The Powers Metaphysic 0198833571, 9780198833574

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The Powers Metaphysic

To Charlie, for introducing me to powers, and to Kelly, for helping me exercise them.

Acknowledgements A great many people have helped me in the writing of this book. So many that there is no way I can thank them all (sorry!), but I want to briefly thank a few who have really helped this book come to fruition. A big thanks must be extended to C. B. Martin, the great patriarch of the powers theorist family, and my undergraduate teacher some two decades ago. It was Martin who first introduced me to metaphysics, to dispositions, and to powers. I owe a great deal to Martin, not just in terms of my thoughts about powers, but for instilling in me an ontology-first approach to metaphysics and philosophy in general. Some of the ideas in the book grew out of acorns planted in my dissertation at Columbia University. I was most fortunate to have the guidance of a committee that included Achille Varzi, John Collins, David Armstrong, and Peter Unger. More recently I have benefited from numerous discussions with my colleagues at Buffalo, and from the many graduate students on whom most of this material was first tested. Three of those graduate students deserve special mention for having worked through more than one draft of the book and for providing numerous comments on its content and its writing. They are John Beverley, David Limbaugh, and Robert Kelly. Others who have read full drafts of the book and helped it along the way include: Matthew Slater, Chris Haufe, Michael Brent, Tyler Hildebrand, Travis Dumsday, and Carl Gillet. I also want to thank the anonymous referees from OUP. Their comments were thoughtful and extensive. Lastly, there are lots of people in lots of places who I have made listen to parts of the book over the many years at conferences, seminars, workshops, and over cocktails, and who have provided all sorts of feedback. To them, and to anyone I may have missed, I offer a large collective thanks. Your help is truly appreciated. The epigraph at the beginning of Chapter 8 is reprinted from Theodore Sider, FourDimensionalism: An Ontology of Persistence and Time. Copyright © 2001, Clarendon Press. It is reproduced by permission of Oxford University Press through PLSclear: https://global.oup.com/academic/product/four-dimensionalism-9780199244430.

1 Revolutionary Metaphysics 1.1 The Soft Sell THE SOFT SELL -: Suited SALESPERSON knocks on the door of an average suburban home. Slightly dishevelled HOMEOWNER opens the door and stands impatiently in the doorway. : Good evening! Do you mind my asking if you are happy with your vacuum cleaner? : I guess so . . . it gets the job done. (pauses) Hold on—are you selling something? Now’s really not a good time for me to . . . : (interrupting) No! Not now anyway. I’m in the sales game, but that’s not why I’m here today. : Then how can I help you? : I’m here to talk to you about your vacuum. You say you are happy with it; do you recall when you got it, or why you chose it? : I got it from my parents some years back; it’s the newer version of the one they have. I’m happy enough with it, but I wouldn’t say I chose it. It was the one I’d grown up with, plus a few updates, mostly cosmetic. I guess I didn’t even know there were other vacuums. But mine’s fine thanks. : steps back and starts to close the door. SALESPERSON steps forward. : (hurriedly) Most people don’t know they have a choice. Most people, like yourself, use the same vacuum they grew up with. But there’s another vacuum on the market; I’m here to let you know that. : Like I said, I’m pretty happy with . . . : (continuing) And this vacuum doesn’t use bags—it’s bagless. No expense or annoyance of buying new bags; no messing with removing filthy full ones. And it has attachments for stairs, and for pet grooming, for ceiling fans, for cleaning up spills, and plenty more, too. : Bagless? Hmmm. That’s something I could go for; I hate changing the bags. And an attachment for cleaning ceiling fans? My vacuum can’t do that. : Then you’ll also be interested to know that this new vacuum outperforms yours on a range of tasks. : Sounds like this new vacuum is better than mine!

The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

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  : I think it is, but I won’t deny that the old one does a good job and has some attractive features. I just think the new one is preferable overall. I have one with me in the car: would you like to take a look at it? : I’d mostly just be interested in the ceiling-fan attachment. Can I see just that? : Unfortunately . . . : (interrupting) Package deal, eh? Gotta buy the lot to get the small part I want? : It’s not that I wouldn’t show you just the ceiling-fan attachment if I could, but it’s not compatible with your vacuum. I’d love to be able to take the best of your vacuum and combine it with the best of this new one, but there’s simply no à la carte option: the two systems aren’t alike. : So it’s one or the other? : Yes. Just like yours, there are a few optional components, but there’s no mixing and matching across brands. I take the new one to be superior, on balance. But don’t take my word for it. Why don’t I leave it with you for the weekend, and you can decide for yourself? See how it compares to your current one; I think you’ll be surprised. There are some pretty neat features on the new one, and you might find that you aren’t as happy with your current one as you think. Then again, you might decide that you are happy enough with what you’ve got, but at least you’ve had the chance to think about it and make a choice. : Sure, I’m game.

Unless you are reading this first chapter out of context, you will know that this is not a book about vacuums, and that I am not in the business of selling them. But I do have something to sell, and it, too, will be a soft sell. This is a book about metaphysics, and what I am selling is a metaphysic. A metaphysic (note the lack of terminal ‘s’) is what you get when you embed a fundamental ontology within a larger metaphysical framework by repeatedly appealing to elements of that ontology in explaining metaphysical phenomena. At its most basic, an ontology is an answer to the question ‘what is there?’ To respond, all one need provide is an inventory of the types or categories of things that make up fundamental reality. It is a laundry list of the types of entities countenanced in the most basic theory of the world, along with a description of their natures. A metaphysic, however, does a great deal more. A metaphysic explains how the items on the list are connected to one another, and tells the story of how the items on the list work together to produce the world around us. An ontology is a list of ingredients, but creating a dish requires a recipe that tells us how those ingredients are to be treated, what measures they come in, what directions one must follow to combine them correctly, and what their assemblage will produce. It is only when we see an ontology in the context of a grander theory that we can begin to see what it is worth.

  

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One such metaphysic dominates not just contemporary metaphysics, but contemporary philosophy as a whole.¹ This dominant metaphysic is called the ‘neo-Humean metaphysic’ (or ‘neo-Humeanism’), owing to its Humean ancestry. According to it, properties are inert, causation is illusory, and possibility is unbounded. The neo-Humean metaphysic was originally adopted for what then seemed like adequate reasons—such as its compatibility with a strong form of empiricism in vogue in the early modern era—but many of those reasons have long since been forgotten, and others no longer apply. In the period that followed, neo-Humeanism became the status quo, and remains so. This was due, in no small part, to its success at dealing with problems. But its establishment was further aided by the lack of any serious competitor. This latter reason is far from ideal as justification: a metaphysic is supposed to capture the fundamental aspects of nature; it is a posit about the world at its most basic. Thus, our confidence that a metaphysic gets things right goes up when it is adopted critically, selected as best from among viable alternatives. There has not been an alternative for quite some time. This makes it harder to be critical, meaning that we tend to overlook or downplay flaws, perhaps even embracing them as features. After all, how can you treat aspects of a metaphysic negatively if you are unable to recognize that metaphysic as replaceable? Without a viable alternative it gets harder to appreciate that the neo-Humean metaphysic is a posit at all. Having an alternative, of course, is not to suggest that which metaphysic is right is in any way up to us. We also choose among scientific theories, and that no more justifies attitudes of anti-realism or scepticism in science than it does in metaphysics. But gaining that critical eye, and having a real choice, demand that we have a credible alternative. Up until recently, neo-Humeanism was the only game in town. But in the last few years a serious competitor has started to take form. We do have a choice. That alternative comes in the form of the powers metaphysic.² The powers metaphysic is built on a radically distinct ontology from that which props up the neo-Humean metaphysic, replacing the neo-Humean’s impotent properties with inherently powerful ones. These powerful properties—powers—bear strong relations to other properties, and are genuine causes of their effects.³ From the powers ontology emerges a very different picture of the world. Unlike neo-Humeanism, the powers metaphysic paints the world as dynamic: it treats action as coming from within; it puts the oomph back in causes; and treats possibility as genuine and ¹ Or so I contend. Informal polling among non-metaphysicians finds that folks often take for granted many of the theses discussed in Chapter 2. Groff (2012) argues that a good deal of contemporary social and political philosophy is built on a neo-Humean ontology. And though many metaphysicians reject the views they credit Hume with holding, the same does not apply to neo-Humeanism. ² The already classic works in the field include, but are not limited to: Harré and Madden (1975), Shoemaker (1980), Mumford (1998), Ellis (2001), Heil (2003), Molnar (2003), Bird (2007a), and Martin (2008). ³ My powers are what sometimes get called ‘dispositions’. I prefer the use of ‘power’ over ‘disposition’ because the latter has been less carefully used. However, as so much of the relevant literature speaks of ‘dispositions’, I am forced to use that term at times. We will see in Chapter 3 that I have a more refined way of separating them.

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bounded. As we shall see, it is a strikingly different metaphysic to that which currently holds sway. I am a friend of powers and an early adopter of the powers metaphysic. Like neoHumeanism, it has its costs and its warts, but I believe that on balance it comes out ahead. I cannot help but think that others ought to join me in choosing the powers metaphysic over neo-Humeanism, but getting you to join me is not the primary aim of this book. My aim here is the soft sell: I want to make clear that there is a coherent alternative to neo-Humeanism. I want to tell you about the alternative, have you think about it, and have you come to see the neo-Humean metaphysic as replaceable. And I want you to cast a critical eye over both. That way your choice is genuine. And though at times I indicate aspects of the neo-Humean metaphysic that look more like flaws than features, it is not my plan to construct devastating objections against it. In fact, we should be sceptical of anything presented as a devastating objection against neo-Humeanism as a whole: it is a solid, coherent, and all-round attractive metaphysic.⁴ At this point one might wonder why having an alternative leaves us with a choice, rather than an opportunity for integration. Why not take the best of each? The answer is that central parts of a metaphysic connect to one another in such a way that mixing is difficult. As detailed in §10.4, the parts rely on and inform each other in such a way that they are largely package deals, much like the vacuums above. There are options, but there is little room for combination. Such is the nature of systematic metaphysics, as I will soon explain. I believe that on balance the powers metaphysic is to be preferred, but that is something you will have to come to on your own. Or not—maybe after seeing the alternative you will stick with the status quo. That is fine, too, as long as the result is a more critical adoption of the dominant metaphysic. My job is to flesh out the powers metaphysic and the ontology at its core so you can appreciate its worth. I will then leave it with you for the weekend to try out.

1.2 Systematic Metaphysics I approach the question of which metaphysic the reader ought to adopt delicately. I offer an alternative, but leave it to you to weigh up the differences and choose accordingly. That is one overarching form of argument at work in the book, subtle as it may be. But it is not the only one. The other meta-argument is an indirect argument for the powers ontology and the powers themselves. When you adopt a metaphysic, you thereby adopt the ontological core around which it is developed. In effect, one endorses the ontology if one prefers the picture of the world it can be used to paint. This form of argument—selling the ontology on the basis of the metaphysic—is known as an ‘argument-by-display’.⁵ Hence, by situating the

⁴ I also believe it to be false. But that is beside the point, which is why mention of it has been stuck down here. ⁵ Bigelow (1999: 45).

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powers ontology within the powers metaphysic, I not only present a metaphysic for your consideration, I provide an indirect defence of the powers ontology at its core.⁶ I have three reasons for approaching the defence of the powers ontology in this way. Firstly, I am not convinced that this is a debate best conducted in the trenches, offering direct arguments for the existence of powers via pointed criticisms of neoHumean ontology. This is good work if you can get it, but without an alternative it is unclear what those criticisms add up to. Moreover, a metaphysic is a grand thing, and it is tough to walk away from one, even if you want to. It is, after all, the foundational theory by which you structure your understanding of the world. And if I am right that each metaphysic is mostly a package deal, wherein your foundational ontology constrains your metaphysical options, then the majority of changes you can make are going to be wholesale changes, which are not easily made. Hence, though there is already a growing literature on powers that tackles the neo-Humean ontology head-on, adding to it will not have the desired result unless coupled with a viable alternative. And even then it may not succeed without recognizing the wholesale nature of each.⁷ Furthermore, there is no denying that neo-Humeanism is a decent and coherent metaphysic. Like your parents’ vacuum, it does a pretty good job. And so even if close inspection identifies further flaws, they will be overlooked in light of its general success. Hence, the advancement of metaphysics is better served by the development of a serious alternative than it is by stockpiling bigger and bigger weapons to be used against neo-Humeanism. With that in mind, I do very little to respond to neo-Humeanism directly. Instead, I present the key features of the neo-Humean metaphysic so we can know it when we see it, appreciate its interconnections, and recognize how it differs from the powers metaphysic. Along the way I point out some of the potentially unsavoury things to which a neo-Humean might be committed, and how aspects of the metaphysic might lead to certain kinds of problems (§2.6 especially), but I do not offer detailed arguments to that effect. Dare I say, little is to be gained by rehearsing arguments already in the literature: that is a waste of ink, even if some of the arguments are quite good. And though there might still be ground that can be taken from the neoHumean by engaging with her views directly, the neo-Humean metaphysic is unlikely to be deposed in this way. My second reason for offering an indirect argument for the powers ontology is, as George Molnar attests, that some of the strongest reasons for accepting an ontology come from the metaphysical work it can do.⁸ Hence, rather than adding to the first order, there is much to be said for developing a second-order argument for powers,

⁶ I thereby find myself in good company: Ellis (2001), Molnar (2003), Heil (2003, 2012), Bird (2007a), Chakravartty (2007), Martin (2008), Mumford and Anjum (2011), and Vetter (2015) are among those who devote space to developing a metaphysic with powers. See Jacobs (2017) for a collection of articles offered in that vein. ⁷ Bernstein (2013) suggests that the powers metaphysic will not be taken seriously until it connects itself with the dominant neo-Humean framework. I deny that this is possible. ⁸ Molnar (2003: 186).

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and thereby engaging a second wave of challenges to the status quo. Hence, I hope to show the value of the ontology by utilizing it when doing metaphysics. Quite frankly, the powers ontology is so foreign to many contemporary thinkers that exploring what sort of picture can be developed with it is key to assessing its strength and viability. The powers theorist has a different starting place, a different set of assumptions, and, most importantly, a different set of tools. From this new ontology comes new problems and new answers to old problems. In fact, with new tools even the old problems start to look new. We thus get a reworking of metaphysics in light of this change in thinking—a metaphysics reboot, if you will.⁹ We see this happening in some recent works within the powers metaphysic. Brian Ellis offers a series of first-order attacks on neo-Humeanism, but rounds that out with a secondorder account of natural kinds.¹⁰ Mumford and Anjum use an ontology of causal powers in developing a unique theory of causation; and Barbara Vetter adopts a similar jumping-off point in championing a powers-based theory of possibility.¹¹ There are others, and there are sure to be more. Of course, in order to get to the point of doing metaphysics with powers I need to make clear what exactly they are. Not only because they are largely foreign, but because even friends of powers disagree about their nature. This is relatively new territory: neighbourly turf wars are to be expected! Hence, the reader will find that I spend time presenting my take on the powers ontology, but the disputes in those sections are friendly in-house debates, not attempts to show that the neo-Humean metaphysic is broken. This brings us to the third reason for the indirect approach: when it comes to systematic metaphysics (those that attempt to solve a range of problems via repeated applications of some core ontological entity or entities), indirect arguments of this second-order variety are not only strong arguments for an ontology, they are the best game in town. Our picture of the world as given by the scientific and manifest images (including intuitions about how to answer various metaphysical questions) are tested against the sorts of answers the fundamental ontology can be used to generate. Through negotiation of these two vantages we arrive at a picture of the world that gets the highest overall score. Thus, Molnar may have understated the importance of a metaphysic in defending an ontology: systematic metaphysics and indirect arguments go hand in hand. Systematicity in metaphysics is to be contrasted with a piecemeal approach, wherein metaphysical problems are solved one at a time, in isolation, without any attempt to apply a solution proffered in one case to further problems.¹² The benefits of approaching problems in a piecemeal way are twofold: first, one avoids the philosophical handcuffing that comes with retrofitting an ontology for a new ⁹ But we should not overstep our bounds, as Bird (2016) argues has been done. It is one thing to apply the ontology to a range of problems, but it is quite another to think that the ontology itself offers direct solutions to these problems, or that no other metaphysic is capable of offering similar indirect solutions. ¹⁰ Ellis (2001). ¹¹ Mumford and Anjum (2011), Vetter (2015). ¹² I do not mean to suggest that piecemeal metaphysics is an intentional activity wherein systematicity is actively avoided. Though some theorists might have principled reasons for avoiding systematicity, more often than not piecemeal metaphysics is simply the failure to engage with metaphysical problems systematically. See Hawthorne (2006: vii).

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problem, rather than navigating the specific contours of the problem and custom-building to fit; and second, a custom-built ontology may avoid unforeseen errors or difficulties that plague the original. But these benefits—creativity aside—can be more costly than they appear. The restrictions that working systematically imposes are not without a basis. Rather, they are a corollary of treating the world as having a single unified ontological structure, which is nothing more than any sensible form of realism about the world should demand of its ontology. Systematicity also ensures that one’s ontological debtors are paid only once. To knowingly cast aside systematicity in favour of a piecemeal approach runs foul of these realist presuppositions. This is not to deny that there are certain advantages in doing so, but they may prove to be short-lived and artificial. Hence, new and potentially ingenious piecemeal solutions ought to be held accountable to systematic standards. David Lewis famously adopted a systematic approach to metaphysics. His was the incredible claim that ours is but one of innumerably many causally isolated concrete universes: we are occupants of one universe within a vast pluriverse. How could one hope to defend such an outlandish claim? The answer is that you step away from the incredible claim—a first-order claim about what there is—and show its value in second-order debates regarding what it can do. First-order debates are debates about fundamental ontology. Second-order debates, on the other hand, concern the sorts of metaphysical questions with which Lewis engaged, regarding the laws of nature, possibility, causation, and the like. In providing satisfactory responses to these questions he built a case for taking his fundamental ontology seriously. Lewis denies having set out to do metaphysics systematically, and might well have preferred to approach problems in a piecemeal way.¹³ There is, after all, something attractive about pretending there is nothing more to the world than the problem with which one is currently concerned. That artificial isolation permits solutions that often do better by our intuitions than any systematic solution could; to wit, systematic solutions can be entirely at odds with intuition. But this benefit of isolated solutions is lost when they are applied elsewhere, on some other problem. Lewis admits to having found himself repeatedly applying the same basic framework to every problem he approached, starting with the same set-up and showing how it could be developed to solve the problem at hand. Though bested here and there by this or that piecemeal solution in isolation, when applied to a wide range of problems the systematic solution scores higher on average and overall. This is the manner in which a systematic solution earns it keep. It is via this approach that Lewis defends the existence of the pluriverse, however implausible its existence might initially appear. It is the same methodology David Armstrong uses in arguing for a robust account of laws as universals.¹⁴ Taken at face value, laws like this are unattractive postulates. But once put to work, one can see how they can earn their keep, and this is the reason Armstrong endorses their candidacy as members of the correct fundamental ontology. My aim is to enact this same

¹³ The same appears to have been true of David Armstrong. See Mumford (2007: 95). ¹⁴ Armstrong (1978, 1997, 2010). I understand Armstrong as offering a distinct metaphysic from both neo-Humeanism and the powers metaphysic.

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systematic-style project as it pertains to powers, simultaneously claiming that this is the right way to think about the powers debate in contemporary metaphysics.¹⁵ But this is not the only reason why an advocate of systematic metaphysics would employ an argument by display, nor is it the only reason I employ it here. The other reason has to do with methods of reduction and reductive analyses that a systematic metaphysic employs. A reductive analysis is one that provides an alternative set of concepts by which some target concept can be understood. To be successful, an analysis must be non-circular, and given in terms of concepts that are themselves better understood. We thereby ‘tame’ the analysandum, replacing it, as it were, with homier concepts. There is, metaphorically speaking, a downward direction here: concepts with which we are less familiar are replaced by those with which we are more comfortable. As the concepts shift downwards, the entities with which those concepts are connected start to move, too. That is, replacing one concept with others puts us in an excellent position to do the same with the entities involved: the would-be reducer of concepts is likewise the would-be reducer of the corresponding entities. Ideally, the entities associated with the analysans can play whatever role we might otherwise have required of the entities associated with the analysandum. One no longer needs to countenance the reduced entities in one’s ontology; the reducing entities do the work. Or, for those less inclined towards elimination, this manoeuvre renders the reduced entities second class, expunging them from the fundamental ontology, but not from the world altogether. However, whereas the downwards direction of analysis leads to increased familiarity (the analysandum is replaced by more familiar concepts), downward movements in the ontological side do not have the same effect. Reduced entities are tamed by the reduction—their reduction means that they are unpacked, demystified, eliminated, or the like—but the reducer is not similarly tamed. In fact, the ontological reduction moves us towards entities that are thereby less well understood, because they themselves are not similarly reduced. The reduced entity starts out as a ‘black box’ whose mystery is solved via the reduction. But the exposed mechanism within that black box introduces a new set of cogs and pulleys, and thus a new set of mysteries or black boxes. We can solve those mysteries, too, but only through further downward moves. But what if further downward moves are not forthcoming? In that case the reducing entities constitute the bottom of the ontological structure. They are a primitive of the ontology. Initially this sounds like a bad thing. We have demystified one sort of entity only to replace it with one or many entities which are themselves equally mysterious, if not more so. How is this progress? Do not despair. Recall that the reducing entities—when they are themselves incapable of reduction—are entities with which a host of problems are to be solved. They are theoretical entities, postulated to do serious metaphysical work. So, we have clearly gained in one sense. Further, we have reduced the number of mysterious entities through the work they do, which is another plus. Nonetheless,

¹⁵ In contrast to those who would cast the debate as a local debate about properties. See Schaffer (2005) and Wang (2016).

     ?

