highly unusual people. Perhaps their behavior reveals no information about normal people. We beg to differ. Numerous errors of awareness exist even for people with wholly intact brains. In a study of the timing of motor control, Libet asked participants to move their fingers at will.25 While participants were doing this, Libet measured the brain activity as well as the muscle activity that produced the finger movements. Further, Libet used an ingenious ‘clock’ (a dot of light that moved at a quick and steady pace around a circle) to allow people to report exactly when they decided to move their fingers. Not surprisingly, brain activity always preceded muscle activation—and thus finger movement. A little more than half a second after the initiation of brain activity, people first moved their muscles. No one would expect otherwise. However, Libet also found that people’s self-reports of the exact moment they decided to move their fingers took place only about 200 milliseconds (1/5 second) before they moved their fingers. This is about 300 milliseconds after their brains had already begun the neural activity responsible for finger movements! People are poor observers of many of their own inner mental states.

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Critics of Libet’s study argue that it is highly artificial or that his participants had no good reason to want to move their fingers. Like studies of split-brain patients, then, Libet’s study has proven to be controversial. Rather than delving deeply into why we think most critiques of such lab studies are erroneous, we confront such critiques about the artificiality of lab experiments head-on (later in this chapter). To foreshadow a bit, we present data from both lab experiments and field studies showing that regular people with intact brains believe they have conscious control over decisions over which they have no true conscious control.

3 Philosophical Arguments Against Free Will If human beings are more like puppets than puppeteers, free will may be an illusion. Because the concept of free will has so many interpretations, we should clarify that our focus here is on free will as defined by thinkers such as Clarke.26 Clarke defines free will in terms of personal control over one’s decisions. It is the idea that ‘what you do, when you act freely, is up to you’. In contrast to this idea, psychological science suggests that the causes of much of our own behavior (behavior we believe we freely chose) lie in unconscious forces that are outside our awareness and control. Psychologists are not the first to question free will. Philosophers have long done so. Among the pre-Socratic physiologoi, some of the earliest skeptics were Leucippus and Democritus, who both believed in a fundamental atomistic materialism. Leucippus famously claimed that all things are governed by a logos (an antecedent that pushes a thing toward what it must do).27 Likewise, the tragic poets presented life’s most important outcomes as matters of fate. Where we today might see introspection and choice, the poets often saw the direct promptings of gods. We often assume that people have long believed in free will. However, Frede suggests that this idea only began with Epictetus, who was born in about 55 A.D.28 The question of free will is intimately tied to questions about causality. Aristotle conceived of four possible causes. His four causes are commonly known today as the material, efficient, formal, and final causes. As described in Physics II.3, the material cause denotes the physical stuff of something. The material cause of a statue is the stone or metal from which it was made. The formal cause, in contrast, is the organizational principle that allows a thing to exist. Aristotle suggests that the formal cause is what makes a thing a this.29 Consider a table versus a bookcase. What makes the same boards a bookcase or a table is how they are organized. The third Aristotelian cause is the efficient cause—the source of action that brought a thing into existence. In the case of a table, the efficient cause might be a finish carpenter. The final cause is the telos or the purpose. The purpose of a statue might be to memorialize a hero. The purpose of a bookcase is to hold books. When speaking of living

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things, Aristotle does not speak of matter and form but of body and soul (psyche). Soul is the organizing and animating principle of all living things. As form makes a non-living thing a this, soul makes a living thing a this.30 Why all the focus on causality? The question of free will is largely dependent upon how we construe causality. Most modern scientists accept only two of Aristotle’s four causes, namely, the deterministic material and efficient causes. Early modern philosophers, especially Thomas Hobbes, focused solely on these two deterministic accounts of causality. For example, in the Leviathan, Hobbes developed an account of human psychology, ethics, and politics grounded solely on matter and motion. Whereas some of Hobbes’s accounts seem quaint today, he moved both philosophy and psychology forward by thinking about people mechanistically rather than metaphysically. Along these lines, Hobbes described the will as being ‘free’ only in the sense that water can be said to be free to descend a channel. The will is ‘free’ only in the sense that it has ‘liberty’, which he defines as the absence of external impediments. Hobbes writes: [a]s in the water, that hath not only Liberty, but a Necessity of descending by the Channel: so likewise in the Actions which men voluntarily doe; which (because they proceed from their will) proceed from Liberty; and yet because every act of mans will, and every desire, and inclination proceedeth from some cause, which causes in a continuall chaine (whose first link in the hand of God the first of all causes) proceed from Necessity.31 Hobbes also denied that decisions are the end products of a ‘deliberate desire’. In the Leviathan, he claims there are two sorts of motion at work in human behavior. The first is vital motion, which includes natural processes such as cardiopulmonary activity and digestion. The second is animal or voluntary motion, such as speech and arm movements. Animal or voluntary motion is presumably caused wholly by the things we perceive.32 Even perception, imagination, and ‘fancy’, Hobbes argues, are merely motions in the matter of the body caused by the motions of matter outside the body.33 Deliberation, he argues, is simply the end product of desires or aversions. The will is simply the last ‘appetite’ in a deterministic chain of deliberations over which we have no true control. With the benefit of his understanding of Newtonian physics, Nietzsche offered more sophisticated variations on this theme. As suggested previously, Nietzsche conceived of the self as a bundle of lower-order, biologically grounded drives that continually strive against one another. Like Hobbes, Nietzsche was no fan of free will. The logic of the modern scientific method also poses problems for free will. Virtually all scientists endorse determinism—the idea that everything is subject to orderly, predictable laws.34 This epistemological

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assumption has implications that many people find unpalatable. For example, if everything is subject to natural laws, then supernatural gods are not plausible. After all, deities would have to be subject to natural laws. Likewise, whatever people think free will is, it must be subject to natural laws. A second logical problem with free will has to do with the process of scientific discovery. Because modern science is a synthesis of empiricism and rationalism,35 explanations of human behavior must be strictly logical. Appealing to free will as a cause of behavior violates a cardinal rule of logic—which is that one must not beg a question. Logically speaking, begging a question is not merely raising another question (the way the term is used informally). Instead, begging a question is raising the same question once again. If you ask Bea why she did something, you have good reason to be dissatisfied with the answer: “I chose to do it”. Bea’s nonanswer forces you to beg the question and ask, “But why did you choose to do it”” In light of such arguments, it is surprising how popular the belief in free will is—even among avid fans of determinism. A 2015 survey of more than 4,500 readers of Scientific American revealed that 59 percent of respondents said they believed in free will.36 In fact, many philosophers appear to feel that free will is wholly compatible with determinism. This school of thought is known as compatibilism. To summarize our response to compatibilism, we find it unconvincing. In the interest of space, we will critique only one popular compatibilist argument. McKenna and Coates argue for compatibilism by suggesting that scientific laws are variable.37 Beginning with the premise that it is often possible for people to act in more than one possible way, they argue that a person has the “ability to act in such a way that, if she were to so act, some law of nature that does obtain would not” (emphasis in original). Of course, McKenna and Coates do not believe the present influences the past. Instead, they argue, the compatibilist view tells us that a person who acted a certain way at a certain time possessed abilities to act in various sorts of ways. Had she exercised one of those abilities, and thereby acted differently, then the laws of nature that would have entailed what she did in that hypothetical situation would be different from the actual laws of nature that did entail what she did actually do.38 In our view, this reflects a deep misunderstanding of the laws of nature. Laws are invariable. If a measured force was different today than it was yesterday, no self-respecting physicist would suggest that a different set of laws was at work today than yesterday. Instead, any physicist would assume that the specific levels of the variables that are universally at work in matters of force were different on the two different days: F = ma, period. If F is smaller today than it was yesterday, it is not because

136 Brett W. Pelham, et al. F today = m/a (rather than ma). Not everyone agrees with scientists that everything in the universe obeys orderly laws.39 But virtually all scientists believe that natural laws are constant and invariable. We should not confuse changing the specific level of a variable at work in a situation for the mistaken idea that the laws of nature are variable. A slightly more reasonable cousin of this argument for compatibilism suggests that the laws of nature do not change. Rather, the particular law that wins the day at one moment, or for one person, may be very different than the particular law that wins the day at a different moment or for a different person. This is merely a corollary of the principle of equifinality: human behavior is subject to a great many laws and principles, and these laws often push people in different directions.40 For example, there are at least a dozen well-documented reasons people behave aggressively. A partial list includes downward social comparisons, scapegoating, competition, reciprocity, hot temperatures, priming, modeling, the culture of honor, and genetics.41 However, the fact that human behavior is complex does not mean that free will is the magical tiebreaker when two psychological forces push people in opposite directions. If the ambient temperature nudges me to punch a person who disagrees with me about compatibilism, while social learning nudges me with equal vigor to be civil, there are a dozen other psychological forces at work that will serve to break what might otherwise seem like an impossible tie. Incidentally, the principle of equifinality also resolves the philosophical dilemma of Buridan’s hungry ass—which finds itself equidistant from two identical piles of hay. Any one of a dozen other reasons why the ass might prefer one pile over the other (e.g., spontaneous alternation) will keep it from being frozen in indecision. Free will does not rescue human decision makers from the dilemma of complexity. In fact, it unnecessarily complicates things. In so doing, free will also violates another scientific canon—which is the canon of parsimony.

4 Psychological Evidence Against Free Will But is there any psychological evidence suggesting that free will is an illusion? In a word, yes. A growing body of research in implicit social cognition suggests that people make both mundane and important decisions for reasons that are grounded not in free will but in their environments. If forces outside our awareness and control are often the true drivers of our behavior, then free will must often be illusory. Presumably, shoppers who preferred the fourth pair of Nisbett and Wilson’s pantyhose felt they freely chose their favorite pair. But Nisbett and Wilson’s experimentally engineered order of presentation rather than free will was the true reason behind these shoppers’ decisions. There is a popular rebuttal to this argument. It is this. Yes, in the artificial confines of the lab—where people make unimportant

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decisions—unconscious forces may nudge people toward a decision. But when people face important decisions, the conscious decision maker takes over, weighs and balances the available evidence, and makes a rational decision. This position is not wholly without merit. Research on dual-process theories in social cognition suggests that when a decision is important, people are more likely to ignore surface cues or gut impulses—in favor of thinking hard about the decision. Thus, studies of the elaboration likelihood model of persuasion show that when people have both the motivation and the ability to think deeply, they are more persuaded by central processes (e.g., rational arguments) than by peripheral processes (e.g., speaker attractiveness).42 But the finding that central processes sometimes rule the day does not guarantee that free will is in the driver’s seat of central processing. Further, even if one assumes that free will matters when it comes to some forms of persuasion, this does not guarantee that free will matters for all forms of persuasion. As Pelham and Neter argued, the logic of good persuasive arguments is almost always obvious.43 Few people have difficulty telling the difference between a weak and a strong argument for raising college tuition. Compare “The dean would like a raise” with “The money will fund job placement programs”. In the case of more complex judgments under uncertainty, however, it is often unclear what normative decision rules one should use. Many judgmental heuristics are so seductive, and so many logical decision rules so demanding, that even experts often rely on heuristics. In fact, Pelham and Neter showed that when people had to make difficult decisions under time pressure, or when using normative decision rules was mentally taxing, increasing people’s motivation to answer a question correctly increased the likelihood that people used unconscious (heuristic) decision rules.44 Bargh made a similar point.45 If people are ever to control for the unintended effects of unconscious influences on their judgment and behavior, they must (i) know about the specific unconscious bias in question, (ii) be motivated to correct for it, (iii) be aware of the direction and magnitude of the unconscious effects in question, and (iv) be capable of doing what is necessary to shrug off any biases. Because all four of these barriers must be overcome if conscious processing is to prevail, this makes unconscious judgmental processes very pervasive. Thus, even if Brook is highly motivated to offer a correct answer to a question, knows that an unconscious bias is at work, and knows its likely magnitude and direction, asking her to find a parking spot on a busy street will usurp enough of her cognitive resources that she will be forced to rely heavily on automatic information processing. Even tasks as mundane as trying to impress a stranger often debilitate controlled processing.46 Overcoming automatic processing is often a very tall order. A similar problem for advocates of free will and conscious deliberation arises when decisions have a heavy emotional component. Consider

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incest. In cultures across the globe, incest is considered morally deplorable. If you want a reminder of this, consider the uncomfortable scenario studied by Jon Haidt: Julie and Mark are brother and sister. They’re traveling together in France on summer vacation from college. One night they are staying alone in a cabin near the beach. They decide that it would be interesting and fun if they tried making love. At the very least, it would be a new experience. . . . Julie was already taking birth control pills, but Mark uses a condom too, just to be safe. They both enjoy making love, but they decide never to do it again. They keep that night as a special secret, which makes them feel even closer to each other. What do you think about that? Was it ok for them to make love?47 Almost everyone who hears this story agrees that there is something deeply yucky about sex between siblings. But any logical argument judges offer to justify their condemnation has little merit. When people are reassured that there is no chance the behavior could lead to any genetically compromised offspring, this does little to change their minds. Likewise, even though the behavior is legal in France, and even when it seems to have brought these siblings closer, almost everyone agrees it was immoral. Haidt suggests that eons of evolutionary programming have produced a distaste for incest. In fact, he suggests that in many human judgments ‘the tail wags the dog’. We are programmed by evolution to fnd something deplorable (or delightful). But we justify the conclusion after the fact— accepting the illusion that we (willfully) arrived at the position. Rozin and colleagues have made a similar point about people reacting with disgust to things (e.g., chocolates shaped like poo) that logically should produce no such response.48 Nonetheless, many still insist that when a judgment is important, people settle on a rational, self-determined course of action. Social scientists have leveled exactly this critique at research in implicit social cognition. For example, both Gallucci49 and Simonsohn50 argued that implicit egotism should evaporate outside the laboratory. Implicit egotism refers to an unconscious preference for people, places, and things that resemble the self.51 Because most people have positive unconscious associations about the self (one’s name, one’s birthday number, and even one’s earlobe shape), people should gravitate toward things that resemble the self (usually without realizing why). Pelham, Mirenberg, and Jones found that people gravitate toward states and cities whose names resemble their own first or last names (e.g., Cal moves to California, Virginia to Virginia).52 Likewise, Jones and colleagues showed that people are much more likely than one would expect by chance to marry others whose surnames match their own.53 Moving to the lab, Jones et al. showed that people liked an

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attractive woman more than usual when her arbitrary jersey number had been paired (without their awareness) with their own names.54 Simonsohn suggested two specific reasons why implicit egotism might not exist outside the lab.55 First, some apparent evidence for implicit egotism in the field might be due to confounds—such as ethnic matching. Second, he suggested that implicit egotism is too small an effect to make a difference in most real-world decisions. Specifically, Simonsohn argued that implicit egotism “can tip the balance one way or the other” only when people are relatively indifferent to two or more very similar options (e.g., choosing blueberry ice cream versus cookie dough ice cream—not marrying Beryl versus Cookie).56 In response to Simonsohn’s critiques, Pelham and Carvallo conducted studies that in our view, invalidate his arguments.57 For example, to address concern about ethnic matching in marriage, Pelham and Carvallo looked at both birthday-number matching and birth-month matching in two large sets of state-wide marriage records. Although African Americans are named Johnson more often than they are named Smith, it is unlikely that a disproportionate number of African Americans are born in September, or on the 24th of the month. But people prefer their birthday numbers just as much as they prefer their names.58 Pelham and Carvallo documented reliable birthday number—and birth month—matching effects in all the marriage records they could locate that allowed them to assess implicit egotism in marriage.59 Figure 9.1 shows the findings for birthday number matching in Ohio marriage records. There was a modest but reliable 6.5 percent bias for people to marry others who shared their birthday numbers. Further, this 6.5 percent bias became a nearly 20 percent bias in the subset of people who seem to have liked their birthday numbers enough to have gotten married on them. Implicit egotism appears to be robust outside the lab. Pelham and Carvallo also provided new data on implicit egotism and career choice. They were able to do so because in April 2013, the 1940 U.S. Census data were released to the public. Before analyzing these records, Pelham and Carvallo identified all 11 of the common male career names (e.g., baker, carpenter) that doubled as exact surnames. This eliminated the need for judgment calls about sampling specific names or careers. Findings from this study appear in Figure 9.2. For each of these 11 male careers, men were at least modestly overrepresented in a career when the career name happened to match their surname. When we used population base rates rather than using this specific set of careers as the comparison standard, these effects grew larger. Using these same census data, we were able to control for ethnic confounds. This could occur, for example, if Black men in the United States in 1940 were disproportionately named Porter and often worked as porters. The career–surname matching effect was robust not only

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Figure 9.1 Implicit egotism in marriage decisions. People with the same birthday number were disproportionately likely to marry. This effect was much stronger than usual for brides and grooms who got married on their birthday numbers (suggesting that they liked them). The same patterns held for month rather than day of birth. All these effects replicated in a large set of Minnesota marriage records.

Figure 9.2 Ratio of observed to expected surname-occupation matches for men with common surnames that also serve as male occupation names. Source: 1940 U.S. Census.

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for both Black and White men considered separately but also for Black and White men whose level of education was held constant. Using these same operational definitions, we replicated these surname–career matching effects in the 1911 English Census. We also found that these effects waxed and waned in theoretically predictable ways. For example, we knew that single women are not as attached to their maiden names as married women are to their married names. Accordingly, we found that the longer women named Cook had been married, the more strongly they gravitated toward working as cooks. Implicit egotism does not evaporate in the field. Finally, lab studies of implicit egotism show that implicit egotism is, in fact, implicit.60 Virtually none of the participants in any of our lab experiments on implicit egotism were able to report the true reasons for their preferences for stimuli that resembled the self. Instead, like Gazzaniga’s split-brain patients, our participants seem to have manufactured after the fact justifications for their unconsciously determined judgments and decisions.

5 Research on Free Will If such studies were not enough to raise doubts about free will, Wegner and Wheatley specifically argued that free will is illusory.61 Their key idea is that assessing whether we have caused something is much like assessing whether a physical object caused something (e.g., whether one billiard ball made another ball move). We perceive ourselves to be the causes of our own thoughts or behavior only when each of three logical requirements has been met. Wegner and Wheatley refer to these three requirements as priority, specificity, and exclusivity. Priority means causes must precede effects. If we think of a behavior after we have engaged in it, we experience no sense of agency. The second rule is specificity. The consequences must be logically consistent with the thought. If we think of scratching our noses, and spontaneously kick a stone, we have no sense of agency. Finally, exclusivity requires that other forces (confounds) cannot easily account for the observed effect. If either another person or an external force engages in activities that could have produced an effect, people feel limited agency for it. Because unconscious forces are often the true causes of what we think and do, and because Wegner and Wheatley’s three requirements are often fulfilled, the perception that we have willfully engaged in a behavior may thus be a common and forgivable reasoning error. In support of their position, Wegner and Wheatley provide many examples of how people can either fail to experience a sense of agency for something they themselves have caused or experience a sense of agency for an event they did not cause. Using divining rods to find water or lost objects, using Ouija boards, engaging in ‘automatic writing’, and serving as facilitators in the debunked ‘facilitated communication’ technique are

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all examples of how a person can cause a behavior and be wholly unaware of having done so. In such cases, Wegner and Wheatley argue, some quirk of the unusual activity in question muddies the waters responsible for the perception of personal agency (see, e.g., Wegner and Wheatley’s analysis of supernatural devices such as divining rods). Wegner and Wheatley also argued that one can manipulate variables such as temporal priority to create the illusion of conscious will.62 To do so, they asked participants to play a computerized variation on the game I Spy. Participants and a confederated were seated next to a monitor containing images of about 50 objects (e.g., a plastic dinosaur, a swan). The real participants and a confederate (posing as a co-participant) moved a cursor around the computer screen, sharing control of the cursor by using a special mouse. Participants were told that they and their partners would individually and intermittently hear words over a set of headphones. These words would serve as distractions. Further, participants were told that they and their partners would be distracted using different words. On four crucial trials, the confederate alone had complete control of the mouse, and the confederate usually stopped the cursor on an object whose name the real participant had heard most recently (satisfying the condition of specificity). However, the delay between the time the real participant heard the target word and the moment at which the confederate brought the mouse to rest on the named object varied widely. After the real participant heard the name of the object, there was a delay of 30 seconds, 5 seconds, or 1 second before the confederate stopped on the image in question. In a fourth condition, the real participants heard the name of the object 1 second after the confederate had stopped on it. When the real participants (who had no control, of course) heard the name of an object and the cursor stopped on the object either 5 seconds later or 1 second later, participants reported an illusion of control (they said they had more than 50 percent of the control of the cursor). However, when the object was named 30 seconds prior to the time at which the confederate stopped the cursor on it—or was named shortly after the confederate stopped the cursor on it—participants reported that the other participant had been mostly in charge of the action. Experiments such as these suggest that the powerful feeling that we have free will may be largely, if not completely, illusory. At this point in the early history of the empirical study of free will, we are most comfortable saying that the perception of free will is probably greatly exaggerated. And it seems very safe to say that people do not always have free will. But as advocates of free will such as Nahmias have been quick to point out, saying that people do not always have free will and saying that free will is always an illusion are two different things.63 This distinction is hard to criticize. However, given the long and growing list of unconscious influences on social judgments and decision-making, one can make the

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case that the edifice of free will is being chipped away, study by study, by hundreds of modern studies on implicit social cognition. One more example should help clarify both how powerful and how mundane unconscious influences are. In 1996, Bargh, Chen, and Burrows argued that a great deal of goal-directed behavior is influenced by unconscious priming.64 Specifically, they showed that activating social concepts such as personality traits (e.g., ‘politeness’) and stereotypes (e.g., ‘Old people are slow’.) can influence people’s goal-directed behavior. In one study, students unscrambled a list of sentences. In one condition of one pair of these experiments (2a and 2b), most of the sentences referred to old people (e.g., ‘He collected social security’. ‘She forgot her reading glasses’.). In the other condition, none of the sentences made any mention of old people. After thinking they’d been dismissed from the experiment, participants headed for the elevator. Unbeknown to participants, a research assistant kept blind to conditions unobtrusively timed how long it took participants to walk to the elevator. Averaging across two studies, it took participants about 16 percent longer than usual to walk to the elevator when they had recently been thinking about old people. In another experiment, Bargh, Chen, and Burrows primed students either with the trait of rudeness or the trait of politeness (a control group received neutral primes).65 Participants primed with politeness were more than three times as likely as those primed with rudeness to sit patiently for 10 minutes while an experimenter who was supposed to be helping them explained (and re-explained, and re-explained) some simple instructions to a clueless fake participant. When participants were asked near the end of the experiment what had influenced how long they waited, no one made any connection between the primes and how long they had waited. Presumably participants felt they were the freely acting agents who made these decisions. But most of the agency in this situation rested in the hands of the experimenters. Behavioral priming studies such as these were initially met with great enthusiasm. Eventually, however, critics argued that these unconscious behavioral priming effects were at best fragile and at worst fraudulent. In one high profile non-replication, Doyen, Klein, Pichon, and Cleeremans found no effect of their priming manipulation on walking speed—unless the person doing the unobtrusive timing was aware of each participant’s priming condition.66 This study suggested to many that behavioral priming studies may demonstrate the unconscious phenomenon known as experimenter bias67 rather than the unconscious phenomenon known as behavioral priming. In our view, at least, part of the controversy over behavioral priming may stem from the fact that it threatens the popular notion that people have free will. Like research on implicit egotism, research on behavioral priming may always have its detractors. However, a recent meta-analysis (a mathematical

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synthesis of multiple studies) strongly suggests that behavioral priming, too, is alive and well. In their summary of 133 studies, Weingarten, Chen, McAdams, Yi, Hepler, and Albarracin argued that behavioral priming is not a statistical or methodological artifact.68 Because this team had access to the results of so many studies, they were able to identify moderators (boundary conditions) of behavioral priming effects. One moderator they identified was how important the goal being activated was (e.g., ‘walk to an elevator’ versus ‘do well on an exam’). If people resist unconscious influences when decisions are important, behavioral priming effects should be smaller than usual for more important goals, perhaps disappearing altogether for very important goals. Weingarten et al. found exactly the opposite.69 Behavioral priming effects are larger for more important goals. Research on implicit egotism suggests a similar conclusion. In a study of preferences for chocolate candy, Brendl and colleagues found that people prefer brands of chocolate that include their own initials.70 On average Mina prefers M&Ms more than Tina does. Brendl et al. also found that these name–letter branding effects were larger than usual for people who reported being hungrier.71 There is thus some reason to suspect that unconscious effects on human behavior may be stronger, not weaker, for more important decisions. Some advocates of free will are aware of some of the studies reviewed here. For example, Nahmias argues that Libet’s 1985 study simply shows that we probably do not have as much free will as we think.72 One of his arguments is that current neuroscientific technology falls well short of predicting perfectly what people will do a few seconds from now based on their detectable neural activity. In our view, this argument is easily turned on its head. Given the imperfect technology we currently have, we can often predict only modestly from neural activity what people are about to do. But it seems likely that in the future we will be able to predict behavior from neural activity much better than we can now. Further, many existing studies of implicit social cognition reveal surprisingly large effects of unconscious forces under the right conditions.73 The part of human behavior that we cannot yet predict is presumably just as lawful as the part that we currently can. Nahmias argues that even perfect prediction of human behavior from brain activity would not destroy most people’s confidence in free will.74 Nahmias, Shepard, and Reuter told participants to imagine that neuroscience had progressed so far that scientists could predict a woman’s daily behavior perfectly, even if the woman (Jill) tried to fool the machine that read her brain waves.75 As Nahmias put it, “More than 80 percent of the participants reported that they believed that such future technology was possible, yet 87 percent of them responded that Jill still had free will”.76 In our view, an alternate interpretation of this study is that many human beings report that they would steadfastly refuse to abandon their belief in free will even if they were presented with clear evidence against it. This

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may say more about the psychological appeal of believing in free will than it does about the likelihood that it is real. Nahmias makes other arguments for free will.77 He notes that recent research shows that “conscious reasoning improves performance on logical and linguistic tasks” and that conscious self-control helps people behave less impulsively. In our view, it is not at all clear that free will and free will alone prompts the conscious reasoning that may help people make superior decisions. It is not even clear that conscious reasoning (or the unconscious forces that covary with it) leads to the superior decisions in question. Nahmias also argues that it is evolutionarily implausible that conscious thought would have ever arisen if it did not lead to superior decision-making grounded in free will. There are problems with this argument, too. It assumes, for example, that the main adaptive consequence of our large brains was to produce a creature that freely makes superior decisions. But human brains are not general-purpose reasoning machines. Instead, they are the complex results of evolution for social living.78 Social cooperation is greatly facilitated by language, and it is plausible that the illusion of free will is an epiphenomenal by-product of the evolution of language. All languages allow people to refer to both past events and future events.79 Language also allows for deception and abstraction. But there is no reason to assume that language evolved specifically because it allows free will or that free will would lead to superior decision-making relative to a lack thereof. In short, human brains evolved in response to many environmental pressures, and they are capable of many complex activities. Natural selection for brains that possess free will is evolutionarily implausible.