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it is clearly not desirable that one have genuinely mysterious entities at the heart of one’s ontology. So, how does one make the fundamental entities less mysterious, given that further reduction is out of the question? The answer is that the aspects of the fundamental ontology get understood via the very same procedure by which they are defended: systematicity. That is, one can gain greater understanding of these fundamental entities by situating them in a wider metaphysic and showing what they can do. We cannot open a cog, but we can see where the cog stands in relation to other cogs, how it turns the pulley, and how it is turned by another. And we can see what many such cogs and pulleys are jointly capable of. This is how we demystify the fundamental and irreducible aspects of our ontology. Hence, my aim in situating the powers ontology within a wider metaphysical framework is not only to argue that the powers ontology is worthy of adoption, but so that more can be learned about powers and the powers ontology in the process. It is only when an ontology is at home in a metaphysic that we can really start to see what it is like. That said, total understanding is likely to remain beyond our reach, because you can only fully understand something when you can get inside it and pull it apart. This cannot be done for the fundamental entities, and so learning what they are like by finding them a home is the best we can hope to do.¹⁶ There is, of course, no reason to think that there is just one metaphysic for each ontology. (An ontology lists the raw ingredients of existence, but many dishes can be prepared from those same ingredients by adjusting the recipe.) Nevertheless, there might still be a best metaphysic for a given ontology (where what counts as best depends on what virtues are in play). My aim is to develop part of a powers metaphysic, but it is too early to say if it is part of the best. Getting to that point requires taking the powers ontology seriously when doing metaphysics. Once that step is taken we can develop rival metaphysics from the same ontological base. That stage of metaphysical theorizing is the philosophical equivalent of Kuhn’s ‘normal science’, wherein practitioners operate within a shared paradigm.¹⁷ For the time being, the shared metaphysical paradigm is neo-Humean, and most debates are internal to it. We are thus in a phase of ‘normal metaphysics’. Hence, before we can hope to find the best metaphysic for the powers ontology, the paradigm needs shifting. And doing that takes nothing short of a revolution.

1.3 The Start of a Revolution? In what proved a major development in the debate over whether disposition ascriptions are analysable in terms of stronger-than-material conditionals, C. B. Martin argued that the proposed ‘simple conditional analysis’ fails due to the possibility of finks.¹⁸ The simple condition analysis (SCA) tells us that:

¹⁶ This is why I find Barker’s (2013) criticism of powers unreasonable; he wants to see the insides, but there are no insides to be seen. ¹⁷ Kuhn (1962). ¹⁸ Martin (1994).

   [SCA] Something x is disposed at time t to give response r to stimulus s iff, if x were to undergo stimulus s at time t, x would give response r.¹⁹

A fink is a device that senses the occurrence of the stimulus that would otherwise trigger a given disposition, and quickly acts to add a disposition if it was absent, or remove it if it was present. In the scenario Martin describes, a dead wire is made finkish by attaching it to a device that adds current when the wire is touched. In those cases where a regular (non-finkish) wire would conduct electricity, the device livens the dead wire so it then conducts. In this finkish case, the wire lacks the disposition in question (being live), but the associated conditional (if the wire is touched by a conductor, then electric current flows from the wire to the conductor) is nevertheless true, owing to the actions of the fink. (The dead wire will conduct if touched.) Operating the fink on the reverse cycle renders the conditional false even when the disposition is present. Hence, the analysis fails. What Martin then proposes—perhaps prematurely—is that the reductive project be abandoned altogether and that we embrace an ontology of irreducibly dispositional properties (a powers ontology). Having considered Martin’s rejection of the SCA, Lewis writes: Once we scrap the simple conditional analysis, what should we say about dispositions? Martin’s own response is radical: a theory of irreducible dispositionality . . . Since dispositionality is irreducible, it is not to be explained in terms of the causal and nomological roles of properties, but rather vice versa. Those who are disappointed with the usual menu of theories of lawhood and causation might do well to try out this new approach. But those of us whose inclinations are more Fabian than revolutionary, and who still back one or another of the usual approaches to lawhood and causation, may well suspect that Martin has over-reacted. If what we want is not a new theory of everything, but only a new analysis of dispositions that gets right what the simple conditional analysis got wrong, the thing to try first is a not-quite-so-simple conditional analysis.²⁰

Unsurprisingly, Lewis follows his own advice, offering in place of the failed analysis a revised and much more complex analysis. Unfortunately for him, though his revised conditional analysis successfully evades the problem of finks, it is susceptible to a different problem, that of antidotes (another class of manifestation preventers).²¹ Yet further modified versions of the conditional analysis have been offered since, but we can save ourselves time by skipping past the details and cutting to the chase: as yet no wholly satisfying analysis of dispositionality has been located.²² There are a number of reasons why this is the case, but the one that matters most to friends of powers is that the proposed analyses have been reductive in nature. Though ostensibly about mere disposition ascriptions, there is much more to the Martin/Lewis debate than just the question of when we are warranted in applying certain predicates to objects. That is to say, it is a short step from talk of disposition ¹⁹ Lewis (1997). ²⁰ Lewis (1997: 148). ²¹ Bird (1998). See also Kvanvig (1999). We will revisit the problem of antidotes—albeit for a somewhat different reason—in Chapter 6. ²² Those interested in the cottage industry of attempts to analyse disposition ascriptions via counterfactual conditionals are advised to start with the summary in Choi (2012).

     ?

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ascriptions to that of what sort of properties objects have. Hence, though the debate is posed at the level of conceptual analysis, the real meat is at the ontological level. The reason this debate can shift so quickly from predication to properties is simple enough: the proposed analyses are reductive. A successful conceptual analysis shows how one or many concepts can stand in for another without loss, where the stand-ins are preferable, because they are better or more easily understood. And once we have a successful replacement of concepts, it opens the door to an ontological reduction. That is because we can then limit our ontological commitment to just those entities corresponding to the stand-ins. In other words, the proposed analysis would allow us to make sense of dispositionality using concepts that do not themselves rely on the notion of dispositionality to be understood. Once this substitution is accepted, we are no longer required to take seriously the existence of sui generis dispositions, just as long as we endorse the existence of the entities picked out by the stand-in concepts. Or, as a weaker variant, we are then in a position to treat dispositions as non-fundamental, as long as we endorse the fundamentality of the reducing entities. Either way, dispositions suffer a diminished status: they are at best properties non grata. As I say, there is more at stake in this debate than mere predication. Martin’s shift in the debate—from talk about conceptual analysis to that of properties—makes the stakes clearer: there is ontological territory to be won or lost. This attitude is mirrored in Lewis’s response: he wants to rescue the analysis precisely because he is concerned with its ontological implications. But the stakes and ramifications do not end there; there are metaphysic-level implications, too. Lewis recognizes that the downfall of the conditional analysis might mean surrendering his accounts of laws, of causes, and of many other aspects of the metaphysic he endorses. This explains why there is more at stake than disposition ascriptions alone, but it does not yet explain why a powers theorist would be sceptical that a satisfying analysis can be found. The answer, quite simply, is that powers theorists deny that dispositionality can be removed from our fundamental ontology. And this is where things really start to get interesting. Lewis, recall, describes Martin’s suggestion that we abandon the reductive project as ‘revolutionary’ and ‘radical’, and goes on to claim that adopting Martin’s sort of approach to the nature of properties would require us to develop ‘a new theory of everything’. Given the intimate ways in which metaphysical theories are connected and the centrality that a treatment of properties has within a larger metaphysic (not to mention what such an account of properties would mean for issues of laws, causes, and modality), he is surely correct: following Martin’s proposal would require a massive upheaval of the metaphysical status quo. Lewis warns us against such a revolution, citing his Fabian preference to stick with what he later claims are ‘widely shared ideas about properties, causation, lawhood and counterfactuals’.²³ It cannot be denied that Lewis’s ideas (or ideas near-enough-Lewisian) about the aforementioned metaphysical matters are widely held: they constitute a key part of the neo-Humean metaphysical framework that dominates contemporary thought. But that alone does not make them correct, nor is it a good reason to subdue any

²³ Lewis (1997: 148).

   uprising that may be in the offing. When it comes to questions regarding the nature of properties, causation, laws, or all that is built upon the metaphysical foundation they form, we should not adopt Lewis’s ideas without at first having considered what alternatives are available. After all, deep dissatisfaction with the metaphysical status quo may be a minority view, but there are known difficulties with the neoHumean framework that are often swept under the carpet. I thus suggest we enact the metaphysical revolution that Lewis fears, if only to see what is left when the dust settles. If the neo-Humean framework deserves to keep its place, then it should have no problem withstanding such a challenge. But I advise against placing any bets just yet. The opening shot of that would-be revolution has already been fired. Martin has proposed that we give up on trying to make sense of dispositionality in terms of causes, laws, and inert qualities, and that we instead invert the metaphysical framework so that dispositions (powers) are the ontological foundation. And more volunteers are starting to sign up. Like with so many revolutions, we seek to challenge the neo-Humean orthodoxy with something new, but born of what was there long before the neo-Humean orthodoxy took hold. Just as the neo-Humean orthodoxy owes much to its Humean origins, any metaphysic that countenances irreducible powers owes something to its Aristotelian ancestry, the very thing Hume fought to undermine. On the face of it, this might look like this is a case of out with the old and in with the older, but just as neo-Humeanism is not merely Hume warmed over, adopting a metaphysic based on an ontology of irreducible powers is much more than Aristotle exhumed.

1.4 A New Theory of Everything Lewis warns us that inverting the neo-Humean’s ontological structure will result in ‘a new theory of everything’.²⁴ He is, for the most part, correct: things will not be the same once turned on their heads. The core ontology will be radically different, as will the totality of any metaphysic built around it. But it is too early to say whether everything that makes up the powers metaphysic must also be different. However, as finding out might require having the whole metaphysic in front of us, the answer will have to wait for another time. Therefore, as I start to develop the powers metaphysic, it is the differences that will rule the day. The differences du jour concern the nature of causation and the nature of persistence over time. The aim of this book is thus twofold: on the one hand the book is an attempt to operate within a different metaphysic to that which presently dominates the philosophical landscape. The second aim of the book is no more modest than the first: it is to develop the parts of that new metaphysic that concern the nature of causation and how fundamental objects persist. It would be very difficult to provide the entire powers metaphysic within a single volume, but focusing on the matters of causation and persistence gives us insight into much of that grander metaphysic, and just how

²⁴ Lewis (1997: 148).

    

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different it is to the status quo. Regarding the theory of persistence, the account promises to do more than is typically done in such accounts, by offering an explanation of persistence. To that extent, the powers-based account of persistence has something to offer friends and enemies of temporal parts alike. The account of causation is similarly innovative, restoring genuine potency to the world. As we shall see, drawing on the resources of the powers ontology makes available solutions previously unavailable or inaccessible. The powers metaphysic has a great deal to offer, but you might be hesitant to take that first step. With that in mind, here is an initial reason for taking powers seriously (it also allows me to set the record straight regarding the force of that reason). The reason is this: physical theory describes the fundamental physical entities exclusively in terms of what sound like powers. When physicists describe the fundamental physical entities, they use such terms as ‘spin’, ‘charge’, ‘mass’, and so on. These terms look to be power terms: they concern what the fundamental entities can and will do. For instance, ‘charge’ names the power to produce electromagnetic fields, ‘spin’ the power to contribute to the total angular momentum of a system, and ‘mass’ the power to produce gravitational force.²⁵ Furthermore, not only do physicists use power terms to characterize the fundamental physical entities, they only use power terms: none of the ascriptions they apply look the least bit categorical. Why does this matter to the present debate? The neo-Humean takes all properties to be inert categorical properties. She might occasionally employ power terms, but these terms name second-class properties. They are either a shorthand for the categorical properties that are used in a proper analysis of them, or they are terms we use until we know more about the genuine categorical properties at work. Thus, the neo-Humean does not take her use of power terms to carry any serious commitment to the existence of powers. But if it turns out that physics—the science concerned with the most fundamental entities—continues to make use of power terms, then the neo-Humean’s placeholder strategy runs into trouble. She might maintain that these so-called ‘fundamental’ entities are not fundamental after all, and that they, too, will give way to yet more fundamental categorical structures, but this runs counter to what science suggests. Attempts to locate structure within the fundamental entities have consistently come up empty, well beyond the point we might have expected to find some.²⁶ It starts to look like some properties—maybe all of the fundamental ones—are powers.²⁷ As it turns out, this last claim is too hasty. Despite the willingness of friends of powers to declare the battle won in their favour, this fact about scientific practice does not win them the day.²⁸ Physicists employ power terms—that is for certain. But two points stand in the way of this settling the debate. First, these are the only descriptions available to them. As Frank Jackson indicates,

²⁵ Ellis (2002: 47) and Mumford (2006). See Livanios (2017) for a dissenting opinion. ²⁶ Molnar (2003: 133). ²⁷ On a sparse conception of properties, all properties are fundamental. Hence, on that view, all properties will be powers. ²⁸ I discuss this matter in detail in Williams (2011a).

   when physics tells us about the properties they take to be fundamental, they tell us about what these properties do. This is no accident. We know about what things are like essentially through the way they impinge on us and on our measuring instruments.²⁹

And second, the terminological usage does not dictate the ontological facts. Even if— as it appears—these power characterizations mark the end of scientific explanation in microphysics (owing to the nature of its methodology), this alone does not fix the ontological picture. It could still be the case that these properties are categorical, even if we are unable to characterize them as such. Try as you might (and many have), you cannot properly reason from facts about terminological use in microphysics to facts about powers. Physical theory is, unfortunately, more ontologically innocent than it appears. But even though this does not win the day for the friend of powers, it ought to have the neo-Humean sweating under the collar. She lacks a non-powers-based description of the fundamental properties. The ontological question is an open one, but there are minor theoretical advantages to treating the fundamental properties as being as described. If the neoHumean wants to deny that what you see is what you get (or more correctly, what you infer from certain test behaviours is what you get), then she needs to offer reasons in defence of her hidden categorical structure. Perhaps, in time, she will. Even if she can, we nevertheless have a good reason for looking beyond the neo-Humean status quo and taking the powers metaphysic seriously.

1.5 Ontology Fundamentals There are many ways of developing a powers ontology, and many ways a friend of powers might understand the natures of the powers themselves. Thus, if you are relatively new to powers, you should keep in mind that mine is but one example: the friends of powers is a club with an increasing number of members, and we do not all see eye to eye on matters ontological or metaphysical. What you will find in this book is one way that a powers ontology can be configured, along with the requisite domestic squabbling and territory-marking involved in defending my preferred configuration. That goes double for the metaphysic developed with it. That said, the differences between the various configurations only look significant from nearby. From the much removed neo-Humean perspective, they will appear similar. Even as one gets closer, it is clear that the range of plausible powers ontologies form a close-knit family developed with a similar vision and a shared set of primitives. As with neo-Humeanism, one finds a similar flavour running through them all. Thus, though the ontology on offer is (unsurprisingly!) what I ultimately believe to be the correct one, and it has quirks that are peculiar to it, it nevertheless ought to be sufficiently representative. Regarding the details of the ontology, the powers are the star of our show, and as we move forward they will hog the spotlight accordingly. But they are not the only member of the cast: the supporting cast consists not only of the parts of the ontology that get lower billing, but also certain meta-ontological assumptions on which the ²⁹ Jackson (1998: 23).

 

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ontology and metaphysic rely. Some of those will be specific to the present view, too. This last section provides a brief rundown of the supporting cast. Those interested in these topics in their own right will find them rather terse, but spelling them out in the full detail they deserve would take us too far afield. Properties. Powers are properties. That is, they are ways that objects are. Objects can be red, objects can have a mass of 0.0034 kilograms, and objects can be attracted to other objects with like charge; these are all ways that objects can be. Moreover, properties are repeatable ways that objects are, meaning that many objects can be the same way. Many objects can each be exactly 0.0034 kilograms, or red, or attracted to like-charged objects, and so on. These ways that objects can be constitute a fundamental ontological category. Properties are thus not reducible to sets or classes of exactly resembling objects, nor to mere predications, or any other nominalist reduction. Put bluntly, I take properties to be real. This should come as no surprise: an ontology that puts powers at its core ought to be one that treats those powers as genuine existents.³⁰ I do not, however, take a stance on the matter of property similarity. Property instances are genuine entities, and properties constitute a category of being distinct from the object category—the category of property bearers—but I do not here endorse the realist thesis that two instances of the same property type are strictly numerically identical (universals) over the theory that property instances are particulars, pairs of which might be exactly similar (trope theory), or vice versa. Both theories take properties to be real, and both afford an account of property and object similarity, and that is sufficient for the ontology I develop.³¹ Furthermore, as ways objects are, properties are not substantial particulars in their own right. Thus, the properties—those ways that an object might be—cannot, in and of themselves, be the sorts of things out of which objects are composed. Thus, they are not tiny building blocks of reality, or anything of the sort.³² Objects. Objects are the things that bear properties: they are the things that are the ‘ways’. Objects may be thought of as particular substances (a particle; a field; an electron), as some underlying ‘I know not what’ (substratum), or as particularized natureless ‘property-havers’ (bare particulars), but I reject the claim that objects are themselves nothing more than bundles or collections of properties (bundle theory).³³ There is an object category, and it is not reducible to mere collections of properties. This is the flipside of the account of properties just presented. Properties are ways. That phrase is not the clearest, but it gets across the main idea that objects are capable of taking on a variety of forms. They come in this form or that, and can change forms throughout their lifetimes. Those different forms are the ways that

³⁰ For a different tack, see Unger (2006). Unger defends a (non-trope) nominalist account of powers. I am uncomfortable with this, to say the least. ³¹ See Tugby (2013a) for reasons to prefer universals, and Platonic realism in particular. ³² Pace Campbell (1981, 1990). Any trope theory would thus have to be more like Martin’s substance-based trope theory (1980). This will prove significant to my powers-based accounts of causation and persistence. ³³ See Black (1952).

   objects are. But you cannot have a way without a something that is that way. The objects are the somethings.³⁴ In order to take seriously the suggestion that objects are nothing more than bundles of properties, one would have to take properties to be sufficiently substantial. They must be robust enough to be able to enter into building relations with one another such that they can form objects. This makes properties more like minisubstances: building blocks from which objects are composed. But I do not see properties as at all like this.³⁵ So, what are objects, if not bundles of properties? Beyond saying that they are something more—the something that has the properties; the something that is the ways—I have little to add. But (I believe that) everything I have to say about powers, and their role in the powers metaphysic, works equally well under any of the standard non-reductive treatments of objects. I take the object category to be real and fundamental. I likewise reject those ontologies that take processes or ‘goings-on’ to be fundamental, such that objects are second-class existents, abstracted away from those processes.³⁶ There are processes to be sure (they are protracted events), but they depend on the objects and properties that comprise them, and not the reverse. Property instances are dependent entities because they depend for their existence on the objects that instantiate them. But the dependence runs in the reverse direction, too. There is no sense to be made of an object that is not some way(s). However limited or expansive that range of ways might be, and however banal or unusual those ways are, any object that exists must be some way(s). It must, for instance, occupy some region, and differ from the region that it is in and from those around it, and it must have capacities for how it will be soon after. It is impossible that any object should fail to be any way at all, and thus all objects are such that they depend on their properties as much as the properties depend on them. (My claim that objects cannot exist ‘unclothed’ should not be read as a rejection of substratum or bare particulars. I take both to be live options. What I deny is that either should exist at any time without properties.) States of affairs. There can be no property instances without objects that bear them. And there can be no objects without ways those objects are. We can thus conclude that entities from these two categories come as a package deal: nature presents us with objects bearing properties. These package deals are known as ‘states of affairs’.³⁷ These are the basic existential units of the powers ontology I defend. Like Armstrong, I take the world, at base, to be a world of states of affairs; unlike Armstrong, I take the primary case to be objects bearing powers.³⁸ ³⁴ For contrast, see Brian Ellis (2009) for an example of bundle theory plus powers. ³⁵ Consider: if properties were independent entities, then one might reasonably expect to find them ‘floating free’ of other properties or bundles. Pace Campbell (1981), this does not seem to be the case. ³⁶ The champion of process ontology is Whitehead (1931); his acolytes are few and far between. That said, I detect shades of process ontology in some recent accounts of powers, including: Mumford and Anjum (2011), Heil (2012), and Marmodoro (2017). ³⁷ Armstrong (1978, 1997). I follow Armstrong in understanding states of affairs as instances of particulars instantiating properties and complexes thereof, not as abstract objects. ³⁸ Whether or not this is sufficient to fix all the facts about the world—to wit, whether a totality fact is needed, too—is not something I have the space to explore here. See Armstrong (2004a).

 

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‘State of affairs’ is not a complicated notion. In fact, as presented, it resembles objecthood, especially once we appreciate that objects cannot exist without properties. So, why not limit the ontology to objects? The answer is that not all states of affairs are objects. Included as states of affairs are objects standing in relations to one another. Armstrong himself understands a state of affairs to be ‘a particular’s having a certain property, or two or more particulars standing in a certain relation’.³⁹ In fact, relations play a key role in Armstrong’s argument for the existence of states of affairs. Consider the asymmetrical relation loves, the fact that Joanie loves Chachi, and the (lamentable) fact that Chachi does not love Joanie. The mere existence of Joanie and Chachi and their instantiating the loves relation does not alone determine the right set of facts in this case. With just those three constituents, three different sorts of facts could obtain: (i) Joanie’s unrequited love of Chachi; (ii) Chachi’s unrequited love of Joanie; or (iii) Joanie and Chachi’s mutual love of one another. We are after (i). That means the world must be appropriately arranged such that Joanie stands in the loving relation to Chachi, but not the reverse. The constituents alone are not up to the task, but states of affairs can come to our rescue. Joanie’s loving Chachi (and no similar loving relation going the other way) is a specific state of affairs. Hence the need for states of affairs.⁴⁰ As the above implies, including states of affairs in one’s ontology constitutes an ‘addition of being’ to the world.⁴¹ This nebulous phrase means that something extra must be included in the world in order to fix the facts. But that something need not be some thing, if by ‘thing’ one means an object or a property. The extra something is perhaps a structural feature, in the sense of ‘structure’ Sider employs, but it need not be a concrete (or even abstract) entity of any sort.⁴² This addition of being stands in contrast with Armstrong’s notion of the ‘free lunch’. To the layman, a ‘free lunch’ is a lunch you do not have to pay for. For the ontologist, a ‘free lunch’ is a fact/truth/ entity that obtains/holds/exists in virtue of some more fundamental fact/truth/entity obtaining/holding/existing (it can be any or all of these). For example, it is commonly held that if the parts of an entity are properly configured, then the whole that those parts form is something one gets for free.⁴³ Armstrong takes determinable properties to be on the menu for the free lunch: if some object is a determinate shade of red, crimson say, then it is true that something is red in virtue of that object’s being crimson. The redness comes for free when crimson is instantiated; the redness is no addition of being.

³⁹ Armstrong (1978: 80). Armstrong uses ‘particular’ where I would use ‘object’. ⁴⁰ Armstrong (1989: 17). As Armstrong notes, a trope theorist can avoid the need for these states of affairs if her tropes are non-transferable, meaning that Joanie’s love of Chachi is essentially Joanie’s love of Chachi, and could not have been the reverse, or a love of anyone else by or for anyone else. This fixes all the relations without the need for states of affairs. For convenience, I will continue to speak of states of affairs, with the recognition that a trope substitute is available for some of these. ⁴¹ Armstrong (1997). ⁴² Sider (2012). ⁴³ It is customary to think of free lunches as things of a higher level that depend on things of a lower level. Armstrong analyses ‘free’ in terms of supervenience, but nothing prevents us from employing other building relations. I myself am rather sceptical of free lunches, ontological or otherwise. Amusingly, Armstrong once went to some lengths to buy me lunch, but I do not believe it was in an effort to prove a point!

   Sparsism. To be a sparsist—as opposed to an abundantist—about properties, is (at least) to believe in the existence of only those property types required ‘to characterise things completely and without redundancy’, where the characterizations are (typically) those coming from our best sciences.⁴⁴ Some versions of sparsism add further restrictions; Lewis’s sparsism, for instance, adds that the sparse properties are those that: underlie qualitative similarity, carve at the joints, are intrinsic, and are highly specific, to name a few. Some of these are harmless restrictions, but let us put them to one side and stick with just the minimal understanding.⁴⁵ On that minimal understanding, a sparse property type is one that a realist account of the natural sciences cannot do without when characterizing the relevant objects. I am this sort of sparsist, and will assume sparsism in what follows. (Why just the minimal interpretation? I ultimately endorse maximal sparsism, but some of the additional restrictions step on the toes of what I defend elsewhere in the book, and so are not restrictions I want to assume without argument.) The world needs to have certain properties in it to do all the things it does, and also to account for what things it could or might do, and so our best account of the world needs to make reference to those properties. But those same theories do not require that the world have in it any additional properties beyond those just mentioned, and so I reject abundantism. This minimal sparsism, then, is really just a kind of property minimalism, in the spirit of Occam’s razor. It is a refusal to posit properties that our best theories of the world do not demand we include. Regarding those ‘best’ theories, I have presented them as coming from our best sciences, and for the most part I take that to be true. In fact, I tend to further restrict the set of theories to those just coming from our fundamental sciences (more on this below), but we need to leave room in case there is more than this required to make the world tick. Hence, I reserve space for something more. The more might well come from decidedly non-empirical investigations into the nature of the world. That is, it may come from philosophy, and from metaphysics in particular. Consider: it might be that the account of the world as given by the natural sciences—or physics in particular—is complete. But it just as well might not be. And not just because the picture of the world as given by physics might miss out on essential aspects of macroscopic phenomena (which it perfectly well might), but because even the fullest final account that incorporates every scientific domain might still be incomplete. The methodology of the sciences is such that some properties might simply be outside of its scope. Take ethical properties, for instance. Assuming they are real and evade reduction, then there may be properties present in the world to which science has little or no access. There may be similarly evasive metaphysical properties. And so I would rather leave open the epistemic possibility that there are properties (however mysterious) beyond those that science discovers, than legislate against them from the word go. Micro-reductionism. I have said something about the general form that objects and properties take, and I have indicated that I presuppose the sort of minimalism that

⁴⁴ Lewis (1986a). See Armstrong (1992) and Schaffer (2004). ⁴⁵ As Schaffer (2004) shows, there is room for disagreement regarding one’s sparsism.

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sparsism entails. But I have not said much about which sparse properties there are, nor anything specific about the objects that have them. The short story is that I pair my property sparsism with a general property and object fundamentalism. That is, I will assume (to some extent) that the properties and objects that exist are those that we need to ground the truths about all other would-be objects and properties. In other words, I pair my minimalism with yet more minimalism. The basic assumption behind both is that we should make do with as little ontology as we can. Naturally, this needs to be balanced with any rise in complexity that comes with a reduction in ontology.⁴⁶ My fundamentalism is therefore defeasible, and would be defeated if the theoretical cost of a minimalist ontology is too great. But on the assumption that the theoretical costs are less than, or at least no more costly than, any richer ontology, then we should refrain from postulating the existence of entities that we can do without. Of course, ‘doing without’ is one very large promissory note that will surely bounce if you try to cash it any time soon, but the lack of present concrete answers and explanations regarding the ‘hows’ should not dissuade us from wanting to explain less fundamental things in terms of those which are more fundamental.⁴⁷ As previously indicated, what is fundamental might not simply come from the picture of the world as given by our best future physics. It might turn out that people are fundamental existents, or that the fundamental base is not an array of tiny particles or fields, but a giant universe-sized field, or all of spacetime. That is, it is not a requirement of fundamentalism that the fundamental entities be microphysical. If there is just one (giant) fundamental entity on which all else relies, that would still be in keeping with my fundamentalism, just as long as the other candidate objects and properties are ultimately explained in terms of it. That said, my bet is on the rather unoriginal thesis that the fundamental entities will be those postulated in our best physical theses, along with whatever not-the-subject-of-physics properties we need to postulate in order for the world to run. Consequently, you will find me leaning towards a micro-reductive picture of the world, when and if I can. And when I cannot—which is much of the time, owing to the aforementioned promissory note—I happily make use of mid-sized ontology (it is a better place to find homey examples). In the long run, that midsized ontology will either give way to something smaller, or it will not. I am happy with either scenario, as long as there is no ontological waste involved. I would be similarly happy to learn that there is just one giant object, or that the only property bearers are fields. I will continue, for the time being, to talk of particles and tables, with the recognition that the latter will probably give way to the former, and that even the former might not be the last stop in the descent to the universe’s basement. For those who are worried about micro-reductionism, or worried about any form of fundamentalism, I remind you that these theses alone do not entail the nonexistence of macroscopic phenomena. That is, it does not follow from the fact that ⁴⁶ Compare with Sider (2012). ⁴⁷ I leave the details up to the grounding theorists, or whomever replaces them in that particular philosophical niche. See Correia and Schnieder (2012).

   some entities are fundamental that the non-fundamental entities are non-existent. One might combine micro-reductionism with a building relation that gets you macroscopic entities for free.⁴⁸ Nor is it any part of the micro-reductionism that I favour that all (or even the best) explanations of all phenomena will be couched in those terms. Micro-reductionism is an ontological thesis concerning what entities exist fundamentally; this implies, but does not entail, micro-explanationism. Eternalism? I am not going to assume that eternalism is true. Eternalism is the view that the temporal dimension is analogous to the spatial extension, wherein all times (and the objects that exist at those times) are on equal ontological footing, and the present is not ontologically privileged.⁴⁹ Just as you do not consider your present location to be ontologically privileged—meaning that being spatially removed from your present location does not affect the existence of those things so located (when you are in John o’Groats, the cliffs at Land’s End are no more or less real than the couch on which you are sat)—eternalists do not consider objects located at times earlier than or later than the present to be any more or less real. Eternalism is standardly contrasted with presentism, the account of time according to which the only things that exist are those which presently exist, but can be contrasted with any account that privileges the present, such as the growing block or moving spotlight accounts.⁵⁰ When push comes to shove, I consider myself an eternalist, but I will not here assume that eternalism is true. Nor will I defend eternalism. In fact, eternalism does not play a significant role in my ontology as far as the present discussion is concerned. Those who have a problem with eternalism are thus invited to forget I brought it up. So, why did I bring it up, you ask? The first reason is that Chapter 8 offers a powers-based account of persistence, and though the account is friendly to perdurantists, endurantists, and stage theorists alike (and their preferred accounts of the metaphysics of time), the basic framework favours the eternalist. (It is friendly to all, but a little more friendly to some.) The second reason is going to sound rather wiggy. It is so that you can be on the lookout for eternalist modelling. An ontology centred on causal powers is compatible with all standard theories of time, yet one finds that many friends of powers favour the combination of presentism and endurantism.⁵¹ I favour neither. But the point is not that we have different beliefs about time and persistence, nor that these matters are largely orthogonal to the present discussion, it is that it is useful to model powers in broadly eternalist ways, and this is not the norm. I am thus putting my cards on the table. Finally, should it turn out that the metaphysics of time and persistence are not orthogonal to the best way of configuring a powers ontology, it is good to have had the eternalism out in the open.

⁴⁸ Bennett (2011) makes use of a general class of metaphysical relations that she calls ‘building’ relations, that includes grounding, dependence relations, and the like. ⁴⁹ See Smart (1963), Mellor (1998), and Sider (2001). ⁵⁰ See Cameron (2015) and Skow (2015). If one drops the requirement that all times be on equal ontological footing (or conversely if one denies that the spotlight of the moving spotlight carries with it ontological privilege), then eternalism and the moving spotlight could be combined. ⁵¹ See Mumford (2009a), Wahlberg (2009), and Heil (2012).

2 The Neo-Humean Status Quo 2.1 The Humean Stain The vast majority of contemporary metaphysics is pursued from within what is best described as a neo-Humean framework. This is not to suggest that the ranks of metaphysicians run deep with Hume scholars, nor that doctrines lifted directly from the Treatise or the Enquiries hold sway in contemporary debate. But many of the core metaphysical principles and ideals at work in the contemporary arena have a distinctly Humean flavour, and can be seen as natural extensions of those that Hume endorsed or assumed. I hazard that most of what passes for good metaphysics these days bears some Humean stain, intended or otherwise. The same could easily be said of the metaphysical aspects of contemporary philosophy in general. Hume’s influence is ubiquitous. Nowhere is this influence more evident than in the work of arch-neo-Humean David Lewis. Lewis was the modern-day Humean par excellence, and unashamedly so. The influence of Lewis’s work on contemporary metaphysics has been profound, and for quite some time the debates at the forefront of metaphysics have been those set by Lewis. Many of the popular solutions are his, too. Even the dissenters tend to be more congenial to his solutions than not. I would not hesitate to declare Lewis the most influential metaphysician of the last quarter of the twentieth century, and the incumbent for the first quarter of the twenty-first; few would disagree. A by-product of Lewis’s influence on contemporary metaphysics—if not constitutive of it—is the widespread adoption of views consonant with (if not identical to) those he held. This has only added to the prominence of the neo-Humean metaphysic. The pervasiveness of this influence can be seen in the extent to which adopters can be unaware of just how much their views borrow from the Lewisian-cum-Humean corpus. Consider: given the ways in which metaphysical theses are interlaced, conscious adoption of a Lewisian (or near-enough Lewisian) thesis brings with it unconscious adoptions (not unlike the way little extra programs might be added to one’s computer when loading a targeted program). Friendly dissension from those same theses can have much the same effect, as the space of purportedly viable alternatives is itself highly circumscribed: when you set the debate you thereby determine the range of ‘acceptable’ solutions. Consequently, many debates in contemporary metaphysics are more like internal debates than they first appear, situated within the Lewisian-cum-Humean framework and criticizing one or another aspect of it, even when they are conducted in earnest, with an effort to keep assumptions at a minimum. Indeed, even those apples that fall furthest from the Lewisian tree still tend to fall within the greater neo-Humean catchment area. Solutions and The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

  -   suggestions that deviate too greatly from that corpus are given short shrift for exactly this reason, despite any independent plausibility they might boast. Any philosopher worth her salt ought to be willing to adopt the conclusion of a deductively valid argument based on independently plausible premises. But many of the so-called ‘independently plausible’ premises that pass muster in contemporary metaphysics are developed within a neo-Humean framework, and hence we might question the independence of those that appear to support neo-Humean conclusions. Plenty of folks deny that they subscribe to anything neo-Humean, not even in a distantly removed form. But the nature of metaphysics makes it hard to avoid adopting various theses even when they are not one’s focal topic. Contemporary metaphysics is ‘theory-laden’ in the Duhem–Quine sense: theories are connected to one another, rely on one another, and are applied in groups.¹ Hence, you cannot pick out this piece or that without bringing along another. Moreover, the most successful metaphysics is systematic: its parts are interconnected in such a way that a few central theses have wide application across the scope of metaphysics. And even when systematicity is not the aim, it is not feasible to engage in metaphysical thought in a way that legitimately isolates one metaphysical puzzle from all others. At any given time a specific puzzle will take centre stage, but rough solutions to others will be working behind the scenes, pulling the ropes of constraint and preference. Metaphysics is all but impossible to do without either having a rough framework in mind or developing one en route, even if that framework remains largely in the background. This is where the neo-Humean metaphysic hides when it is not out front for all to see. I am thus claiming that most folks employ a metaphysical framework that is largely neo-Humean—be it in the foreground or the background—even if its possessors are unaware that they employ one at all. When we do metaphysics, we work with a background framework, however rough and ready, and try to resolve this or that metaphysical puzzle from within it. In the introduction to his first volume of collected papers, Lewis explains that it was not his aim to be a systematic philosopher. He ended up one regardless, but notes that he would have liked to have approached problems piecemeal, offering ‘independent proposals on a variety of topics’. It was not to be. As he says, he ‘succumbed too often to the temptation to presuppose [his] views on one topic when writing on another’.² Metaphysics, quite frankly, is very hard to do. With so many moving parts, progress is made easier by fixing as much of the framework at a time as one can. Thus, I do not think Lewis can be criticized for having gone about things in the manner he did. I doubt he could have made the progress he did had he done otherwise. Perhaps the ways we reason make us incapable of doing anything else. But this procedure is not limited to metaphysics. We have a background in place— a metaphysical background—when we engage in most philosophical investigations. This should not come as a surprise. One can hardly ask, for instance, whether deteriorating artworks should be restored to their former glories, without thinking of them as objects with mutable properties. As we start to find solutions, the background becomes increasingly fixed. And even though ideas about the nature of properties will

¹ Duhem (1954), Quine (1951).

² Lewis (1986b: ix).

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not be at the forefront of one’s thoughts on those occasions, how one envisions them will place subtle restrictions on the sorts of solutions one can entertain. As will one’s beliefs about change, time, possibility, objects, and so on. The background metaphysic need not be well formed or ever at the forefront for it to exist or make a difference: even a background impression of properties as inert qualities impacts how one sees the place of artworks in the world. I will spare us all the tedious task of showing the influence one’s background metaphysic can have on our thinking, philosophical or otherwise; hopefully the point is clear enough.³ But even if it is not, one might begin to appreciate the role neo-Humeanism plays in one’s own thinking as I present the core of the account. So, what exactly is this neo-Humean metaphysic that has contemporary metaphysics in its grasp? I see it as having four main components, concerning: properties, possibility, laws of nature, and causes. More specially, they are that: (i) properties are inherently non-modal and passive; (ii) what is possible is restricted only by imagination and coherence; (iii) the laws into which objects enter do not force them or push them around—they are non-governing descriptions of the positions and states the objects take up; and (iv) causation is a similarly weak and extrinsic relation. The components of the neo-Humean metaphysic overlap in various ways, but at their heart is the doctrine of Humean Supervenience, according to which the most fundamental or sparse properties are categorical, thus lacking modal or causal characteristics, and so whatever causal or modal facts obtain do so because they are determined by the ‘vast mosaic of local matters of particular fact’ (that is, the limited base of categorical properties).⁴ What follows is an introduction to the neo-Humean metaphysic. I warn the reader that this is not supposed to be anyone’s view in particular; there is no exact canon to which all neo-Humeans subscribe. What typifies neo-Humean metaphysics is a family of connected theses that play off one another in various ways. My aim is to provide the metaphysical ‘flavour’ these views tend to share, thereby presenting some of the neo-Humean theses that dictate contemporary metaphysical thought and that lurk in the metaphysical dimensions of the rest of philosophy. The components of the view I set out most clearly resemble those of David Lewis, but the point is no more Lewisian scholarship than it is Hume scholarship.

2.2 Of Possibility and Necessity A natural ancestor of Hume’s account of what is possible (and of what serves as an adequate guide to discovering what is possible) is the first major aspect of the neoHumean metaphysic we will consider. According to Hume, if a proposition can be properly entertained (a mental exercise of some sort), and it does not run foul of the constraints of logical consistency, then it describes a genuine possibility. Hume thus claims that conceivability is a guide to possibility. He famously states that: ³ I will, however, direct you towards Groff (2012), in which she provides evidence of the neo-Humean stain in contemporary social and political philosophy and discusses the restrictions it imposes on the range of viable views. ⁴ Lewis (1986b: ix). See also Carroll (1994).

  -   ’Tis an establish’d maxim in metaphysics, That whatever the mind clearly conceives includes the idea of possible existence, or in other words, that nothing we imagine is absolutely impossible. We can form the idea of a golden mountain, and from thence conclude that such a mountain may actually exist. We can form no idea of a mountain without a valley, and therefore regard it as impossible.⁵

For the most part, what Hume treats as possible is constrained by logic and imagination alone. That means that the space of possibilities is particularly generous. If you can dream of talking donkeys without contradiction (you can), then such fantastical things are possible, despite their being non-actual. Round squares, by contrast, do not fare so well, failing on both counts. Something’s being both round and square is not only contradictory, it is unimaginable, too. Just as Hume takes only ‘clear’ conceiving to be a guide to what is possible, contemporary versions of this conceivability-driven approach to possibility place various demands on the sort of conceiving adequate for picking out what is possible. Some follow Hume, insisting that only deep or clear conceiving can tell us what is possible; others place no limits on the operations of the imagination, but restrict the role of conceiving to that of providing evidence for what is possible. Nonetheless, even with those conditions in place, the range of possibilities remains vast.⁶ Talking donkeys? Sure. Fire-breathing dragons? Why not. One-eyed, two-toed, three-armed, vengeful giants? But of course, this is a catholic approach to possibility! There is virtually no limit to the ways in which the constituents of the world could legitimately have been combined, or how they can be recombined, or how all these can or could have been arranged.⁷ One can limit the scope of possibilities under consideration for some particular purpose or other (like if we were to consider only those possibilities in which the laws of nature are exactly like the actual ones), but this does not restrict the scope of what is possible in general. A sister thesis, often considered part of that mentioned above, takes epistemic possibility as a guide to metaphysical possibility. For a proposition to be epistemically possible is for it to be such that (for some subject) it might be the case that the proposition is true, for all that subject knows.⁸ A proposition is epistemically possible for some agent just in case the proposition’s being true is compatible with everything the agent knows (or seems so to the agent), even if not suggested by it. Hence, it is often claimed that a proposition’s being such that it could be true for all we know is taken to be sufficient for (or evidence for) its describing a genuine metaphysical possibility. If, for all we know, gold could have been a thinking substance, then ours could have been (or is) a world in which gold thinks. Thinking gold is thus, according to this account, a genuine possibility. We can now ask what sorts of things the neo-Humean takes to be possible, based on what we can imagine. Pausing first to put on our Humean hats, let us return to the talking donkeys. The ability to speak is, by and large, restricted to humans. But imagine a human who cannot speak (this, unfortunately, takes very little imagination). We can imagine—without contradiction—a human lacking this ability, and ⁵ Hume (1978: I.ii.2.2). ⁸ Chalmers (2011).

⁶ See Yablo (1993) and Chalmers (2002).

⁷ Lewis (1986a: 87).

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therefore what we have imagined is a genuine possibility. The two (being a human and the ability to speak) are now metaphysically cleaved, because we can clearly imagine cases of one without the other. Two things result from this mental cleaving. First, we take our ability to cleave these two as evidence for (if not constitutive of ) the fact that the ability to speak is not necessary to humans.⁹ Second, it adds being human and the ability to speak to our cache of raw constituents that can be combined and recombined to form new imaginings. Drawing on that recently expanded cache of constituents, we can now combine the ability to speak with that of something’s being a donkey. No apparent contradiction arises, and so again we have described a genuine possibility: that of talking donkeys. ‘To form monsters, and join incongruous shapes and appearances’, writes Hume, ‘costs the imagination no more trouble than to conceive the most natural and familiar objects.’¹⁰ It is surely the case that no donkey has ever spoken, and it is unlikely that any ever will, but according to Hume and the neo-Humeans it is nevertheless possible. Perhaps this would have required evolution to have taken a different path, or Doctor Moreau’s work to have received more funding, but it is deemed possible nonetheless. Through two simple acts of imagining, one has undermined the claim that the ability to speak is a necessary feature of humans, and recombined the constituents to factually describe something that is not the case but could have been. The world is, to borrow Hume’s phrase, ‘loose and separate’ in this cut-and-paste sense. Bits of the world can be cleaved from one another in the imagination, and the imagination is then free to attach them elsewhere in a variety of ways. There is virtually no limit to the mental ‘collages’ you can construct from dicing your experiences into tiny bits and sticking them back together in different ways. A few collages are off limits, but most are fine. The range of logically consistent imaginable recombinations is vast, and therefore so, too, is the neo-Humean’s space of what is possible.¹¹ Hume’s cases build upon the set of impressions gained from experiencing the world. The ideas we have ‘are copy’d from our impressions, and there are not any two impressions which are perfectly inseparable’. Consequently, any time ‘the imagination perceives a difference among ideas, it can easily produce a separation’.¹² But the neo-Humean does not ‘limit’ herself to impressions alone. She extends the range of what is possible to things we have never seen and that cannot be formed through recombination of the parts of those we have. The neo-Humean thus adds to the pool of available constituents a set of ‘alien’ properties: properties not possessed by any actual entities (past, present, or future), nor obtainable by means of conjunction, interpolation, or extrapolation, of actual properties.¹³ The result is a staggeringly liberal account of possibility: you can construct a lot of collages! Adopting this general approach to what is possible leads to a great deal of

⁹ It may be that our ability to imagine the separation of the two is a reflection of our believing that having the ability to speak is not necessary to humans, but the order here is not significant. ¹⁰ Hume (1975: I.ii.13). ¹¹ See Lewis (1986a: 87–90). Lewis denies that imaginability is much of a guide to possibility, unless used in the way I have described. ¹² Hume (1978: I.i.3.4.). ¹³ See Lewis (1986a: 159–65), Armstrong (1989), Heller (1998), and Divers (1999).