6 Why the Illusion? If free will does not exist, why do so many believe in it? Psychological research suggests that people are strongly motivated to predict and control their worlds. In fact, when our sense of predictability and control is threatened, we become motivated to restore it. In fact, we often do so by deciding that we can control the uncontrollable. Langer showed exactly this.80 Even in games whose outcomes were determined completely by chance, most people acted as if they could predict or control the outcomes. Thus, people believed they could predict which of two players would win a game of chance. In another study, participants purchased a lottery ticket for $1, hoping to win a $50 raffle prize. Half the participants were assigned a lottery ticket at random and half were allowed to select a specific lottery card. When offered the chance to sell their tickets back, both groups of participants behaved as if they had some control over the lottery. Even participants who received their lottery cards at random said they would only sell them if offered about twice what they had paid for them ($1.96). Among participants who had been allowed to choose their

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own tickets, this average asking price increased to $8.67. Studies have confirmed this ‘illusion of control’ in many other ways, including ways that can have life or death consequences.81 Many other studies offer similar viewpoints. For example, Kay, Whitson, Gaucher, and Galinksy argued that people “protect the belief in a controlled, nonrandom world by imbuing their social, physical, and metaphysical environments with order and structure when their sense of personal control is threatened”.82 Accordingly, Kay et al. showed that after people experienced threats to their sense of personal control, they found superstitious beliefs and conspiracy theories more believable—and they were more likely to perceive order in random events. In the wake of threats to a felt sense of control, people also place more faith in cultural beliefs that promise control, including the belief that God intervenes in human affairs. A growing body of psychological evidence suggests that the notion of free will may soon be added to a long list of comforting beliefs that science has now falsified. The earth is not flat, our planet is not at the center of the universe, and we are not the only animals on the planet that are self-aware. The idea that we have free will may soon be added to this list of comforting but empirically unsustainable beliefs.83

Notes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28.

Rensberger (1986). Nietzsche (2002). Nietzsche (2002, § 16). Nietzsche (2002, § 16). Nietzsche (2002, § 17). Plato, Republic 588c—e. Nietzsche (2006, “On the Pale Criminal”). Nietzsche (2002, § 23). Nietzsche (2005, “The Four Great Errors”, § 3). Nisbett and Wilson (1977). Nisbett and Wilson (1977). Millar and Tesser (1986) and Sabini and Silver (1981). Johansson et al. (2005). Johansson et al. (2006). See Warren and Warren (1970). Warren and Warren (1970). Hixon and Swann (1993). Nisbett and Wilson (1977). Bem (1972). Tulving (1993); see also Lieberman et al. (2001). Banaji and Hardin (1993), Kahneman (2011), and Zajonc (2001). Shiffrin and Schneider (1977). Chartrand and Bargh (1999) and Gilbert (1991). Gazzaniga (2005). Libet (1985). Clarke (2000). Cf. Leucippus, fragment from On Mind, in Taylor (2010). Frede (2011).

Psychological Challenges to Common Sense 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82.

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Cf. Aristotle, On the Soul II.1. Aristotle, On the Soul II.1 in general. Hobbes (1994, XXI.4). Cf. Hobbes (1994, VI.1–2). Cf. Hobbes (1994, I–III). Pelham and Blanton (2018). Birnbaum (1984). Stix (2015). McKenna and Coates (2019). McKenna and Coates (2019). See Pelham and Blanton (2018). Pelham and Blanton (2018). Pelham (2018). Petty and Cacioppo (1986). Pelham and Neter (1995). Pelham and Neter (1995). Bargh (1994). Gilbert, Krull, and Pelham (1988). Haidt (2001). Rozin et al. (1986). Gallucci (2003). Simonsohn (2011). Pelham, Carvallo, and Jones (2005) and Pelham, Mirenberg, and Jones (2002). Pelham, Mirenberg, and Jones (2002). Jones et al. (2004). Jones et al. (2004). Simonsohn (2011). Simonsohn (2011, 19). Pelham and Carvallo (2015). Kitayama and Karasawa (1997). Pelham and Carvallo (2015). See, for example, Jones et al. (2004). Wegner and Wheatley (1999). Wegner and Wheatley (1999). Nahmias (2015). Bargh, Chen, and Burrows (1996). Bargh, Chen, and Burrows (1996). Doyen et al. (2012). Rosenthal and Fode (1963). Weingarten et al. (2016). Weingarten et al. (2016). Brendl et al. (2005). Brendl et al. (2005). Nahmias (2015). Pelham and Carvallo (2015). Nahmias (2015). Nahmias, Shepard, and Reuter (2014). Nahmias (2015, 79). Nahmias (2015). Pelham (2018). Hockett (1958, 1960). Langer (1975). See Casarett (2016). Kay et al. (2009, 264).

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83. We thank Tim Wilson for his encouraging expert feedback on this chapter. We also thank John Bargh, whose encouraging conversations with the first author facilitated the development of this chapter. Please pose questions or comments to Brett Pelham ([email protected]).

References Aristotle. 1984a. “On the Soul.” Translated by J. A. Smith. In The Complete Works of Aristotle. Vol. 1, edited by Jonathan Barnes, 641–692. Princeton: Princeton University Press. Aristotle. 1984b. “Physics.” Translated by R. P. Hardie and R. K. Gaye. In The Complete Works of Aristotle. Vol. 1, edited by Jonathan Barnes, 315–446. Princeton: Princeton University Press. Banaji, Mahzarin R., and Curtis D. Hardin. 1993. “Automatic Stereotyping.” Psychological Science 7: 136–141. Bargh, John A. 1994. “The Four Horsemen of Automaticity: Awareness, Efficiency, Intention, and Control in Social Cognition.” In Handbook of Social Cognition, edited by Robert S. Wyer, Jr. and Thomas K. Srull, 1–40. 2nd ed. Hillsdale: Erlbaum. Bargh, John A., Mark Chen, and Lara Burrows. 1996. “Automaticity of Social Behavior: Direct Effects of Trait Construct and Stereotype Activation on Action.” Journal of Personality and Social Psychology 71: 230–244. Bem, Daryl J. 1972. “Self-Perception Theory.” In Advances in Experimental Social Psychology. Vol. 6, edited by Leonard Berkowitz, 1–62. New York: Academic Press. Birnbaum, Michael H. 1984. “Philosophical Criteria for Psychological Explanation.” Bulletin of the Psychonomic Society 22: 562–565. Brendl, C. Miguel, Amitava Chattopadhyay, Brett W. Pelham, and Mauricio R. Carvallo. 2005. “Name Letter Branding: Valence Transfers When Product Specific Needs Are Active.” Journal of Consumer Research 32: 405–415. Casarett, David. 2016. “The Science of Choosing Wisely: Overcoming the Therapeutic Illusion.” New England Journal of Medicine 374: 1203–1205. Chartrand, Tanya L., and John A. Bargh. 1999. “The Chameleon Effect: The Perception: Behavior Link and Social Interaction.” Journal of Personality and Social Psychology 76 (6): 893–910. Clarke, Randolph. 2000. “Modest Libertarianism.” Philosophical Perspectives 14: 21–45. Doyen, Stéphane, Olivier Klein, Cora-Lise Pichon, and Axel Cleeremans. 2012. “Behavioral Priming: It’s All in the Mind, But Whose Mind?” PLOS One, January 18. https://doi.org/10.1371/journal.pone.0029081. Frede, Michael. 2011. A Free Will: Origins of the Notion in Ancient Thought. Edited by A. A. Long with a foreword by David Sedley. Berkeley: University of California Press. Gallucci, M. 2003. “I Sell Seashells by the Seashore and My Name Is Jack: Comment on Pelham, Mirenberg, and Jones (2002).” Journal of Personality and Social Psychology 85: 789–799. Gazzaniga, Michael. 2005. “Forty-Five Years of Split-Brain Research and Still Going Strong.” Nature Reviews, Neuroscience 6 (8): 653–659. Gilbert, Daniel T. 1991. “How Mental Systems Believe.” American Psychologist 46: 107–119.

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Gilbert, Daniel T., Douglas S. Krull, and Brett W. Pelham. 1988. “Of Thoughts Unspoken: Social Inference and the Self-Regulation of Behavior.” Journal of Personality and Social Psychology 55: 685–694. Haidt, Jonathan. 2001. “The Emotional Dog and Its Rational Tail: A Social Intuitionist Approach to Moral Judgment.” Psychological Review 108: 814–834. Hixon, J. Gregory, and William B. Swann. 1993. “When Does Introspection Bear Fruit? Self-Reflection, Self-Insight, and Interpersonal Choices.” Journal of Personality and Social Psychology 64 (1): 35–43. Hobbes, Thomas. 1994. Leviathan. Edited by Edwin Curley. Indianapolis: Hackett. Hockett, Charles F. 1958. A Course in General Linguistics. New York: Macmillan. Hockett, Charles F. 1960. “The Origin of Speech.” Scientific American 203: 88–96. Johansson, Petter, Lars Hall, Sverker Sikström, and Andreas Olsson. 2005. “Failure to Detect Mismatches between Intention and Outcome in a Simple Decision Task.” Science 310 (5745): 116–119. https://doi:10.1126/science.1111709. Johansson, Petter, Lars Hall, Sverker Sikström, Betty Tärning, and Andreas Lind. 2006. “How Something Can Be Said about Telling More Than We Can Know.” Consciousness and Cognition 15: 673–692. Jones, John K., Brett W. Pelham, Mauricio R. Carvallo, and Matthew C. Mirenberg. 2004. “How Do I Love Thee? Let Me Count the Js: Implicit Egotism and Interpersonal Attraction.” Journal of Personality and Social Psychology 87: 665–683. Kahneman, Daniel. 2011. Thinking, Fast and Slow. New York: Macmillan. Kay, Aaron C., Jennifer A. Whitson, Danielle Gaucher, and Adam D. Galinsky. 2009. “Compensatory Control: Achieving Order through the Mind, Our Institutions, and the Heavens.” Current Directions in Psychological Science 18: 264–268. Kitayama, Shinobu, and Karasawa Mayumi. 1997. “Implicit Self-esteem in Japan: Name Letters and Birthday Numbers.” Personality and Social Psychology Bulletin 23: 736–742. Langer, Ellen J. 1975. “The Illusion of Control.” Journal of Personality and Social Psychology 32 (2): 311–328. https://doi.org/10.1037/0022-3514.32.2.311. Libet, Benjamin. 1985. “Unconscious Cerebral Initiative and the Role of Conscious Will in Voluntary Action.” Behavior and Brain Sciences 8: 529–566. Lieberman, Matthew D., Kevin N. Ochsner, Daniel T. Gilbert, and Daniel L. Shacter. 2001. “Do Amnesics Exhibit Cognitive Dissonance Reduction? The Role of Explicit Memory and Attention in Attitude Change.” Psychological Science 12 (2): 135–140. McKenna, Michael, and D. Justin Coates. 2019. “Compatibilism.” In The Stanford Encyclopedia of Philosophy (Winter), edited by Edward N. Zalta. https:// plato.stanford.edu/archives/win2019/entries/compatibilism/. Millar, Murray G., and Abraham Tesser. 1986. “Effects of Affective and Cognitive Focus on the Attitude-Behavior Relationship.” Journal of Personality and Social Psychology 51: 270–276. Nahmias, Eddy. 2015. “Why We Have Free Will.” Scientific American  312 (1): 77–79. Nahmias, Eddy, Jason Shepard, and Shane Reuter. 2014. “It’s OK If ‘My Brain Made Me Do It’: People’s Intuitions About Free Will and Neuroscientific Prediction.” Cognition 133 (2): 502–516.

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Nietzsche, Friedrich. 2002. Beyond Good and Evil: Prelude to a Philosophy of the Future. Translated by Judith Norman. Edited by Judith Norman and RolfPeter Horstmann. Cambridge: Cambridge University Press. Nietzsche, Friedrich. 2005. “Twilight of the Idols.” In The Anti-Christ, Ecce Homo, Twilight of the Idols and Other Writings, translated by Judith Norman, edited by Aaron Ridley and Judith Norman, 155–229. Cambridge: Cambridge University Press. Nietzsche, Friedrich. 2006. Thus Spoke Zarathustra: A Book for All and None. Translated by Adrian del Caro. Cambridge: Cambridge University Press. Nisbett, Richard E., and Timothy D. Wilson. 1977. “Telling More Than We Can Know: Verbal Reports on Mental Processes.” Psychological Review 84: 231–259. Pelham, Brett W. 2018. Evolutionary Psychology: Genes, Environments, and Time. London: Palgrave-MacMillan. Pelham, Brett W., and Hart Blanton. 2018. Conducting Research in Psychology: Measuring the Weight of Smoke. 5th ed. Thousand Oaks: Sage. Pelham, Brett W., and Mauricio R. Carvallo. 2015. “When Tex and Tess Carpenter build Houses in Texas: Moderators of Implicit Egotism.” Self and Identity 14: 692–723. Pelham, Brett W., Matthew C. Mirenberg, and John K. Jones. 2002. “Why Susie Sells Seashells by the Seashore: Implicit Egotism and Major Life Decisions.” Journal of Personality and Social Psychology 82: 469–487. Pelham, Brett W., Mauricio. Carvallo, and John T. Jones. 2005. Implicit egotism. Current Directions in Psychological Science, 14, 106–110. Pelham, Brett W., and Efrat Neter. 1995. “The Effect of Motivation on Judgment Depends on the Difficulty of the Judgment.” Journal of Personality and Social Psychology 68: 581–594. Petty, Richard E., and John T. Cacioppo. 1986. “The Elaboration Likelihood Model of Persuasion.” In Advances in Experimental Social Psychology, edited by L. Berkowitz, Vol. 19, 123–205. New York: Academic Press. Rensberger, Boyce. 1986. How the World Works: A Guide to Science’s Greatest Discoveries. New York: William Morrow. Rosenthal, Robert, and Kermit Fode. 1963. “The Effect of Experimenter Bias on the Performance of the Albino Rat.” Behavioral Science 8: 183–189. Rozin, Paul, Linda Millman, and Carol Nemeroff. 1986. “Operation of the Laws of Sympathetic Magic in Disgust and Other Domains.”  Journal of Personality and Social Psychology 50 (4): 703–712.  https://doi.org/10.1037/00223514.50.4.703. Sabini, John, and Maury Silver. 1981. “Introspection and Causal Accounts.” Journal of Personality and Social Psychology 40 (1): 171–179. Shiffrin, Richard M., and Walter Schneider. 1977. “Controlled and Automatic Human Information Processing: II. Perceptual Learning, Automatic Attending, and a General Theory.” Psychological Review 84: 127–190. Simonsohn, U. 2011. “Spurious? Name Similarity Effects (Implicit Egotism) in Marriage, Job, and Moving Decisions.” Journal of Personality and Social Psychology 101 (1): 1–24. Stix, Gary. 2015. “Site Survey Shows 60 Percent Think Free Will Exists: Read Why.” Scientific American, January 15. https://blogs.scientificamerican.com/ talking-back/site-survey-shows-60-percent-think-free-will-exists-read-why/. Taylor, C.C.W. 2010. The Atomists, Leucippus and Democritus: Fragments: A Text and Translation With a Commentary. Toronto: University of Toronto Press.

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10 Radically Self-Deceived? Not So Fast Fleur Jongepier and Quassim Cassam

Suppose Phineas gets into a railroad accident, and a large iron bar is driven through his head.1 Upon regaining consciousness, Phineas— previously a kindhearted, modest fellow—now has a general contempt for humankind and a strong belief in his own superiority. If we want to know why Phineas believes he is superior to everyone else, we might ask him for his reasons. In response, he might say that he believes he is superior because his colleagues are untrustworthy or because he has a higher IQ or something along those lines. This is a rational explanation that centrally involves the reasons individuals themselves cite in favor of believing what they believe. Alternatively, we can give a non-rationalizing explanation of why Phineas believes what he believes. A non-rationalizing explanation in Phineas’s case would concentrate on the iron bar being driven through his brain and the fact that significant brain injuries can lead to significant psychological change. Pelham et al. suggest that being ignorant of why we believe what we believe in the non-rationalizing sense gives us reason to think we don’t know why we believe what we believe. They for instance write that “people often have little or no access to their own thought processes”. But, first, knowing one’s thoughts and knowing one’s thought processes are not equivalent, and ignorance about the latter does not amount to ignorance about the former. We often find ourselves with ‘passing thoughts’ that occur to us for no apparent reason.2 One might suddenly find oneself thinking about cats, say, without really knowing why. But one still knows one is thinking about cats. So ignorance about underlying thought processes doesn’t undermine the fact that we know what we are thinking. Second, Pelham et al. are not clear about what they mean by the notion of a thought ‘process’. A thought process might be the inferential steps one takes to reach a conclusion (a personal-level explanation) or the cognitive mechanisms that were involved (a sub-personal-level explanation). The former is something a person does, whereas the latter is something in which “the person, qua person, does not figure”.3 When it comes to knowing why we believe what we believe, we expect people to know about personal-level thought processes, not sub-personal ones.

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Third, acquiring more knowledge about our reasons for belief in the sub-personal non-rationalizing sense does not automatically undermine knowing what we believe in the personal, rationalizing sense. Take Phineas: the explanation of why he believes what he believes in terms of the iron bar running through his head may well leave intact the reasons Phineas himself has for believing other people are inferior. Only if Phineas himself were to become convinced that the non-rationalizing explanation is the (only) right explanation of his beliefs will his rationalizing explanation be weakened or undermined. But even if this were to happen, it’s questionable whether results from social psychology can play a similar role as the iron bar did for Phineas. The more general point is that knowing about sub-personal thought processes does not seem necessary for most types of self-knowledge. One can know that one believes the weather is fine or that one has the desire to go for a walk without knowing anything about the neurobiological or sub-personal thought processes that underpin these mental states. To think individuals need to know about the latter to have self-knowledge would amount to requiring that individuals need have to have a degree in neurobiology or cognitive science to have self-knowledge. Regarding knowledge of our actions, the same ambiguity of asking ‘why’ applies. When we want to know why someone performed action A, we can either ask for ‘agential reasons’ or what according to the individual in question speaks in favor of doing A, or we can ask about the ‘motivational factors’ that lead people to do A. Constantine Sandis gives the following helpful example: I may be motivated to buy a bottle of a certain brand of rum by the advert portraying beautiful, happy, people on a yacht in some exotic location. My agential reason here will not be the thought that I could in some way be like them but, rather, the purported fact that the rum will be of good quality.4 Apart from advertisements, there are all kinds of motivating factors that move individuals to do the things they do, including as Sandis writes, their “upbringing, a past trauma, or a fact about human nature” as well as people’s “neu- roscientifc make-up”. Things like upbringing or neuroscientifc makeup help explain, in a non-rationalizing sense, why someone did what he or she did, but they are not the sort of thing the individual would take to speak in favor of doing A. To claim that individuals don’t know why they do what they do is thus ambiguous between claiming they are ignorant about their own agential reasons and being ignorant about the relevant motivational factors.5 This distinction is particularly relevant to the ‘implicit egotism’ studies that lie at the heart of Pelham et al.’s argument. These are studies about people’s unconscious bias to “gravitate towards things that resemble

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the self” (see Pelham, Harding, and Hardin, Chapter 9). It turns out for instance that people have a preference for marrying people with surnames matching their own and also that “people with the same birthday number [are] disproportionately likely to marry”. Pelham and colleagues also studied common career names that are also common surnames such as ‘baker’, ‘cook’, or ‘carpenter’ and found that there is a ‘surname-career matching effect’. The longer people named Cook had been married, for instance, “the more strongly they gravitated toward working as cooks”. What are we to make of this? Pelham et al. write that “virtually none” of the participants in their lab experiments on implicit egotism were “able to report the true reasons for their preferences for stimuli that resembled the self”. This almost makes it sound as if we should have expected them to. Imagine the surprise if these participants explained their actions (e.g., career choices) by citing the most recent literature on implicit egotism (“I wanted to be a cook because my last name is Cook”) or if the participants in the classic Nisbett and Wilson stockings experiments explained their choice by saying they wanted the particular pair because they had a right-sided response bias. That individuals don’t come up with explanations of their actions in terms of motivational factors should come as no surprise. If it does come as a surprise, one has confused agential reasons and motivational factors. More importantly, the authors imply that the ‘true reasons’ here are the motivational factors, but why should this be so? Why should implicit egotism be the ‘true reason’ for marrying one’s partner rather than the agential reasons individuals have? The concept of ‘true reasons’ is not particularly helpful. There are valuable and less valuable explanations of people’s actions, but what makes an explanation valuable is highly context dependent. Pelham et al. claim that the fundamental assumption that we are capable of free choice is undermined by “growing list of unconscious influences on social judgements and decision-making” and that the “edifice of free will is being chipped away, study by study, by hundreds of modern studies on implicit social cognition”. But if those studies concern motivational factors, and motivational factors don’t automatically undermine people’s agential reasons, this dramatic conclusion doesn’t follow. The authors (implicitly) suggest that we cannot make our own free choices because we are constantly being ‘influenced’. But the fact that one’s actions are influenced by factors we are not aware of does not mean one’s actions were unfree or that one was not responsible for performing them. It depends on the shape that influence takes, and influence comes in many forms.6 Persuading and coercing both count as influencing a person. Influencing someone’s attitudes and actions by engaging in rational debate is not freedom undermining, whereas influencing them by holding a gun to their head is. Coercion and manipulation are standardly assumed to undermine our capacity for free choice, so if the ‘influence’