  -   monstrous things which, according to the neo-Humean, could have been the case, despite their not being so. But the largely unconstrained cutting and pasting does not end there. So far I have considered examples concerning the recombination of objects and their properties. But the neo-Humean’s liberal space of possibilities extends well beyond just these ontological categories. If Hume is known for anything, it is that there is nothing deep to be discovered about the sequence of events, vis-à-vis their causal ordering, beyond certain psychological projections we contribute. As much as one might take a pair of events to be causally related such that one must precede the other, Hume believes that if one can imagine the former having occurred without the latter, then such an occurrence could have taken place. And though past experience might tell us that the two events are constantly paired, that is all we have to go on when we consider what—if anything—must follow from the former event. Once you have satisfied yourself that objects, properties, and events, can be cleaved from one another in the imagination, one has a hard time seeing why any entity should be so fixed that it, too, could not be separated from the circumstances in which it was found, and, at least in theory, placed anywhere else. Everything—that is, every thing—begins to look loose and separate. This sort of thinking about what is possible goes hand in hand with what is referred to as ‘Hume’s Dictum’: the principle that there are no metaphysically necessary connections between distinct, intrinsically typed entities.¹⁴ What is this principle supposed to mean? To be intrinsically typed just means that what determines the sort of thing the entity is depends on nothing outside of it; that leaves us with the rejection of metaphysically necessary connections between distinct entities. A metaphysically necessary connection is a connection that could not fail to hold, come what may. If one entity is necessarily connected to another, then nature dictates that where you find the first (or when the first obtains, or is, or what have you), the other will be there, too. This could be: the having of some property by an object; two objects so connected; two events such that one event is always followed by the other; and so on. But in every case the entities are ‘fixed’ together, so to speak. Hence, their being separate in nature (as opposed to one’s imagination) would not be possible. You might now wonder what it means for them to be distinct, given their fixity. After all, if they are necessarily connected, in what sense are they distinct? The picture gets clearer if we start with non-distinctness. Clearly non-distinct (that is, identical) entities bear necessary connections to ‘each other’. (They are one and not two, and so talk of connections between ‘them’ is artificial, but it ought to be easy to grasp how facts or features of the ‘one’ would thereby necessitate the same in the ‘other’.) Now consider non-identical entities. Something about their being nonidentical opens up the conceptual space for difference. We might even say we can imagine one without the other, and in so doing we see both the sense in which we understand them to be distinct, and the source of the controversy. To believe in necessary connections in nature is to believe that things we can imagine as apart

¹⁴ This formulation is due to Wilson (2010). Wilson (2015) presents the role of Hume’s Dictum in Lewis’s system. See also: Hume (1975: I.iii.6), Lewis (1986a: 87–8), and Armstrong (1997, 2010).

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cannot, in fact, obtain as such. That does not make them one, but rather means that it is up for grabs whether the ways we individuate objects entail their being separable in nature. The neo-Humean claims that this is so entailed: to be distinct is to be free of necessary connections. Hume applied Hume’s Dictum to the case of causal connections, but neoHumeans expand its application to virtually any putative connection between entities of any ontological category. It is a neo-Humean rule of thumb that necessary connections are prohibited. The ramifications this has on how the neo-Humean understands laws and causes are straightforward: causal relata are loose and separate—there is no oomph, in the sense that the cause and laws do not make their effects come about necessarily—and could have been otherwise. What laws obtain need not have done so. Similarly straightforward are the implications the principle has for the powers-based metaphysic I develop: according to the neoHumean, there cannot be properties whose natures have it that their potential manifestations are part of their essences, as any property (or law, or cause, or effect) can be pulled apart from any other. Powers are properties that have possible futures built into them, and hence they do not play well with Hume’s Dictum or the neoHumean account of possibility more generally. I will discuss the neo-Humean approach to laws and causes shortly, once I have talked about the neo-Humean’s thinking regarding the nature of properties. But before getting there I want to say something more about the lack of necessity in the neo-Humean framework. According to the neo-Humean, there is a great deal that is merely contingent in the world. As indicated, if you eschew necessary connections, then you are going to endorse accounts of laws and causes that permit the possibility of them being quite different than they actually are. Likewise, your properties will be capable of attaching themselves to those laws in all sorts of different ways. Things could have been really quite different from how they are. Contingency abounds. But an interesting extension of this thesis gets applied—somewhat surprisingly—to metaphysics itself, as I shall now explain. One of the many ways in which the neo-Humean and I part company over matters of possibility concerns the possibility of alternative metaphysics. Consider what we might call the ‘basic metaphysical facts’ about the world. These facts constitute the solutions to a great many metaphysical puzzles. They are, so to speak, rules about how things must be, metaphysically. Take the debate over the structure of concrete particulars. Some folks deny they have structure, others take them to be complexes formed by uniting an underlying substratum with property instances, others yet claim that they are nothing but collections of appropriately related property instances. This last view is the bundle theory. Let us assume, for argument’s sake, that the bundle theorists are right about the composition of concrete particulars.¹⁵ That is, we shall assume that bundle theory is true. This fact—the truth of bundle theory—is what I am calling a ‘basic metaphysical fact’. Why this is a fact, and a metaphysical one at that, ought to be obvious. But its being basic is less obvious. What I mean by describing it as ‘basic’ is that it gives a rule regarding the construction of

¹⁵ They are not. But that is a discussion best had elsewhere.

  -   concrete particulars, but does not describe any specific instance. A basic metaphysical fact then is just a rule regarding the ways in which the world must be constructed.¹⁶ Any concrete particular that exists—if any do—must be such that it is a collection of property instances, in accordance with the rule. Let us assume that there is no controversy in claiming that there is a set of facts like this in operation in the world. This is the stuff of long-standing first-order metaphysical debate, and so ought to be as good as true. Nevertheless, there seems to be some difference of opinion regarding the status of these facts. I claim that the basic metaphysical facts are necessary; that is, any ways in which the world might have been (or could have been constructed, if you prefer) must conform with those facts. Neo-Humeans typically deny this, treating these facts as contingent. Not only do they think that there are many possibilities concerning what specific bundles could have obtained, they hold that it is possible that there are concrete particulars that are not bundles of properties. This might be easier to understand if we resort to possible worlds talk. It is commonplace for neo-Humeans to express the great range of what they take to be possible in terms of possible worlds: a possible world is a complete description of a way the entire world could have been (if not the entity picked out by that description). It captures a complete history of the universe (all the objects, properties, relations, and so on) not just as it is, but as it would have been had this or that (or this and that!) been different. In the manner of possible worlds speak, the neo-Humean thinks that there are many possible worlds that match ours with regard to the basic metaphysical facts, but claim that there are plenty of others that do not. They take the basic metaphysical facts to be up for grabs just as much as the application of those facts. There are worlds, they claim, where concrete particulars have no structure, and others where they are built around substratum. There may even be worlds that have all of the above, or one for some time and then others.¹⁷ I do not deny that the debate over the structure of concrete particulars—like many other first-order metaphysical debates—is a live one, and a lively one, too. There is some fact of the matter one way or the other, and it is fair to say that we do not know what it is. But I do not see how our ignorance in these matters translates to genuine ways the world could have been. If ours is a bundle theory world, then that is what it is, knowledge be damned. We can—of course—imagine worlds where the basic metaphysical facts differ from our own (an obvious truism; its being the case is an antecedent condition of metaphysical debate). And we are unsure what sort of metaphysic is active in the world. Throw in the neo-Humean’s liberal approach to what is possible, and the neo-Humean arrives at the conclusion that we must treat the alternatives as genuine possibilities. I cannot help but think of these basic metaphysical facts as much more fixed than the neo-Humean does. We can all make sense of what it would mean for these facts to

¹⁶ There is a larger set of metaphysical facts about the world that are not basic in this sense. They concern individuals. ¹⁷ It may be that the neo-Humean has some incredibly basic metaphysical facts that hold in every world, such as ‘any world must have a principle for the formation of concrete particulars’, but there are bound to be some who deny even that.

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differ, but why think we can make sense of them really being that way unless we are just talking about what, for all we know, could have been the case? Our ignorance should not be offered as evidence that something is possible. If the neo-Humean is treating our expressions of ignorance as a basis for genuine possibility, then something has gone awry. Granted, our ignorance makes us unable to rule things out, but that does not thereby rule them in. I am inclined to feel the same about conceivability: how can our imagining something’s being the case constitute evidence for that something’s being possible? This makes possibility awfully cheap. This is one of the major pitfalls of this sort of thinking about possibility and possible worlds talk: if you can describe a world, it lends artificial credence to thinking that things really could have been that way.

2.3 Of Categoricalism If you are comfortable believing that anything separable in one’s imagination is similarly separable in nature, and thus attracted to the thought that there are no necessary connections in nature, then you are likely to be okay with removing the laws and causes typically associated with specific properties, and thinking that properties—in and of themselves—have meagre essences. Laws and causes, you would believe, are only contingently connected with those properties, and so the real nature of the properties is what you find when they are stripped ‘bare’ of their contingent causal profiles. But you need not stop there: everything modal has got to go, too. Only when you remove all this contingent detritus do you finally get down to the property’s real essence. Only then do you get to properties as the neo-Humean understands them. Only then do you get categorical properties. According to the neo-Humean, the most basic properties are categorical. To describe a property as categorical is to say that it is in ‘pure act’; that is, exhibiting all of its nature at all times. With categorical properties, what you see is what you get; there is nothing more to the property that is hidden, and nothing it—unaided—is liable to do.¹⁸ (By contrast, power properties keep much hidden, revealing parts of themselves only in specific circumstances.) Categorical properties, in and of themselves, are thus entirely passive. They lack potential: they can only act if pushed around by something outside them, like a law. According to the neo-Humeans, all properties—all those that are owed a proper place in our ontology, anyway—are like this. Given the ubiquity of the neo-Humean metaphysic, most readers should have no trouble producing lists of putative examples of categorical properties. They are, we are told, the familiar properties we ascribe to objects every day. They are such properties as shape, size, number, colour, and so on.¹⁹ The neo-Humean conception of properties as categorical is clearly at odds with that of properties as powers: whereas the latter understands properties as inherently ¹⁸ Well, sort of. You could not see a categorical property without causal intervention, and so observation is no way to learn about the non-contingent nature of categorical properties. ¹⁹ As we will see, there is much dispute to be had here. Many—myself included—contend that all properties are powers. Hence, it is part of the powers ontology that these properties will be powers, if they are properties at all.

  -   powerful, the former strips them of all such responsibility. A simple version of the difference can be seen by contrasting the shape of a martini glass with its fragility. If the distinction genuinely obtains, then its shape is not something that in and of itself is full of threats and promises. Shape is just the topological arrangement of the glass’s constituent molecules. Its fragility, however, is a capacity that is future-directed: it threatens what sort of future will obtain if the glass is treated in the wrong way. It is not, therefore, in pure act. With fragility what you see is not what you get. You might find it strange to think that properties could fail to have potentialities built into them. It is surely commonplace to think that a change in a thing’s properties would mean a change in its capabilities. To wit, if you deflate a soccer ball, it can no longer roll, and if you paint it black, it would be hard to find in an unlit room. But there is an important distinction to be made between conceiving of properties as having these sorts of potentialities built right into them versus those potentialities being something that is added to them later. The distinction concerns the essence of the properties: powers are essentially such that they have their causal capacities built into them (properly understood, they just are those causal capacities²⁰). By contrast, causal capacities play no part in the essence of categorical properties. Categorical properties can acquire such potentialities in the right environments, but in and of themselves they are inert. These acquired causal capacities are not part of what a categorical property is. Key to understanding properties as categorical requires seeing them as non-modal; that is, not having any other ‘modes of being’ built into them. This is a rather odd way of speaking, but all it means is that there is nothing more to the properties than what they now display. Contrast this with a (putative) power like fragility: fragility has one foot firmly planted in things as they presently are, and yet is directed at future states that do not presently obtain (and might never obtain). Inasmuch as we understand fragility in terms of a potential future state of brokenness, we are speaking of the property in a qualified way, and so it is a modal property. To be directed at the future, as any power property is, is to exhibit some other mode than that of being in pure act. How, you might well ask, could anyone seriously maintain that all properties are non-modal? After all, if fragility names a modal property, then excluding it from what exists would demand one reject the obvious truism that glasses and a good many other things are fragile. Surely this is nonsense. Unfortunately, the case against the neo-Humean cannot be made so easily. For starters, the neo-Humean need not deny that glass is fragile, nor that fragility is a genuine property. Hers is the slightly weaker position that the sparse or fundamental properties are purely categorical. The sparse properties are all and only those properties that carve nature at its joints (that is, they are those properties referred to by our best scientific theories).²¹ They are fundamental to the extent that the categorical properties are the most ontologically basic: all other properties rely on the fundamental properties for their existence.²² On this view, the non-fundamental properties are very much second-class existents, if they are existents at all. The

²⁰ Plus a little something more that can wait until Chapter 5. ²² See Sider (2012) and Hawthorne and Dorr (2013).

²¹ Schaffer (2004).

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neo-Humean who countenances non-fundamental properties thus takes reality to have a hierarchical structure. At its base are the properties the ontology cannot do without. These are the properties the neo-Humean claims are categorical (though she may claim the same of the non-fundamental properties, too). When push comes to shove, the fundamental categoricals are the properties to which the neo-Humean is most committed. As one moves up the structure, the strength of commitment to higher-level properties diminishes. Some outright deny that these second-class properties exist at all; others admit them, but to a lesser degree. One way of picturing this concerns what actions a god would have to take to create a world like ours. According to neo-Humeanism, a god need only create the sparse set of categorical properties; the other properties come ‘for free’. A story about the manner in which the base properties support them is required, but the god does not lift another finger. By structuring things in this way, the neo-Humean is well within her rights to speak of the glass’s fragility without violating her categoricalism about properties. (It is worth noting that I, too, employ this hierarchical strategy, and that I am primarily concerned with the most fundamental properties. At times— typically to make examples more homey—I appeal to macroscopic properties to illustrate features of the microscopic level, but my apparent commitment to those macroscopic properties is a convenience. I will not yet take a stance on whether such properties are second-class or worse.) A key element of neo-Humeanism involves explaining how features the world appears to contain, such as powers, can be ‘explained away’ by the categoricalist framework. This sort of task is really the hard work of any metaphysic, and underlines the difference between an ontology and a metaphysic. An ontology is an answer to the question what exists, but a ‘metaphysic’ tells you how instances of those ontological entities give rise to the world as we know it. A metaphysic thus explains how the things that seem to exist are accounted for via an ontology that does not (strictly speaking) include them. The relevant part of the neo-Humean metaphysic is the story of how objects have powers, couched only in terms of categorical properties. The most common approach is the SCA (§1.3), which attempts to analyse the having of a power (disposition) in terms of stronger-than-material conditionals, or ‘counterfactual conditionals’. The story works in two steps: first, analyse the having of powers without recourse to powers themselves, by appealing to counterfactuals, and second, give an account of counterfactual conditionals that avoids commitment to any properties that are not categorical.²³ We need not assess the success of that reductive project here. The point is that powers seem to be a part of the world, so those who deny there are any such properties owe us an account of how any wouldbe powers are accounted for in an ontology that eschews them, which this attempts. Another strategy available to the neo-Humean (one I also employ for nonfundamental powers) makes use of the difference between predicates and properties. It may well be true that the glass is fragile, but the truth of the corresponding proposition does not demand that the glass possess the property of fragility, only

²³ It is bound to have other features, but it is not a worry so long as those other features are not powers (or merely powers in disguise).

  -   that the predicate truly applies. And all this demands is some truthmaker; that is, some portion of the world that makes the proposition true.²⁴ For some predicates, this will be a matter of the object in question possessing the corresponding property. This is a common truthmaker for such claims, but there are true predications whose truthmakers are more complicated, potentially involving the obtaining of various states, facts, principles, properties, and arrangements thereof. Hence, it might be that the glass counts as fragile in virtue of its having other properties working in concert with one another in some specific nomological context, and not fragility at all. (This sort of approach sits well with the austere neo-Humean ontology mentioned above.) This is part of a larger metaphysical lesson concerning the connection between predicates and properties: the relationship between the predicates and properties is not standardly isomorphic. There is sometimes a one-to-one correspondence between a predicate we use and a property in the world, but it will just as often be one-many, many-one, one-none, or none-one. Hence, it does not follow from an instance of true predication that there is any one property the predicate picks out, or any property at all. True predication requires no more of the world than that the predication is apt. And that can be achieved by possessing a categorical property in the right context, as imagined by the SCA. By now you can hopefully appreciate that the neo-Humean has many strategies for accommodating powers within her non-power ontology. To wit, there are plenty of ways for the neo-Humean to make sense of the glass’s being fragile that do not commit her to the sorts of properties a powers theorist endorses. If she did not, the game would already be up. But it is far from up. The nature of properties as categorical is the central aspect of the neo-Humean metaphysic I seek to challenge. But the differences between the neo-Humean and the powers theorist do not end there. An ontology and the metaphysic that surrounds it are integrated in such a way that with a change in properties comes a change in how we see many other aspects of the metaphysic. We have already seen how the neoHumean thinks differently about the nature of possibility, and that this ties in to her conception of properties as categorical. I turn now to the two areas of the neoHumean metaphysic that the accounts of possibility and properties impact most heavily: laws of nature and causation.

2.4 Of Laws of Nature Much of the neo-Humean account of the laws of nature can be traced back to the rejection of necessary connections in the world. This rejection undergirds the thesis of Humean Supervenience, and fuels the following quintessentially neoHumean claims: (i) that the laws of nature are contingent; (ii) that the laws are outside of, and distinct from, the objects they govern; (iii) that the objects subject to those laws are inherently passive; and (iv) that causation lacks most or all of the ²⁴ See Smith et. al (1984) and Armstrong (2004a) for the basic idea, and Beebee and Dodd (2005) for discussion.

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oomph we typically think it does. The last I save for the next section; here I deal with the first three. For the neo-Humean, what is possible is guided (if not dictated) by what can be conceived, and this leads to a rejection of necessary connections. The reasoning is simple: imagine a case wherein two things—events, say—are putatively necessarily connected. This putative necessary connection might be of the form that the occurrence of the first necessitates the occurrence of the second, in the way causation is commonly understood. But now imagine one without the other. We can, and therefore the neo-Humean believes the putative necessary connection between the two is broken. Hence, no connection between them (causal or law-like) is one in which the former event necessitates the latter. So, neither laws nor causes necessitate their effects. And because we can further imagine there having been different laws or none at all, the laws are contingent in a second sense. The laws neither act nor hold of necessity. This is a brief characterization of the neo-Humean’s negative account of the laws of nature. For the neo-Humean’s positive account, we need to build from the bottom up. And that means starting with the doctrine of Humean Supervenience. When presenting his doctrine of Humean Supervenience, Lewis employs a metaphor of the world as a ‘vast mosaic’.²⁵ The mosaic metaphor is a good tool for understanding supervenience and the neo-Humean account of the laws of nature. A mosaic is a piece of art constructed out of ever-so-many small tiles of coloured ceramics or glass, typically arranged so as to create some image or pattern. The patterns themselves are not found in any tile in particular; they only appear or emerge from groups of tiles once they are arranged. The pattern is thus said to ‘supervene’ on the arrangement of the tiles; the arrangement of the tiles determines what pattern emerges. It follows that one could not have a different pattern without moving the tiles.²⁶ In typical cases, the patterns or images are formed by following a plan: the tiles are placed in order with the resultant image in mind. But what happens if the tiles are arranged without a plan? Rather than following any rules or guidelines about tile placement, imagine the tiles are randomly distributed throughout the mosaic. The distribution is random, but patterns nevertheless emerge. Not intended patterns, nor patterns the artist sought to create through a specific ordering of tiles, but patterns nonetheless. If one were to track those patterns through the mosaic, one could begin to develop rules that would appear to have governed the placement of tiles. But they would only appear to have done so; we know that no plan was followed. (This is the equivalent of tea-leaf reading, and like tasseography falsely suggests plans where none exist.) However, if these after-the-fact rules are carefully developed, using the largest possible region of the mosaic, then they will serve as an excellent guide for navigating the mosaic, despite not having served as a plan for its construction. Faced with an infinitely large mosaic, these after-the-fact rules would prove very handy indeed, rather like a map does, despite not having determined the landscape. With this idea of after-the-fact rules at hand, shift now to properties. We find properties littered about the universe. Think of this spatiotemporal distribution of

²⁵ Lewis (1986b: ix).

²⁶ Kim (1982, 1990, 1993a), McLaughlin (1995), and Jackson (1998).

  -   properties (not just the present distribution but past and future as well) as tiles in a huge mosaic. Just like the artistic case, patterns emerge, as do after-the-fact rules concerning the relative locations and orderings of sets of properties in the universe. These after-the-fact rules are the neo-Humean’s laws of nature. They do not govern in the sense that they require (even weakly) that this or that property come after or before some other, or be partnered in this or that way; they do not determine the arrangement of the properties or the pattern that emerges. But from the patterns that randomly arise we can develop useful guides to the universe and its navigation— guides that the neo-Humean understands as the laws of nature. The archetype of this account of laws is the Mill–Ramsey–Lewis ‘best systems’ account, according to which laws are those generalizations that best systematize this information, where ‘best’ is a balance of simplicity and strength.²⁷ These laws are after-the-fact laws. They do not push around the objects or their properties; they do not govern. But nor do the objects or their properties propagate their own movement and change (as the powers theorist claims). The neo-Humean metaphysic thus sees physical objects as inherently passive: objects are lifeless puppets whose apparently perfectly choreographed dance is really just a series of random positions. The dance is not choreographed at all; it is a log book, and nothing more. Objects appear in various locations and configurations—their properties sometimes changing, other times not—but nothing makes this the case; all changes and similarities are ‘explained’ after the fact. There is no saying why such and such occurred, only that it did, and that it occupies a place in a wider pattern of such happenings. If you want to know why something happened, the neo-Humean refers you to the after-the-fact laws. Natural laws are thus stripped of their causal efficacy and demoted to the status of mere statements and facts about the positions and formations the objects and their properties happen to occupy. Understood this way, laws of nature are powerless, but clearly far from useless. There is little more we could want from a mature science than what the strongest and simplest map of the distribution of properties could offer. In fact, in some respects I have made this view sound worse than it is. One thing to be said in its favour is that it coheres with basic operating procedure in the natural sciences. For those sciences that offer laws, those laws are the most unified and systematic generalizations of the patterns of property distributions we find in the world. They track behaviours and patterns, and they predict on that basis. Our application of laws within science demands little more of our metaphysics than the neo-Humean picture delivers. But one should not mistake scientific practicality for metaphysical fact. It is the role of science to track patterns and positions, and to make predictions on that basis. It is not for the scientist to answer what ultimately affords these positions and patterns. Moreover, if you are inclined to think that laws govern what occurs—that is, if you have the common intuition that laws dictate the behaviours of objects and form part of the explanation of why the properties are distributed as they are—then this picture of laws will not ultimately be for you. It offends against the sense that the

²⁷ Mill (1967), Lewis (1973b, 1983b, 1999), Ramsey (1978), Beebee (2000), and Cohen and Callender (2009).