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Pelham et al. describe takes on a coercive or manipulative form, then that would give reason to think our actions aren’t free in the relevant sense. Coercion involves drastically reducing people’s options and forcing them to perform a particular action or making it impossible for them to perform the action they wish to perform. Coercion can come in radical and easily detectible forms (e.g., life or death choices) but also comes in subtler forms that are more difficult to detect, such as offers one can’t refuse where it’s hard to assess whether the option was genuinely impossible to refuse (e.g., being ‘coerced’ to stay on Facebook, given the lack of adequate alternatives). But it’s evident that the studies discussed by Pelham et al. do not involve coercion in either a drastic or subtle sense. One clearly isn’t forced to buy stockings on the right-hand side or marry partners with the same birth date. What about manipulation? At times, the authors refer to the ‘psychological forces at work’ as ‘nudging’ individuals to act in certain ways, suggesting that being nudged is incompatible with acting freely.7 The implicit thought seems to be that nudges are ways of manipulating people and being manipulated is incompatible with acting freely. But being nudged as such isn’t freedom undermining and can in fact be freedom enhancing. To the extent that biases or weakness of will, for instance, stand in the way of someone’s acting in accordance with their own goal of eating a healthier diet, certain nudges, such as placing healthy products at eye level, can allow them to act more in line with their own goals.8 Also, it isn’t clear why being nudged should lead us to think people aren’t responsible or prepared to take ownership for their own choices. Suppose we confront individuals that were nudged to pick an apple: “you were being nudged. You picked the apple. Is that really what you wanted?” It seems unlikely that many people would object. At least, the deliberate choice architecture in supermarkets has not yielded mass protest on this account (“Honey, I don’t know what just happened. I wanted to pick up some fruit, but I only have Twinkies in my bag. Darn these folk at Walmart!”).9 Nudges aren’t necessarily manipulative. Being nudged to do something counts as manipulative by defnition only if we understand manipulation in a descriptive sense as simply the bringing about of a certain change (one might for instance ‘manipulate’ a pencil by sharpening it). But manipulation in the descriptive sense isn’t freedom undermining. Manipulation is only potentially freedom undermining on a normative conception of manipulation. Manipulation in the normative sense typically involves intentionally “perverting” the way a person “reaches decisions, forms preferences or adopts”.10 Often, this happens through bypassing, undermining, or subverting someone’s capacity for rational deliberation (although not necessarily).11 Clearly, manipulation of this sort isn’t going on in the

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studies discussed by Pelham et al. This is so even if we drop the requirement that manipulation necessarily involves an intention to manipulate because, even on weaker accounts of what manipulation involves, there is no going around the fact that manipulation involves a person or institution getting another person to do something. So unless we choose to anthropomorphize implicit egoistic or right-sided response biases, biases don’t manipulate in a way that affects free choice. All of this goes back to the distinction between agential reasons and motivating reasons. For the claim to be plausible that there is no such thing as our capacity to make free choices in the supermarket, at work, and in life in general, what needs to be shown is that there’s something suspicious about our agential reasons, but it’s not clear that the studies discussed by Pelham et al. give reason for suspicion in that regard. One might worry that we have not really been taking seriously the challenge put forward by Pelham et al. If it’s true that nonrational explanations of our actions are available, and that in a significant class of cases these explanations do not match the reasons we ourselves give, then our personal-level reasons are not as decisive as we take them to be; indeed they seem to be way off the mark. Even if motivational factors, and thus insights from (social) psychology, do not automatically undermine people’s personal-level reasons and their knowledge of them because these are two distinct domains; large-scale mismatches between the two should still be unsettling, and we have reason to be suspicious of our own agential reasons all the same. The question, though, is whether they really are mismatches and whether they are really large scale. As Pelham et al. themselves point out, a longer-standing worry about experiments in social psychology is that the results usually only emerge in “artificial confines of the lab where people make unimportant decisions”. For dramatic claims about self-knowledge and free will to be genuinely unsettling and thus relevant to our self-understanding, the results should be replicable in the wild, with people who have intact brains and who make nontrivial decisions. Hence Pelham et al.’s proposal to focus on implicit egotism studies that are “robust outside the lab” and which concern “major life decisions”12 is admirable. The result is, though, that Pelham et al.’s dramatic claims hinge primarily on a handful of studies of which the effect is, as the authors acknowledge, rather modest (there was a 6.5 percent bias for people to marry others who shared their birthday numbers). Just how ‘large scale’ the effects really are is not entirely clear. More importantly, the effects don’t bring about any mismatches per se. The fact that for a (small) number of people their last names or birth dates turn out to be a factor in their decisions remains just that: a factor. Sometimes arbitrary facts about one’s last name or birth date co-determine one’s actions. But the ‘co’ is important here: nonrational factors play a role, but not the only role, and it seems in most cases not

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even a particularly dominant role. This at least helps explain why Adam Smith didn’t become a smith, Lynne Rudder Baker didn’t become a baker, and Judith Butler didn’t become a butler. Clearly also people whose occupations and last names do match don’t need to go into existential crises for also in their cases many other factors led them to pursue the careers they chose to pursue. The presence of nonrational factors explaining our actions do not as such point to there being any mismatches because the two aren’t necessarily competing explanations. Having Cook as one’s last name might indeed influence one’s decision to become a cook, but this doesn’t mean one has become a cook because one is named Cook or that being named Cook is the ‘real’ reason one became a cook, again unless one had no personal-level reasons whatsoever to become a cook. Perhaps there will be many more implicit egotism studies. It may for instance will turn out that people who live in places like Catford (London) or Dogtown (California) are more likely to get themselves a pet; that people living in Drogen (Germany) are more likely to use drugs, or that people living on Chopin lane or Mozart street are more inclined to listen to classical music. None of this would show that our choices aren’t free in the relevant sense or that we are massively self-deceived about why we do what we do. There’s more that moves one to buy a pet, do drugs, or listen to classical music than facts about where one lives. It does follow that many of our choices also have nonrational co-determinants, but that should not be news to anyone. This is not to say that agential reasons are somehow immune to alternative non-rationalizing explanations or that finding out about the motivational factors of our actions can have no impact on one’s agential reasons. The question is what is required for this to happen. Helpful in this context is John Christman’s proposed condition of ‘hypothetical resistance’: a person is not free or autonomous relative to his or her attitude or action if he or she would have resisted the development leading to that action or attitude.13 What matters is, according to Christman, “what the agent thinks about the process of coming to have the desire, and whether she resists that process when (or if) given the chance” (ibid.). If one came to realize that one’s decision to marry one’s partner was the result of coercion or manipulation, or indeed a massive brain lesion as in Phineas’s case, then that would presumably lead to resistance in the relevant sense and thus to the conclusion that one’s choice was not (sufficiently) free.14 The question then becomes: would the implicit egotism studies discussed by Pelham et al. lead to hypothetical resistance? This seems unlikely. Suppose the couples in the birthday number studies who married partners with the same birthday number were given a call and were informed about the existence of implicit egotism and were told that their preference of marrying their partner was influenced by an unconscious preference for things that resemble the self. This is unlikely to be the sort

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of ‘process’ that would lead to resistance and is not something that would undermine the agential reasons for marrying their partners or for going on in their jobs as cooks and bakers. Perhaps the news might make one uncomfortable for a moment, but the discomfort will fade so long as one also has robust personal-level reasons for marrying one’s partner or pursuing one’s career. We are far from omniscient when it comes to knowing our own mental states, and we probably credit ourselves with too much agency in making decisions on numerous occasions. But it’s a little early to conclude that because we don’t know about all of the non-rationalizing processes underlying our mental states and actions, we’re deluding ourselves into thinking we are capable of knowing our own mental states and making our own choices.

Notes 1. This example is a loose adaptation from the actual case of Phineas Gage, who underwent profound personality changes due to a brain lesion (Damasio et al. 1994). 2. Cassam (2011). 3. Elton (2000, 2). 4. Sandis (2015, 268). 5. As Ryan Cox (2018) observes, there’s also some evidence that psychologists agree that people have privileged knowledge about their reasons. Nisbett and Ross (1980), for instance, write that people are “often right in their accounts of the reasons for their behavior” and that “[a] person who answers a telephone and asserts that he did so ‘because it was ringing’ is surely right” and “[a] person who asserts that he opened the refrigerator door because he was hungry is usually right”. 6. See also Coons and Weber (2014). 7. Nudging is typically understood as changing people’s behavior by making use of people’s psychological weaknesses, such as their biases and the suboptimal decisions they make on autopilot and under time pressure, without “forbidding any options or significantly changing their economic incentives” (Thaler and Sunstein 2009, 6). Biases themselves do not, in this sense, nudge individuals at all. Rather, biases can be used to nudge individuals. When Pelham et al. talk about ‘nudging’, they thus seem to have in mind something much broader, such as being motivated to act on the basis of nonrational means. 8. Thaler and Sunstein (2009). 9. Nys and Engelen (2017, 204). 10. Raz (1986). 11. See Gorin (2014). 12. Pelham and Mauricio (2015, 718). 13. Christman (1991). 14. A lot can be said about whether this criterion is a plausible one. Our main aim here though is not so much to defend this particular criterion as to sketch a possible way in which the two explanatory domains might meet, that is, how motivational factors and evidence from empirical psychology could become relevant for, or potentially undermine, agential reasons.

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References Cassam, Quassim. 2011. “Knowing What You Believe.” Proceedings of the Aristotelian Society 111: 1–23. Christman, John. 1991. “Autonomy and Personal History.” Canadian Journal of Philosophy 21: 1–24. Coons, Christian, and Michael Weber, eds. 2014. Manipulation: Theory and Practice. Oxford: Oxford University Press. Damasio, Hanna, Thomas Grabowski, Randall Frank, Albert M. Galaburda, and Antonio R. Damasio. 1994. “The Return of Phineas Gage: Clues about the Brain from the Skull of a Famous Patient.” Science 264: 1102–1105. Elton, Matthew. 2000. “The Personal/Sub-Personal Distinction: An Introduction.” Philosophical Explorations 3: 2–5. Gorin, Moti. 2014. “Do Manipulators Always Threaten Rationality?” American Philosophical Quarterly 51 (1): 51–61. Nisbett, Richard E., and Timothy DeCamp Wilson. 1977. “Telling More than We Can Know: Verbal Reports on Mental Processes.” Psychological Review 84 (3). Nys, Thomas, and Bart Engelen. 2017. “Judging Nudging: Answering the Manipulation Objection.” Political Studies 65: 199–214. Pelham, Brett, and Carvallo Mauricio. 2015. “When Tex and Tess Carpenter Build Houses in Texas: Moderators of Implicit Egotism.” Self and Identity 14: 692–723. Raz, Joseph. 1986. The Morality of Freedom. Oxford: Oxford University Press. Sandis, Constantine. 2015. “Verbal Reports and ‘Real’ Reasons: Confabulation and Conflation.” Ethical Theory and Moral Practice 18: 267–280. Thaler, Richard H., and Cass R. Sunstein. 2009. Nudge: Improving Decisions about Health, Wealth, and Happiness. London: Penguin.

11 Common Sense Morality and Its Evolutionary Underpinnings Michael Ruse

1 Common Sense and the Challenge of Morality Common sense tells me that two plus two equals four. Common sense tells me that it is not fake news that Donald Trump is president of the United States of America. Common sense tells me that simplistic solutions don’t work, whether it be God wiping out everyone but Noah or Bush and Blair invading Iraq. Common sense tells me that if I drink two bottles of wine this evening, I will probably wake with a headache tomorrow. Common sense tells me that it would be not just unwise but wrong to sleep with one of my students in exchange for a good grade. Let me pick up on the last point, about right and wrong, about what we call ‘morality’ and what philosophers discuss under the heading of ‘ethics’. Let’s not mess around but choose an unquestionable example. Rape is wrong. That’s just common sense. You may be able to get away with it, as do too many star athletes on American college campuses. You may even be encouraged in it, as were Russian soldiers marching into East Prussia toward the end of the Second World War. There are perhaps psychological or biological reasons for it. No one is much surprised that it goes on in prisons. But it’s still wrong and basically no defense is needed to justify its wrongness. The sky is blue. Philosophy is boring. Rape is wrong. It’s common sense! But is rape really wrong? Or, at least, is it wrong in the sense that we all take it to be? This is the challenge of Darwinian evolutionary biology for it suggests—doesn’t just suggest but positively insists—that moral sentiments are merely adaptations like the hand and the eye put in place to make us efficient reproducers. They have no ontology or justification over and above that. Those of us with moral feelings—including the feeling that rape is wrong—get on better with our fellows and thus do better in the struggle for survival and reproduction than those (psychopaths) without moral feelings. If, say, we had evolved to think rape is wrong except where there is a nubile young female and you can get away with it and everyone will think not only that you did not do wrong but that you did your duty to God and to King and country, then so be it. Rape is wrong when it comes to grandmothers. Rape is very much OK when

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it comes to undergraduates. And if you don’t agree, then turn to Kant’s Critique of Practical Reason, Mark Two, for a very lengthy discussion of why you are wrong. There must be more to things than this. By and large, your average evolutionist is as sexually conventional as your average philosopher. We must, and can, show that Darwinism’s undercutting of the foundations of common sense morality does not plunge us into an unrestrained nightmare of sexual frenzy—or any kind of moral frenzy for that matter—but why, nevertheless, has the common sense view of morality such a hold on us all, philosophers and biologists. Could it be that natural selection is clever enough to undermine common sense morality but also to make it very implausible psychologically that natural selection is clever enough to undermine common sense morality? These are the questions I ask in this essay.

2 Darwin’s Theory of Evolution Let’s start at the beginning with the science. I am going to take for granted what is overwhelmingly the dominant paradigm in the circles of today’s professional biologists.1 I accept without argument the modern version of Charles Darwin’s theory of evolution. Thanks to ongoing population pressures and limited resources, there is a struggle for existence—more pertinently, a struggle for reproduction. This leads to a kind of winnowing of numbers, what Darwin called ‘natural selection’. Combined with constant new variations—Darwin had little idea about these, but today we know a lot about genetics—there is an evolution of new forms. What is crucial in the Darwinian world is that the features of organisms are as if designed. The eye, the ear, the penis, the vagina, the wing, the fin, the tooth, the claw, the root, the branch, the leaf—all of these adaptations work to the benefit of their possessors. Why? How have all those exquisite adaptations of one part of the organisation to another part, and to the conditions of life, and of one distinct organic being to another being, been perfected? We see these beautiful co-adaptations most plainly in the woodpecker and missletoe; and only a little less plainly in the humblest parasite which clings to the hairs of a quadruped or feathers of a bird; in the structure of the beetle which dives through the water; in the plumed seed which is wafted by the gentlest breeze; in short, we see beautiful adaptations everywhere and in every part of the organic world.2 The answer is natural selection brought on by the struggle for existence. Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an

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Note that Darwin always intended his theory to cover behavior as well as physical shape, that is, morphology. A small creature like a rabbit vanishing down a hole is showing adaptation as much as a white polar bear concealed in the Arctic. In fact, in the Origin of Species Darwin had detailed discussions of social behavior, particularly in the Hymenoptera—the ants, the bees, and the wasps. Then in his follow-up book on our species, The Descent of Man,4 there is more detailed discussion of human behavior, particularly human social behavior. It is true that in the first hundred years after the Origin, behavior took a backseat in evolutionary studies. In part, this is because it is so difficult to work with. It is far easier to study the markings on a butterfly’s wings than to record its mating behavior. Especially when you know that if you try to recreate natural conditions inside cages, or whatever, you often alter the behavior drastically. The numbers of hybrids you get only in zoos and the infertility of many species in captivity both speak strongly to this. In part, the neglect of behavior was a function of the rise of the social sciences and their territorial demands that the study of behavior be exclusively in their domain—with expected consequences. You have seen one white rat; you have seen them all. What need is there of butterfly mating studies? Things started to change dramatically around 1960. Evolutionists created powerful new models—kin selection, reciprocal altruism, evolutionary stable strategies—to explain social behavior.5 At the same time, there were extensive studies of social behavior in the wild—chimpanzees, lions, red deer, dung beetles—to name some subjects.6 And naturally, it was not long before attention turned to humans. With this came the call to apply Darwinian evolutionary theory to our behavior and thinking. In his magisterial Sociobiology: The New Synthesis,7 the leading Darwinian evolutionary biologist Edward O. Wilson firmly put ethics at the front of his endeavors. If the title of the first chapter, “The Morality of the Gene”, does not flag you, then the opening words surely will: Camus said that the only serious philosophical question is suicide. That is wrong even in the strict sense intended. The biologist, who is concerned with questions of physiology and evolutionary history, realizes that self-knowledge is constrained and shaped by the

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emotional control centers in the hypothalamus and limbic systems of the brain. These centers flood our consciousness with all the emotions—hate, love, guilt, fear, and others—that are consulted by ethical philosophers who wish to intuit the standards of good and evil. What, we are then compelled to ask, made the hypothalamus and limbic system? They evolved by natural selection. That simple biological statement must be pursued to explain ethics and ethical philosophers, if not epistemology and epistemologists, at all depths.8

3 Thinking About Ethics Obviously, we are now pushing our science, threatening to take over the lands of the philosophers. Leaving the epistemologists—students of the theory of knowledge—to their own fates, let us think about our area of inquiry, ethics.9 You will hardly be surprised to learn that professional philosophers reacted to Wilson as though they were virgin aunts to whom an indecent proposition had been made. They immediately argued that the fact that evolution may have had something to do with the causes of morality has nothing to do with the justification of morality. The fact that we may have evolved to think that we should be good (and, given Hitler, this is a dubious proposition) has nothing to do with whether we should be good (like Mother Teresa). However, those were the philosophers. More generally, despite kneejerk opposition from the Marxists,10 Wilson’s thinking was welcomed. This was hardly a great surprise because he wrote in a tradition that goes back to the time of Darwin—a tradition that can certainly been seen in certain forms in the Descent of Man. Even more generally, despite even more knee-jerk opposition from the Marxists,11 work—especially by so-called evolutionary psychologists—on human social behavior including ethical behavior has exploded, yielding many interesting and often unanticipated insights. Finally, even some philosophers are starting to take seriously the idea that Darwinian evolutionary biology might have something interesting to say about evolution and ethics. After some— let us be ecumenical—knee-jerk opposition by an earlier self,12 I have long been passionate about this, thinking that although he may be quite wrong on details and approaches, Wilson is absolutely right in principle and his science (and that of others) is a key part of the story.13 So, let us plunge in. Actually, before we get into the water, let us put on our bathing suits— perhaps goggles is a better metaphor. If we are going to look at evolutionary biology with an eye to ethics, what kind of filter or lens are we going to use to focus our attention. Traditionally—what you teach students in introductory philosophy classes—ethical questions are divided into two kinds. There are those that deal with what you ought to do. This area is

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known as ‘substantive’ or ‘normative’ ethics. A good example yielding obvious norms or demands is Christianity: Mother Teresa behavior. 38 Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth: 39 But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also. 40 And if any man will sue thee at the law, and take away thy coat, let him have thy cloak also. 41 And whosoever shall compel thee to go a mile, go with him twain. 42 Give to him that asketh thee, and from him that would borrow of thee turn not thou away. 43 Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. 44 But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you.14 Then there are questions to do with foundations. This is known as ‘metaethics’. In the case of Christianity, notwithstanding objections that were raised years before in Plato’s Euthyphro, many subscribe to what is known as the divine command theory. Doing what is right is doing what God tells you to do—beginning and end of discussion. After he has laid down the law, as it were, Jesus continues, “That ye may be the children of your Father which is in heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust”. He ends, “Be ye therefore perfect, even as your Father which is in heaven is perfect”.15 There is no argument or justification. Do what you are told. At a personal level I can attest to the power of this suggestion. In the years after the Second World War, I was brought up as a Quaker and hence a pacifist. After the war against Hitler, it was not easy arguing that violence is always wrong. But the answer at the end of the discussions for us Junior Young Friends was always this: that’s what God wants—end of argument. My excursion into Christian moral theory has a point. If we are going to look at Darwinism and ethics, then we need some answers at the substantive level and also at the metaethical level. Any approach that does not speak to these is incomplete at best. Thus framed, think back now to the immediate reaction of the philosophers toward Wilson. He has to be wrong because, to get ethics from evolution, we would have to get moral commands from matters of fact. This is impossible. The sainted David Hume told us so. In every system of morality, which I have hitherto met with, I have always remark’d, that the author proceeds for some time in the

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ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surpriz’d to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is, however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, ‘tis necessary that it shou’d be observ’d and explain’d; and at the same time that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it.16 Incorporated into what the early 20th-century philosopher G. E. Moore17 was to call the “naturalistic fallacy”, this seems defnitive. Whatever evolution can tell us about morality, conceptually it cannot speak to the issues of ethics or the philosophical issues of ethics. Or is it such a conversation stopper? Two counter options seem open. On the one hand, one might simply refuse to accept the is/ought distinction, that is, the naturalistic fallacy. It doesn’t apply ever or at least it doesn’t apply in this case. On the other hand, one might accept the is/ought distinction but then try to get around it. The distinction doesn’t block a fruitful interaction between evolution and ethics. Both approaches have found followers. Let us take them in turn, keeping to the fore the substantive ethics/metaethics questions.

4 Social Darwinism Traditional evolutionary ethics, which in the end does not accept the is/ ought distinction, is often known as Social Darwinism. This is something of an unfortunate misnomer because, on the one hand, it was not a term in general use at the time—the first 70 or 80 years after the Origin in 1859—when supposedly it flourished most vigorously.18 On the other hand, at the level of substantive ethics, it has an unfortunate aura of being always harsh even unto violence. Darwin’s contemporary, Herbert Spencer, on the subject of the poor, is thought a prime example of such thinking. We must call those spurious philanthropists, who, to prevent present misery, would entail greater misery upon future generations. All defenders of a Poor Law must, however, be classed among such. That rigorous necessity which, when allowed to act on them, becomes so sharp a spur to the lazy and so strong a bridle to the random, these pauper’s friends would repeal, because of the wailing it here and there produces. Blind to the fact that under the natural order of things, society is constantly excreting its unhealthy, imbecile, slow, vacillating, faithless members, these unthinking, though well-meaning, men

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As it happens, Spencer wrote this before he became an evolutionist, and his target was the upper classes, whom he thought—with good reason—used things like the Poor Law to keep people at a barely livable level and restricted them from getting out and competing and bettering themselves.20 (Sound familiar? Margaret Thatcher came from the same nonconformist, lower-middle-class, British Midlands slice of society as did Spencer.) But there were certainly those, later in the century and into the next, who were Darwinians and who did argue this sort of way in the name of evolution. Leading barons of industry like Andrew Carnegie, the great steel magnate, and John D. Rockefeller, of Standard Oil fame, were enthusiasts—“The law of competition may be sometimes hard for the individual, [but] it is best for the race, because it insures the survival of the fittest in every department”21—as were some of the professors and others who wrote on these sorts of things. A drunkard in the gutter is just where he ought to be . . . The law of survival of the fittest was not made by man, and it cannot be abrogated by man. We can only, by interfering with it, produce the survival of the unfittest.22 Or, think of some of the fiction. His teeth closed on Spitz’s left fore leg. There was a crunch of breaking bone, and the white dog faced him on three legs. Thrice he tried to knock him over, then repeated the trick and broke the right fore leg. Despite the pain and helplessness, Spitz struggled madly to keep up. He saw the silent circle, with gleaming eyes, lolling tongues, and silvery breaths drifting upward, closing in upon him as he had seen similar circles close in upon beaten antagonists in the past. Only this time he was the one who was beaten. There was no hope for him. Buck was inexorable. Mercy was a thing reserved for gentler climes.23 This is from The Call of the Wild, by Darwin-enthusiast Jack London. Again, though, take caution. Spencer, as soon as he became an evolutionist, also became enthused by organic holism, seeing society as a whole, as a living thing. Yes, there is struggle within the society, however not to break it apart but to improve it.