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world has more oomph to it than after-the-fact laws provide. The natural sciences do not demand that the world be governed by the laws we locate in the patterns, but we might want to insist that there is oomph nonetheless. And our desire for oomph would lead us to the conclusion that the after-the-fact laws are merely our first step in learning what the real story is. It would follow that the neo-Humean picture of laws falls short: it is sufficient for scientific practice, but not for the scientists themselves. For the purposes of contrast—especially as it pertains to laws—it is worth our briefly considering the metaphysic that sits roughly between neo-Humeanism and the powers metaphysic. This middle-ground position is that most commonly associated with the work of David Armstrong. Like the neo-Humean’s, Armstrong’s properties are categorical, and the laws are strictly independent of them. But unlike neo-Humeanism, Armstrongian laws necessitate their effects: they actually govern.²⁸ These laws—call them ‘strong’ laws—match up with our pre-theoretical desiderata regarding the laws of nature in that they push objects around in virtue of the properties they possess. And though the properties and objects that bear them are inherently inert, they take on a quasi-powered nature when in the presence of strong laws. Furthermore, instances of those laws double as instances of causation, meaning Armstrongian causation is both intrinsic and oomphy. On this view, then, the mosaic is created according to a genuine set of rules, and is not random. The Armstrongian metaphysic shares its property passivism with neo-Humeanism, but stands apart through the robust modal element it adds in the shape of laws and causes. And though these strong laws are contingent (they could have been different), they nevertheless impact the Armstrongian’s space of possibilities.²⁹ The Armstrongian metaphysic is a clear departure from neo-Humeanism, but one has to go further still to get to the powers metaphysic. Going further requires additional changes in the nature of possibility, but, more importantly, it takes rejecting passivism outright, by treating the properties as the seat of the laws. In other words, you need to take the governing force of the Armstrongian laws and make it part of a property’s essence. The force must be in the property, not outside it; it must be incorporated into the very nature of property itself. Rejecting categoricalism in favour of an ontology of causal powers thus puts the rules that generate the patterns of the mosaic into the properties themselves. I find the strong account of laws far more attractive than its neo-Humean counterpart, but both have their merits. As I say, it is not my aim to show that this view or any like it is false; what I want to show is how the flavours of neo-Humeanism blend together, so that we can properly assess what the powers metaphysic has to offer without accidentally tipping the scales against it. We have tasted a good portion of the flavour of the neo-Humean metaphysic, with regards to possibility, properties, and laws. Last up is causation.

²⁸ Armstrong’s account of laws is known as the ‘DTA’ account, because it was independently proposed by Dretske (1977), Tooley (1977), and Armstrong (1978, 1983). ²⁹ Meaning that the Armstrongian metaphysic differs from neo-Humeanism on three of the four main components listed at the end of §2.1.

  -  

2.5 Of Causation The final cog in the neo-Humean metaphysic concerns causation. It should come as little surprise that the neo-Humean account of causation is decidedly weak, in the sense that causal relations pack no oomph. On this picture of causation, causes do not push the world towards effects as much as they just stand next to them. This is well and truly Hume’s legacy. Nevertheless, despite rendering causes impotent, the neo-Humean account of causation is an attractive and useful account—at least to the extent that we want an easy-to-understand account of causation that plays well with our everyday folk concept. I ultimately believe that the best answer to the question of what causation is depends on the exercising of powers, but that makes the neoHumean account no less useful for other purposes. To build up to the neo-Humean account of causation it will be handy to start with a short refresher on Hume’s account. If the popularized (perhaps cartoonish) version of Hume represents him as famous for anything, it is as being a great sceptic when it comes to causation. Some historians of philosophy have questioned this reading, but my purpose here is with flavours and not facts, and so we can leave the history to the historians and make do with the CliffsNotes version of Hume.³⁰ So, what did Hume say about causation? The short version is that he examines the world looking to find the source of his idea that causes necessitate their effects, and comes up short. He concludes that the powers or forces we credit causes as possessing have nothing of the sort: we add this in our understanding of them. What he claims is in fact present, and thus what forms the basis of his positive account, are the following: temporal succession (the one event precedes the other, often immediately), and spatial contiguity (the two events occur in the same space). But as Hume is well aware, this cannot be sufficient for causation, as not all pairs of events related in this way are instances of causation. Something more is needed. Hume’s response is that we move away from the specific case to something we find in similar cases, something we find in all similar cases. That is, we move to a regularity. When we consider the single case, and/or we see the cause event, we recall the many times we have seen a (causal) pair of events, and infer that the effect will follow. We are thus conditioned to infer the effect. This gives rise to the third feature, that of constant conjunction: we consistently (perhaps unfailingly) find the cause paired with the effect. We come to ‘see’ them as connected. He thus arrives at the following account of causation: an event c is a cause of an event e just in case: (i) c is followed by e; (ii) c and e are in the same region; (iii) c and e are events of kind K₁ and kind K₂ respectively, where events of kind K₁ are succeeded by events of kind K₂. This is known as a ‘regulatory’ view of causation. You might already have noticed the parallels between Hume’s account of causation and the neo-Humean account of laws. Both give a central place to pattern-tracking. In one case those patterns ground the laws, in the other they constitute the basis on which pairs of events are causally connected. It follows that the Humean account of causation is extrinsic: what makes it the case that a pair of events is causally connected depends on there being patterns of exactly similar pairings of events of ³⁰ For recent and non-canonical interpretations of Hume, see Strawson (1989) and Winkler (1991).

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that type, elsewhere and elsewhen. Moreover, intrinsically causally paired events constitute a violation of Hume’s Dictum, and so extrinsicality is the only game in town. On the traditional Humean view, the causal connection is also subjective (the connection is something we draw from our experience), but contemporary regulatory views of causation drop this aspect, bringing them more naturally in line with the neo-Humean account of natural laws. The classic Humean regulatory account of causation meets with some similarly classic objections.³¹ The most pressing of these concerns the possibility of spurious causation. As presented, the regulatory account of causation would count any regular pairing of events as causal, even if we took this to be merely accidental. As a simple case, imagine that a dog barks all and only those times that a specific light switch is flicked to the up position. The account would mistakenly imply that the flicking is the (or a) cause of the barking. Similar cases are easy to come by, and there is no obvious way for the Humean to rule them out without importing assumptions that run counter to the account.³² Let us put aside the extent to which Hume or the Humean can satisfactorily respond, so I can highlight what I find important about the objection. What it suggests is that we think there is something to genuine causation the account fails to capture. That we can sort regularly paired events into those we think are mere accidents versus those we think belong together—prior to considering any account of causation—suggests that we take causal relations to be intrinsic. We can, of course, be wrong about causes (maybe the switch really is causing the dog to bark), but we see the pattern as the expression of the causal facts, and not constitutive thereof. There is more the Humean can say in support of the regulatory view, and more that can be raised in objection to it, but what I have said is enough for our purposes. What I want to do now is move on to the neo-Humean account of causation. The neo-Humean account of causation I have in mind is the one popularized by Lewis in the 1970s, which went on to create something of a philosophical cottage industry. According to the Lewisian/neo-Humean account of causation, causation is to be analysed in terms of counterfactual dependence. Like its forebears, it is an extrinsic account of causation, in which causation lacks oomph. Hence it, too, runs foul of our intuitions about the inherent force of the causal relation. However, unlike its predecessor, it is nevertheless considered an attractive account of causation. Inspired by a quote from Hume’s Enquiries, the counterfactual analysis of causation seeks to make good on Hume’s claim that we can understand a cause as obtaining when some object is followed by another, ‘where, if the first object had not been, the second never had existed’.³³ We have already met with one counterfactual analysis, that which attempts to analyse what it is for an object to have a power in terms of counterfactual conditionals. Here those same counterfactuals are employed in an analysis of causation: causation is understood as a relation between

³¹ See Armstrong (1983) and Psillos (2002) for a few of them. ³² Not, that is, unless the Humean can relegate the differences to mere differences in how we treat the cases. This is a level of subjectivism about causation that few would tolerate. ³³ Hume (1975: I.vii.29).

  -   events where both obtain, but they are such that had the former event (the cause) not occurred, then the latter event (the effect) would not have either.³⁴ As I have said, this is a reasonably attractive account of causation. Part of the attraction is due to the account’s malleability: it applies just as well to microphysical causes as it does to chemical reactions, human actions, historical events, and everything in between. It is more or less a one-size-fits-all account of causation, and that is certainly something to brag about. It also does a good job of capturing our everyday use of the term ‘cause’, especially as an element of a sufficient condition for an effect. In fact, as far as our common-or-garden concept of causation goes, you can do a lot worse than the counterfactual analysis of causation. Hold on—have I given up on powers already, just two chapters into a book-length defence of them? Hardly; there is a distinction to be made between the best way of understanding how we use the terms ‘cause’ or ‘causation’, and what, if anything, counts as real causation in the world. I will have more to say about this distinction in Chapter 6, but the lesson here is that the counterfactual analysis is well suited to the first job, but it is powers that do the latter one best. I think the concept versus genuine relation distinction also goes some distance to explaining why folks keep returning to the counterfactual analysis (or close relatives) despite the massive literature on the problems with the account (the still lively cottage industry previously mentioned). Some of our concepts—like causation—are rough around the edges: they are not constructed with well-defined boundaries or developed to deal with problem cases like symmetrical overdetermination or trumping.³⁵ The analysis thus has a good fit. But when folks raise problems like these for the counterfactual account, they demonstrate the difficulties it has when understood as capturing genuine causal relations in the world. As an account of what causation in the world really is, that is, what makes the world tick, I think the counterfactual analysis fails on two counts. The first concerns the many problems the account runs into, one of which I outline below. The second reason is that it treats causation as weak and extrinsic. It thus lacks the oomph that causation needs to have if it is to deserve the name. Here is an example of the sort of problem the counterfactual analysis runs into when seen as an account of how causation really operates. Imagine a cause with a back-up mechanism, where the back-up mechanism makes sure the job gets done even if the first should fail. For instance, you want to make sure that a bill gets paid, and so you mail a cheque and submit payment online; or you shoot your mark in addition to poisoning them; or you set two alarm clocks. Because the putative cause is backed up by another would-be cause, the effect is not counterfactually dependent on the original. Had the original not occurred, the back-up would have caused the effect. Hence, there is no counterfactual dependence—and so no causal dependence— between the putative cause and the effect. It is therefore not a cause. But of course

³⁴ Lewis (1973a). ³⁵ See Lewis (1986f), Schaffer (2000a, 2000b), and Collins et al. (2004). Symmetrical overdetermination is when two processes lead to an effect for which each is sufficient. Trumping is a form of pre-emption in which a sufficient process is cut off by another that ‘trumps’ it, as might happen when a policewoman and a red light both demand you stop. (You would stop either way, but you obey the policewoman because her order supersedes the red light.)

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it is a cause, and so counterfactual dependence is not necessary for causation. So, even though the counterfactual analysis gets many cases right, it runs into problems. That is fine for our concept, but I have no idea what it would mean for real causal relations in the world to ‘get it wrong’ sometimes. Nevertheless, it is the extrinsicality that I find most problematic. On the counterfactual analysis, causation holds between events. But events cannot themselves be related by counterfactual conditionals, as those conditionals range over propositions. So, the first step in the analysis is to replace every event with a corresponding proposition. We then set up a dependence between families of propositions, of which the event-capturing propositions are members. We next define causal dependence in terms of the counterfactual dependence between the families of propositions, such that an event e causally depends on an event c just in case the propositions that correspond to e and c are members of counterfactually dependent proposition families. That last step gets causation from causal dependence, as causal dependence implies causation. None of this yet explains why the account is extrinsic. The extrinsicality is a by-product of the neo-Humean treatment of counterfactuals. The short story is that the counterfactuals rely on the neo-Humean accounts of laws and of possibility. In assessing the truth of the counterfactuals we ‘look’ to the goings-on of nearby possible worlds. The worlds, recall, are complete descriptions of ways things could have been; a nearby world is one that obeys the same (nongoverning) laws as the actual world, and which differs only minutely in terms of the positions of the properties that make up the mosaic (it diverges just enough to allow that the putative cause does not obtain, and then in all law-abiding ways afterwards). It is through the ‘examination’ of these nearby worlds that we establish what would have happened had the cause-event not taken place, and how we determine if the effect-event depends on it.³⁶ The account is thus extrinsic because it relies on extrinsic accounts of laws and possibility. We have to look beyond the pair of events to determine whether they constitute a cause and its effect. These same aspects render the account of causation weak: no event brings about any other, they are merely related to each other according to patterns of similarity and imaginability. For those of us who think that causal connections are strong, that is, for those of us who take causes to be oomphy in that they bring about their effects, the counterfactual account will fall short of the mark. Like the regulatory account before it, the counterfactual account boils down to sequences of events that lack internal relations to one another. There is just one event, then another. Nothing about the first demands, dictates, or makes the latter so. They just happen to be found together. And where they just happen to be found together with great frequency, we describe them as causally connected. This cannot be what causation is.

³⁶ I have put ‘look’ and ‘examine’ in scare quotes, because these are not genuine acts of looking or examining; they are acts of imagining.

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2.6 Warts ’n’ All There is a chance that my brief presentation of the neo-Humean metaphysic has you recognizing that you endorse parts of it, if only implicitly. You might even find yourself having the altogether reasonable response that your endorsement is justified, as you find much of it agreeable. I willingly concede that the neo-Humean metaphysic works pretty well, just like that vacuum you got from your parents does. If it did not have some good features and do a reasonable job of providing a metaphysical background for our thinking about the world, then it would not have become the status quo. It is a cohesive and lucid systematic metaphysic, and one could do a lot worse than navigating the world with it in your back pocket. If it were not, then it would not be worth our time. But by no means should my concession be taken as an endorsement of the neoHumean metaphysic, nor does being a pretty good metaphysic mean that it is without its problems. In The Concept of Mind, Gilbert Ryle wrote: There is a doctrine . . . which is so prevalent among theorists and even among laymen that it deserves to be described as the official theory. Most philosophers, psychologists and religious teachers subscribe, with minor reservations, to its main articles and, although they admit certain theoretical difficulties in it, they tend to assume that these can be overcome without serious modifications being made to the architecture of the theory.³⁷

Echoing Ryle’s words, many of these difficulties are known, and the assumption seems to be that they can be overcome without serious damage to the view. I am less optimistic, but my task in this book is to develop an alternative, not dwell on the negatives of neo-Humeanism. Nonetheless, just in case our sojourn has you regarding the neo-Humean metaphysic just a bit too fondly, I want to refresh your memory of the problems it faces. Recalling the Kuhnian ‘revolutionary’ metaphor in Chapter 1, you might see this section as suggestive of the ‘crises’ the neo-Humean metaphysic now faces (though to be fair, ‘crises’ might be just a tad hyperbolic).³⁸ What follows is not to be construed as a set of decisive arguments against the neoHumean metaphysic; they are some of its difficulties, its ‘warts’. I start by shining the spotlight on some of the warts of neo-Humean causation. (a) Causation. The neo-Humean takes the oomph out of causation. This is a nasty wart. A theory of causation ought to tell us how particular states of the world came to be. Learning that pairs of states partner up will not do; replying that the pairs often and reliably partner up continues to miss the point. Regularities are not causes, however you dress them up. Dependency relations do mildly better, but only because we think they are true of the paradigmatic examples of causation. For a good many instances of causation, the effect would not have obtained had the cause not been present. But it is one thing to recognize that an effect is counterfactually dependent on a cause, and another altogether to believe that this dependency is all there is to causation. It is simply

³⁷ Ryle (1949: 10).

³⁸ Kuhn (1962).

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too weak to do the job. It is insufficient as an account of causation. But nor is it necessary either. The ugly hair growing out of this wart has been raised countless times in the literature (including by me, above), but once more cannot hurt. Add to any actual cause a back-up plan that would kick in should the actual cause fail to produce the effect, and the effect is no longer dependent on the actual cause. And so if causes just are those events on which the effects counterfactually depend, then the cause is no longer a cause at all. Not a good result. Moreover, back-up plans are just one way of undermining necessity: symmetrical overdetermination and trumping produce the same result.³⁹ Not all neo-Humean accounts of causation treat causation as a transitive relation, but the majority do, and it, too, looks like a wart. If the causal relation is transitive, then if A causes B, and B causes C, then A causes C. Sometimes we are okay with this: after all, who does not love a good Rube Goldberg machine? But not all chain reactions are made equal. If I break your right hand and thereby influence the manner in which you perform some act you would have otherwise performed anyway (you are forced to play tennis with your weaker left hand), it hardly seems that the break was a cause of your winning, should you win.⁴⁰ You might also be troubled by the thought that nothings—such as an absence or an omission—should turn out to be causes.⁴¹ But if I fail to feed your cat while you are away, then your cat’s untimely demise is counterfactually dependent on my not having fed your cat, and so it is a cause. Worse yet, not only did my inaction have this unpleasant effect, so did your not feeding your cat, the Queen’s not feeding your cat, and everyone else’s, too. Once you allow omissions to be causes, they have a nasty habit of multiplying excessively, and it is very hard to keep them under wraps. Lastly, I remind you of the extrinsicality wart. There is something very odd, if not flat-out mistaken, about the causal relation being determined any way but locally. Why should it matter what is going on elsewhere (or elsewhen) when dealing with a local cause and effect? It seems that causal relations should be constituted by aspects intrinsic to that cause and that effect, not any goings-on at any other time or place. (b) Categoricalism. It is standard in metaphysical debates for one side to market itself as the ‘common-sense’ view, meaning that its proponents believe it to be the view that does least damage to common sense, and that this is a virtue. Case in point, neo-Humeans operate as if they occupy the common-sense high ground when it comes to the nature of properties. But do they really have the high ground? I suspect that this is really a wart that has been cleverly disguised with make-up. Categorical properties are purportedly familiar properties. They are supposedly the good ole’ mom-’n’-pop properties we grew up with, not the mysterious modal properties the powers theorist is fond of. In one respect, the neo-Humean is correct. Powers have partly hidden natures, whereas categorical properties do not; point to the neo-Humean. But now consider what categorical properties are like. Pace the ³⁹ Lewis (1986f ), Collins et al. (2004). ⁴⁰ Hall (2000). Though perhaps we would be willing to call it a cause if you lose a match you were otherwise likely to have won. ⁴¹ Beebee (2004), McGrath (2005), and Varzi (2007).

  -   neo-Humean, they are not familiar properties at all. What is familiar to a property concerns the ways in which the property impinges on us, how we respond to it, and how it reacts and responds to other properties. That is, what is familiar about any property are aspects of its causal profile. But knowing a categorical property via its causal profile is not to know a categorical property at all. The causal profile is not part of its essence. What a categorical property is—what it really is—is a thing that is identical with itself and different from all others. It is thus a quiddity.⁴² What properties do we know like this? Put bluntly, the neo-Humean’s categorical properties are properties whose essences include nothing more than that they are the same as themselves and not the same as others, and are not familiar in the least.⁴³ I return to this point in Chapter 3, but there is really very little to the nature of a categorical property. There is certainly nothing at all homey about the neo-Humean’s properties, and there is no way the neo-Humean can claim the high ground.⁴⁴ Here is another wart of categoricalism. Imagine that everything in the world stays exactly as it is; the laws are the same, the locations of all objects are the same, the pattern of causes are all the same, and so on, save one change: all the properties are swapped out.⁴⁵ Spin goes where mass was, mass takes the place of square, square replaces circular, etcetera; repeat until every categorical property has a new home. I know what you are thinking—that it would be utter mayhem, if it worked at all— but you would be mistaken. If properties are as the neo-Humean claims they are, then this swapping can take place, and not only would it leave things otherwise untouched, the swapping would be utterly undetectable.⁴⁶ Unbeknownst to you, your favourite property would now be elsewhere, and an imposter will have taken its place. But you would never know (or be able to know), and nothing would be any different. This is a strange and unsavoury consequence of the neo-Humean account of properties. (c) Laws of nature. Here is a wart that is about both the laws of nature and categorical properties. Neo-Humean laws emerge from patterns of regularities that obtain. This sounds perfectly reasonable, especially if you are thinking that certain pressures and temperatures are correlated with certain volumes and the like. But neoHumean properties are not pressures or volumes. Some property—whose nature is nothing more than its difference from the properties around it, and such that it has no natural ties to those properties—is often followed by a property that is not identical with the first. That is all. The laws, properly understood, are barely about anything. They concern the best way of organizing the arrangement of properties, but this, it turns out, is nothing more than mapping patterns of thisnesses and thatnesses. They do not resemble the laws offered in the natural sciences at all. The properties are the real offenders here, as patterns of more robust properties might look more like familiar laws, but it is the laws that suffer. (d) Possibility. I end this section first by noting some concerns with the neoHumean approach to possibility, and then sketching an alternative. Like the warts ⁴² See Wang (2016). ⁴³ Armstrong (1997), Schaffer (2005). ⁴⁴ I suspect that contemporary neo-Humeans have led themselves down a bad path by treating categorical properties as pure quiddities. We will see later on that I think there must be more to qualitative aspects than just this. ⁴⁵ Bird (2007a). ⁴⁶ Lewis (2009).

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already on offer, this is not to be interpreted as an argument, but allows us the chance to observe some difficulties. Neo-Humeans may not be wrong about what is possible, but the criterion is so weak as to make us wonder what it could possibly tell us, except that we can imagine one thing without another. For instance, what if it really is the case that certain properties are possessed by certain individuals of necessity? Applying the imaginability test is going to give you the wrong answer. As far as we seem to know, and certainly within the limits of what logic permits, it makes sense to talk about that individual being separated from any of its properties. What we can imagine does not help, because we can imagine what would be consistent impossibilities. Faced with this objection, the neo-Humean sensibly replies that we can add ‘rules’ that limit the worlds under consideration. These rules restrict the scope of what is possible relative to a given purpose. Just like shopping for cars on the Internet, you can look at just the blue ones, or only those made prior to 2008. The other cars are all there, but they do not conform to the rule, and so the search does not return them. Hence, if some individual has some property necessarily, we apply the rule that we are no longer permitted to imagine worlds where those two come apart. Fair enough, but if the only ways the world (our world, the actual one) could have been are found within the set of worlds that conform to that rule, then why think that non-rule worlds are possible in any interesting sense at all? Moreover, it looks like the rule is doing the most important work. The imagining just confuses us. It is the rule that determines the real boundaries of possibility. Now ask: where did the rule come from? The rule comes from investigation into, and reasoning about, the actual world. We learn from the actual world, and this provides the rules about what is possible. In the same vein, if we were to consider just those things that are nomologically possible (that is, possible given the actual laws of nature), we first determine the laws of nature (again by examining the world around us), and then apply a rule to our imagining that allows us to consider only those worlds where the actual laws of nature are held fixed. Let us push on this last rule just a little. We will see later that a powers theorist has no real need for laws, at least not any sort of laws that go beyond the powers.⁴⁷ To the extent that the powers theorist has laws at all, they will be necessary. If, for instance, water boils at one hundred degrees Celsius (at standard pressure), then it could not have been the case that water boils at any other temperature, because this is built into its properties. When the neo-Humean applies the equivalent rule, the same appears to be true in their thinking. But the neo-Humean takes this to be a rule, and so as a rule it can be revoked. The laws thus come out as contingent, as there are ways the world could have been that omit the rule (just drop the rule in your imagining). That, to my mind, is the danger in this sort of thinking. It might well be the case that this law is necessary, but on the neo-Humean approach to possibility it will never come out that way; little does.

⁴⁷ Bird (2007a) argues for their identity; Mumford (2004) calls for the elimination of laws. Here I speak only of fundamental laws; for more on laws see Chapter 10.

  -   The application of rules within the neo-Humean account of possibility allows us to imagine possibilities without those rules, and so it has the potential to mislead us in what is possible. This makes me sceptical of the neo-Humean approach. But these rules point us in what seems a better direction for possibility. It is one that comes from looking at the world and learning from it the sort of ways things could have been or could be. That is, genuine possibilities should come from facts about the actual world. Follow the world, the only world! I will sketch the basics of that view here.⁴⁸ According to the powers theorist, objects possess powers, and those powers dictate what the objects will do. But they also dictate what objects could do, and thus what can or could have come about had those objects met with different circumstances. Building on this idea, possibilities are grounded by the powers present in the actual world. In order for some state of affairs to be possible, there must be some actual power for which the possible state of affairs in question is its manifestation (or part of the manifestation). In its simplest form, the basic principle can be expressed thusly: (P1) State of affairs S is possible iff there is some actual power p, the manifestation of which is (or includes) S. The view gets slightly more complicated in order to include possibilities that must move through a number of power-manifestation pairs (a glass is a possible cutting tool if first it is broken, for example), but the core of the account is given by P1. As ought to be obvious, what is possible on an account like this has nothing to do with our imaginings, however restricted. Like any account, it is not without its difficulties, but I leave the details—good and bad—for another day.⁴⁹ All I want to indicate here was that there are ways of dealing with possibility that have nothing in common with the neo-Humean account. I end this section with one of the biggest problems the neo-Humean account of possibility faces. It might just be the mother of all neo-Humean warts. Behind every good metaphysic is an even better ontology. Without the ontology, the metaphysic has nothing to make it true; it is just talk. So, what lies behind the neo-Humean talk of possible worlds? According to Lewis, there is an endless supply of worlds, causally and spatiotemporally isolated from our own, but just as real in every way. These concrete worlds are what make our possible worlds talk true. This pluriverse has in it a world corresponding to absolutely every way things might have been. Travel and interaction between the worlds is impossible—they are postulates whose existence grounds claims of possibility—but this makes them no less real. Most people—by which I mean virtually all but Lewis—find this claim to be outrageous. But the existence of all those concrete universes is not the worst wart here. Granted, this is an incredible claim and a massive cost, ontologically speaking. But at least Lewis is honest about the demands of the account. He is willing to pay his ontological debt, however great. The bigger wart is that no one else is. If Lewis is to be believed, then there is no way of having this ‘paradise’ of possible worlds talk on the ⁴⁸ A fuller account is found in Williams and Borghini (2008). Congruous approaches to possibility can be found in Contessa (2010), Jacobs (2010), Pruss (2011), and Vetter (2015). ⁴⁹ See Vance (2014), Wang (2015), and Yates (2015) for some of the difficulties faced by this view.

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cheap.⁵⁰ And yet, that is what ever-so-many concrete-world-denying neo-Humeans attempt to gain. Hence, if Lewis is correct about the ontological cost of the neoHumean account of possibility, then there are scads of neo-Humeans who endorse the metaphysic but not the ontology that supports it. That is a most distressing wart indeed.

2.7 Beyond the Status Quo The neo-Humean metaphysic is smartly crafted and hugely influential, despite its problems. Like the neo-Humean metaphysic, the powers metaphysic has a lot going for it, too. And that is why they are in competition: each gives a complete picture of the world (in some areas the picture is better than others), and thus we must evaluate both to see which does the better job overall. That is why we needed to get clear about the neo-Humean metaphysic, so we can test it against the powers metaphysic. In that regard, the powers metaphysic is a serious competitor, and well worth a careful look. And a fair look, too. It would be an unfair test if every suggestion regarding the powers ontology and its applications was filtered through a neoHumean lens and thus obscured. Having the neo-Humean metaphysic before us should make it a little easier to see neo-Humean impulses for what they are, and help to keep them at bay. You might, when all is said and done, decide that the powers metaphysic does not win the day. So be it, as long as it has been given a fair chance. At the very least, having a viable alternative might help us learn something about what might be wrong—or right—about the received view.

⁵⁰ Lewis (1986a). Cue boos from the gallery of miserly neo-Humeans.

3 Introducing Powers 3.1 Meet the Powers So what, then, are powers, and what is it to have a powers ontology? The answer to both questions will take up this chapter and the two that follow. We will start by developing a rough outline and then filling it in. That outline begins by distinguishing powers from the other members of the dispositions family, for the contrasts are just as informative as the comparisons. In fact, though our understanding of powers is informed by the ways we talk about objects and their dispositions, it should be clear soon enough that the familiar examples of dispositions are not quite the same as the powers that lie at the heart of the powers ontology. This is a theme we will see repeated throughout this book, the core of which is developed in this chapter. It is time to meet the powers. Let us start with the basics. According to the powers ontology, the world is made up of objects, and those objects have properties. I do not have much to say about the nature of the objects per se, beyond claiming that they are whatever the fundamental substances of the universe happen to be (presumably some sort of physical simples). As for the properties, the properties are powers. Though some friends of powers add a sui generis category of non-power properties to their ontologies, I favour a monistic approach. But my powers ontology is not a pure monism, it is a ‘mixed’ monism: all properties are powers, but a property’s powerfulness does not exhaust its nature.¹ There is more to a property than just its being powerful. Not much more, to be sure, but more nonetheless: all properties are an uneven mixture of power and nonpowerful quality. I will get to this in time, but first we need to get clearer about what it is for a property to be a power. Let us consider some very general facts about our powers and dispositions talk, only some of which plays a role in how powers are here understood. When we say of an object that it has a power or a disposition, we seem to be saying a number of things. First of all, we are saying something about the object as it is right now, regardless of what else may come to pass. To say of the salt that it is soluble is to say something about the way the salt is, something about its nature. Second, just as much as we are saying something about how the salt is right now, we are also saying something about how the salt could be in the future, or what it might do, should it find itself in the right (or wrong!) circumstances. It is a warning of sorts, an indication about specific ways in which the salt or the world around it is ¹ This puts me in the same neighbourhood as Heil (2003, 2010, 2012), Martin (2008), and Jacobs (2011), but we are only neighbours, not room-mates. The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

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liable to change if the salt should find itself in some equally specific context. They are ‘threats and promises’ of future states.² In one sort of context, say, that of its immersion in an adequate amount of previously salt-free water, the salt will go into solution. In another, like when heat is added in the form of a flame, it will react differently, producing an orange flame. It is this second feature of powers that justifies our calling them modal properties, as their mode of presentation is not restricted to how they now appear. They are not, so to speak, in ‘pure act’.³ In fact, even when they act, powers rarely produce all the manifestations they are capable of producing, and hence there is more to them than one learns from seeing a particular manifestation produced. Third, we might—in some cases—be saying something more than this. We might be saying that an object, or objects similar to the one under consideration, are prone to responding in such and such a way to various stimuli, or that they do so habitually. We might do this when we say of someone that she is a smoker, or irritable. You are not a smoker if you smoke only once, nor by merely having the capacity to smoke. There might be other things we have in mind when we say of someone or something that it has a power or disposition, but these three will suffice for our starting to get clear about the present understanding of powers. In fact, though the ‘habitual’ meaning is common, of the three things we might be saying when we speak of dispositions and the like, only the first two (regarding how objects now are, and how they could be in the future) play a central role here.⁴ There are many instances in our daily lives when we ascribe powers or dispositions to objects intending any or all of the above. Successfully navigating the world demands that we take stock of the capacities and tendencies of the things around us. It is thus no surprise that talk of dispositions, capacities, abilities, tendencies, powers, potentialities, liabilities, propensities, and the like, is part of our everyday interaction with the world. As ought to be obvious, these notions are all closely connected: they form something of a family of terms that refer, one way or another, to the sorts of dispositions that objects and persons (themselves just objects, albeit special ones) possess. But not all these notions are what I have in mind when I speak of the powers ontology. They will be connected, but what I have in mind is a very basic set of powers: the sorts of powers that underlie these tendencies, liabilities, and pronenesses to act. So which are the powers I am concerned with? When introducing her account of dispositions, Elizabeth Prior says that the dispositions she is interested in are not the dispositions of ordinary language, such as the psychological dispositions of irritability or moodiness. Rather, she is interested in what she calls ‘philosopher’s dispositions—solubility, fragility, elasticity, hardness, and the like’.⁵ What I have to say will have some bearing on our understanding of these ‘philosopher’s dispositions’, but, unlike Prior, my primary interest is with a class of even more basic dispositions, those which underlie solubility, fragility, and so on. Thus my interest

² Goodman (1983: 40). ³ Martin (2008: 54). ⁴ Those interested in the habitual understanding of dispositions should see Fara (2005). ⁵ Prior (1985: 1).

   is with the properties on which the philosopher’s dispositions depend. These are what I call ‘powers’. For example, consider the fragility of a martini glass. I do not deny that the glass is fragile, nor that there is an interesting project to be had in saying what exactly it is we mean when we say that the glass is fragile. But those with even a passing knowledge of the relevant science will have a hard time believing that the glass’s fragility is entirely independent of its molecular structure. In fact, most people aware of the relevant science will flat out deny that the fragility has any genuine role to play in the breaking of the glass when the glass is dropped and it shatters.⁶ But the glass’s molecular structure—says the friend of powers—is a complex set of powers. Some of those powers account for the martini glass maintaining the shape it does, and some of them (maybe even the same ones) are involved in the explanation of how it is that the glass as a whole is fragile, and why it breaks when dropped. Hence the glass’s fragility (a paradigm philosopher’s disposition) gives way to a set of powers on which that disposition depends. Now, it might be the case that the molecular story will itself give way to yet more fundamental powers, but let us pretend for the time being that it does not. What I care about is the nature of those molecular powers. Not which powers they are exactly; that is the job of science. But what they are like in terms of the model under which they operate: what powers are like, and how they interact with other powers. The case of fragility has a place in this picture, because it somehow stands above the molecular powers, built upon them. It is also a more familiar disposition, and so aids us in our thinking. Smaller powers are hard to get at directly, and so we are forced, at times, to model our reasoning about the smaller powers on the larger dispositions like fragility. If thinking about the mechanisms of larger dispositions were not at all illustrative of them, then we would have little chance of making progress in understanding of the latter, and would condemn ourselves to ignorance of their natures. Part of the lesson here is that we should not get bogged down with simple talk of dispositions. The other part is that those dispositions can nevertheless provide a defeasible guide to the nature of the molecular powers. As I have indicated, when speaking of the powers that underlie the philosopher’s dispositions, I typically call them ‘powers’ rather than ‘dispositions’. Part of the reason for doing so is that the term has suffered less abuse: ‘disposition’ has been used in many different (but related) ways, and I want to stay away from any prior notions one might have about them.⁷ ‘Power’ is therefore a technical term, perhaps not entirely free of any prior use, but not nearly as sullied as the alternatives. This allows me to use ‘disposition’ in that more general, and perhaps less careful, way. Thus we can all agree that the glass has the disposition of fragility, and I can, without too much confusion, credit this fact to the presence of the underlying powers. Another reason I avoid the general use of ‘disposition’ is to distance my understanding of ‘power’ from that of dispositions as tendencies. Anything that we say tends to act some way or other must be such that it has acted in the relevant way a ⁶ Most is not all. Some take the fragility to act along with the underlying structure. ⁷ McKitrick (2009a, 2018) argues that there is a general understanding of ‘disposition’ applicable to all cases. As I am interested in a specific use, that term is best avoided.

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number of times before.⁸ This notion is clearly dispositional in essence, but it requires that the object’s ability has been exercised often enough and reliably enough that we are able to track it. It is, therefore, a historical notion, perhaps even an epistemological one. Tendencies might be nothing more than repeated cases of powers being exercised, but the significance of drawing the line comes from the fact that a given aspect of a power might never be exercised. Powers are capable of producing numerous types of effects, but a power can be present even if many of the ways it can be exercised never transpire. To have a power is to have a range of abilities, but not all abilities get used. Okay, I have said that powers are part of a family of connected notions that concern a state of an object and some potential that can be exercised. And I have warned us against confusing the powers with other members of that family, or with features best attributed to other members of that family, especially when they rely on our tracking repeated exercisings. But I have said little more, and little that is positive. I will do that now, along with introducing some of the terminology that will become familiar by the end of this book. A power is a property that provides its possessor with the ability to bring about some states of affairs—the manifestations of the power—when the power finds itself in the appropriate circumstances (themselves states of affairs). Actually, to say it provides its possessor with abilities is misleading: a power is that object’s ability to bring about those states of affairs. Each power is thus a set of such abilities, as any power is capable of bringing about a variety of different states according to what circumstances it finds itself in. As such, powers are what Ryle first called ‘multi-track’, meaning that they are capable of producing a variety of different manifestations when met with diverse stimuli.⁹ This is in contrast to ‘single-track’ powers—those restricted to a single type of manifestation, regardless of the circumstances in which the power finds itself. For the most part, the circumstances in which powers are exercised are nothing more than localized arrangements of other powers. That is, a specific effect of the power will only be produced when the power is placed in the required environment for this or that manifestation. This environment consists in a certain arrangement of other powers, and it is owing to the complementary powers of all objects involved that they jointly produce the manifestation they do. These complementary powers are what are known as the ‘reciprocal partners’ of the power.¹⁰ When the power is appropriately arranged with some set of reciprocal partners, they will jointly produce what is their mutual manifestation. I refer to these required circumstances for manifestation as ‘constellations’. This is because not only does the power need to find itself in the vicinity of various reciprocal power partners, those partners must be appropriately arranged. And nowhere are

⁸ ‘Tendency’ is here understood in an everyday, non-technical sense. Mill (1967), Bhaskar (1975), and Johansson (1989) use the term to mean something more like what are elsewhere called ‘contributions’ (see §4.2). ⁹ Ryle (1949: 43–5). I defend multi-tracking in §4.2. ¹⁰ This use of ‘reciprocity’ comes from C. B. Martin (1993b, 1997, 2008). See also Martin and Heil (1999), Ingthorsson (2002), and Heil (2003).

   arrangements more important than in the astronomical constellations from which the notion has been lifted. From far away, all stars look much the same. Thus, from a pragmatic standpoint, arrangements are the only things that differentiate constellations. Arrangements are therefore an essential feature of them. Power constellations, of course, are not limited to differences of arrangement alone, as the powers themselves can differ from one constellation to the next, but it would be a mistake to overlook the different manifestations that can arise from the very same set of powers when differently arranged. Speaking in terms of ‘constellations’ allows us to appreciate the role that arrangements play in determining which manifestations are produced. It also detracts from the potentially misleading picture that ‘partnering’ talk can lead to: powers work in concert with one another, but rarely are only two powers involved. Though we might employ toy examples with what appear to be just two powers, most manifestations arise from a great many powers at once, and even the two-power cases are probably underdescribed. Furthermore, it is important to note that constellations are sets of powers synchronically arranged. A power might be involved with a series of constellations as a causal process evolves, but each step in that process is a constellation of co-present powers producing a manifestation. As one should expect, no power can interact with future or past powers, only those with which it is contemporaneously instantiated. Powers are exercised in constellations, but it might be that the constellation type required for some specific manifestation type never obtains. Consequently, the corresponding manifestation type will not be produced either. (A manifestation type need not ever have an instance.) That is, some aspects of powers might go unmanifested. However, that a power might have potential manifestations that go unmanifested is no threat to the power’s existence, not even in the rare case that not a single instance of that type of power ever produces an instance of a given manifestation type. Part of what it is to have an ontology of powers is to take seriously the claim that powers are properties of objects. As properties they are ways those objects now are, and they remain such even if they never get to express all aspects of them. This is among the reasons that powers need to be clearly distinguished from those members of the dispositions family that rely on repeated manifestations. Though it might be the case—coincidently—that a state of affairs of the same type as the manifestation comes about in some other way, this would not count as an instance of that power (or those powers) being manifested. We thus can—in principle, if not practice—distinguish genuine manifestations from mimic cases, such as when the angel makes the fragile glass break in exactly those circumstances in which the glass would have broken otherwise. A key aspect of the powers ontology, and one that most clearly distances it from any account that treats powers as non-fundamental properties, is that when powers are manifested, those powers are the causes of their effects. As indicated, powers are exercised when they appear in the right sort of constellation. The result is the mutual manifestation of the powers involved. But it is not the case that the production of the manifestation can be traced to the actions of some other entities. It is not the case, therefore, that the credit we give a constellation of powers for producing a manifestation is a mere façon de parler, as many competitor views maintain. The realism

  



about powers runs deep: they are genuine properties and genuine causes of their effects. They do the work—nothing else does it for them. They are not, in this sense, reducible to the actions of some laws or what have you: the powers of the powers ontology are irreducible. This is not to claim that all putative instances of powers are not reducible. The would-be power of the glass to shatter when struck is really nothing more than a handy way of describing the far more complicated actions of the powers of the molecules that make up the glass. That is, at the very least, how I understand it. But according to the powers ontology, these reductions bottom out somewhere, and once we hit bottom, the powers are no longer reducible. They are not reducible to the actions of any other smaller powers, nor to the actions of non-power properties plus the laws of nature. In fact, on my powers ontology there are no non-power properties or laws of nature, not in any robust sense anyway. It might be that the potential actions of the powers constitute the laws, or that we develop laws in accordance with what manifestations we observe having obtained in the world, but in neither case are there independent and governing laws that are forceful or responsible for producing these effects.¹¹ They would be supervenient laws at best: useful for navigating the world but inherently inefficacious. Furthermore, as the powers ontology takes all properties to be powers, there are no non-power properties to falsely credit with having produced one or another effect. Another way of expressing the irreducibility of the powers is to say that the powers of the powers ontology are baseless.¹² A power is said to be ‘baseless’ when it is not ultimately grounded by any categorical (i.e. non-power) property, where to be grounded is to have some distinct causal basis that is responsible for the manifestation we initially credit the powers with producing. Categoricalism is the neoHumean thesis that all powers must ultimately have categorical properties that ground them; it is this thesis, above all, that the powers ontologist rejects when she claims that powers are baseless. I have said that most of the time powers are exercised in concert with other powers, but not all powers work this way. An interesting class of powers—about which I will have more to say later in the book—can operate in the absence of other powers, or perhaps irrespective of the presence or absence of other powers. These unilateral powers do not require any constellation to bring about their manifestations (or conversely, they operate in constellations of one). These powers are capable of producing effects entirely on their own, as might be found in cases of locomotion and particle decay. The unilateral powers seem a peculiar breed of powers, but as there might be lots of them at work in the universe, it would be a mistake to ignore them just for being different. Given the ways in which powers are exercised, it is not hard to see the powers as belonging to networks. After all, a constellation is nothing more than a network of comanifesting powers. But this is not the only way in which the powers of the powers ontology form a network. I have already indicated that I take all fundamental

¹¹ See Bird (2007a) for a version of the former. I discuss the latter in §10.1. ¹² One might also say they are ‘ungrounded’ (Mumford 2006) or ‘bare’ (McKitrick 2003b).

   properties to be powers. It follows that manifestations will involve a set of powers. (I take manifestations to be states of affairs, and therefore powers will be constituents of those manifestations.) Hence we have a picture wherein powers beget powers. But now we see a different sort of network emerging. Any given power type will have as its potential manifestations states of affairs composed of powers. It thus stands in a potentiality relation to those other powers that it would bring about in the right circumstances. (I describe a power as being ‘for’ manifestations of that type.) The constellations are also networks of powers. And just like the powers they are capable of producing, they stand as potential manifestations to some other network of powers that is capable of producing them. The result is a hugely interconnected network of states of affairs, reflected in the power types. A power is for the generation of certain manifestations, and will itself be part of many potential manifestations. This generates a network; a power’s position in the network corresponds directly to its identity.¹³ That is, to be an instance of such and such a power type is to have specific manifestations that the power is for, and to have specific constellations by which it can be generated. It is common practice to characterize dispositions by the manifestations they produce (for example, fragility has as its manifestation a shattering or breaking of the fragile object, so fragility is a disposition for shattering or breaking), and though sometimes handy when dealing with disposition ascriptions, characterizing powers this way detracts from the power’s full nature.¹⁴ Case in point: powers are multi-track, so there may be many manifestation types that a given power is for. Singling out just one obscures that fact. It is also biased in a forward-looking direction: powers are not just the producers but also the produced. With that in mind, I opt for a two-tiered perspective on powers. Their identities are reflected in their place in the network, full stop. This is forwardand backward-looking.¹⁵ But we can—harmlessly enough—consider just this or that specific manifestation type that a power is for, and think of it as the power for that. What emerges is a hub-and-spoke model for powers: powers are the hubs, and the spokes represent individual manifestation types the power can produce, or be produced by. The ‘spoke’ talk is not to be taken too seriously when it comes to the power’s nature, but having a way to speak about specific relations in which the power might stand can be very useful, and allows us to keep the best part of the characterized-by-manifestation strategy. To say that a power’s identity is reflected in its place in the network is to say that it is necessarily the case that it is for certain manifestations and would be produced by certain constellations of powers. No sense can be made, therefore, of that same type of power having different possible manifestations than those it is capable of producing. Two seemingly similar powers with different ‘spokes’ could never be identical. The set of spokes a power possesses is its essence; a change in essence demands a

¹³ The identity of a power is reflected in the network, and the network offers a convenient way of characterizing the potentiality relations between the property and state types, but I deny that this network is what (strictly) determines the identity of a power. See §4.3. ¹⁴ Vetter (2015) characterizes dispositions this way. ¹⁵ This is sometimes described as a property’s ‘causal profile’ (Shoemaker 1980), but I worry that speaking this way has only forward-looking connotations.

   



change in identity. Likewise, it is impossible for a power to have the same set of spokes as another without the two being type-identical. Furthermore, as any change anywhere in the network would entail a change in the identity of every power in the network, we see that powers come as a package deal. This is a form of holism for powers—power holism—whereby any manipulation of the network constitutes a replacement of the network. This brief outline lays out the basic features of the powers ontology, and provides some sense of what the reader can expect to find in the middle chapters of the book. Much of what appears in this section is expressed in greater detail in Chapters 4 and 5.