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The parts of an animal form a concrete whole, but the parts of society form a whole which is discrete. While the living units composing the one are bound together in close contact, the living unit composing the other are free, are not in contact, and are more or less widely dispersed. . . . Though coherence among its parts is a prerequisite to that cooperation by which the life of an individual organism is carried on, and though the members of a social organism, not forming a concrete whole, cannot maintain cooperation by means of physical influences directly propagated from part to part, yet they can and do maintain cooperation by another agency. Not in contact, they nevertheless affect one another through intervening spaces, both by emotional language and by the language, oral and written of the intellect. . . . That is to say, the internuncial function, not achievable by stimuli physically transferred, is nevertheless achieved by language.24 In addition—no doubt in part refecting Quaker elements in his family— Spencer was always against militancy, thinking that (real) arms races are a waste of time and money.25 Especially deplorable was the arms race at the end of the 19th century between the British and German navies. He was also in favor of free trade, thinking that among other things this would encourage relationships among nations, if only from self-interest. In the same vein, consider for a moment the nature of Andrew Carnegie’s great philanthropy. It was to found and support public libraries.26 These would be places where the poor but talented could go and improve themselves—all very Darwinian, but not very Social Darwinian, at least as the term is generally understood. The same is true of Jack London. As soon as Buck has defeated Spitz, he turns into a high school principal! The other dogs are whipped into line; slackers and the inadequate are chastised and made to improve. Pike, who pulled at Buck’s heels, and who never put an ounce more of his weight against the breast-band than he was compelled to do, was swiftly and repeatedly shaken for loafing; and ere the first day was done he was pulling more than ever before in his life. The first night in camp, Joe, the sour one, was punished roundly—a thing that Spitz had never succeeded in doing. Buck simply smothered him by virtue of superior weight, and cut him up till he ceased snapping and began to whine for mercy.27 At the substantive level, we continue to find the same ambivalence or more about the harshness of the Darwinian principle. Writer after writer pulls back from a scenario of constant naked mudwrestling, a Hobbesian nightmare—“the life of man, solitary, poor, nasty, brutish and short”— made actual. Julian Huxley—the grandson of Darwin’s great supporter and self-styled ‘bulldog’ Thomas Henry Huxley—was ever an enthusiast

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for this kind of evolutionary approach to ethics. In line with many in the 1930s, he saw science as the key to avoiding disasters like the Great Depression, let alone horrendous worldwide warfare. In a book that he wrote in the interwar years, If I Were Dictator,28 he stressed the need for science in the running of an efficient state and that such science would need to be of the social variety as well as physico-chemical and biological. During the Second World War, he wrote a highly laudatory essay on the Tennessee Valley Authority, that marvel of the Rooseveltian New Deal, whereby the federal government built and ran a massive system of river damming and irrigation in what had hitherto been one of the more desolate parts of the United States.29 Then, after the war it was Huxley who insisted on the science being added to UNESCO (United Nations Educational, Scientific and Cultural Organization), and he wrote a vigorous polemic arguing that the organization had to be run on evolutionary lines—lines demanding lots of science.30 So vigorous was his polemic indeed that he upset his masters and was refused a full four-year term as director general. Today we have none other than Edward O. Wilson singing this song—or hymn. He sees all of life as an interconnected whole. This is expressed through his ‘biophilia’ hypothesis. “To explore and affiliate with life is a deep and complicated process in mental development. To an extent still undervalued in philosophy and religion, our existence depends on this propensity, our spirit is woven from it hope rises on its currents”.31 Individual organisms, individual species, are part of a larger network, and no one or group can take itself apart in isolation. Morally, therefore, our obligation is to preserve (human) life. It is in terms of human welfare that Wilson sees the significance of sustainability and of the cherishing of the environment and the preservation of species. If we destroy the rainforests of South America in pursuit of short-term ends like cattle rearing, we stand in danger of destroying many plants that could in the future prove to have invaluable medicinal properties. We must therefore tackle the paradox of “the two themes that form the fundamental basis of ethics, the expanding-circle theme that gives rights to all species, versus the anthropocentric theme that measures all good in the coin of human welfare”. This will not be easy, but it will not be impossible. The two are resolved in part by noting that for human survival and mental health and fulfillment we need the natural setting in which the human mind almost certainly evolved and in which culture has developed over these millions of years of evolution. Perhaps both of those arguments can be joined to create the prudence concerning the environment and our own populations that is so desperately needed.32

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5 Adolf Hitler What about the biggest blot on the Darwinian story? What about German militarism leading to Hitler? There is grist for the mill.33 Above all, coming before the outbreak of the Great War, there was the German general, a member of the Grand General Staff, Friedrich von Bernhardi. His Germany and the Next War laid things out starkly. “War is a biological necessity of the first importance, a regulative element in the life of mankind which cannot be dispensed with, since without it an unhealthy development will follow, which excludes every advancement of the race, and therefore all real civilization. ‘War is the father of all thing’”.34 He was happy to use the authority of Darwin—“The struggle for existence is, in the life of Nature, the basis of all healthy development”.35 War is an inevitability. There is the organic nature of the state and how it leads to struggle with others. Every nation possesses an individuality of its own, and all progress among nations is based on their competition among themselves. As the competition among nations leads occasionally and unavoidably to differences among them, all real progress is founded upon the struggle for existence and the struggle for power prevailing among them.36 This is a good thing. “That struggle eliminates the weak and used-up nations, and allows strong nations possessed of a sturdy civilisation to maintain themselves and to obtain a position of predominant power until they too have fulfilled their civilising task and have to go down before young and rising nations”.37 Then for an encore after the Great War, there was Adolf Hitler. All great cultures of the past perished only because the originally creative race died out from blood poisoning. The ultimate cause of such a decline was their forgetting that all culture depends on men and not conversely; hence that to preserve a certain culture the man who creates it must be preserved. This preservation is bound up with the rigid law of necessity and the right to victory of the best and stronger in this world. Those who want to live, let them fight, and those who do not want to fight in this world of eternal struggle do not deserve to live.38 There must be something in all of this. After all, if you eliminate Martin Luther and his vile anti-Semitism for the rise of Hitler and if you excuse Darwin and Social Darwinism for the rise of Hitler and if you . . . Well, you know the tune. Before long, Hitler seems to have risen for no

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reason at all. And there is grist for the mill. Listen to Darwin, toward the end of his life, writing to a correspondent. I could show fight on natural selection having done and doing more for the progress of civilisation than you seem inclined to admit. Remember what risks the nations of Europe ran, not so many centuries ago of being overwhelmed by the Turks, and how ridiculous such an idea now is. The more civilised so-called Caucasian races have beaten the Turkish hollow in the struggle for existence. Looking to the world at no very distant date, what an endless number of the lower races will have been eliminated by the higher civilised races throughout the world.39 This said, there are complicating—mitigating—factors. In the case of von Bernhardi, often his sources are far more Germanic than British. “To supplant or to be supplanted is the essence of life”, says Goethe, “and the strong life gains the upper hand. The law of the stronger holds good everywhere”. Much of his thinking is lifted wholesale from Hegel. War, in some sense, is not so much a good thing or a necessary thing but a morally healthy thing. I have remarked elsewhere, “the ethical health of peoples is preserved in their indifference to the stabilisation of finite institutions; just as the blowing of the winds preserves the sea from the foulness which would be the result of a prolonged calm, so also corruption in nations would be the product of prolonged, let alone “perpetual”, peace.”40 The comment about perpetual peace is a nasty crack at Hegel’s philosophical predecessor Immanuel Kant, who had written an influential essay on the possibility of perpetual peace. In the case of Hitler, as the quote given clearly indicates, with all of that stuff about blood poisoning, the real target is the Jew, thinking totally anathema to Charles Darwin, who spent his whole life protesting against slavery.

6 Metaethical Justification Darwin and his fellows cannot be let entirely off the hook. However, at the normative or substantive level, traditional evolutionary ethics— Social Darwinism—is more complex and varied, and often far from as vile, as often supposed. What about the metaethical level? What about foundations? The answer is simple. Enthusiasts for this approach simply don’t accept the is/ought distinction. They think that the course of evolutionary life is progress, upward, from the “monad to the man,” and that value thereby incurs and our moral obligations follow.41 It is our duty to cherish and help the evolutionary process, making sure that it

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does not fall back but advances where possible. Herbert Spencer is quite explicit. Organic evolution as being but one facet of the overall upward progress that characterizes the whole world process: from the undifferentiated to the differentiated or, in his words, from the homogeneous to the heterogeneous: [n]ow we propose in the first place to show, that this law of organic progress is the law of all progress. Whether it be in the development of the Earth, in the development of Life upon its surface, in the development of Society, of Government, of Manufactures, of Commerce, of Language, Literature, Science, Art, this same evolution of the simple into the complex, through successive differentiations, hold throughout. From the earliest traceable cosmical changes down to the latest results of civilization, we shall find that the transformation of the homogeneous into the heterogeneous, is that in which Progress essentially consists.42 Nothing escapes this law. Humans are more complex or heterogeneous than other animals; Europeans are more complex or heterogeneous than savages; and (hardly a surprise) the English language is more complex or heterogeneous than the languages of other speakers. From this, the notion of moral obligation follows at once. “Ethics has for its subjectmatter, that form which universal conduct assumes during the last stages of its evolution”.43 He continues: “And there has followed the corollary that conduct gains ethical sanction in proportion as the activities, becoming less and less militant and more and more industrial, are such as do not necessitate mutual injury or hindrance, but consist with, and are furthered by, co-operation and mutual aid”. Julian Huxley thought in a similar way. Huxley was a fanatic about evolutionary progress, thinking that it justifies moral behavior. Our ethical duty is to work with and within this process to see that it is realized as fully as possible. The teleologically-minded would say that this trend [progress] embodies evolution’s purpose. I do not feel that we should use the word purpose save where we know that a conscious aim is involved; but we can say that this is the most desirable direction of evolution, and accordingly that our ethical standards must fit into its dynamic framework. In other words, it is ethically right to aim at whatever will promote the increasingly full realization of increasingly higher values.44 Similar sentiments come out in his polemic for UNESCO: [f]rom the evolutionary point of view, the destiny of man may be summed up very simply: it is to realize the maximum progress in the

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The same tune comes from Wilson: the overall average across the history of life has moved from the simple and few to the more complex and numerous. During the past billion years, animals as a whole evolved upward in body size, feeding and defensive techniques, brain and behavioral complexity, social organization, and precision of environmental control—in each case farther from the nonliving state than their simpler antecedents did.46 He continues: “Progress, then, is a property of the evolution of life as a whole by almost any conceivable intuitive standard, including the acquisition of goals and intentions in the behavior of animals” and so on and so forth. Looking at this thinking critically, looking specifically at this metaethical justification, there are two lines of response for the philosophical traditionalist. One is to defend yet again some version of Hume’s law. This is the route taken by G. E. Moore in his Principia Ethica,47 where Spencer is held up as a particularly egregious sinner with respect to the naturalistic fallacy. I doubt however that this would greatly trouble Spencer and his supporters. I know, from cowriting a paper with Wilson, that it bothers him not at all to the extent that he cannot see the point of the criticism.48 Harking back to beginning of the 19th century and to German Romanticism—Spencer was greatly influenced (through the plagiaristic writing of the poet Samuel Coleridge) by the thinking of Friedrich Schelling—the world is seen in Platonic terms.49 The teenage Schelling wrote an enthusiastic 60-page essay on the Timaeus—the dialogue in which Plato claims that the world has a soul or life in some form, a version of the Form of the Good. Cartesian res extensa—dead matter—is simply not an option. Spencer and everyone down to and including Wilson would say that it is self-evident—common sense!—that humans are superior to warthogs and they in turn to fish and so forth back to the first blob. Of course, there are setbacks, but overall it is onward and upward.

7 Progress? I am not quite sure how you solve this disagreement philosophically. I long thought that the Humeans were right, almost a priori—common sense to me! More and more I am not sure. Things like quantum entanglement, where information can be transmitted instantly across the universe, suggest that it is a much stranger world in which we live than most

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of us think.50 In any case, perhaps there is something to be said about the physical world and value. A year or two back, I spent four months at a research institute in Stellenbosch, the grape-growing area of South Africa north of Cape Town. It is among the most beautiful places in the world. If a mining company suggested taking off the top of one of the neighboring mountains for minerals or whatever, I would be the first to cry “rape”. And if that is not to make the world a living being, I do not know what is. And honestly, I do think that Grace Kelly was superior to warthogs, which dates me, I guess! Moving from philosophy to science, a more promising attack is perhaps going after the notion of evolutionary progress. Thomas Henry Huxley, of all people, was very critical of many such ideas—he had Spencer in his sights. It is often the case that those attributes that lead to success in the struggle are precisely those that we do not think well of. “Man, the animal, in fact, has worked his way to the headship of the sentient world, and has become the superb animal which he is, in virtue of his success in the struggle for existence”.51 He continues: [f]or his successful progress, throughout the savage state, man has been largely indebted to those qualities which he shares with the ape and the tiger; his exceptional physical organization; his cunning, his sociability, his curiosity, and his imitativeness; his ruthless and ferocious destructiveness when his anger is roused by opposition. But, in proportion as men have passed from anarchy to social organization, and in proportion as civilization has grown in worth, these deeply ingrained serviceable qualities have become defects. After the manner of successful persons, civilized man would gladly kick down the ladder by which he has climbed. He would be only too pleased to see “the ape and tiger die”. In an updated version of this kind of argument, the paleontologist Jack Sepkoski has commented colorfully. “I see intelligence as just one of a variety of adaptations among tetrapods for survival. Running fast in a herd while being as dumb as shit, I think, is a very good adaptation for survival”.52 So much for university education—cow power rules supreme!

8 Darwinian Normative Ethics Leave things here, and turn to an alternative approach, one that continues to take the Humean is/ought distinction seriously.53 The first move is the science, drawing heavily on a Darwinian approach not just to behavior but to moral thinking. Darwin himself set the pattern. It must not be forgotten that although a high standard of morality gives but a slight or no advantage to each individual man and his

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Darwin sees what this means: There can be no doubt that a tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to give aid to each other and to sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection. And so, we get the consequence. “At all times throughout the world tribes have supplanted other tribes; and as morality is one element in their success, the standard of morality and the number of well-endowed men will thus everywhere tend to rise and increase”. In other words, morality is a good adaptive strategy for survival. Essentially, right down to and including both human sociobiology and evolutionary psychology, this is the ongoing message of the Darwinian.55 Morality is a good adaptation. Working together and sharing is the wise way to go in this world, and through our reason and loss of fighting adaptations—like fangs and claws—we show that in our case it has been very successful. If then this is the science, what of the moral philosophy? At the substantive level, things seem not just possible but positively beckoning. One of the most influential systems in the second half of the past century was that of John Rawls56 and his ‘justice as fairness’. You should put yourself in the ‘original position’, not knowing where you will be in society—white, male, strong, and healthy or colored, female, weak, and sickly. If you knew you were going to be the former, you would want a society that favored the former—and if the latter, the latter. But if you don’t know what you will be, then you want a society that maximizes the good and help for both. It doesn’t mean that everyone will be equal. It may be in all interests to pay doctors more to get the best people in as doctors. But it will be fair. Rawls particularly pointed out that evolution solves the big lacuna in any social contract approach to morality—which is obviously his approach—namely, how did the contract get put in place in the first place? It was not a group of old men over a few beers but the genes. “The theory of evolution would suggest it is the outcome of natural selection; the capacity for a sense of justice and the moral feelings is an adaptation of mankind to its place in nature”. Rawls continued, It seems clear that for members of a species which lives in stable social groups, the ability to comply with fair cooperative arrangements

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and to develop the sentiments necessary to support them is highly advantageous, especially when individuals have a long life and are dependent on one another. These conditions guarantee innumerable occasions when mutual justice consistently adhered to is beneficial to all parties.57 Rawls pointed out that this kind of situation would be precisely what one would expect were a biological mechanism like reciprocal altruism at play. I suspect there will be some evolutionary twists to this picture but generally those that most of us would think right and proper. If I learned for instance that you give 90 percent of your income to the poor, and your own children have to eat at soup kitchens and shop at Goodwill, I will not be overly impressed. Charles Dickens is good on this in Bleak House.58 He is scathing about Mrs. Jellyby, who spends all of her time worrying about the deserving poor in Africa. “We hope by this time next year to have from a hundred and fifty to two hundred healthy families cultivating coffee and educating the natives of Borrioboola-Gha, on the left bank of the Niger”. There is no concern for the needs of her own family or for the poor in her own society, notably Jo, the crossing sweeper. Darwinians would be on the side of Dickens, as incidentally was David Hume. A man naturally loves his children better than his nephews, his nephews better than his cousins, his cousins better than strangers, where every thing else is equal. Hence arise our common measures of duty, in preferring the one to the other. Our sense of duty always follows the common and natural course of our passions.59

9 Darwinian Metaethics What of foundations? What of metaethics? What particularly if you continue to hold sacred the Humean is/ought distinction? The answer is simple. Evolution does not justify normative ethics because nothing justifies normative ethics. To quote a paper I co-wrote with Wilson, the only quote that I will ever have in the stakes to get into the Oxford book of Quotations: “ethics is an illusion put in place by our genes to keep us good cooperators”.60 (I am not sure, candidly, that Wilson ever believed this, but that’s no matter here.) Normative ethics exists; of course it does. The white rabbit running up the wall of the alcoholic exists in that sense. But it doesn’t have any foundation in either this world or the next. It has the stature of the rules of baseball—a human creation, if involuntary, through natural selection working on the genes. I realize that you might well object that being the product of natural selection does not in itself make normative morality subjective, let alone an illusion. After all,

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we sense the oncoming train through evolved organs of perception, and the train is objectively real. In a moment, I will speak to this objection, arguing that in the case of morality, there might be functioning alternatives. In the case of the train, you might have different senses to locate it—echolocation like bats—but in the end, it is the same, real train you must sense and avoid. Why morality? Why not have us all acting from self-interest? Kant, of all people, spoke to this. If the aim of morality is getting along with each other, Kant allows that we might have no morality at all and work through self-interest. [A man] who is in prosperity, while he sees that others have to contend with great wretchedness and that he could help them, thinks: “What concern is it of mine? Let everyone be as happy as Heaven pleases, or as he can make himself; I will take nothing from him nor even envy him, only I do not wish to contribute anything to his welfare or to his assistance in distress”! Now no doubt if such a mode of thinking were a universal law, the human race might very well subsist and doubtless even better than in a state in which everyone talks of sympathy and good-will, or even takes care occasionally to put it into practice, but, on the other side, also cheats when he can, betrays the rights of men, or otherwise violates them.61 Kant realized however that human nature as it is could not handle this. But although it is possible that a universal law of nature might exist in accordance with that maxim, it is impossible to will that such a principle should have the universal validity of a law of nature. For a will which resolved this would contradict itself, inasmuch as many cases might occur in which one would have need of the love and sympathy of others, and in which, by such a law of nature, sprung from his own will, he would deprive himself of all hope of the aid he desires. Of course, an evolutionist could say that we might have evolved so we don’t need sympathy and love. But Kant does point to the truth that often it might be of self-interest to help others as a kind of insurance for when we need help. More, we can point out that making rational decisions can take time, and often time is money—less metaphorically, a resource that often you don’t have in real life. A lion is on the prowl. Should I warn my fellow villagers? By the time I have made a decision, we are all eaten. Sometimes morality backfres. Being a good Samaritan does not pay off. But overall, morality is a very effective, quick and dirty solution.

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Simply saying that morality has no foundation is not proving that morality in the world of evolution has no foundation. Darwin put his finger on this one, filling the gap. He showed that because of the nondirective nature of evolution—he believed in overall progress but allowed that there could be many variants and sidetracks along the way—we could have an entirely different form of moral code (normative ethics). It may be well first to premise that I do not wish to maintain that any strictly social animal, if its intellectual faculties were to become as active and as highly developed as in man, would acquire exactly the same moral sense as ours. In the same manner as various animals have some sense of beauty, though they admire widely-different objects, so they might have a sense of right and wrong, though led by it to follow widely different lines of conduct. If, for instance, to take an extreme case, men were reared under precisely the same conditions as hive-bees, there can hardly be a doubt that our unmarried females would, like the worker-bees, think it a sacred duty to kill their brothers, and mothers would strive to kill their fertile daughters; and no one would think of interfering.  .  .  . The one course ought to have been followed, and the other ought not; the one would have been right and the other wrong.62 Either there is no objective morality, or if there is we could as well have evolved in other directions and be entirely ignorant of it. And that does seem to be a reductio ad absurdum of what we usually mean by objective morality. Because it is so crucial, expand on this for a moment. The argument is taking up the point raised earlier about the implications of an evolved morality for its status as an objective morality. I take it that an objective morality is going to be binding on rational humans—no doubt there will be psychopaths—just as mathematics is binding on rational humans. Two plus two equals four, and it is really not up to you to decide if it is true. You might ignore it—gamblers often do—but still in your heart of hearts you know it is true. Darwin’s example shows that we might have evolved thinking that when winter comes, females feel an obligation to kick their brothers out into the cold, but as we know, really they should do no such thing. They should love even their brothers! If you object that the brother-excluding females are different from us, that is true, but still you must allow the possibility of the nondirectional evolutionary process might have yielded only hymenoptera-like humans, in which case there is no alternative to brother exclusion. Brother-loving humans might never evolve, so humans—or, if you like, humanoids—would never know true morality. If you object that God would be fine with this—now morality (by natural law theory) is directed to brother exclusion—you are already

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introducing a subjectivity I doubt many objectivists—Platonists or Christians (or both)—would much favor. In any case, suppose we had evolved more or less like us, but for accidents of culture we subscribe to what I have elsewhere called the John Foster Dulles system of morality, so named after Eisenhower’s secretary of state during the Cold War.63 He hated the Russians with a moral fervor. He also knew that the Russians felt the same way about him. So, pragmatically, they got on. We, poor deluded fools, think we should love our neighbor, whereas what objective morality really demands is that we hate our neighbor. That, in my book, crosses over into the realm of the reductio ad absurdum. An objective morality, of which we can blissfully live our lives unaware, is not much of an objective morality. We cannot live our lives blissfully unaware of approaching trains. Epistemologically, there can be objectivity. The final question: if morality is subjective, with no objective foundation, why don’t we ignore it? I have told you the truth; now go out and rape and pillage. It’s the Raskolnikov problem from Crime and Punishment. The poor student tries to do this, but in the end his or her conscience makes him or her confess. Even if morality is subjective, it is part of its evolved nature to make us think that it is objective. If we did not thus objectify, it would soon break down under the pressure of cheating.64 In other words, the reason why you find this argument difficult to accept is not because it is a bad argument but because your biology is working flat out to make you think it untrue! Rape is wrong means it really is truly wrong to rape. It is not a matter of not liking rape. It is wrong.

10 Conclusion These are my thoughts on morality. Without being prissy, I am really quite conservative on these things. I think we have obligations to our families and our societies. I think that as a teacher for more than 50 years, I have done something of great moral worth. I do not lie awake at night thinking it is all ephemeral, nothing more than genes in motion. I do think thoughts about foundations—Plato’s forms, God’s will, nonnatural properties (Moore, although he was essentially Platonic)—are mistaken or illusions but only in one sense. It is not an illusion in baseball that if three people are out, that is the end of that team’s time at bat in that innings. I don’t think that this is something handed down to Moses by God on Mount Sinai—the late Stephen Jay Gould, brilliant paleontologist, gifted popular-science writer, and baseball fanatic, would probably disagree on this! Moreover, if you do insist that the Christian God exists, then I think that everything I have said should be hugely welcome, especially if you are in the Thomistic tradition of natural law.65 It is natural to be moral, and that is precisely what I am claiming. I am a totally common sense moralist. Rape is wrong, and you should not buy your way into the kingdom of heaven through using your children to

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that end. Given his behavior toward Isaac—let me show you, God, what a good servant I am—Abraham is no hero of mine. I am not too keen on his behavior toward Hagar and Ishmael either. For me, this second approach toward evolution and ethics that I have outlined extends and makes comprehensible my attitude. It does not in any sense challenge it. It confirms it. That is absolutely the best way to bring science to bear on the world of common sense.

Notes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.

See Ruse (2006, 2018a). Darwin (1859, 60–61). Darwin (1859, 80–81). Darwin (1871). See Hamilton (1964), Williams (1966), Trivers (1971), Maynard Smith (1974), Dawkins (1976), and Ruse (1979). Goodall (1986), Packer (1994), Clutton-Brock, Guinness, and Albon (1982), and Parker (1970a, 1970b, 1970c, 1970d, 1970e, 1970f, 1970g, 1971). Wilson (1975). Wilson (1975, 3). Ruse and Richards (2017). Lewontin (1981). See Lewontin (1991). See Ruse (1979). See Ruse (1986a, 1986b). Matt. 5. Matt. 5:48. Hume ([1739–1740] 2000, 3,1,1). See Moore (1903). See Ruse (2017b). Spencer (1851, 323–324). See Richards (1987). Carnegie ([1889] 1962). Sumner (1914). London (1903, 24). Spencer (1860). Spencer (1904). See Russett (1966). London (1903, 26). Huxley (1934). See Huxley (1943b). Huxley (1948). See Wilson (1984). Larson and Ruse (2017, 273). See Ruse (2018b). Von Bernhardi (1912, 18). Von Bernhardi (1912, 18). Von Bernhardi (1912, 26). Von Bernhardi (1912, 26). Hitler (1925, Chapter 11). Letter to William Graham, July 3, 1881, Darwin Correspondence Project Letter 13230.

180 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65.

Michael Ruse Hegel ([1821] 1991, 324). See Ruse (1986, 2017a, 2017b). Spencer (1857, 2–3). Spencer (1879, 21). Huxley (1943a, 42). Huxley (1948, 11). Wilson (1992, 187). Moore (1903). See Ruse and Wilson (1986). See Ruse (2013). See Ruse (2019). Huxley ([1893] 2009, 51). Ruse (1996, 486). Ruse (1986, 2012). Darwin (1871, 1:166). Ruse (2009). Rawls (1971). Rawls (1971, 502–503). Dickens ([1853] 1948). Hume ([1739–1740] 2000, 483–484). See Ruse and Wilson (1985). Kant ([1785] 1959, § 2, question 4). Darwin (1871, 1:73–74). See Ruse (1986b). See Mackie (1977). See Ruse (2010).

References Carnegie, Andrew. (1889) 1962. “The Gospel of Wealth.” In The Gospel of Wealth and Other Timely Essays, edited by Edward Chase Kirkland, 14–49. Cambridge: Harvard University Press. Originally published in the North American Review. Clutton-Brock, Timothy H., Fiona E. Guinness, and Steve D. Albon. 1982. Red Deer: Behaviour and Ecology of the Two Sexes. Chicago: Chicago University Press. Darwin, Charles. 1859. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. London: John Murray. Darwin, Charles. 1871. The Descent of Man, and Selection in Relation to Sex. 2 vols. London: John Murray. Dawkins, Richard. 1976. The Selfish Gene. Oxford: Oxford University Press. Dickens, Charles. (1853) 1948. Bleak House. Oxford: Oxford University Press. Goodall, Jane. 1986. The Chimpanzees of Gombe: Patterns of Behavior. Cambridge: Belknap. Hamilton, William. 1964. “The Genetical Evolution of Social Behaviour.” Journal of Theoretical Biology 7: 1–16, 17–32. Hegel, Georg W. F. (1821) 1991. Elements of the Philosophy of Right. Edited by Allen W. Wood. Cambridge: Cambridge University Press. Hitler, Adolf. 1925. Mein Kampf. London: Secker and Warburg. Hume, David. (1739–1740) 2000. A Treatise of Human Nature. Edited by David F. Norton and Mary J. Norton. Oxford: Oxford University Press.

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Huxley, Julian S. 1934. If I Were Dictator. New York and London: Harper and Brothers. Huxley, Julian S. 1943a. Evolutionary Ethics. Oxford: Oxford University Press. Huxley, Julian S. 1943b. TVA: Adventure in Planning. London: Scientific Book Club. Huxley, Julian S. 1948. UNESCO: Its Purpose and Its Philosophy. Washington, DC: Public Affairs Press. Huxley, Thomas Henry. (1893) 2009. Evolution and Ethics. Edited with an introduction by Michael Ruse. Princeton: Princeton University Press. Kant, Immanuel. (1785) 1959. Foundations of the Metaphysics of Morals. Indianapolis: Bobbs-Merrill. Larson, Edward J., and Michael Ruse. 2017. On Faith and Science. New Haven: Yale University Press. Lewontin, Richard C. 1981. “Sleight of Hand” (review of Genes, Mind, and Culture). The Sciences, July/August: 23–26. Lewontin, Richard C. 1991. Biology as Ideology: The Doctrine of DNA. Toronto: Anansi. London, Jack. 1903. The Call of the Wild. New York: Macmillan. Mackie, John L. 1977. Ethics. Harmondsworth: Penguin. Maynard Smith, John. 1974. “The Theory of Games and the Evolution of Animal Conflicts.” Journal of Theoretical Biology 47: 209–221. Moore, George E. 1903. Principia Ethica. Cambridge: Cambridge University Press. Packer, Craig. 1994. Into Africa. Chicago: University of Chicago Press. Parker, Geoffrey A. 1970a. “The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga Stercovaria L. (Diptera: Scatophagidae). I. Diurnal and Seasonal Changes in Population Density around the Site of Mating and Oviposition.” Journal of Animal Ecology 39: 185–204. Parker, Geoffrey A. 1970b. “The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga Stercovaria L. (Diptera: Scatophagidae). II: The Fertilization Rate and the Spatial and Temporal Relationships of Each Sex around the Site of Mating and Oviposition.” Journal of Animal Ecology 39: 205–228. Parker, Geoffrey A. 1970c. “The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga Stercovaria L. (Diptera: Scatophagidae). IV: Epigamic Recognition and Competition between Males for the Possession of Females.” Behaviour 37: 113–139. Parker, Geoffrey A. 1970d. “The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga stercovaria L. (Diptera: Scatophagidae). V: The Female’s Behaviour at the Oviposition Site.” Behaviour 37: 140–168. Parker, Geoffrey A. 1970e. “The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga stercovaria L. (Diptera: Scatophagidae). VIII: The Origin and Evolution of the Passive Phase.” Evolution 24: 744–788. Parker, Geoffrey A. 1970f. “Sperm Competition and Its Evolutionary Consequences in the Insects.” Biological Reviews 45: 525–567. Parker, Geoffrey A. 1970g. “Sperm Competition and Its Evolutionary Effect on Copula Duration in the Fly Scatophaga Stercovaria.” Journal of Insect Physiology 16 (7): 1301–1328. Parker, Geoffrey A. 1971. “The Reproductive Behaviour and the Nature of Sexual Selection in Scatophaga Stercovaria L. (Diptera: Scatophagidae). VI: The

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Adaptive Significance of Emigration from the Oviposition Site during the Phase of Genital Contact.” Journal of Animal Ecology 40 (1): 215–233. Rawls, John. 1971. A Theory of Justice. Cambridge: Harvard University Press. Richards, Robert J. 1987. Darwin and the Emergence of Evolutionary Theories of Mind and Behavior. Chicago: University of Chicago Press. Ruse, Michael. 1979. Sociobiology: Sense or Nonsense? Dordrecht: Reidel. Ruse, Michael. 1986a. “Evolutionary Ethics: A Phoenix Arisen.” Zygon 21: 95–112. Ruse, Michael. 1986b. Taking Darwin Seriously: A Naturalistic Approach to Philosophy. Oxford: Blackwell. Ruse, Michael. 1996. Monad to Man: The Concept of Progress in Evolutionary Biology. Cambridge: Harvard University Press. Ruse, Michael. 2006. Darwinism and Its Discontents. Cambridge: Cambridge University Press. Ruse, Michael, ed. 2009. Philosophy after Darwin: Classic and Contemporary Readings. Princeton: Princeton University Press. Ruse, Michael. 2010. Science and Spirituality: Making Room for Faith in the Age of Science. Cambridge: Cambridge University Press. Ruse, Michael. 2012. The Philosophy of Human Evolution. Cambridge: Cambridge University Press. Ruse, Michael. 2013. The Gaia Hypothesis: Science on a Pagan Planet. Chicago: University of Chicago Press. Ruse, Michael. 2017a. On Purpose. Princeton: Princeton University Press. Ruse, Michael. 2017b. “Social Darwinism.” In On Human Nature: Biology, Psychology, Ethics, Politics, and Religion, edited by Francisco Ayala and Michel J. Tibayrenc, 651–660. Amsterdam: Academic Press. Ruse, Michael. 2018a. The Darwinian Revolution: Why It Matters to Philosophers. Cambridge: Cambridge University Press. Ruse, Michael. 2018b. The Problem of War: Darwinism, Christianity, and Their Battle to Understand Human Conflict. Oxford: Oxford University Press. Ruse, Michael. 2019. A Meaning to Life. Oxford: Oxford University Press. Ruse, Michael, and Robert J. Richards, eds. 2017. The Cambridge Handbook of Evolutionary Ethics. Cambridge: Cambridge University Press. Ruse, Michael, and Edward O. Wilson. 1985. “The Evolution of Morality.” New Scientist 1478: 108–128. Ruse, Michael, and Edward O. Wilson. 1986. “Moral Philosophy as Applied Science.” Philosophy 61: 173–192. Russett, Cynthia E. 1966. The Concept of Equilibrium in American Social Thought. New Haven: Yale University Press. Spencer, Herbert. 1851. Social Statics: Or, the Conditions Essential to Human Happiness Specified, and the First of Them Developed. London: J. Chapman. Spencer, Herbert. 1857. “Progress: Its Law and Cause.” Westminster Review 67: 244–267. Spencer, Herbert. 1860. “The Social Organism.” Westminster Review 73. Spencer, Herbert. 1879. The Data of Ethics. London: Williams and Norgate. Spencer, Herbert. 1904. Autobiography. London: Williams and Norgate. Sumner, William G. 1914. The Challenge of Facts and Other Essays. New Haven: Yale University Press. Trivers, Robert L. 1971. “The Evolution of Reciprocal Altruism.” Quarterly Review of Biology 46: 35–57.

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Von Bernhardi, Friedrich. 1912. Germany and the Next War. London: Edward Arnold. Williams, George C. 1966. Adaptation and Natural Selection. Princeton, NJ: Princeton University Press. Wilson, Edward O. 1975. Sociobiology: The New Synthesis. Cambridge: Harvard University Press. Wilson, Edward O. 1984. Biophilia. Cambridge: Harvard University Press. Wilson, Edward O. 1992. The Diversity of Life. Cambridge: Harvard University Press.

12 Evolution and Moral Common Sense Why You Can’t Have It Both Ways; a Response to Ruse Regina Rini Michael Ruse wants to have it both ways. He wants to be able to say, on one hand, that evolution explains our moral judgements and there’s nothing more to morality than that (“Evolution does not justify normative ethics, because nothing justifies normative ethics” [Ruse, Chapter 11, 14]). There’s no objective morality out there. He also wants to be able to say, on the other hand, that he upholds the claims of moral common sense (“I am a totally common sense moralist” [Ruse, Chapter 11, 17]). You are not supposed to be able to say both these things at once, at least not without doing some fancy quasi-realist metaethics first. But Ruse presents the conjunction as a fairly simple matter. Evolution both explains our moral judgments, and it explains why we can’t help but go on believing them: “natural selection is clever enough . . . to make it very implausible psychologically that natural selection is clever enough to undermine common sense morality” (Ruse, Chapter 11, 2). This is where many philosophers set their hair on fire. Ruse must be missing something! You can’t simultaneously acknowledge a truthobviating causal explanation of your beliefs and go on affirming the content of those beliefs! But Ruse doesn’t have time for this. His essay’s implicit challenge to the doubters is: can’t I? What am I doing right now but saying those two things at once? Indeed, Ruse has been saying them for decades, and he has not yet been smote by the gods of dialectical propriety. So the burden of vindicating that ‘can’t’ seems to weigh heavily on the doubters. I’ll use these comments to articulate what I think is the best reason for doubting. To skip the suspense, I think Ruse’s position requires a form of existential bad faith. I don’t think Ruse’s position is truly sustainable, at least not in most human lives, without a lot of motivated self-deception. But before I explain that idea, let me set aside alternative reasons for doubt. First, there’s the old philosopher’s saw of logical inconsistency. On this approach, Ruse must be making some logical error somewhere, perhaps to do with the so-called is/ought gap. Maybe philosophers are right about this, but I’m with Ruse when he waves abstruse metaethics away. Morality is a fundamentally practical subject about how best to live our lives.

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If the charge against Ruse is merely that he misses some rarefied logical niceties of the sort only philosophers care about, then I think he’s right to shrug off the worry. As he puts it, “An objective morality, of which we can blissfully live our lives unaware, is not much of an objective morality. We cannot live our lives blissfully unaware of approaching trains” (Ruse, Chapter 11, 16). So let’s leave the logic-chopping out of it. The next possible charge against Ruse is that he flirts with encouraging gross immorality. By exposing the undermining evolutionary origins of moral common sense, he risks breaking our motivation to do good. This charge is as old as Victorian panics about Darwinism: moral motivation is a fragile thing, so don’t let’s show it any rudeness! Again, though, I think Ruse handles this charge correctly. He writes, If morality is subjective, with no objective foundation, why don’t we just ignore it? . . . It’s the Raskolnikov problem from Crime and Punishment. The poor student tries to do just this, but in the end his conscience makes him confess. Even if morality is subjective, it is part of its evolved nature to make us think that it is objective. If we did not thus objectify, it would soon break down under the pressure of cheating. In other words, the reason why you find this argument difficult to accept is not because it is a bad argument, but because your biology is working flat out to make you think it untrue! (Ruse, Chapter 11, 16) This seems right to me. We’re evolved to take morality seriously whether we want to or not. For most of us, our fundamental moral motivation is simply not up for revision, no matter what we discover about its causal origins. So the motivational charge can be set aside as well.1 But this answer to the motivational charge leads right into my own worry, which I’ll call the existential charge. Accepting everything Ruse says—morality is fully explained by evolution, there’s nothing more to it than that, and we’re going to do what morality demands anyway—leaves a reflective person in a predicament. It’s starting to sound like morality is an inescapable, arational compulsion. That is—and should be—an unsettling thought. This worry becomes clearer when we pay attention to our ability to look at morality from at least two directions.2 One is the external perspective, or what I like to think of as the space alien economist perspective. How would an extraterrestrial behavioral scientist, lacking firstperson experience of human life, try to make sense of our distinctive motivational profile? The other perspective is internal, phenomenological. What is it like to live an actual human life, made up of actual projects, vulnerabilities, desires, and worries? From the internal perspective (which gets expressed

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in what we call ‘common sense’), morality has characteristic deliberative force to it, something we tend to call ‘conscience’.3 I might deeply want to avoid doing X, but it strikes me that morality requires X, and I just can’t overcome that sensation. This can be true even when X is deeply aversive, dangerous, disgusting, or scary. Here’s an example to work with. Wendy has a severe medical phobia. She hyperventilates at the sight of needles, and the alcohol smell of a hospital gives her nightmares. She’s been lucky enough to reach early middle age without any serious medical procedure. But now it turns out that her cousin, Xavier, needs a bone marrow transplant. And she is a rare immunological match for Xavier; it seems there’s no other donor available. The procedure will be painful and (for someone with Wendy’s phobia) traumatic. And she doesn’t even know Xavier well nor like him. She last saw him at a family reunion six years ago, where he casually insulted her politics. But, despite all that, Wendy feels like she must help. He’s family, his life is at risk, and the cost to her is survivable pain and trauma. Morality requires it, even though she really doesn’t want to. So she agrees to undergo the marrow donation procedure. I think Wendy’s thought process must be familiar to most of us. The sensation that morality compels a choice, even a highly aversive one, is something we all experience at some point, although hopefully not frequently. Importantly, it would be a mistake (at least from the internal perspective) to describe this situation as a weighing of competing motivational forces, as if Wendy’s desire not to experience medical trauma and her desire to uphold morality were all behavioral vectors rattling around inside a directional summation device. No, Wendy does not experience this moral demand as anything like a desire. She very much does not want to undergo the procedure. Rather, she feels morality as an overriding compulsion that trumps her desires. The question is whether this compulsion is an acceptable one. Obviously some compulsions are not; the obsessive-compulsive disorder (OCD) sufferer’s compulsion to triple-check every last light switch and window lock is at best something to cope with and ideally something to cure. In some cases, morality can seem like this, as it once did to Freud: The super-ego has the ego at its mercy and applies the most severe moral standards to it; indeed it represents the whole demands of morality, and we see all at once that our moral sense of guilt is the expression of the tension between the ego and the super-ego. It is a very remarkable experience to observe morality, which was ostensibly conferred on us by God and planted deep in our hearts, functioning as a periodical phenomenon. For after a certain number of months the whole moral fuss is at an end, the critical voice of the super-ego is silent, the ego is reinstated, and enjoys once more all the rights of man until the next attack.4

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But Freud was talking about a particular patient with a pathologically melancholic disposition. The idea that morality is always just a compulsion, the sort that requires cure or coping, is an idea of a different scale. Confronting that thought, we want some sort of reason-making answer, something that makes the moral compulsion an acceptable one, even something to be proud of. What’s interesting about evolution is that it does provide a reasonmaking answer, but it’s an answer of the wrong sort. The space alien economist can explain why Wendy feels compelled to help her cousin despite the pain. Like other humans, Wendy carries around a psychology evolved to favor the interests of genetic kin, such as her cousin Xavier. Because close relatives share a significant proportion of their genes, and because mutual aid increases the likelihood of propagating those genes into future generations, a genetic profile that drives its individual instantiations to look out for one another—to compulsorily look out for one another—is more likely to be successful than one that does not. So Wendy feels compelled to help Xavier, and she calls that compulsion morality. The space alien economist can be now reassured that the world is ticking along in a way that makes explanatory sense: where it might have at first seemed that Wendy’s moral compulsion is irrational (because her preferences don’t add up to favor it) evolution steps in to dispel the worry. Unlike OCD—which seems to be a maladaptive over-excitation of an otherwise adaptive mechanism—there is an evolutionary reason for Wendy to be compelled to aid her cousin. Beneath the turbulent psychological surface, all is well. But this is a reason-making answer from the perspective of the space alien economist. Is it a reason-making answer from Wendy’s internal perspective? Should it be? I don’t see why this should be a reason-making answer from the internal perspective. Why should Wendy care whether some genetic sequence gets propagated? If I catch a cold, my coughing and sneezing will propagate the genetic bits carried in the rhinovirus, but this doesn’t seem like a reason to be content with my respiratory misery. It’s certainly not a reason to go out and actively try to become a rhinovirus gene vector. Why is it any different if the genes are mine rather than those of the rhinovirus? I suppose you could take a sort of pride in what your genes accomplish simply because they are yours in the way some people are proud of a hometown from which they moved away long ago. Feeling causally bound to a successful enterprise has some value. But is this associative glow enough to make it reasonable to undertake costly actions involving pain and trauma, like Wendy’s bone marrow procedure? It’s important to keep tabs on the force of this worry. I am not here worrying about whether Wendy will go through with the procedure. That’s the motivational charge again, and we’ve already dispensed with it. I agree with Ruse that human morality has evolved to make itself

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compelling whether or not its motivational force is internally reasonable. The issue isn’t whether Wendy will go through with it but how she should feel about the fact that she can’t not go through with it. Sometimes when I get a bad cold, I feel a weird form of resentment. I’m mad at the rhinovirus, or maybe just at biology generally, about the fact that I have to spend weeks feeling miserable so some meaningless bits of genetic material can continue to spew themselves around the planet. Of course I recognize that this attitude doesn’t really make sense—there’s no point to resenting a rhinovirus in the way I might resent the actions of a moral agent. Still, when I am awake at 3 am, unable to sleep through the coughing fits, my self-pity carries a tinge of directionless moral complaint: it’s cosmically unfair that I should have to suffer for no real reason. Learning to cope with that thought—this situation is unfair but no one can do anything about it—is part of what it means to be an adult. On Ruse’s view, so far as I can tell, there’s no reason not to view morality itself in the same way. Morality is an afflictive by-product of genes going about serving their gene-relevant interests, forcing us to endure aversive experiences for no real reason. It’s a compulsion from the domain of the space alien economist, and its apparent meaningfulness in human life is an illusion woven by the mind-controlling powers of our genes. Recognizing this fact isn’t enough to overturn morality’s hold on us, no more so than diagnosing rhinovirus cures us of sneezing. The best we can do is simply learn to cope. That’s a very sad picture of the nature of morality. Perhaps it’s a true one. But it’s certainly not common sense. And that’s what I mean when I say there’s an element of existential bad faith in Ruse’s trying to have it both ways at once. You can say that evolution fully explains morality (the space alien economist is nodding along), and you can say you accept the demands of common sense morality (Wendy certainly does), but you aren’t really talking about the same thing in these two thoughts. The morality of our common sense is not an arational compulsion with which we achieve (at best) a resigned acceptance. And that brings us back to Camus’s suggestion, so quickly dismissed by evolutionary biologist E. O. Wilson, that the most fundamental philosophical question is whether—and, more importantly, why—to go on. Wilson offers the space alien economist’s reply, but in doing so he’s merely sidestepping the question that Camus means to ask. In real life, if I’m trying to determine the course of my life—should I stay in this career, should I continue this relationship, should I suffer trauma to aid this relative?—the effort starts to look a bit meaningless if I admit that my deliberations are tightly constrained by a moral compulsion that carries only the dubious authority of mindless genetic imperatives. There are ways of approaching this predicament. Camus, Kierkegaard, Nietzsche, Sartre, and Beauvoir each offer some manner of reckoning with the contingency of our moral nature. But none should be described

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as common sense. (I have some thoughts of my own on grappling with the meaningfulness of contingent human morality, although a responsory essay is not the place for them.)5 The point is only that this problem arises naturally from reflection and is not resolved by reaffirming basic moral precepts. Philosophers’ worries (these ones, anyway) are not so easily shrugged off. So this, I think, explains why so few philosophers have been receptive to the infamous claim of Wilson, an expert on social insects, that evolution would “explain ethics and ethical philosophers, if not epistemology and epistemologists, at all depths”.6 Explaining, after all, isn’t the problem here; it’s making sense of that explanation within a human life. Ruse characterizes the philosophical reaction to Wilson as prim scandalization, “as though they were virgin aunts to whom an indecent proposition had been made” (Ruse, Chapter 11, 4). But I think the sentiment is both more nuanced and inchoate; it’s the frustrated bemusement of witnessing a person congratulate him- or herself on having seen clear through the bowels of hell, when in fact he or she has merely stuck his or her head in an anthill.

Notes 1. We shouldn’t entirely dismiss it. Even if spending a lot of time thinking about evolution won’t make you into a rapist, as Ruse scoffs about, it might make you more likely to come up with excuses for your friends if they turn out to be rapists. Evolutionary biologist Robert Trivers said about the alleged victims of accused child-rapist Jeffrey Epstein: “[b]y the time they’re 14 or 15, they’re like grown women were 60 years ago, so I don’t see these acts as so heinous”. See Walling (2019). 2. This point is far from novel. It goes back at least as far as Kant’s Antinomy of Practical Reason, and my particular framing owes a lot to Thomas Nagel (1986). But I don’t side with the way Nagel and some other Kantians resolve the tension: I think that dismissing the science (Nagel 2012) is a different sort of bad faith response. 3. Philosophers sometimes call it other things. Lisa Tessman (2015, 73) calls it a ‘non-negotiable requirement’. Richard Joyce (2006) calls it ‘practical oomph’. Harry Frankfurt (1982) calls it a ‘volitional necessity’. 4. Freud ([1932] 1989, 83). 5. See Rini (2020). 6. Wilson (1975, 3).

References Frankfurt, Harry. 1982. “The Importance of What We Care About.” Synthese 53 (2): 257–272. Freud, Sigmund. (1932) 1989. New Introductory Lectures in Psycho-Analysis. Edited by James Strachey. New York: Norton. Joyce, Richard. 2006. The Evolution of Morality. Cambridge: MIT Press. Nagel, Thomas. 1986. The View from Nowhere. Oxford: Oxford University Press.

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Nagel, Thomas. 2012. Mind and Cosmos. Oxford: Oxford University Press. Rini, Regina. 2020.“Contingency Inattention.” Philosophical Studies 177: 369–389. Tessman, Lisa. 2015. Moral Failure: On the Impossible Demands of Morality. New York: Oxford University Press. Walling, Alexandra. 2019. “Why Jeffrey Epstein Loved Evolutionary Psychology: And Why Evolutionary Psychologists Loved Him Right Back.” The Outline, September 19. https://theoutline.com/post/7956/jeffrey-epstein-evolutionarypsychology. Wilson, Edward O. 1975. Sociobiology: The New Synthesis. Cambridge: Harvard University Press.