3.2 Powers vs Disposition Ascriptions We have had a brief rundown of the powers ontology, and now shift our focus to the powers themselves. However, before we do, one thing must be crystal clear: the account offered in this book concerns powers, and should not be interpreted as offering an analysis of our disposition ascriptions (not, at least, in the familiar sense of ‘disposition’ or our concept thereof.) A disposition ascription involves our saying, claiming, or believing, of an object or person, that it or she can behave in some way or other. For example, we might say of a person who frequently gets angry that he is irascible, or of a glass that it is fragile; these are ascriptions of dispositions to those objects. Analysing what is going on when we ascribe a disposition to an object—in particular, asking under what conditions the connected assertions would count as true—gets a lot of attention in the dispositions literature, and rightly so. After all, disposition ascriptions are essential to the sciences and common to our everyday lives. However, figuring out what we take ourselves to be doing when we make such ascriptions (and determining their truth conditions) is not the same as considering the properties at the core of powers ontology. In fact, failing to distinguish these two projects can lead to confusion; a rather fanciful case may help to explain why. Consider an ordinary drinking glass. Like most glasses, it is fragile, and so you handle it carefully to avoid breakage. However, one day, for reasons that escape us, a passing angel takes a shine to the glass, and decides to permanently protect it from damage. The angel does not change the glass itself, choosing instead to preserve it exactly as it is, but vowing to intervene at all and only those moments the glass would normally undergo damage, such as when it hits the floor. To the extent it matters, assume the angel’s intervention occurs at the point of impact, or whenever the glass is about to break, but not sooner. Further assume that we are unaware of all of this (as you would expect!). Sometime later, having tipped back the last of the glass’s contents, you drop the glass on the concrete floor. To your surprise, it does not break. You count yourself lucky. But after the fourth or fifth clumsy episode you start to question your belief that the glass is fragile. Skip forward a few months, and your intellectual curiosity has taken you from clumsiness to intentional attempts to break the glass, all with the same result. Within a few years you have no doubts about the solidity of the glass, and routinely use it to hammer nails.

   There is a lot going on in this scenario—it is a masking case, relevant to matters of intrinsicality—but we can ignore much of that for now.¹⁶ Think about what you would say about the glass: what dispositions would you ascribe to it? Hardness? Unbreakability? Perhaps both. But certainly not fragility. Why not? Well, whatever else you might mean by ‘fragility’, you are convinced that it would require breaking in exactly the sorts of circumstances in which the glass failed to break. Its failure to do so is surely a deal-breaker vis-à-vis your considering the glass fragile. And after showing the glass to the scientists at the local university, they reach the same conclusion. Now imagine asking the angel what sort of dispositions the glass has. You will get a different answer. ‘Fragility,’ responds the angel, ‘for if the glass was not fragile I would not need to protect it.’ Who is right? Given the assumptions we started with—to wit, that the glass is fragile—it is surely the angel. The glass was fragile to start, and it has not undergone any change. As the angel says, this is what demands vigilance and readiness to intervene. If the glass was not fragile, the angel’s vow would be vacuous. But on the other hand, what you, me, and the scientists have to say about the glass is perfectly reasonable too. This glass is never going to break, ever. It will remain intact in all circumstances in which (normal) fragile objects would break, and even in those when sturdy objects would break too. The glass is super-sturdy, not fragile! What we ought to say here depends, in part, on whether we take dispositions to be intrinsic or extrinsic. Also relevant is how we understand dispositional concepts, especially those like fragility, and whether something’s being fragile entails breaking in certain contexts or not. On the one hand, there are the properties possessed by the glass, in and of itself. Intuitions here clearly lean towards the intrinsic nature of the glass, and favour the angel’s claim that the glass is fragile. Claims like this, that would see the glass as fragile, tend to be (largely) immune to changes in context. On the other hand, there are the matters of: what sort of behaviours we can reasonably expect from the glass; how we standardly employ our concept of fragility; and the extent to which these both rely on features of context.¹⁷ These lean towards the extrinsic, and favour the claim that the glass is not fragile. Hopefully you can feel the tug of intuition pulling you in both directions. There is something right about both, but let us try to avoid being dismembered. I thus propose we keep the two matters distinct, to the extent that we can. Both are important, but our present concern—the nature of the power properties—fits best with the angel’s perspective (though not perfectly). To that end, there are some properties possessed by the glass in virtue of which it counts as fragile, and the powers theorist takes those properties to be powers. Those are the properties on which the powers metaphysic is based. The other perspective—that which sees the glass as non-fragile—belongs in the disposition ascription camp, as it concerns not

¹⁶ See Lewis (1997) and Johnston (1992) especially. Intrinsicality is discussed in §4.1. ¹⁷ You might also feel the tug of your inner neo-Humean, telling you that there are no nearby worlds in which the glass ever breaks, and leading you to conclude that the glass is non-fragile (on the basis of what those worlds tell you about counterfactuals, what your inner neo-Humean believes those counterfactuals tell you about disposition ascriptions, and your natural enough desire to work backwards from behaviours to disposition ascriptions).

   



just properties in the world, but also human elements, such as how we use terms like ‘fragile’, aspects of how we access and navigate the world, the truths of certain counterfactuals, how we interpret those counterfactuals, and, perhaps most importantly, features of context. Unlike the former, the latter is highly sensitive to context, and possibly to our interests too. It may also be more in keeping with pure empiricism than with metaphysics: after all, it is common to generate disposition ascriptions by working backwards from a’s exhibiting some behaviour type φ to the ascription to a of the disposition to φ. As far as it concerns the debate between the neo-Humean and the powers theorist, disposition ascriptions are ontologically neutral. Asserting of a glass that it is fragile commits us to the existence of whatever truthmakers are needed to make that assertion true, but it does not yet commit us to any specific ontology. There is some ontological fact of the matter (possibly concerning more than just the glass itself), but our ignorance of the relevant ontological facts leaves us free to offer competing accounts of what they are. Case in point, the neo-Humean has her story of what the world must be like for the glass to be fragile, and the powers theorist has hers. Those stories utilize aspects of the ontology each takes to be right, and hence the stories, like the ontologies they rely on, are bound to be incompatible. (It follows that there is unlikely to be a neutral analysis of disposition ascriptions.) One tells us that for an object to be fragile is for it to have such and such a categorical property (or properties) in such and such a context; the other takes it to be a matter of what power properties are instantiated by the glass, and the objects it is likely to interact with. As I say, we are interested in the power properties that undergird these ascriptions, not the ascriptions themselves, or what would constitute a proper analysis of them.¹⁸ You will notice that fragility comes out as context-sensitive within both frameworks, albeit to different degrees. I take this to be a feature of the concept. There is, however, nothing context-sensitive about the undergirding powers themselves, so ‘fragility’ is not a very good name for any power, even those that underlie this disposition ascription. Unlike the having of powers, the exercising of powers— powers-based causation—is a contextual matter, as we will see in Chapter 6. (For what it is worth, there is nothing context-sensitive about the having of categorical properties on the neo-Humean metaphysic either.) Building on the terminological distinction outlined above, I use the term ‘power’ when speaking specifically of members of the small set of causally efficacious properties at the core of the powers ontology, and ‘disposition’ when speaking of ascriptions and predications. (Ideally I would apply this convention consistently, but much of the literature makes no distinction—either because its authors did not see any distinction or because they run these two projects together—and so when I discuss the views of others I am frequently required to employ their way of speaking.) To reiterate, I am not here interested in an analysis of what it means for us to say that an object will tend to behave in some way or other. I am interested in the sort of

¹⁸ Something of a proto-analysis can be gleaned from the book as a whole (see §10.2 especially), but I do not think a fully illuminating analysis is possible (regardless of one’s ontological commitments).

   powers that make the world tick. Nevertheless, I am frequently forced to rely on potentially risky examples that belong in the ascriptions camp, such as fragility, solubility, being a poison, and so on. Why do I do this if these disposition ascriptions only vaguely and indirectly pick out genuine powers? The short answer is that examples like these are familiar and therefore easier to think about and discuss. This requires a small leap of faith on our part: we must trust (cautiously) that what we gain from thinking about disposition ascriptions can aid our thinking about powers. Sometimes this leap will lead us into error, but we are modelling as best we can. Some disposition ascriptions will be undergirded by some set of microscopic powers, and so those will be good as guides, but we will not always be so lucky. (In a few cases the light they shed is crucially informative about the difference between genuine powers and merely true disposition ascriptions.) Thus we can proceed, albeit carefully.

3.3 Powers and Categorical Properties When it comes to powers and categorical properties, there are four fundamental ontologies one might hold.¹⁹ There is power monism, according to which all properties are powers, and exhaustively so; categorical monism (or categoricalism), wherein all fundamental properties are categorical; dualism, which admits fundamental properties of both the previous types; and mixed monism, which holds that there is a single class of non-conjunctive, hybridized fundamental properties that are at once powerful and categorical. In Chapter 5 I defend my version of mixed monism, but successful navigation of this quadripartite debate would be impossible without some generally shared interpretation of what it means for a property to be a power or categorical. It thus behoves us to get clear about the distinction between powers and categorical properties.²⁰ The power/categorical distinction is taken to be an ontological distinction, not merely a conceptual one. Power monists and categorical monists each claim that the fundamental properties are entirely of one sort or the other, and hence that the other category is empty, but that is no barrier to treating the distinction as ontological. In fact, if one endorses either monism, one ought to claim that the properties of the empty class are impossible, but again that is no barrier to the distinction’s being ontological. Dualism is clearly unproblematic in this regard, but there is a prima facie difficulty with the mixed monist taking the distinction ontologically, as her properties are neither exclusively nor exhaustively powerful or categorical. We could say that for the mixed monist the distinction is merely conceptual, and that her properties are ones that fall under both concepts, but there is something unsatisfying about this. It suggests—misleadingly, if not falsely—that the properties of mixed monism are not

¹⁹ These are the mainstream views; I discuss some less conventional ones in Chapter 5. ²⁰ This distinction concerns power properties—not dispositions in the ascription or mere predicative sense—and how they should be distinguished from the categorical properties the neo-Humean promotes. Hence, a categorical monist might claim that all properties—not just the fundamental ones—are categorical, while still believing that we can truthfully ascribe dispositions to objects. All she needs is the story that translates those ascriptions into her favoured ontology.

   



literally powerful or categorical; but the view is that they are both, not neither.²¹ Hence, even the mixed monist should treat the distinction ontologically, with one caveat, as follows. For a property to be a power or a categorical property is for the property’s essence to be one or the other. That essence captures its nature—better yet, it is its nature: it is whatever general sort of property that it is. For all but the mixed monist, that essence is fully captured by the specific powerfulness or categoricity it has (as laid out in the rest of this section.) On these views the powerfulness or categoricity exhausts the property’s essence, to the exclusion of the other. The mixed monist denies this. The caveat the mixed monist thus employs in treating the distinction as ontological is that she drops the exclusivity, thereby allowing for essences that include both. Furthermore, because categorical monism is a key aspect of the neo-Humean ontology, the neo-Humean eschews any fundamental property whose essence is at all powerful. This distances categorical monism from the other three ontologies, all of which take (some, if not all) properties to have (at least partly) powerful essences. As views that endorse powers, those three constitute the different fundamental ontologies available to the powers theorist. I approach the distinction between categorical properties and powers in five connected ways. I briefly outlined above one basic way powers can be distinguished from categorical properties. That way concerns the modal nature of powers, and is the first of the five. (i) Modality. Powers are not in pure act: whatever manifestations they might produce on one occasion, there is still much of them hidden.²² We witness other aspects of a given type of power when instances of it appear in different circumstances, but we can never see all of its nature at once, and it is never doing all that it can do at once. Even the manifestation a power is about to produce is not a state it is now in; that is a future state, a state that it itself may not be part of. Powers thus ‘point at’ or are ‘directed at’ those future states they can produce, but those states are not now present, and many of them might never be actual.²³ Thus the mode in which a power presents itself is more complicated than those properties that have (strictly) nothing more to them than that which is always on display. And even when the display of a power is manifest, there will be other displays, only made apparent in different circumstances. In contrast, categorical properties are in pure act: what you see is what you get. (Well, not quite; what you see is the product of some causal interaction with the categorical property, but the property itself is in pure act. Really, what it is is what you get. More on this below.) There is nothing more to them than what is there at any given moment. This

²¹ It should not, therefore, be confused with a view on which properties answer to both descriptions but are strictly neither, as with Mumford’s (1998) neutral monism. ²² I am assuming that powers are multi-track; see §4.2 for the defence. On a single-track view, producing a manifestation leaves very little of the power’s nature hidden, but one can still consider them hidden when not manifesting. ²³ See Martin and Pfeifer (1986), Place (1996, 1999a, 1999b), and Molnar (2003: ch.3.) for more on the notion of directedness.

   difference in modal nature is the first way in which powers and categorical properties differ. (ii) Causal profile. A second aspect of the distinction concerns how strongly each type of property binds to its causal profile. A causal profile is what you get when you consider the complete spectrum of effects (manifestations) a property is capable of producing, along with the scenarios under which it would produce them.²⁴ Powers are those properties that bind most tightly to their causal profiles. So tightly, in fact, that their causal profiles determine their essences (exhaustively so under power monism and the relevant half of dualism; only partially so for mixed monism). A common way of putting this is to say that powers are properties that have their causal profiles necessarily. A note of caution: speaking this way can be slightly misleading, as it makes it sound as if there is the property and its causal profile. That is unproblematic when thinking of categorical properties (it is ideal in fact, because the causal profile is not part of the essence of a categorical property), but it gives the wrong impression for powers. On all but the mixed view, powers just are their causal profiles.²⁵ Categorical properties, on the other hand, have their causal profiles contingently. They bind to their causal profiles only weakly, and could in principle arise in scenarios where they have no causal profile at all. Recalling the mosaic metaphor (§2.4), categorical properties are inherently passivist. In and of themselves, the categorical properties have no causal profile. Any causal profile they acquire comes from outside them, after the fact, via the addition of laws of nature. Within a particular scenario, the superadded causal profile might bind reasonably tightly to the property (if the properties of our world are categorical, then they seem bound up with the laws in this way), but nothing about the categorical properties requires this be so. Unlike the case for powers, causal profiles play no part in the essences of the categorical properties. Let us explore this second aspect of the distinction from a different angle. A power is a property whose essence is given (partly, if not wholly) by the property’s causal profile, but causal profiles play no part in determining the essences of categorical properties. So what determines the essence of a categorical property? The answer: identity and difference. Deep down—beneath any accidental causal features a categorical property might acquire—all there is to a categorical property is that it is this categorical property and not some other. That is all. Its thisness and not-thatness exhaust its essence. We call these identity-only essences ‘quiddities’.²⁶ A categorical ²⁴ See Shoemaker (1980). ²⁵ The mixed view includes a qualitative element with that profile, but the mixed properties are not merely qualitative properties to which a causal profile is attached. ²⁶ Black (2000), Whittle (2006), and Bird (2007a) credit Lewis and Armstrong with endorsing this ‘extremely austere quidditism’, according to which ‘there is nothing qualitative that distinguishes fundamental properties from one another’ (Smith 2016). I take this to be the dominant form of categoricalism. However, Black (2000: 91) writes that, for Lewis, ‘[j]ust about all there is’ to a neo-Humean property is ‘its identity with itself and distinctness from other qualities’, suggesting a version of quidditism that adds an unknowable extra something to categorical properties. This is compatible with Lewis’s (2009) account of ‘Ramseyan Humility’ (Locke 2012). See also Hildebrand (2016). I am partial to the something more, and think that all accounts of properties should include it, but it does not make categorical properties any more homey.

   



property then just is a quiddity. By contrast, powers either have much richer essences (mixed monism), or exclude quiddities altogether (power monism). It is worth highlighting how little there is, deep down, to the positive conception of a categorical property. For instance, most people familiar with the concept of a categorical property can reliably produce a list of paradigm examples. This list includes such (putatively) categorical properties as being triangular, having some particular structure, being at some location, pain states, and qualities like being blue. Putting aside worries about whether any of these is fundamental, let us pause for a moment and think about what instances of these paradigm categorical properties are like. Let us start with being blue. I hazard that most—perhaps all—of the ways in which you envision an instance of blueness concern what it is liable to do in certain circumstances, such as how it will look with the light on, what wavelengths of light it is prone to reflect, or whether that blue and black dress only appears that way due to the ambient lighting.²⁷ These all concern what sorts of effects or manifestations the property is involved in bringing about. Thus, these are all aspects of the property’s causal profile, and as a categorical property, they are not part of its essence. Hence what you have imagined is not the categorical property itself. With that in mind, think about that blue property instance again, but this time immediately dismiss any part of your envisioning that involves how it might act. In other words, think about that property without any part of its causal profile. What is it like? It can no longer be thought of in terms of its characteristic hue—that of skies and oceans—because that is the impression it produces in us when we observe it under illumination, and so is part of its causal profile. So, too, is the spectrum of wavelengths it will reflect, and those it will absorb. Similarly off limits are the effects it has on the appearances of the objects around it. Thinking about blue without a causal profile is hard. In fact, I suspect it cannot be done.²⁸ This is interesting all on its own, but it should help give you some sense of how little there is to the essence of a categorical property. If you were to somehow succeed in imagining it sans causal profile, you would find yourself envisioning nothing more than that it was it; a property that was identical with itself and no other. Maybe you think there is a little more to blue. Perhaps, for all I know, you believe that its essence contains a hue that is somehow connected to the phenomenal states you enjoy when viewing illuminated blue properties.²⁹ There is, of course, no reason that this non-phenomenal hue would have to line up with that of your experience; it could just as well be anything, for all you know, that produces your experiences. Long story short, most of our thinking about properties is thinking about their causal profiles. When it comes to their essences, a power is a property for which the causal profile is most or all of its essence, whereas a categorical property is one from which it is stripped away. That categorical properties have such meagre essences constitutes what I call the ‘myth of categoricalism’. The myth is that the categoricalist ontology is founded on ²⁷ I am assuming, for the sake of convenience, that blueness is a physical property of surfaces. ²⁸ Remember Kant? Not to mention many of his early modern predecessors. ²⁹ Unger (2006) defends qualities like this.

   familiar, everyday properties. Claims that the categoricalist has the common-sense high ground in the ontological debate are built on the back of this myth. Categorical properties are supposedly familiar; powers are ‘spooky’ and ‘shameful’, and not to be trusted.³⁰ But categorical properties are not at all familiar. It is causal profiles that are familiar, not mere identity and difference. And even if you think that there is something more to an instance of blue than its not being an instance of some other property, it is a mysterious extra something, not a familiar something. Of course, the case is not limited to blueness: triangularity concerns the sorts of spaces into which an object can be fitted, whether it rolls easily on inclined planes, how light moves around it, and so on, all of which are part of its causal profile. It might be argued that its essence includes geometric qualities not exhausted by its causal profile, but those are hardly familiar.³¹ (iii) Counterfactuals. Thinking about properties with or without their causal profiles brings us to the third aspect of the distinction. By far the most popular suggestion for distinguishing powers from categorical properties is that the former, but not the latter, possess a special relationship to subjunctive conditionals (that of supporting them, or perhaps entailing them). These conditionals are also known as ‘counterfactual conditionals’, or just ‘counterfactuals’ for short. Accordingly, for an object x to have the power to r would mean that if x were to undergo stimulus s, x would give response r. Some, myself included, claim that this strong connection is one of entailment.³² Hence, when the property you are dealing with is a power, it will, owing to its very nature or essence, make true certain counterfactual conditionals. This is not to suggest that categorical properties cannot also support counterfactuals, but if and when they do, it is a contextual matter twice over (concerning what laws hold, and the properties’ local environments). As you may have guessed, this difference is merely an extension of the powers having their causal profiles determine their essences and the categorical properties not. The causal profiles are just what the property will do in this or that circumstance; taken singularly, these single circumstance-to-effects pairings can be expressed as counterfactual conditionals.³³ However, Hugh Mellor has argued that making the distinction this way might lead to problems, as even archetypical categorical properties such as triangularity pass the subjunctive-supporting test.³⁴ Mellor rightly indicates that for an object to be triangular ‘is at least to be such that if the corners were (correctly) counted the result would be three’, where ‘correctness’ concerns how the counting is done, not what result it gives.³⁵ Hence even shape properties—supposed paradigms of categoricity— have the feature that all and only the powers were thought to have.

³⁰ I cannot point to anyone who explicitly promotes this myth, but I take it to be implied by the claim that powers are spooky. Hugh Mellor (1974: 157) once quipped that powers ‘are as shameful in many eyes as pregnant spinsters used to be’. I am glad we are well past that, on both counts. ³¹ I welcome categoricalists who would endorse richer essences, and think their ontology would be all the better for them. See also Smith (2016). ³² Bird (2007a) agrees. ³³ Nothing I have said should be interpreted as my having implied that powers are analysable in terms of counterfactual conditionals. That would require, at the very least, that the holding of certain counterfactuals entailed the having of certain powers, which I deny. ³⁴ Mellor (1974: 1982). ³⁵ Mellor (1974: 171).