13 Dual Inheritance, Common Sense, and the Justification of Religious Belief Taylor Davis

1 Introduction The explosion of evolutionary theories of religion in the last two decades began with a tradition now widely known as cognitive science of religion (CSR), which explains religious beliefs by appeal to the evolved functions of genetically inherited cognitive capacities. Accordingly, this perspective seems to show that religious beliefs are ‘natural’ products of universal common sense, and the connection to common sense has been used in various ways to defend the epistemic justification of religious belief. Clark and Barrett1 appeal to the common sense tradition inspired by Reid2 to argue that CSR vindicates a non-inferentialist, non-evidentialist justification. In contrast, Jong and Visala3 defend religious belief on evidentialist grounds, claiming that they can “be justified in the court of common sense in much the same way that scientific beliefs can” through justified inferences from common sense starting points. Braddock4 also pursues an evidentialist strategy, claiming that common sense contains a ‘supernatural disposition’ that is biased specifically toward theistic beliefs and arguing that this is more easily explained by theism than by naturalism. However, the science of religion has, in more recent years, moved beyond the assumptions of the CSR tradition, which are based on an increasingly outdated conception of cultural evolution in general. CSR explains the cultural fitness of religious beliefs according to what is known as the ‘epidemiological’ theory of cultural evolution,5 which has largely been supplanted by the more comprehensive and fruitful ‘dual-inheritance’ approach.6 Consequently, instead of appealing solely to genetically inherited cognitive biases as features of panhuman common sense, evolutionary theories of religion now appeal, in addition, to humans’ sophisticated capacities for social learning and to the evolutionary dynamics these capacities produce at the population level.7 The most fully developed version of this approach has been dubbed the ‘big gods’ account because it affords a central role to beliefs about ‘big’ gods who monitor and enforce moral behavior. But on this view, the cross-cultural prevalence of theistic beliefs, and supernatural beliefs in general, can be explained without any appeal at all to biases in cognitive content. The only universal features

192 Taylor Davis of human psychology necessary are content-neutral capacities for social learning in general. That is, the cultural fitness of religious beliefs can already be explained entirely by the role such beliefs play in facilitating large-scale cooperation, so there is no reason to think that this cultural fitness is due the content biases identified by CSR. Consequently, our best current science does not support CSR’s claims about common sense, or the claims that philosophers of religion have made, on that basis, about the epistemic justification of religious belief. In what follows, I first explain how the dual-inheritance theory of religion differs from, and improves upon, the CSR tradition. I then discuss the implications of this for the three arguments already mentioned, which attempt to justify religious belief by appeal to common sense.

2 Dual-Inheritance Theory Versus the Epidemiological Theory When the interdisciplinary scientific field of the evolution of religion was first beginning to bloom, it was dominated by a specific approach to cultural evolution in general. In response to the growing popularity of meme theories,8 Sperber9 developed the ‘epidemiological’ theory of cultural evolution, according to which cultural representations are not replicated, as meme theorists would have it, but are rather reconstructed—with varying degrees of fidelity—according to the adapted functions of genetically inherited cognitive capacities. Thus, cognitive biases at the individual level were said to explain the distribution of cultural beliefs at the population level. This approach was skillfully applied to religion by two of Sperber’s students, Atran and Boyer,10 and it quickly became the standard approach to cultural evolution among CSR theorists. Boyer’s notion of minimally counterintuitive beliefs was especially influential. On this view, the transmission of religious representations is explained by certain basic concepts, or ‘ontological categories’ (e.g., person, living thing, artifact), which are products of genetic selection in our species. These concepts are said to generate a wide range of intuitions and expectations, and representations that violate these intuitions and expectations are said to be particularly interesting and memorable, making them more likely to spread through populations. Of course, highly counterintuitive representations would simply be incoherent, or ‘hard to think’, and would thus spread less easily than other representations. But ‘minimally’ counterintuitive beliefs would be not be hard to think and yet would also be interesting and memorable, possessing a higher degree of cultural fitness11 than other representations. Although particular cultural beliefs are not genetically inherited traits, they can nevertheless be said to be traits that are inherited by one individual from another through social learning. Consequently, at the population level it makes sense to say that such beliefs are selected for in a Darwinian

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sense as certain culturally inherited traits increase in frequency in the population at the expense of others. Boyer’s claim, then, is that cultural fitness depends on degree of counterintuitiveness: minimally counterintuitive beliefs are selected for over competing alternatives, which are either too counterintuitive or not counterintuitive enough. But counterintuiveness, in turn, is explained solely in terms of genetically inherited biases in cognitive content due to our ontological categories. Thus, the cultural fitness of religious beliefs is explained entirely by appeal to genetically inherited content biases. Other CSR theories posit additional content biases based on other genetically adapted cognitive capacities, including capacities for detecting agents12—even if they are invisible and bodiless13—and for attributing mental states to them.14 Another CSR account identifies a content bias for teleological explanations over non-teleological, mechanistic explanations,15 and further genetic traits can always be added to the list. Jointly, then, CSR theorists claim that a specific constellation of genetically inherited content biases renders religious belief a ‘natural’ product of universal common sense. As Braddock puts it, “CSR theorists have argued for what is now commonly called the naturalness of religion thesis: humans are naturally cognitively disposed to believe in supernatural agents and these beliefs are constrained in certain ways”.16 More recently, however, a different approach to cultural evolution in general has been applied to religion. Following the title of Norenzayan’s book-length treatment,17 the specific theory of religion is known as the big gods theory, although the same account has also been defended elsewhere without this label.18 As I explain further, this title is somewhat misleading because it overemphasizes the role of theistic beliefs in the account. Whereas any adequate theory of religion must explain the extreme cultural fitness of theistic beliefs, what is most distinctive and important about the account is the general theory of culture on which it is founded, which enables it to explain the cultural fitness of much more than theistic beliefs alone. Dual-inheritance theory is ultimately the result of the methodological innovation of constructing Darwinian models that rigorously maintain the distinction between cultural selection and genetic selection but, at the same time, integrate them to describe coevolutionary interactions, known as gene-culture coevolution.19 And the ‘dual-inheritance’ label is quite apt because the whole theory rests on the simple assumption that traits are inherited in two different ways: culturally, through social learning, or genetically, through reproduction. It is this assumption that entails the existence of two distinct Darwinian processes, and it is only by focusing on the details of social learning at the individual level that the relevant population-level dynamics can be adequately described. Outside the context of religion, dual-inheritance models have produced and confirmed a wide range of novel predictions, and explained a wide range of facts, that cannot be identified or explained by epidemiological

194 Taylor Davis theories. These include facts about the psychology of social learning, on one hand,20 and about human genetics, on the other.21 But they also include fundamentally important facts about distinctly human forms of cooperation and prosocial behavior in general,22 as well as more specific historical facts both within cultures23 and across cultures,24 and much more. In short, the epidemiological approach in general has not achieved anywhere near the degree of empirical success and fruitfulness exhibited by the dual-inheritance approach. Ultimately, there is one simple reason for this: dual-inheritance theory is much more comprehensive in its empirical scope. It encompasses everything that epidemiological theories explain and much more besides. At the level of individual psychology, epidemiological theories focus too narrowly on cognition, neglecting traits of acquisition and motivation. That is, epidemiological theories address only the cultural fitness of representations and inferences because they explain cultural fitness only by appealing to genetically inherited biases in cognitive content. Dualinheritance theory also recognizes the existence of such content biases, but it contrasts them with model-selection biases,25 which concern whom a person learns from, or whom one chooses as a model, rather than what is being learned. For example, conformity bias occurs when individuals choose the models who occur most frequently in the population.26 For example, one might learn to plant a crop at a specific time of year by observing that all their neighbors plant that crop at that time. A different model-selection bias, called prestige bias, occurs when learners choose the most successful or knowledgeable individuals—experts—as their models.27 Several other types of model-selection biases are described by Chudek, Zhou, and Henrich,28 including preferences for learning from in-group members over outgroup members, from older models over younger ones, from same-sex models over members of the opposite sex, and others. By definition model-selection biases are neutral with regard to the content of any representations that may be acquired. I refer to model-selection biases as traits of ‘acquisition’ because they are capacities for acquiring other capacities. And although some of the capacities we acquire through these mechanisms are capacities for representation and inference, others are not. Consider the acquisition of cultural norms, which include both a cognitive component and motivational component. When we internalize the norms of our culture, we not only acquire new beliefs about what is right or wrong but also new intrinsic desires to do what is right and avoid what is wrong, along with further intrinsic desires to enforce these rights and wrongs upon others.29 Moreover, Henrich30 identifies another type of model-selection bias that is especially important for explaining religious motivations. Gervais and Henrich31 and Gervais et al.32 point out that religious belief is not just belief because it also involves some degree of commitment or devotion. But motivations of commitment to religious representations cannot be

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explained by capacities for representation themselves. As these authors note, people today can represent and reason about Zeus—a minimally counterintuitive supernatural agent who provides teleological explanations for thunder and lightning—as well as the ancient Greeks could. Yet no one today actually believes in Zeus, to say nothing of sacrificing their sheep to him. To explain such motivational differences across cultures, these authors identify what they call ‘credibility-enhancing displays (CREDs)’. By engaging in acts of self-deprivation, or painful rituals, or through other means, religious devotees display the depth of their commitment to supernatural beliefs by performing actions they would never perform if they were not truly committed. As a result, they function as cultural models who enhance the credibility of their beliefs in the eyes of cultural learners, causing learners to acquire not just the relevant beliefs but also the corresponding motivations of commitment. Thus, CREDs are a (noncognitive) acquisition mechanism that explains the (noncognitive) motivational difference between merely representing Zeus and being willing to sacrifice sheep to him. And together, the combination of CREDs and the internalization of norms can explain many of the distinctive motivational features of religion, which are not addressed by biases in cognitive content. By appealing to content-neutral capacities of acquisition and motivation, then, dual-inheritance theory identifies a wide range of individuallevel facts that fall outside the scope of the epidemiological theory. However, these individual-level facts also enable the theory to explain a corresponding set of population-level facts that fall outside the scope of the epidemiological theory. Most notably, these include the evolutionary dynamics of gene-culture coevolution and cultural group selection. Regarding the former, dual-inheritance models have shown how cultural selection and genetic selection exhibit reciprocal causal interactions. This entails that the prior history of genetic selection influences the subsequent course of cultural selection, as epidemiological theories claim. However, it also entails that the causal relationship runs in the other direction as well; the prior history of cultural selection also influences the subsequent course of genetic selection in important ways.33 Regarding the latter, dual-inheritance models predict that selection at the group level should not occur in genetic evolution34 but that it should have been a crucial factor in cultural evolution, at least over the last 12,000 years, since the agricultural revolution.35 Neither of these population-level dynamics is predicted by biases in cognitive content, but both are necessary for explaining distinctively human forms of cooperative behavior, especially large-scale collective action. In humans, unlike any other species, non-excludable public goods are produced by cooperative interactions involving millions of genetically unrelated strangers.36 At the heart of this account of human cooperation

196 Taylor Davis is what Boyd and Richerson37 call the theory of ‘tribal social instincts’, which appeals to both gene-culture coevolution and cultural group selection to explain humans’ distinctive capacity to behave prosocially, or in ways that are beneficial for others, but costly for themselves (in the currency of genetic fitness, at least in the short term). On this view, cultural group selection first produces a social environment that contains strong genetic selection pressures for prosocial behavior, and the genes subsequently respond, producing innate capacities for prosocial motivations such as guilt, shame, sympathy, and so on. Particular norms are inherited culturally, not genetically, and norms are enforced through social punishments and rewards that may or may not be formalized into explicit laws and policies. These punishments and rewards, in turn, make a big difference for the genetic fitness of individuals. Moreover, many norms are prosocial, meaning that they require people to behave in personally costly ways. Thus, the theory of tribal instinct holds that after cultural selection acting on particular norms has already established a social environment in which the enforcement of prosocial norms is a common, stable feature, prosocial motivations such as guilt, shame, and sympathy will increase the genetic fitness of individuals who possess them. In a prosocial society, innately prosocial individuals will be more capable than other individuals of avoiding normative punishment and gaining normative rewards. This raises the question of how this prosocial environment could have evolved in the first place, and the answer is through cultural group selection. Groups whose norms are more prosocial than other groups are better able to reap benefits from cooperation, especially when these benefits take the form of non-excludable public goods such as collective defense (e.g., armies), public infrastructure (e.g., roads), and resource management (e.g., water). This, in turn, enables these groups to grow more quickly in size and to compete more successfully for resources. And this growth and material success, in turn, enables these groups to spread their cultural traits more effectively than their competitors—including the prosocial norms that made them more successful in the first place. Further, once the prosocial cultural environment began to produce prosocial motivations such as guilt, shame, and sympathy, these capacities would serve to further reinforce cooperation and thus group-level selection for prosociality. A coevolutionary positive feedback loop thus explains how our species has become so radically cooperative, relative to other species, in such a short time.38 Recently, epidemiological theorists Boyer and Baumard have offered an account of prosocial religions that does focus on motivational capacities rather than cognitive capacities.39 Nevertheless, this account remains far too narrow in scope. It is based on a theory of the evolution of fairness, in contexts of mutualistic cooperation, or cooperation that is mutually beneficial to all interactants.40 Accordingly, this account explains prosocial

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behavior only in the form of fairness, specifically, offering no account of other types of norms, such as norms of harm, authority, loyalty, or purity41 or of autonomy, honesty, possession, integrity, or others. It also does not explain cooperation in the form of collective action, where some interactants benefit more than others, and some do not benefit at all (e.g., soldiers who die defending the honor of their group or following norms of authority). By contrast, because cultural group selection promotes prosocial behavior by appealing simply to norms in general, dual-inheritance theory is able to capture the full range of distinctively human prosocial behavior. I thus conclude that the CSR tradition is based on a badly impoverished, narrowly limited theory of cultural evolution. As a result, it has placed far too much emphasis on the role of genetically inherited content biases. Content biases might play a role in boosting the cultural fitness of certain religious beliefs to some degree. But then again, they might not. As I argue in the next section, a theory of religion based on the dualinheritance framework can explain all the facts about cultural fitness that CSR theories purport to explain, and more besides, and it can do so without appealing to any of the content biases that CSR theories posit.

3 Explaining Religion Without Content Biases The universal, genetically inherited content biases identified by CSR offer explanations for (i) why supernatural beliefs are so common across cultures and (ii) why the supernatural beliefs that exhibit the highest cultural fitness tend to be theistic, involving agents who lack material bodies, but possess superhuman powers, and who use those powers to monitor and enforce moral behavior. Braddock42 summarizes these claims nicely, following Barrett, whose work epitomizes the CSR tradition.43 After first claiming, on the basis of the genetically inherited cognitive capacities mentioned, that our minds contain a “supernatural disposition”, Braddock adds that “our supernatural disposition is content biased rather than content neutral”.44 More specifically, he claims that it is biased toward theism: “let us say our supernatural disposition is theistically biased without being precise or biased toward any particular theistic religion”. This claim overreaches the available evidence. What CSR theories do successfully is identify genetically inherited cognitive capacities that are involved in forming theistic beliefs. It is a separate question whether these capacities actually bias individual minds toward such beliefs, as opposed to merely being recruited by cultural beliefs that require them. For example, if someone tells me that aliens are planning to invade earth to harvest our water, then I must employ my genetically inherited capacities for representing agents and attributing mental states to them; the aliens must desire water and believe that we have it on earth. This does not show that I am in any way genetically biased toward forming such representations

198 Taylor Davis by my agency-detection mechanism and my theory of mind mechanism. It simply shows that the formation of a particular representation recruits this particular set of genetically inherited cognitive capacities. And if I live in an isolated cult in which everyone else believes in aliens, and lives in constant fear of them, then I will be more likely to actually believe this representation and to make a concerted effort to spread this belief to others, and my efforts may be quite successful. Thus, a belief that happens to recruit genetically evolved capacities of agency detection and mental state attribution might have high cultural fitness but for reasons that have nothing to with content biases produced by these capacities. In the same way, the big gods theory of religion explains the cultural fitness of theistic beliefs, and other supernatural beliefs, in a way that is independent of any content biases. Instead, the fitness of such beliefs is due to the role they play in promoting prosocial behavior. “Big” gods are said to be “powerful, omniscient, interventionist, morally concerned gods”,45 and the reason for focusing on this specifically theistic type of supernatural belief is that such beliefs are particularly well suited to perform the function of supernatural monitoring. Because prosocial behavior is costly by definition, temptations to violate prosocial norms are often quite strong, so it is often difficult to motivate individuals to comply with and enforce such norms. However, Norenzayan musters a wealth of evidence showing that when people believe they are being watched by powerful, morally concerned agents, they are more likely to resist such temptations.46 Accordingly, a cultural group with a higher frequency of individuals who are deeply committed to big god beliefs will exhibit a higher degree of prosocial behavior than other groups, resulting in greater benefits from cooperation and, ultimately, greater success in spreading its cultural traits—including theistic belief about supernatural monitoring. This account is consistent with the existence of theistic content biases because it is possible that the cultural fitness of theistic beliefs also receives an additional boost from such content biases over and above the role that prosocial behavior plays in explaining their cultural fitness. But content biases are not necessary for explaining why theistic beliefs are so common in the human population in general. According to the big gods theory, the cultural fitness consequences of prosocial cooperation can already explain the spread of theistic beliefs, whether or not content biases are involved, so evidence for the role of content biases must show that such biases make a further contribution to cultural fitness over and above the role of prosocial behavior. I know of no CSR theory that has attempted to do this. Further, there is some reason to doubt that we actually do possess content biases for theistic beliefs because in addition to explaining why theistic beliefs are so culturally fit, it is also necessary to explain why nontheistic beliefs are so culturally fit. Fitness is an inherently relative notion,

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so to explain the high fitness of theistic beliefs is also to explain the low fitness of competing alternatives. This is where, as I already mentioned, the ‘big gods’ label becomes misleading. For although the dual-inheritance framework does make it possible to explain the success of theistic beliefs without appealing to content biases, it also makes it possible to explain nontheistic beliefs in the same way. Gervais et al. emphasize the need to explain religious disbelief in addition to religious belief.47 Focusing on the spread of atheism in Scandinavia, they cite evidence showing that believers were systematically exposed to powerful CREDs as children, whereas nonbelievers were not. This suggests that genetically inherited common sense does not produce supernatural beliefs in the absence of cultural scaffolding. As these authors put it, According to the view that religious beliefs are exclusively produced by intuitions and content biases, atheism is unnatural and improbable. On the other hand, a view that incorporates [model-selection] biases predicts that both religious beliefs and atheism are ‘natural’, in the sense that they are products of different cultural contexts.48 They also note that a large and growing number of people worldwide claim to have no religious beliefs at all: “more than half of a billion people claim to not believe in God or gods, making nonbelievers the fourth largest ‘religious’ group in the world today” (Zuckerman 2007).49 Finally, they point out that even theists are still atheists with regard to theistic beliefs in general because they do not hold the vast array of theistic beliefs that arise in other cultures. Such facts must not only be explained by appeal to cultural evolutionary factors other than theistic content biases, but they must be explained in spite of such biases. A similar argument can be made by looking at beliefs about karma, which also exhibit extremely high cultural fitness but are not theistic. Of course, beliefs about karma are still supernatural, and Hindus and Buddhists also believe in all sorts of supernatural agents. Nevertheless, karma is not an agent but a supernatural force, more akin to a law of (super)nature than a god. It is simply a feature of the supernatural order that all souls strive toward nirvana, or release from the cycle of death and rebirth, and that the way to attain this goal is to be reincarnated into progressively higher castes until eventually one need not be incarnated at all. Good karma, or compassionate, norm-following, prosocial behavior, is what causes one to be reincarnated into a higher caste, closer to nirvana rather than a lower caste further from this goal. There is no agent who, like the proverbial St. Peter at the pearly gates, decides at what level one will be reincarnated each time around. Accordingly, it is not accurate to describe karmic beliefs as involving supernatural monitoring because they do not posit the existence of any agent who monitors human behavior and metes out punishments

200 Taylor Davis and rewards. Instead, the normative value of compassion, and the nonimportance of the self and self-interest, are simply built into the fabric of the universe. Thus, karmic beliefs promote prosocial behavior in very much the same way that big god beliefs do but without appealing to gods at all. This conflicts with the emphasis that the authors of the big gods theory lay on big gods, and supernatural agents in general, but it is entirely consistent with the spirit of their theory, as they recognize. They cite evidence for the role of karmic beliefs in producing prosocial behavior and argue, “Karmic religions are, therefore, also compatible with the prosocial religious elements in the present framework”.50 Quite so, but this shows that any culturally inherited belief that promotes prosocial behavior should exhibit high cultural fitness on this view whether or not it is theistic and whether or not it is supernatural. The source of cultural fitness is content neutral. If humans possess a universal, genetically inherited theistic bias, then the prevalence of karmic beliefs would have to be explained in spite of this bias. If they exist, the panhuman content biases posited by CSR would explain, at best, the prevalence of supernatural agent beliefs across cultures. They would not explain the lack of such beliefs where they are absent or the prevalence of other types of religious belief, which recruit different sets cognitive capacities. They also would not explain why any individual comes to believe in the particular supernatural agents that he or she actually believes in, as opposed to others, or why religious individuals are so devoted to the beliefs they hold. In addition, they would not explain the relationship between religious belief and prosocial behavior, with the exception of norms of fairness in mutualistic interactions. By contrast, the dual-inheritance theory can explain all of these other facts according to the same principles that explain the prevalence of supernatural agent beliefs. But nowhere among these principles do we find genetically inherited biases toward supernatural or theistic content.

4 Epistemological Implications Three different arguments have attempted to defend the rationality of religious belief using CSR’s claims about common sense. I object to these arguments on scientific grounds because of their descriptive views about the cultural evolution of religion. 4.1 Braddock’s Argument From Comparative Confirmation Braddock employs what he calls ‘comparative confirmation’ to argue that the hypothesis of theism is more probable, or less surprising, than the hypothesis of naturalism.51 In an effort to remain neutral about what he sees as ongoing debates in the scientific literature, he identifies six claims made by evolutionary theories of religion and argues that each of

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them would render naturalism more surprising than theism. He describes these claims as identifying six features of our ‘supernatural disposition’ and argues that each feature would be more surprising according to naturalism than theism and thus that a combination of any subset of these six features would only provide further support for the comparative likelihood of theism. In general, the problem with this argument is that it is based on an outdated view of scientific literature, which places far too much emphasis on early CSR theories and does not fully grapple with the implications of dual-inheritance theory. More specifically, the problem is that the argument relies largely on the unsubstantiated claim that we are genetically endowed with a cognitive bias toward theistic content. Feature 1 on Braddock’s list is the claim that theistic bias exists, and here Braddock relies heavily on the claims of Barrett,52 a stalwart of the CSR tradition. Feature 2 is the claim that our theistic bias is a by-product of selection, meaning that it originally evolved in the absence of any selection for religion per se. However, Feature 2 remains neutral with regard to what happened after theistic bias originally evolved. Feature 3 is the claim that there never has been selection for religion per se, or for theistic belief more specifically, and thus that our theistic bias is a functionless by-product. This distinguishes Feature 3 from Feature 4, which is the claim that theistic bias is an exapted by-product. An exaptation is a trait that is coopted by selection only after it has already evolved. Thus, Feature 4 holds that theistic belief first evolved without performing any religious function and only later was exapted by selection to perform a religious function or to contribute reproductive fitness in some specifically religious way. Feature 5 is the claim that theistic belief is an adaptation, which performed a religious function from the very beginning and thus originally evolved because it contributed to reproductive fitness in some specifically religious way. Feature 6 is what Braddock calls ‘theistic progression’, which is actually a purported consequence of theistic bias at the population level rather than a feature of our supernatural disposition itself. This is the pattern by which an increasing number of individuals have come to possess theistic beliefs over time. Regarding Features 1, 4, and 5, Braddock’s argument is that it is not surprising at all that we would evolve a theistic bias according to the hypothesis of theism because God would have structured the laws of nature so that genetic selection would favor theistic belief. By contrast, he argues, theistic bias would be surprising according to naturalism because in the absence of divine intervention genetic selection could easily have favored other, nontheistic types of supernatural beliefs. As he puts it, “[G]iven naturalism our supernatural disposition could have easily had a different and markedly non-theistic content bias than the theistic bias that it does in fact possess”53 because “supernatural beliefs with different content biases could have easily proven equally adaptive if not more adaptive than the theistically-biased beliefs that actually evolved”.54

202 Taylor Davis I find this argument wholly unconvincing because I disagree that genetic selection ever did favor theistic beliefs in the first place. It is clear that ‘adaptive’ in this context implies genetic selection rather than cultural selection, and for reasons already given, I disagree that genetic selection endowed us with a theistic bias. Indeed, I see no reason to think that we possess any supernatural disposition at all. What we possess, as a product of genetic selection, is a disposition to adopt the beliefs of the cultural models around us, whatever they may be. If our models happen to be atheists, or happen to hold nontheistic beliefs about karma, then we are just as genetically disposed to acquire nontheistic beliefs as theistic beliefs. Thus, our minds don’t actually possess the feature that Braddock says would be surprising according to naturalism. Regarding Features 2 and 3, Braddock’s argument against naturalism is that it would also be surprising for theistic beliefs to evolve in the absence of selection for theism itself. According to the claims of by-product theories from the CSR tradition, theistic belief is the result of a number of otherwise independent cognitive capacities beginning to work together in a specifically theistic way. But assuming that these capacities did evolve independently, why would they then begin to consistently work together in a specifically theistic way in culture after culture? In the absence of any selection for theism itself, this would be very surprising. I fully agree with Braddock that this would be surprising, but I see no reason to credit the by-product theories that make such claims. Again, the problem is that these theories see selection only in terms of genetic selection. Following up on vague claims made by the authors of the big gods theory, about integrating by-product theories with adaptationist theories,55 I have developed and defended elsewhere what I call the Goldberg Exaptation Model of religion.56 According to this model, it is precisely selection for theism itself that explains how these otherwise independent, genetically inherited capacities have been brought together into a coherent functional system. However, the model also holds that it is cultural selection for theism has done this, constructing a Rube Goldberg device with a theistic function out of a set of genetically inherited capacities that originally evolved to perform other nontheistic functions. Thus, even if theistic belief is a by-product of genetic selection, it is not surprising according to the correct interpretation of naturalism. For example, the theistic beliefs of Christianity recruit the full suite of proximate mechanisms identified by CSR theories, including detection of agents, attribution of mental states, mind-body dualism, and teleological explanation. By contrast, beliefs about karma recruit only a subset of these mechanisms. Because the karmic system of reincarnation does not involve agents, these beliefs do not recruit capacities of agency detection or mental state attribution. But they do recruit the capacities of mind-body dualism and teleological explanation. Dualism is required because reincarnation entails that the same soul inhabits different bodies. Teleological

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explanation is required because the function of karma depends on the goal of progressing toward nirvana in successive reincarnations. Thus, in India and in Western cultures, we find two different Goldberg devices constructed out of two different but partially overlapping sets of genetically inherited cognitive capacities. However, the two devices share the same evolved function—promoting prosocial behavior—because both are the result of group selection acting on particular cultural beliefs. Where theistic belief has evolved, it has indeed been due to selection for theism. It just hasn’t been due to genetic selection for theism. Moving on to Feature 6, Braddock describes theistic progression as follows: [w]e observe the increasing spread of so-called “big gods” or “high gods” after the dawn of the agricultural revolution 12,000 years ago and the increasing prevalence of the theistic Abrahamic God during the past 2,500 years. Now there are currently more than three billion believers in the Abrahamic God and the total number of believers in a theist-like God runs significantly higher.57 Thus, he calculates, “[I]t is plausible to suppose that the vast majority of humans who have ever lived have possessed the concept of a theistlike God”.58 But why, then, is this pattern more surprising according to naturalism than theism? Curiously, Braddock provides no argument at all. He explicitly acknowledges that the big gods theory can provide an adequate naturalistic explanation for theistic progression.59 Yet he goes on to insist that nevertheless, theistic progression is more surprising according to naturalism than theism. He does not say why or provide any principled way of comparing relative degrees of surprisingness. For my own part, I simply do not share Braddock’s intuition here. Naturalism predicts that the strength of cultural group selection would become stronger as the global population increases in size because increased population densities produce increased competition among groups.60 Moreover, political developments such as empires, and later democracies, provide means for groups to remain stable while growing in size at the same time that other developments, such as colonialism and improved technologies for transportation and communication, provide the means for theistic beliefs to spread more easily both within groups and across group boundaries. Thus, if cultural group selection for prosocial behavior explains the cultural fitness of theistic beliefs, and does so, moreover, because of the role such beliefs play in facilitating large-scale cooperation, then it seems to me that theistic progression fits beautifully with the predictions of naturalism. This is, after all, why the authors of the big gods theory place so much emphasis on big gods: they are the single most culturally fit type of supernatural belief. Moreover, as Braddock himself recognizes, it’s not as though the hypothesis of theism faces no problems

204 Taylor Davis of its own. If God wanted people to form theistic beliefs, why didn’t He just endow us with a strong, genetically inherited theistic bias? As I read the scientific literature, Braddock’s Features 1–5 do not exist, so there is nothing for theism to explain more readily than naturalism. And although Feature 6 does exist, I see no reason to think that theism explains it more readily than naturalism. 4.2 Jong and Visala’s Indirect Milvian Bridge Argument In the course of responding to EDAs, Jong and Visala61 suggest a different way in which religious beliefs may be justified by appeal to common sense. EDAs share a basic strategy of undermining epistemic justification by arguing that the processes involved in forming the relevant beliefs do not track truth because selection for the relevant beliefs is independent from those beliefs’ truth values. As Talmont-Kaminski puts it, the selected function of religious beliefs is ‘nonalethic’—they have been selected for in virtue of their role in producing prosocial behavior, not in virtue of their ability to accurately predict events.62 Consequently, EDAs hold that unlike other beliefs, the history of selection shows that religious beliefs would be formed in the same way whether they are true or not, thereby undermining their epistemic justification. Jong and Visala respond by distinguishing reasons from causes. They argue that nonalethic functions only debunk religious beliefs if their evolved causes are the only justifying reasons one has for holding them. If instead one’s reasons are independent of these causes, then the fact that the causes do not track truth is neither here nor there. In defending this position, they focus on the EDA put forward by Wilkins and Griffiths,63 which proceeds by identifying an important difference between religious and scientific beliefs. Inspired by a legend about the Emperor Constantine, who attributed his success at the Battle of the Milvian Bridge to his Christian beliefs, Wilkins and Griffiths argue that epistemic justification requires us to identify some connection between the truth values of our beliefs and their evolutionary success. In their terms, we must be able to construct a ‘Milvian Bridge’ between truth and adaptive value. Thus, they claim, ordinary, common sense beliefs are generally justified because their adaptive value does depend upon their truth value; their evolved function is alethic. Wilkins and Griffiths use this principle to contrast religious beliefs with scientific beliefs, arguing that a Milvian Bridge can be constructed in one case but not the other. Regarding religious beliefs, Jong and Visala quote Wilkins and Griffiths as pointing out that “none of the leading accounts of the evolution of religious beliefs makes any reference to the truth or falsity of those beliefs when explaining their effects on reproductive fitness”.64 A person who believes that he or she is being monitored by God or that he

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or she must generate good karma will behave accordingly whether such beliefs are actually true or not. Then, regarding scientific beliefs, Wilkins and Griffiths grant that there is no direct Milvian Bridge connecting the truth of scientific beliefs to their adaptive value but claim that an indirect Milvian Bridge can be constructed for scientific beliefs. This is because, they say, we can use our common sense beliefs to evaluate our scientific beliefs. As they put it, if evolution does not undermine our trust in our cognitive faculties, neither should it undermine our trust in our ability to use those faculties to debug themselves—to identify their own limitations, as in perceptual illusions or common errors in intuitive reasoning. Nor should it undermine our confidence in adopting new concepts and methods which have not themselves been shaped by the evolution of the mind, but whose introduction can be justified using our evolved cognitive faculties.65 Jong and Visala argue, however, that if this is suffcient for constructing an indirect Milvian Bridge in science, then we can also construct an indirect Milvian Bridge for religious belief. For if we can trust our common sense faculties to ‘debug’ themselves correctly, through proper reasoning and arguments, then we can use proper reasoning and arguments to justify religious beliefs. As they put it, religious beliefs can be “justifed in the court of commonsense thinking”, in the same way that scientifc beliefs are, by using our alethic common sense faculties to reason in good ways, rather than bad ways, from alethic starting points. If so, then religious beliefs are justifed by these reasons and arguments independently of their evolutionary causes. In evaluating Jong and Visala’s argument, it is important to distinguish between the question of whether religious beliefs can be justified, in principle, and whether they actually are justified, in practice. I have no objection to the claim that good reasoning from common sense starting points can justify religious beliefs. However, few religious believers actually do hold their beliefs for reasons that are independent, in this way, from evolutionary causes. Jong and Visala’s argument might succeed in showing that a few philosophers and theologians are epistemically justified in holding religious beliefs, but it is far from showing that religious belief in general is justified. Most religious believers acquire their beliefs through cultural inheritance, or social learning, not through careful reasoning from common sense starting points. Moreover, the particular beliefs they acquire tend to be the products of long histories of cultural selection for prosocial behavior, not truth. This is why beliefs about karma are much more common in India than in the United States, whereas Christian beliefs are much more common in the United States than in India. For I take it that

206 Taylor Davis common sense, in this context, is something that people in both countries possess in equal measure. If so, and if the court of common sense actually did play a role in determining which beliefs individuals possess, then we should observe a convergence across cultures that is independent from the history of cultural transmission. That is, assuming that Christian beliefs are true, we should observe that people in Europe and people in the Philippines converged upon Christian beliefs in a manner that was independent of cultural contact. Instead, what we observe is that Christianity became popular in the Philippines soon after Spanish colonization. And for the same reason, the convergence we observe in India is toward karmic beliefs, not Christian beliefs. Indeed, religion is infamous for being a domain in which reason and argument fail to produce convergence across cultures. And this points to an important difference between scientific and religious beliefs that both Jong and Visala and Wilkins and Griffiths overlook. In granting that no direct Milvian Bridge connects the truth of scientific beliefs to their evolutionary success, Wilkins and Griffiths assume a gene-based definition of ‘evolutionary success’, and they only consider the effects of selection acting upon genetically inherited cognitive capacities. Jong and Visala follow them in this. In the previous quote, Wilkins and Griffiths explicitly appeal to the effects of religious belief on reproductive fitness when denying the existence of a Milvian Bridge. When Jong and Visala respond to this argument, they respond directly to this quote as follows: “[b]ut of course, the same can be said for our scientific beliefs, and as in the case of scientific beliefs, this simply rules out a direct Milvian Bridge, not an indirect one”.66 Thus, both sets of authors are concerned with connecting the truth values of beliefs to their success in genetic evolution. The problem with this is that the relevant selection process, for science and religion alike, has nothing to with reproductive success or genetically inherited cognitive capacities. It is cultural selection that has structured the particular beliefs and concepts of particular scientific theories, on one hand, and particular religious systems, on the other. And the cultural fitness values of scientific beliefs do depend upon their truth values; scientific norms and methods ensure that false scientific theories are eventually rejected, and the empirical predictions of science get increasingly more precise and accurate over time. Consequently, we observe convergence in science in a way that we do not in religion. Children in both India and the United States are taught that the earth revolves around the sun, and they are not taught that phlogiston is released in combustion. It is because of selection acting on cultural traits, not genetic traits, that a Milvian Bridge can be constructed for scientific beliefs but not religious beliefs. Religious beliefs are culturally inherited traits that have been selected for in virtue of their ability to promote prosocial behavior, regardless of whether they are true or false. By contrast, scientific beliefs

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are culturally inherited traits that have been selected for in virtue of their ability to produce true, accurate predictions. The culturally selected function of scientific beliefs is alethic, whereas the culturally selected function of religious beliefs is nonalethic. Wilkins and Griffiths’ EDA still goes through, once the correct selection process has been identified. Again, this does not conflict with Jong and Visala’s claim that it is possible for religious beliefs to be justified by careful reasoning from common sense starting points, just as scientific beliefs are. But it does show that this possibility is rarely actualized. 4.3 Clark and Barrett’s Non-Evidentialist Argument Clark and Barrett pursue a very different approach to defending the epistemic justification of religious belief.67 Instead of appealing to reasoning and argument, they adopt a non-evidentialist, non-inferentialist epistemology from the tradition of common sense philosophy initiated by Reid. This approach was developed in the religious context by Plantinga, who argues that religious beliefs are justified in virtue of being ‘properly basic’, or justified prior to, and independently from, inference or evidence.68 Clark and Barrett call this the “Plantinga-Reid conception of rational religious belief”, and they attempt to carry it further by incorporating insights from CSR theories. They pursue this approach, they say, because the mind seems to work roughly as Reid conceived (and not as, say, the more famous Descartes or Hume conceived). And because Plantinga’s appropriation of Reid in defense of reason and belief in God offers the most influential conception of rational religious belief of the past thirty years.69 In what way, then, was Reid’s conception of the mind correct? In one sense, in the same way that I appealed to in objecting to Jong and Visala—although we can form beliefs on the basis of reasoning and evidence, on special occasions, this is not how we actually do form most of our beliefs. Further, Reid, Clark, and Barrett correctly note that social learning is often a non-inferential process of belief formation.70 However, there is another sense in which the view of the mind these authors defend conflicts with the one I have been defending: it ignores the role that a prior history of cultural selection has played in shaping the beliefs that we acquire through social learning. Reid’s claims about properly basic beliefs, or at least those that Clark and Barrett cite, occur in the context of his response to Cartesian skepticism: “[s]o, Reid recognizes, we have a tendency or disposition to believe, in the appropriate circumstances, that there is an external world, that we have a mind or self, that there are other persons; and we tend to believe inductively supported statements, what we remember, what we

208 Taylor Davis sense, etc.”.71 Quite so—but these types of beliefs are very different from religious beliefs. They do not depend on social learning, and the relevant genetic adaptations possess alethic functions. Religious beliefs, by contrast, are almost always acquired through social learning, and their contents have largely been shaped by histories of cultural selection for promoting prosocial behavior rather than for attaining truth. When a Christian individual today acquires the belief that Jesus is the son of Mary, or when a Hindu individual acquires the belief that higher-caste individuals are closer to nirvana than lower-caste individuals, he or she is non-inferentially acquiring a belief the contents of which first evolved more than 1,000 years ago. But in either case, the selection pressures that explain why those beliefs have been preserved in the learner’s cultural environment have to do with their role in promoting cooperation and nothing to do with truth. Thus, even if Reid’s view of the mind is correct for other types of non-inferential beliefs, there are special reasons to question the justification of religious beliefs due to their special cultural evolutionary history. In defense of their evidentialist approach, Jong and Visala attack the non-evidentialist, Reid-Plantinga approach on grounds that unlike their own view, this approach falls squarely within the cross-hairs of EDAs.72 This is because, as we have seen, their view relies on a separation between justifying reasons and evolutionary causes, whereas the Reid-Plantinga approach runs these reasons and causes together. For instance, Clark and Barrett approvingly cite Plantinga as follows: “[t]o show that there are natural processes that produce religious belief does nothing to discredit it; perhaps God designed us in such a way that it is by virtue of those processes that we come to have knowledge of him”.73 Dawes and Jong push this point further, appealing again to the fact that in religion, the cognitive mechanisms responsible for non-inferential belief formation have nonalethic functions, due to selection for prosocial behavior.74 However, this argument still exhibits a mistaken focus on genetic selection acting on cognitive universals rather than on cultural selection acting on particular religious beliefs. A more effective objection to the Reid-Plantinga approach is to appeal to the cultural EDA that I have described, in defense of Wilkins and Griffiths. The threat of debunking is due to the fact that the proliferation of religious beliefs is due to a cultural selection process that has nothing to do with truth.

5 Conclusion Religion has evolved through selection acting on particular, culturally local beliefs and practices that individuals acquire through social learning. It is possible that this process of cultural selection is influenced, to some degree, by genetically inherited content biases toward theistic belief, but there is no good evidence for this. The dual-inheritance framework,

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a more comprehensive alternative for explaining cultural evolution than the epidemiological approach, can easily explain the cultural fitness of theistic beliefs by appealing solely to content-neutral capacities for social learning in a manner that also explains the cultural fitness of conflicting beliefs, such as scientific beliefs or karmic beliefs. Thus, if biases toward supernatural or theistic content exist, then evidence for them must show that they provide some additional boost to cultural fitness, over and above the fitness benefits of prosocial behavior, and new explanations must be given for the cultural fitness of beliefs that conflict with these biases. None of this has been addressed by CSR theories. Accordingly, CSR does not succeed in showing that common sense includes the sorts of cognitive biases to which Braddock, Clark, and Barrett appeal in defending the justification of religious belief. And the features of common sense that are involved in the formation of religious belief, such as biases toward learning from experts and authority figures, do not play the justificatory role that Jong and Visala identify. If theistic beliefs are justified by reasoning from common sense starting points, it must be the reasoning that does the justificatory work rather than the common sense starting points because in other cultures the same starting points are as likely to produce entirely different, conflicting beliefs.

Notes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.

Clark and Barrett (2011). Reid ([1764] 1983). Jong and Visala (2014). Braddock (2018). Sperber (1996). Boyd and Richerson (2005), Richerson and Boyd (2005), and Henrich (2016). Wilson (2002), Atran and Henrich (2010), Norenzayan (2013), and Norenzayan et al. (2016). Dawkins (1976) and Dennett (1995). Sperber (1996). Atran (2002) and Boyer (2001). Ramsey and De Block (2015). Guthrie (1993) and Barrett (2004). Bloom (2007). Bering (2006). Kelemen (2004). Braddock (2018, 173). Norenzayan (2013). Atran and Henrich (2010) and Norenzayan et al. (2016). Boyd and Richerson (2005), Richerson and Boyd (2005), and Henrich (2016). Whiten et al. (2009), Chudek, Zhou, and Henrich (2013), Caldwell and Millen (2008), and Schmidt et al. (2016). Laland, Odling-Smee, and Myles (2010) and Holden and Mace (2009). Chudek and Henrich (2011), Boyd and Richerson (2009), Henrich et al. (2010), and House et al. (2013). Slingerland and Chudek (2011) and Henrich (2004b).

210 Taylor Davis 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72.

Henrich, Boyd, and Richerson (2012). Henrich and McElreath (2003), Chudek et al. (2011), and Gervais et al. (2011). Henrich and Boyd (1998). Henrich and Gil-White (2001) and Chudek et al. (2011). Chudek, Zhou, and Henrich (2013). Sripada and Stich (2006), Chudek and Henrich (2011) Davis, Hennes, and Raymond (2018), Schmidt et al. (2016), and Rakoczy, Warneken, and Tomasello (2008). Henrich (2009). Gervais and Henrich (2010). Gervais et al. (2011). Boyd and Richerson (2005), Richerson and Boyd (2005), Holden and Mace (2009), and Laland, Odling-Smee, and Myles (2010). Richerson and Boyd (2005, 203) and Davis (2015). Henrich (2004a), Richerson et al. (2016), Boyd and Richerson (2009), and Sterelny (2016). Chudek and Henrich (2011), Chudek, Zhou, and Henrich (2013), and Boyd and Richerson (2009). Boyd and Richerson (2006, 2009). Boyd and Richerson (2006). Baumard and Boyer (2013). Baumard, André, and Sperber (2013). Haidt (2012). Braddock (2018). Barrett (2011, 2012). Braddock (2018, 177). Norenzayan (2013, 7–8). Norenzayan (2013). Gervais et al. (2011). Gervais et al. (2011, 404). Gervais et al. (2011, 402). Norenzayan et al. (2016, 9). Braddock (2018). Barrett (2011, 2012). Braddock (2018, 183). Braddock (2018, 189). Norenzayan et al. (2016, 4). Davis (2017). Braddock (2018, 190). Braddock (2018, 191). Braddock (2018, 192). Sterelny (2016). Jong and Visala (2014). Talmont-Kaminski (2013). Wilkins and Griffiths (2013). Jong and Visala (2014, 253). Wilkins and Griffiths (2013), cited in Jong and Visala (2014, 253). Jong and Visala (2014, 253). Clark and Barrett (2011). Plantinga (1981). Clark and Barrett (2011, 641). Clark and Barrett (2011, 647). Clark and Barrett (2011, 646). Jong and Visala (2014).

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73. Clark and Barrett (2011, 656). 74. Dawes and Jong (2012).

References Atran, Scott. 2002. In Gods We Trust: The Evolutionary Landscape of Religion. New York: Oxford University Press. Atran, Scott, and Joseph Henrich. 2010. “The Evolution of Religion: How Cognitive By-Products, Adaptive Learning Heuristics, Ritual Displays, and Group Competition Generate Deep Commitments to Prosocial Religions.” Biological Theory 5 (1): 18–30. Barrett, Justin. 2004. Why Would Anyone Believe in God? Lanham: AltaMira Press. Barrett, Justin. 2011. Cognitive Science, Religion and Theology: From Human Minds to Divine Minds. West Conshohocken: Templeton Press. Barrett, Justin. 2012. Born Believers: The Science of Children’s Religious Belief. New York: Free Press. Baumard, Nicolas, Jean-Baptiste André, and Dan Sperber. 2013. “A Mutualistic Approach to Morality: The Evolution of Fairness by Partner Choice.” Behavioral and Brain Sciences 36 (1): 59–78. Baumard, Nicolas, and Pascal Boyer. 2013. “Explaining Moral Religions.” Trends in Cognitive Sciences 17 (6): 272–280. Bering, Jesse M. 2006. “The Folk Psychology of Souls.” Behavioral and Brain Sciences 29 (5): 453–461. Bloom, Paul. 2007.“Religion Is Natural.” Developmental Science 10 (1): 147–151. Boyd, Robert, and Peter J. Richerson. 2005. The Origin and Evolution of Cultures. New York: Oxford University Press. Boyd, Robert, and Peter J. Richerson. 2006. “Solving the Puzzle of Human Cooperation.” In Evolution and Culture: A Fyssen Foundation Symposium, edited by Stephen C. Levinson and Pierre Jaisson, 105–132. Cambridge: MIT Press. Boyd, Robert, and Peter J. Richerson. 2009. “Culture and the Evolution of Human Cooperation.” Philosophical Transactions of the Royal Society B: Biological Sciences 364 (1533): 3281–3288. Boyer, Pascal. 2001. Religion Explained: The Evolutionary Origins of Religious Thought. New York: Basic Books. Braddock, Matthew. 2018. “An Evidential Argument for Theism from the Cognitive Science of Religion.” In New Developments in the Cognitive Science of Religion: The Rationality of Religious Belief, edited by Hans van Eyghen, Rik Peels, and Gijsbert van den Brink, 171–198. Cham: Springer. Caldwell, Christine A., and Ailsa E. Millen. 2008. “Studying Cumulative Cultural Evolution in the Laboratory.” Philosophical Transactions of the Royal Society B: Biological Sciences 363 (1509): 3529–3539. Chudek, Maciej, Sarah Heller, Susan Birch, and Joseph Henrich. 2011. “PrestigeBiased Cultural Learning: Bystander’s Differential Attention to Potential Models Influences Children’s Learning.” Evolution and Human Behavior 33 (1): 46–56. Chudek, Maciej, and Joseph Henrich. 2011. “Culture: Gene Coevolution, NormPsychology and the Emergence of Human Prosociality.” Trends in Cognitive Sciences 15 (5): 218–226.

212 Taylor Davis Chudek, Maciej, Wanying Zhou, and Joseph Henrich. 2013. “Culture-Gene Coevolution, Large-Scale Cooperation and the Shaping of Human Social Psychology.” In Cooperation and Its Evolution, edited by Kim Sterelny, Richard Joyce, Brett Calcott, and Ben Fraser, 425–459. Cambridge: MIT Press. Clark, Kelly James, and Justin Barrett. 2011. “Reidian Religious Epistemology and the Cognitive Science of Religion.” Journal of the American Academy of Religion 79: 1–37. Davis, Taylor. 2015. “Group Selection in the Evolution of Religion: Genetic Evolution or Cultural Evolution?” Journal of Cognition and Culture 15: 235–253. Davis, Taylor. 2017. “The Goldberg Exaptation Model: Integrating Adaptation and By-Product Theories of Religion.” Review of Philosophy and Psychology 8 (3): 687–708. Davis, Taylor, Erin P. Hennes, and Leigh Raymond. 2018. “Cultural Evolution of Normative Motivations for Sustainable Behaviour.” Nature Sustainability 1 (5): 218–224. Dawes, Gregory W., and Jonathan Jong. 2012. “Defeating the Christian’s Claim to Warrant.” Philo 15 (2): 127–144. Dawkins, Richard. 1976. The Selfish Gene. Oxford: Oxford University Press. Dennett, Daniel C. 1995. Darwin’s Dangerous Idea. New York: Touchstone. Gervais, Will M., and Joseph Henrich. 2010. “The Zeus Problem: Why Representational Content Biases Cannot Explain Faith in Gods.” Journal of Cognition and Culture 10 (3): 383–389. Gervais, Will M., Aiyana K. Willard, Ara Norenzayan, and Joseph Henrich. 2011. “The Cultural Transmission of Faith: Why Innate Intuitions Are Necessary, But Insufficient, to Explain Religious Belief.” Religion 41 (3): 389–410. Guthrie, Stuart Elliott. 1993. Faces in the Clouds: A New Theory of Religion. New York: Oxford University Press. Haidt, Jonathan. 2012. The Righteous Mind. New York: Pantheon Books. Henrich, Joseph. 2004a. “Cultural Group Selection, Coevolutionary Processes and Large-Scale Cooperation.” Journal of Economic Behavior & Organization 53 (1): 3–35. Henrich, Joseph. 2004b. “Demography and Cultural Evolution: How Adaptive Cultural Processes Can Produce Maladaptive Losses: The Tasmanian Case.” American Antiquity 69 (2): 197–214. Henrich, Joseph. 2009. “The Evolution of Costly Displays, Cooperation and Religion: Credibility Enhancing Displays and Their Implications for Cultural Evolution.” Evolution and Human Behavior 30 (4): 244–260. Henrich, Joseph. 2016. The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter. Princeton: Princeton University Press. Henrich, Joseph, and Robert Boyd. 1998. “The Evolution of Conformist Transmission and the Emergence of between-Group Differences.” Evolution and Human Behavior 19 (4): 215–242. Henrich, Joseph, Robert Boyd, and Peter J. Richerson. 2012. “The Puzzle of Monogamous Marriage.” Philosophical Transactions of the Royal Society B: Biological Sciences 367 (1589): 657–669. Henrich, Joseph, Jean Ensminger, Richard McElreath, et al. 2010. “Markets, Religion, Community Size, and the Evolution of Fairness and Punishment.” Science 327 (5972): 1480–1484.

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Henrich, Joseph, and Francisco J. Gil-White. 2001. “The Evolution of Prestige: Freely Conferred Deference as a Mechanism for Enhancing the Benefits of Cultural Transmission.” Evolution and Human Behavior 22 (3): 165–196. Henrich, Joseph, and Richard McElreath. 2003. “The Evolution of Cultural Evolution.” Evolutionary Anthropology 12 (3): 123–135. Holden, Clare, and Ruth Mace. 2009. “Phylogenetic Analysis of the Evolution of Lactose Digestion in Adults.” Human Biology 81 (5–6): 597–619. House, Bailey R., Joan B. Silk, Joseph Henrich, et al. 2013. “Ontogeny of Prosocial Behavior across Diverse Societies.” Proceedings of the Natural Academy of Sciences 110 (36): 14586–14591. Jong, Jonathan, and Aku Visala. 2014. “Evolutionary Debunking Arguments against Theism, Reconsidered.” International Journal for Philosophy of Religion 76 (3): 243–258. Kelemen, Deborah. 2004. “Are Children ‘Intuitive Theists’? Reasoning about Purpose and Design in Nature.” Psychological Science 15 (5): 295–301. Laland, Kevin N., John Odling-Smee, and Sean Myles. 2010. “How Culture Shaped the Human Genome: Bringing Genetics and the Human Sciences Together.” Nature Reviews Genetics 11 (2): 137–148. Norenzayan, Ara. 2013. Big Gods: How Religion Transformed Cooperation and Conflict. Princeton: Princeton University Press. Norenzayan, Ara, Azim Shariff, Will Gervais, et al. 2016. “The Cultural Evolution of Prosocial Religions.” Behavioral and Brain Sciences 39: E1. Plantinga, Alvin. 1981. “Is Belief in God Properly Basic?” Nous 15 (1): 41–51. Rakoczy, Hannes, Felix Warneken, and Michael Tomasello. 2008. “The Sources of Normativity: Young Children’s Awareness of the Normative Structure of Games.” Developmental Psychology 44 (3): 875–881. Ramsey, Grant, and Andreas De Block. 2015. “Is Cultural Fitness Hopelessly Confused?” The British Journal for the Philosophy of Science 68 (2): 305–328. Reid, Thomas. (1764) 1983. “An Inquiry into the Human Mind on the Principles of Common Sense.” In Inquiry and Essays, edited by Ronald E. Beanblossom and Keith Lehrer. Indianapolis: Hackett. Richerson, Peter, Ryan Baldini, Adrian V. Bell, et al. 2016. “Cultural Group Selection Plays an Essential Role in Explaining Human Cooperation: A Sketch of the Evidence.” Behavioral and Brain Sciences 39: 1–68. Richerson, Peter, and Robert Boyd. 2005. Not by Genes Alone. Chicago: University of Chicago Press. Schmidt, Marco F. H., Lucas P. Butler, Julia Heinz, and Michael Tomasello. 2016. “Young Children See a Single Action and Infer a Social Norm: Promiscuous Normativity in 3-Year-Olds.” Psychological Science 27: 1360–1370. Slingerland, Edward, and Maciej Chudek. 2011. “The Prevalence of Mind: Body Dualism in Early China.” Cognitive Science 35 (5): 997–1007. Sperber, Dan. 1996. Explaining Culture: A Naturalistic Approach. Malden: Blackwell. Sripada, Chandra, and Stephen Stich. 2006. “A Framework for the Psychology of Norms.” In The Innate Mind. Volume 2: Cognition and Culture, edited by Peter Carruthers, Stephen Laurence, and Stephen Stich, 280–301. New York: Oxford University Press. Sterelny, Kim. 2016. “Cooperation, Culture, and Conflict.” The British Journal for the Philosophy of Science 67 (1): 31–58.

214 Taylor Davis Talmont-Kaminski, Konrad. 2013. “For God and Country, Not Necessarily for Truth: The Nonalethic Function of Superempirical Beliefs.” The Monist 96 (3): 447–461. Whiten, Andrew, Nicola McGuigan, Sarah Marshall-Pescini, and Lydia M. Hopper. 2009. “Emulation, Imitation, Over-Imitation and the Scope of Culture for Child and Chimpanzee.” Philosophical Transactions of the Royal Society of London B: Biological Sciences 364: 2417–2428. Wilkins, John S., and Paul E. Griffiths. 2013. “Evolutionary Debunking Arguments in Three Domains.” In A New Science of Religion, edited by Gregory Dawes and James Maclaurin, 133–146. New York: Routledge. Wilson, David Sloan. 2002. Darwin’s Cathedral: Evolution, Religion, and the Nature of Society. Chicago: University of Chicago Press. Zuckerman, Phil. 2007. “Atheism: Contemporary Numbers and Patterns.” In The Cambridge Companion to Atheism, edited by Michael Martin, 47–65. Cambridge: Cambridge University Press.

14 Cultural Evolution and Debunking Arguments A Response to Davis Aku Visala

In his admirably clear and persuasive article, Taylor Davis suggests that standard forms of CSR have been too focused on biases that discriminate representations on the basis of their content. Against this, he argues that a gene/culture coevolution perspective, especially the dual-inheritance theory, is a better option. These models not only enjoy more support in the sciences as a whole, but they also offer more comprehensive explanations than those focusing on content biases only. Davis then goes onto consider attempts to reply to debunking worries in the light of this conclusion and finds them inadequate. There he proposes a novel debunking argument. Previous debunking arguments, like those of Wilkins and Griffiths, and responses to them invoke content biases of innate cognitive systems.1 Davis’s version invokes ‘model-selection biases’ instead: religious beliefs are formed through a process of cultural selection whose function is prosociality, not truth sensitivity. So, the origin of religious beliefs is not trustworthy in the epistemic sense, and consequently, in the case of most religious believers, their religious beliefs are epistemically unjustified. Scientific beliefs, on the other hand, are driven by cultural evolution that does select beliefs for ever-increasing predictability and coherence. This implies that scientific beliefs are, ultimately, products of mechanisms that are truth sensitive. In this brief response, I will begin by making some points about Davis’s critique of standard CSR. As we will soon see, I am mostly in agreement with him. After that, I will briefly discuss his criticisms of Jong and Visala’s reply to debunking arguments. Here, I am not so sure that Davis’s arguments succeed in showing that an evidentialist reply to debunking arguments ends in failure. Let me begin with a terminological clarification. It concerns the demarcation of cognitive science of religion itself. CSR is best understood as a conglomerate of loosely related fields of research in anthropology, cognitive science, and the study of religion. Where should we draw its boundaries? Taylor seems to assume that the term ‘cognitive science of religion’ refers mainly to the combination of Sperberian epidemiology of representations and the by-product thesis of early theorists like Pascal Boyer and Justin Barrett. This is exactly the theoretical framework he criticizes. It is

216 Aku Visala true that most CSR theorizing in the 1990s and 2000s was indeed conducted inside this ‘paradigm’. If this is what CSR is, it would make sense to insist, like Davis does, that Norenzayan’s big gods theory, for instance, would be antithetical to CSR. However, there are good reasons to think that the term ‘CSR’ has, in practice, wider application that includes the kinds of approaches that Norenzayan and others represent. For instance, in the new textbook showcasing CSR empirical research, research following the standard model and studies that depart from it are introduced as a part of the same field of research.2 Furthermore, most people in the field seem to take Norenzayan and others as parts of the same research field (and the movement), even while they criticize some of its traditional assumptions. Given this, I would suggest that the dialectical situation is not such that CSR is made obsolete by dual-inheritance theories, but rather the debate is internal to CSR. CSR as a field is diversifying theoretically and evolving beyond epidemiology toward gene/culture coevolution models.3 I agree with Davis that the standard model of CSR has put too much focus on content biases at the price of neglecting other social and cultural biases. Nevertheless, I see no strong empirical argument in Davis’s article to rule out content biases having a role in the cultural evolution of religious beliefs in general and theistic beliefs in particular. However, their role in explaining motivational, emotional, and volitional aspects of religion will, most likely, be rather small. What they might explain is a general human tendency to favor certain kinds of ideas. But this claim is hardly new, and even bulwarks of epidemiology and the by-product thesis have acknowledged it. Anthropologist Scott Atran, for instance, pointed out already in 2002 how purely cognitive theories of religion, namely, those that invoke content biases in explaining religious beliefs, cannot account for religious motivations and commitments.4 I take it that this point is widely accepted in the field as a whole. This casts doubt on the idea that there ever was a pure, cognitivist ‘standard model’. Davis mentions psychologist Ara Norenzayan’s big gods theory among the new approaches to religion that are rooted in the dual-inheritance theory. Although this theory and others invoking supernatural punishment5 signify a welcome development theoretically, there is some debate about their empirical basis. In a recent paper in Nature, anthropologist Harvey Whitehouse and a number of colleagues argue, based on a large set of historical data, that the historical record does not support big gods theory.6 They maintain that rather than preceding social complexity and big societies, morally relevant, punishing ‘big gods’ often appear only afterward when large-scale societies have been formed. This result, if correct, partly falsifies the big gods hypothesis. However, Whitehouse and colleagues did find causal links between big societies and big gods: belief in moralizing and watchful gods might be a stabilizing and maintaining factor in large empires. Furthermore, one central finding was that

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whereas big gods are not necessary for big societies, various rituals that support the standardization of religious traditions appear prior to moralizing gods. So, it seems that the standardization of beliefs and practices via rituals and authority contributes to the construction of large-scale identities across ethnic and state lines. The rest of my response deals with Davis’s critiques of Jong and Visala’s response to debunking arguments. This does not mean that I completely agree with Davis’s criticisms of Clark, Barrett, and Braddock’s argument. However, I do think the evidentialist response is the most promising antidebunking strategy, so I will focus here on its defense. Jong and Visala respond to the debunking strategy of Wilkins and Griffiths, according to whom scientific and common sense belief forming mechanisms are ‘alethic’, or as I put it, ‘truth-tracking’.7 That is to say, their origins are such that they reliably produce true beliefs. Common sense reasoning is largely trustworthy because of its adaptive value, and it can subsequently be used to correct scientific reasoning. Between adaptive common sense and nonadaptive, higher-level belief structure a Milvian Bridge can be constructed in the case of science. A similar bridge, however, cannot be erected between common sense and religion, or so the argument goes. Jong and Visala reply to this by arguing that if common sense reasoning and argument can be used to justify scientific beliefs, they could be used to justify religious beliefs. Davis responds that “Jong and Visala’s argument might succeed in showing that a few philosophers and theologians are epistemically justified in holding religious beliefs, but it is far from showing that religious belief in general is justified”.8 In other words, the problem is that most religious people do not acquire their religious beliefs on the basis of philosophical or theological reasoning. First, one might point out that it is not the aim of Jong and Visala’s response to suggest that all or most religious beliefs are justified. It only wants to open an avenue through which some religious beliefs could be justified, if the relevant evidence and arguments were put forward. Settling this issue is more the subject of philosophy of religion then, and it won’t be settled by results of the study of cultural and biological evolution of religion. Second, Jong and Visala’s response also suggests that there might be something wrong in the whole idea of debunking, that is, the idea that epistemic justification depends on the reliability of the source of the belief. Indeed, for an evidentialist, what counts for or against the epistemic status of a belief is the evidence for or against it. The epistemic justification of a belief depends on the evidence to which the epistemic subject has access. Of course, the reliability of the sources of one’s beliefs also counts as evidence for the evidentialist, so evidentialism cannot completely disregard the issue of reliability of one’s belief-forming mechanisms. For my purposes here, it is enough to state that most evidentialists put the issue of reliability to the background. More detailed analyses of this issue can be found in the literature.9

218 Aku Visala Davis’s criticism of Jong and Visala’s response is that most people do not seem to have adequate evidence available to them. Although it is clear that there surely are religious people who acquire their beliefs without access to adequate evidence, the situation might not be as bad as Davis paints it. An evidentialist can still maintain that religious beliefs are justified for many more people than a few philosophers and theologians. Having access to relevant evidence can be much more complex than simply recalling to mind. Even the strong evidentialist is not committed to the claim that the epistemic subject must be in possession of all the justifying arguments and evidence all the time. It is enough to have access to reasons and evidence, if the epistemic situation so requires. This also includes social means, like epistemic authority and testimony.10 Let us call this the division of epistemic labor. For many of our beliefs, we have no sufficient justifying evidence immediately at hand. Further, we do not even have the obligation to acquire that evidence ourselves. It is enough that there are people around who have acquired such evidence, and there are procedures in place how one can acquire adequate evidence from these epistemic authorities. Epistemic authority plays a part in the division of epistemic labor. Take scientific beliefs as an example. Most people hold scientific beliefs, such as ‘current biological species are a product of a long evolutionary history’ and ‘the universe is expanding’. However, apart from teachers and researchers, most people have very little reflectively accessible evidence for these beliefs if they are challenged. People acquire these beliefs on the basis of social learning, not through carefully assessing the evidence. Such beliefs are, for the most part, acquired from teachers, schoolbooks and other sources people deem trustworthy. Moreover, there is a great deal of evidence suggesting that the evidence for, say, Darwinian evolution, is difficult to access and understand; it takes a significant amount of training and reflective work to understand how evolution works.11 Nevertheless, evidentialists could maintain that most people are still epistemically justified in holding beliefs about evolution: they have access to experts and sources that have the relevant evidence, and they can, at least in principle, acquire it. Analogous reasoning applies to the case of religious belief. Religious beliefs are often acquired via social learning. Sometimes, they are not even clearly understood. In both these senses, they do not differ from everyday scientific beliefs. Furthermore, both can be justified because there are experts who, arguably, have access to relevant evidences and arguments. In the case of religion, these experts are often theologians and philosophers, sometimes scientists. Now, the crucial question is whether there is an epistemically significant difference between the reflective enterprises of theology and science that function as epistemic authorities. In other words, do we have reasons to think that model-selection biases provide pressures toward true beliefs in one but not in the other?

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Davis argues for a positive answer. He puts forward a version of an EDA that invokes model-selection biases rather than content biases of innate cognitive systems. Epistemically bona-fide beliefs are such that their functions (in this case cultural selection) are connected to their truth value. In the case of science, such a connection exists, but it does not in the case of religion. Cultural selection of scientific beliefs is based on their predictive success, which requires those beliefs to be true or at least approximately true. Scientific institutions develop a cultural setting in which norms and methods drive scientific beliefs toward better predictive and explanatory power, which in turn leads to more truthful beliefs. This truth-trackingness of the cultural selection process, Davis argues, is manifested in the way in which scientific methods produce convergence and agreement globally. Against this, religious cultural selection does not select for predictive success and explanatory power, only for increased prosociality. This makes the process such that it does not track the truth value of beliefs. This is evident, Davis suggests, in the diversity of religious beliefs across different cultural traditions. If the process were truthtracking, we would expect there to be convergence. One possible response to this type of EDA would be to deny the connection among increased predictive success, explanatory power, and truth. Many empiricist philosophers of science have argued that the predictive success of a belief does not give us warrant taking the belief as true.12 According to this view, science is in the business of producing theories that work in their particular domains; that is, they predict, help to understand, or make sense (or whatever scientific theories and models are supposed to do) of a particular domain. However, the increased predictive power or any such other feature does not justify the inference from success to truth or even verisimilitude. Even though empiricism enjoys some support in philosophy of science, I do not want to resort to it here. Because I hold a critical scientific realist view, I think scientific theories actually aim at truth and that their predictive success indeed provides good reasons to take them moving toward the truth. So, the problem remains: if one wants to avoid the breakdown of the Milvian Bridge between common sense and theology, one would need to argue that the cultural evolution of theology could also be guided by truth-tracking factors. In other words, one would have to put forward a case showing that theological belief formation is not simply and exclusively a product of selection pressures for prosociality. Theologies of religious traditions could, as far as we know, approach and approximate the truth. Unfortunately, there is not enough space here to develop a comprehensive response. However, I want to present some preliminary points. First, I do not think Davis has provided sufficient reasons to think that prosociality is the only or the most central selective force in the cultural evolution of religious ideas. As was suggested, the cultural evolution of religious ideas could be shaped by reflective theologies attempting to

220 Aku Visala make sense of more everyday religious beliefs. In order for Davis’s EDA to succeed, he would have to show that theological ideas were selected for prosociality only. As far as I can see, he has not done this. The only argument Davis produces for the unreliability of theology is its inability to produce convergence independently of cultural selection. One response to this would be to direct attention to the many convergences that the theologies of different religious traditions exhibit. For example, many theological traditions have, without having been in contact with one another, produced similar arguments invoking biological and cosmic design as evidence for supernatural design. In the West, these emerge in Greek philosophy and are later refined by Jewish, Christian, and Muslim authors. Hindu philosophers and theologians have developed similar design arguments for supernatural design as well as arguments invoking beauty.13 Also, there are distinctive parallels in how different theological traditions describe and understand religious experiences as well as many basic ethical norms. Such cases can be invoked to counter the claim that religion is somehow infamous for being a domain in which reason and argument fail to produce convergence. It seems that there are indeed such convergences between great religious traditions, and they pertain especially to reflective theologies. This fact undermines Davis’s claim that the cultural fitness of religious beliefs only depends on their prosocial value. My second point is about common sense and religion. Different religious traditions have different relationships to common sense. There is no single ‘religious hypothesis’, so let me focus on one, theism. From the evidentialist perspective, the question is what the hypothesis in question predicts. If something like Christian theism is true, should we expect people to come to know religious truths simply by common sense? Davis seems to think so: “assuming that Christian beliefs are true, we should observe that people in Europe and people in the Philippines converged upon Christian beliefs in a manner that was independent of cultural contact”. But we do not in fact observe this, so Christian beliefs are not inferred from common sense starting points, nor are they true. But this argument has very little teeth against theists, and Christian theists especially, because they do not expect true religious beliefs to be such that they can be inferred merely from common sense assumptions. Theistic religions are religions of revelation. This revelation takes place in a specific time and place in history, and actual communities transmit it. Thus, such religions necessarily involve social transmission of beliefs, and they, for the most part, reject the notion that central truths of revelation could be inferred from common sense premises by everyday reasoning. Traditions differ as to what extent common sense has a role in religious matters: Roman Catholicism, for instance, maintains that common sense reasoning leads to the conclusion that a creator, an omnipotent and perfectly loving God, exists. Here arguments from, for instance, causation

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and design are invoked. The more specific theological views concerning salvation and the nature of God, however, are only knowable through revelation, and this revelation is transmitted via social learning by religious institutions. Given this point about theological traditions converging over some arguments and evidences, reality resembles very much what the Christian theist would expect. On the one hand, there is some common sense reasoning, argument, and experience that most theologies have independently discovered. On the other hand, specific religious beliefs are transmitted through cultural and social means and upheld by reflective theological thinking. I do not pretend that these points rebut Davis’s EDA. Much more work is needed for that. However, I hope they show that the evidentialist has a potential response to Davis’s type of EDA’s available.14

Notes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Wilkins and Griffiths (2013). Slone and McCorkle (2019). See, e.g., Pyysiäinen (2014). Atran (2002, 14). See, e.g., Johnson (2015). Whitehouse et al. (2019). Jong and Visala (2014). Davis (2020). See, for example, Conee and Feldman (2004). See, for example, Zagzebski (2013). McCauley (2013). See, for example, van Fraassen (2004). Brown (2008). I would like to thank Jeroen de Ridder, René van Woudenberg, Rope Kojonen, and Lari Launonen for helpful feedback and comments. Special thanks go to the Academy of Finland, whose funding made the research for this article possible.

References Atran, Scott. 2002. In Gods We Trust: The Evolutionary Landscape of Religion. New York: Oxford University Press. Brown, Mackenzie C. 2008. “The Design Argument in Classical Hindu Thought.” Journal of Hindu Studies 12: 103–151. Conee, Earl, and Richard Feldman. 2004. Evidentialism: Essays in Epistemology. Oxford: Clarendon Press. Johnson, Dominic. 2015. God Is Watching You: How the Fear of God Makes Us Human. New York: Oxford University Press. Jong, Jonathan, and Aku Visala. 2014. “Evolutionary Debunking Arguments against Theism, Reconsidered.” International Journal for Philosophy of Religion 76 (3): 243–258. McCauley, Robert. 2013. Why Religion Is Natural and Science Is Not. New York: Oxford University Press.

222 Aku Visala Pyysiäinen, Ilkka. 2014. “The Cognitive Science of Religion.” In Evolution, Religion, and Cognitive Science: Critical and Constructive Essays, edited by Fraser Watts and Leon Turner, 21–37. New York: Oxford University Press. Slone, D. Jason, and William McCorkle, ed. 2019. The Cognitive Science of Religion: A Methodological Introduction to Key Empirical Studies. London: Bloomsbury. Van Fraassen, Bas. 2004. The Empirical Stance. Yale: Yale University Press. Whitehouse, Harvey, Pieter Francois, Patrick Savage, et al. 2019. “Complex Societies Precede Moralizing Gods throughout World History.” Nature 568: 226–229. Wilkins, John, and Paul Griffiths. 2013. “Evolutionary Debunking Arguments in Three Domains.” In A New Science of Religion, edited by Gregory W. Dawes and James Maclaurin, 133–146. New York: Routledge. Zagzebski, Linda. 2013. Epistemic Authority: A Theory of Trust, Authority, and Autonomy in Belief. New York: Oxford University Press.