   



In response, Elizabeth Prior contends that the distinction is still well and good, as she believes the proposed analysis of triangularity fails.³⁶ She first points out that if we drop ‘correctly’ from the right-hand side of the analysis it would no longer hold, as one could count badly and get the wrong result. She next indicates that even correct counting cannot secure the entailment, as nothing precludes said correct counting from taking place in a world where the laws of nature differ, and systematic perceptual deception ensues. Lastly, she goes on to argue that attempted fixes of the analysis one might hope to enact (by tweaking how ‘correctly’ is understood) lead to an ambiguity whose resolution is either circular—and therefore no threat to the subjunctive-supporting test—or rendered innocuous as a counterexample. Mellor replies, calling the existence of categorical properties a myth, but at some point Mellor or Prior—if not both—loses the plot.³⁷ Whether ‘triangular’ names a power, a categorical property, or a property at all, is the topic of a substantive metaphysical debate. And it is a debate that is posterior to that of how best to distinguish power properties from categorical ones. One can see the error in Mellor’s reply to Prior. Rather than objecting that the proposed distinction cuts no ice, he opens by complaining that, ‘Prior tries to sustain the myth that there are non-dispositional properties of things.’³⁸ Further, he contends—just as he does in his earlier discussion—that x’s being triangular entails the subjunctive conditional ‘If x’s corners were correctly counted, the result would be three’. In other words, he argues that triangularity is a power property, not a categorical one, by applying the subjunctive–supporting test. If he did not agree with Prior that powers can be distinguished from categorical properties by way of the former’s uniquely entailing subjunctive conditionals, then he would have no basis for his claim that triangularity is a power. There are two lessons I want to draw from the derailment of the Mellor/Prior debate. The first is that we must be careful not to let debate over how best to distinguish powers from categorical properties get entangled with substantive debates over the correct ontology. We have already witnessed the pitfalls associated with failing to do so. It is one thing to say how powers and non-powers differ; it is another to claim that ‘triangular’ names a property of one sort and not the other. Yes, we need to use examples when we are getting started. And yes, some form of reflective equilibrium is at work. But we are trying to find a distinction in which the ontological debate can be framed, and so it is important we not have the debate first. The second lesson is that in order to comply with the disentanglement prescribed in the first lesson, we should not generate a distinction by enumerating paradigmatic cases which we then codify. Despite seeming a natural way to do it, if we decide ahead ³⁶ Prior (1982). ³⁷ Mellor’s initial paper (1974) targets the claim that there are ‘real’ categorical properties that are how a thing is ‘in itself ’ and not merely how they are disposed to behave. Prior responds by claiming that ‘Mellor argues that dispositions do not peculiarly entail subjunctive conditionals’ (1982: 93). Strictly speaking, he does no such thing: what he claims is that all properties—including the paradigmatically categorical candidates—are dispositional, because they all pass the subjunctive-supporting test. His reply to Prior provides further evidence, as he describes categorical properties as those ‘that support no subjunctive conditionals’ (1982: 96). ³⁸ Mellor (1982: 96).

   of time that triangularity is quintessentially categorical and therefore must be categorical come what may, we will have forced the hand of those who claim that all properties are powers. They can no longer claim with Mellor that ‘triangular’ names a power, and must either admit non-powers into their ontology or deny there is any such property, in direct violation of the first lesson. After all, whereas one power monist might consistently concede that triangularity is categorical while denying either that triangularity is instantiated or fundamental, yet another might claim that triangularity is a fundamental power, and the point of having a distinction is to be able to characterize the latter view just as much as the former. To that end, as tempting as it may be to start out by noting that flammability and fragility are paradigmatic powers, and that length and shape are archetypically categorical, we are required to locate our criterion first and only then engage in the substantive matter of property classification. In the meantime, we must treat properties like triangularity neutrally: the nature of triangularity will get cashed out differently in different ontologies (and in different metaphysics). My suggestion that we start with something other than examples might well be resisted, given how natural the particularist approach seems to be. ‘Surely we make a distinction between dispositional and nondispositional properties, and can mention paradigms of both sorts,’ insists Shoemaker.³⁹ I do not deny this. However, when we distinguish as he suggests, we do so from within a particular metaphysic, and this is what is being overlooked. (If it is being done critically at all—it might be nothing more than knee-jerk talk about properties, and not worth taking seriously.) As it happens, Shoemaker follows the above quotation by relegating these would-be paradigm properties to mere predicates, arguing that all properties are clusters of (conditional) powers, so even he does not take his claim seriously.⁴⁰ Our aim then is to have a strong enough sense of the difference (and a general enough notion) that we can meaningfully and sensibly discuss the different sorts of ontologies and metaphysical frameworks one might come across when speaking of powers and categorical properties, without stacking the deck in favour of either. With that in mind, there is no reason—yet considered—to give up on the subjunctive-supporting test. We are, after all, remaining neutral about what sort of property triangularity is, whether it is fundamental, or whether it is a property at all, and so need not be guided by problems it raises. However, two important caveats must be made when applying the subjunctive-supporting test, which undermine the extent to which the ‘test’ is particularly useful. Firstly, the subjunctives will not be the simple conditionals we typically associate with talk of powers, but very complicated ones. It is handy to think of fragility as entailing that if the fragile object is knocked, it will end up broken. But knocked how? And knocked where? Will it always (without fail) lead to a breaking? Is a bit of

³⁹ Shoemaker (1980: 210). ⁴⁰ Shoemaker’s powers are conditional in the sense that they confer non-conditional powers only in concert with other properties. Being knife-shaped confers upon its bearer the ability to cut through butter, but only when co-instantiated with being made of steel; absent steeliness the power is ‘merely conditional’. I am not fond of characterizing powers this way, and see the conditionality as a feature of causation, not properties.

   



cracking a break, or only total destruction? The standard conditionals that are applied when discussing powers do not provide answers to these questions. They are simply too imprecise. This has led to all sorts of worries and objections that might well have been avoided.⁴¹ A proper discussion of why the subjunctive conditionals are so complicated will have to wait, but for now it suffices to say that the antecedents and consequents of those conditionals will be incredibly rich in detail. (Recall how complicated just one intervening angel can make things.) Unless, that is, the power is one for which the antecedent seems to be lacking altogether. The second caveat concerns powers that apparently lack stimuli, such as the decay of radium atoms and gravitational force. The first seem to just happen, and the latter cannot be said to properly start or stop. The antecedents of the corresponding subjunctives would thus be rather odd. Not incapable of formulation, but odd to be sure. Gravity, for instance, might have an antecedent that covers any and all circumstances. But what sort of antecedent is required for the subjunctives of particle decay? No circumstances? All circumstances and a probabilistic consequent? There is no easy response. It is safe to say that if we intended the subjunctive-supporting test to be our only means of distinguishing powers from categorical properties, we would run into difficulties. I conclude that powers are those properties that entail (highly complex) subjunctives, but the subjunctive-supporting test is not—practically speaking—a particularly reliable way of locating powers. (iv) Causation. The fourth way that powers are distinguished from categorical properties concerns their role in bringing about effects. Recall the passivism associated with the categorical properties. What this boils down to is that in and of themselves categorical properties are incapable of producing effects. Their essences, as we have seen, are the thin features of identity and difference. They simply do not have in them—on their own—the ability to bring about states in the world. They can only do so with the help of the laws, and only then if they are governing laws. Add some governing laws of nature, and categorical properties can work with those laws to generate effects. Take away the laws, and you have nothing causal. Powers, on the other hand, are effect-producers by nature. Nothing needs to be added for an instance of a constellation of powers to produce some effect; causal readiness is what makes them what they are. This causal difference, as you might have guessed, is really just an extension of the distinguishing features we have already seen. In fact, all four criteria I have presented are interconnected. What we have, ultimately, are two very different conceptions of properties, spelled out along the lines of causation, causal profile, counterfactuals, and modality. And they provide us with the basis for distinguishing between properties as powers versus properties as categorical. (v) Hume worlds. The fifth and final way of making the distinction is really not a fifth way at all, and is better thought of as a simpler way of capturing what we have already seen. It is my go-to rule of thumb. Following a suggestion made by Ellis, it is handy to sort properties based on whether they can be instantiated at Hume worlds.⁴² First presented by Frank Jackson,

⁴¹ See Choi (2012) for an overview.

⁴² Ellis (2001: 46).

   a ‘Hume world’ is a ‘possible world where every particular fact is as it is in our world, but there are no causes or effects at all. Every regular conjunction is an accidental one, not a causal one.’⁴³ Hume worlds then are worlds whose only properties are categorical properties. It follows that a power is a property that cannot be instantiated at a Hume world. Recall from the previous chapter the mosaic metaphor, in which a random array of tiles is littered about some area. Regardless of how the tiles got there, and despite the fact that there are no rules that guide their distribution, the tiles give rise to a pattern. That pattern supervenes on the tiles. Now assume that the tiles are not tiles but properties littered throughout the universe. Even though we are assuming that their distribution was random, law-like patterns will emerge. These supervenient laws can be systematized in various ways to make them more or less untidy, and in many cases these laws might be infinite and generally unwieldy, but for our purposes we can shelve those sorts of worries. Regardless of how the properties ended up in the configuration they did, laws of nature will emerge from the patterns. In keeping with the theme, call such a law a ‘Hume law’. Hume laws appear in every world, whether the distribution of properties is random, as we have assumed, or not. Compare: an image emerges from a mosaic if the distribution of tiles is random or highly ordered. The same goes for Hume laws: even if the distribution of properties is strictly regulated, patterns of some sort will emerge, and hence there will be Hume laws. But be warned! Only in some cases will the Hume laws coincide with the laws regulating the distribution of properties (if such there be), because of all the contingent factors involved in the expression of the latter.⁴⁴ We are now well on our way to understanding the Hume worlds. Hume worlds are those worlds at which only Hume laws hold; there are no genuine governing forces at work. There are likewise no genuine causes, and nothing that connects one state of the world to the next. There will be Hume causes (singular instances of the Hume laws), but these will be as impotent as the Hume laws themselves. Given our understanding of Hume worlds, we can piggyback on them to define powers as (at least) those properties that cannot be instantiated at Hume worlds. This would include properties whose essence is entirely powerful, but also properties whose nature is only partly powerful. This is because powers are properties whose nature is directed at future states of affairs. They are properties that point towards future states, and bring about those states. What states they bring about will depend on what arrangements they appear in—which constellations obtain—but there is a state that will arise for any such constellation, so it is only the what that changes, not the when or how. This means that power properties stand in cause-and-effect relations between earlier and later stages of the world—relations outlawed at Hume worlds. Furthermore, powers carry their law-like features within them; it is part of their essence, qua power. Their ⁴³ Jackson (1977: 5). Possible worlds should here be thought of as handy conceptual devices and nothing more. ⁴⁴ As a clumsy illustration of this point, imagine that coin tosses operate under regulatory laws for which heads and tails are equiprobable, but luck hands us only tails. The resultant Hume law gets it wrong.

   



pointing at future states just is their internal law-like nature; it is what gets expressed in such and such conditions. But this means that any property like this would be unwelcome in even the most short-lived Hume worlds. Even when an instance of a power lacks the time or partners to do its thing, its very presence brings a governing law within it, in direct violation of the criteria by which Hume worlds are constructed. Hence, even if we could somehow prevent constellations of powers from acting, and thereby sever their causal ties with the futures they generate, their law-like internal nature would be enough to block their entry into Hume worlds. Might it be objected that power monists should find the concept of a Hume world objectionable, and therefore reject the definition on offer? This should not be a problem, as making sense of such worlds does not imply that there are any, or even that there could be any, and certainly not that ours is a Hume world. That is the substantive debate we are now in a position to have. However, there is a nearby worry that is somewhat more troubling. Any power theorist is going to claim that at least some (if not all) properties in the actual world are powers, as part of their substantive view. If that is the case, then those powers will make up some portion of the facts about the world. But how can we now have a world in which all the facts are as they are in our world, but in which there are no genuine laws or causes? That is, how could our world then generate a remotely similar Hume world counterpart? Whereas the requirement that we duplicate all particular facts in the actual world would have us carry over the actual world’s powers into the Hume world, the rejection of all causes and effects demands we leave them out. Hume worlds might thus only be coherent if you already believed that all properties were categorical. This is a genuine concern. But I do not think it forces us to give up our rule of thumb. Instead, I suggest the following. (1) Continue to keep the substantive debates at arm’s length, at least for now. That means that it remains an open question what nature the properties around us have, and we can thus act as if they could be the sort of properties that could populate Hume worlds. (2) Keep in mind that the ‘world’ talk is a useful fiction, and so reasoning over them might require us to cheat, just a little. (Squint a bit, as they say.) It really ought to be the case that the instantiation of even a single power in the actual world means it has no Hume world counterpart, but we can fudge things a little. And (3), if need be we can lessen the first requirement, by reducing the world and considering only that portion which is not powerful. At the end of the day, the concept of a Hume world is a better tool if we worry less about replicating our world per se, and simply consider worlds that have no real laws or causes. And that is what I propose we do. The problem here is one that arises from our trying to find a way of successfully navigating two incompatible ontologies at the heart of two competing metaphysics. As we saw in Chapter 1, we have two very different sorts of frameworks here, and parts built to work with one cannot be fitted onto the other. Hume worlds, properly understood, are constructs that belong on the neo-Humean side of the fence. According to the powers theorist, there is no such thing as a world exactly like ours that has every particular fact that ours does, but lacks any causes or effects. This follows from the belief that all the properties of the actual world are at least partly powerful. But there is no harm in our thinking otherwise in order to get a better grip

   on the nature of power properties. After all, it is no accident that Hume worlds should be hostile to powers! We can thus cautiously—while squinting—understand power properties as those that cannot be instantiated at Hume worlds. As far as definitions go, it is fair to say that this one is not entirely illuminating. If we had not previously reflected on the ways in which powers differ from categorical properties, you might not now be any better off. But at least one thing should be clear: powers are properties that bring causal abilities and laws with them—it is part of their essence, and that is why they are barred from Hume worlds. To know this is to know the most important thing about them. Categorical properties, by contrast, might get connected with certain laws or causes, but it is not part of their nature that they get hooked up with this or that particular law or cause, or any at all. This is not a perfect definition of ‘powers’ or of ‘categorical properties’, but it constitutes a widening of the definitional circle, and that is to have made some headway. Power properties lie at the heart of the ontology I am offering, hence a full unpacking was never in the offing. Our best hope of getting a better grip on their nature does not come from looking closer, but from seeing them at work as part of a broader metaphysic.

4 Understanding Powers 4.1 Intrinsicality We have made some inroads into the nature of powers, but they have been a mix of negative and positive, telling us as much about what powers are not as what they are. This chapter furthers the positive characterization of powers, and sets the stage for Chapter 5, where I argue that powers are properties with complex essences. I defend the view that all powers are intrinsic. A satisfying analysis of ‘intrinsic’ has yet to be found, but rather than waiting around, an intuitive understanding should suffice for our purposes.¹ That intuitive understanding boils down to the following: ‘[a] thing has its intrinsic properties in virtue of the way that thing in itself, and nothing else, is.’² This is a matter of how powers are instantiated.³ It follows that intrinsic properties are those that do not differ between objects that are perfect duplicates of one another.⁴ To say that a power is intrinsic is to say that an object’s having that power depends on ways that that object is, and nothing else, regardless of what the world is like around the object. Of course, the properties an object has at some time t₂ may depend on its interaction with other objects at t₁; the claim here is that the properties an object has at any given time depend on the way the object then is—and not how anything else at that time is. This is perfectly compatible with the object’s being that way in virtue of prior interactions with other objects, as is surely the case.⁵ Building on our intuitive understanding of what it is for a property to be intrinsic, we can develop an intuitive understanding of what it is for a property to be extrinsic, for the two are inter-defined. An extrinsic property will be a property that is nonintrinsic, that is, when its being had by an object is in virtue of objects or properties outside the object in question. My argument that all powers are intrinsic hangs on this duality of intrinsicness and extrinsicness. It is commonly held that powers are intrinsic properties. In fact, up until recently, this claim has enjoyed widespread agreement. Stephen Mumford writes, ‘dispositions

¹ Lewis (1983a). Further discussion can be found in Lewis and Langton (1998) and Yablo (1999). ² Lewis (1983a: 111). ³ We will see later in this chapter that the essence of a power is reflected in a structure, but this is orthogonal to the matter of their being intrinsic. ⁴ Lewis and Langton (1998). ⁵ Contra Vallentyne (1997: 209), who states that ‘a property is intrinsic just in case a thing’s having it (at a time) depends only on what that thing is like (at that time), and not on what any wholly distinct contingent object (or wholly distinct time) is like.’ Vallentyne’s definition is better suited to neoHumeanism; the same might be said of duplicates, especially if envisioned as counterparts. The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

   are actual, intrinsic states or properties’; George Molnar states that ‘[p]owers are intrinsic properties of their bearers’; and John Heil claims that ‘[d]ispositions are intrinsic properties of objects possessing them’.⁶ Despite the widespread agreement, it falls short of universal, and the balance is shifting. Most notably, Jennifer McKitrick and Barbara Vetter champion the view that some powers are extrinsic. This view is growing in popularity, and so there is work for me to do.⁷ But perhaps not as much as one might expect. McKitrick and Vetter are fans of extrinsic powers, but they nevertheless believe that extrinsic powers depend for their existence on intrinsic powers. Once we have intrinsic powers, we get extrinsic powers ‘for free’, which is to say that they are no addition of being. As Vetter says, their inclusion is ontologically ‘innocent’.⁸ In fact, not only do both hold that extrinsic powers are ‘innocent’ ontological additions, they explicitly cite the derivative status of extrinsic powers as further evidence of their existence.⁹ This suggests that their disagreement with me is not a deep one, given that my ontology is sparse.¹⁰ We seem to agree that the sparse powers are intrinsic. As if that was not enough, McKitrick and Vetter make clear that they are operating with ‘generous’ property ontologies; both explicitly endorse abundantism. According to McKitrick, there is a property corresponding to any unique class of objects, however gerrymandered; and Vetter welcomes properties we get ‘automatically’, and thus for free.¹¹ Their extrinsic powers are abundant properties, not sparse ones. If we assume sparsism, this looks like a slam dunk for intrinsic powers. I am not one to meet victories with suspicion, but I nevertheless think there is more to be said. Among the reasons in favour of considering the matter more closely is the (remote) possibility of radically emergent extrinsic powers not grounded in intrinsic powers. But it is also a useful exercise, because of certain confusions it can help us avoid; of payoffs in later chapters; and because it gives me the opportunity to cast doubt in the direction of free lunches (at least ones that give us additional powers at seemingly no cost), which allows me to take the fight to McKitrick and Vetter. I start with a positive argument for the existence of intrinsic powers, then go on to argue that if we have intrinsic powers, then we have no good reason to admit the existence of any extrinsic powers alongside them. I take this as a good reason to think they are all intrinsic. The argument that some powers are intrinsic is straightforward. Recall that I understand properties as ways that objects are, and that no sense can be made of objects existing without being some way or other. Could all those ways that an object is—all those properties it has—be extrinsic? It hardly seems so. Even if some of the ways an object is concern how it stands to other objects or contexts, some of its properties must be intrinsic. There must be some way that it is—in and of itself— however minimal. It follows that if there are objects, then they must have some

⁶ Mumford (1998: 74), Heil (2003: 195), and Molnar (2003: 129). ⁷ McKitrick (2003a, 2018), Vetter (2015: ch. 3). See also Bauer (2011). ⁸ Vetter (2015: 125). ⁹ McKitrick (2003a: §5), Vetter (2015: 124 note 16). ¹⁰ See §1.5. ¹¹ McKitrick (2003a: 158), Vetter (2015: ch. 1). McKitrick (2003a, 2009a) has a liberal understanding of what a disposition is, which comes closer to what I understand as a disposition ascription, so she has more room to admit extrinsic cases. I specifically deny that we should admit extrinsic powers.

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intrinsic properties. Now, consider that we are operating within a powers metaphysic. That means that some or all properties are powers. If all properties are powers (power monism), then the intrinsic properties are powers. The same follows if mixed monism is true. Dualism suggests the same conclusion, as it is likely that some of the intrinsic properties would be powers, even if that conclusion is not guaranteed. Hence, with the exception of dualism, it follows from any metaphysic on which powers are fundamental properties that (at least) some powers are intrinsic. Should we be overly concerned by the lack of dualist guarantee? No. For starters, I argue in Chapter 5 that fundamental dualism is unstable. But even before we meet that argument, the problematic configuration of dualism seems far-fetched, at least as a legitimate form of a powers metaphysic. To be a problematic version of dualism— that which does not guarantee that some intrinsic properties are powers—requires a version of dualism wherein all intrinsic properties are categorical, and thus all powers are extrinsic. This set-up sounds more like categoricalism than dualism, as it is hard to see how these extrinsic powers would count as fundamental (especially if the extrinsic powers depend on the intrinsic categorical properties, in the way most extrinsicalists imagine). Moreover, it is hard to see how these extrinsic powers could depend on the categorical properties at all, without either adopting neo-Humeanism or adding some additional nomological element. In sum, I do not believe we have much to worry about here. Perhaps I have not fully convinced you that there must be intrinsic powers if one endorses a power ontology. Let me remind you that this is uncontentious, so it should be unproblematic for me to assume that some powers are intrinsic, and shift the argument to the question of whether they all are. Let me linger here for just a moment. There seems to be some mysterious desire to posit entities simply because certain terms pop up in our vocabulary. But we should not be so indiscriminate about our posits, even if our talk is properly vetted. The real question about whether there are extrinsic powers is a matter of final ontology, and it is with final ontology that I am concerned. Within those parameters, the virtues of systematic metaphysics take hold, and a form of reflective equilibrium is in place. We thus keep score as an ontology is judged over this and that problem. It is with the standards of systematic metaphysics in mind that I promote the intrinsicness of powers. If the rules of ontology are cast aside, we might find reasons to admit other things into our ontology—but here the rules remain in play. I advocate ontological austerity, and that might mean I am hard pressed to convince those with overly liberal and inclusive ontologies that powers are intrinsic. The reasons I present are thus intended for an audience interested in playing by the rules. The central argument I employ against the existence of extrinsic powers is an argument from parsimony. Powers are theoretical entities of a metaphysical or metaphysical-cum-scientific sort. To wit, they are entities postulated to solve metaphysical problems, especially those concerning causation and the laws of nature. Thus, when considering whether to countenance powers, their ability to satisfy these roles is of great importance. Should it turn out that some powers have no causal role to play (and no causal role they could play), we would have no reason to countenance them, because doing so would offer no theoretical advantage. Hence, any legitimate power must be such that it adds to the causal profile of its possessor, not merely

   duplicates portions of it. Consequently, for any scenario in which we can point to an intrinsic power (or powers) that would be the cause of any putative effects of a would-be extrinsic power, the extrinsic power will be causally redundant. In that case, the extrinsic power would have no causal role to play, and therefore we would have no reason to countenance it (and thus a good reason not to). And it just so happens that in most scenarios that appear to support the postulation of extrinsic powers, those would-be extrinsic powers are causally redundant. Extrinsicality aside, we are considering whether or not we want to admit properties whose essences are powerful. What is it for a property to be powerful? The short answer is that it must be a cause of its effects. That is, the manifestations it is credited with producing are manifestations that it—either alone, or in concert with other properties in a constellation—genuinely produces.¹² A property is not powerful if the effects it purportedly brings about are the result of some other cause; that is, if credit for the effect correctly belongs elsewhere. Those so-called ‘powers’ would be powers only in name: they might be disposition ascriptions we utilize for the convenience of empirical shorthand, but they are not the powers on which the powers ontology is based. Hence, if extrinsic powers are to be admitted into our ontology, they must be capable of producing manifestations. Combining these considerations gives us a general non-redundancy requirement of powers, to the effect that they must legitimately contribute to the range of causal capacities had by the objects that possess them. More precisely, it is reasonable to require of a power that the range of manifestations it is capable of producing not all be such that they can only be produced in those conditions where some other power would produce the identical manifestation. Let us call this the ‘novelty’ criterion. NOVELTY: A power type P is  if and only if the range of manifestation types that instances of P are capable of producing are not all such that they can only arise in those conditions where an instance of some other power type Q would produce identical manifestation types.

I contend that the best cases of would-be extrinsic powers are not novel, so they should not be admitted into our ontology.¹³ It is worth noting that the novelty criterion is not a disguised objection from overdetermination.¹⁴ Overdetermination is a problem for certain accounts of causation, but it is not a problem tout court. Consequently, arguments that lean too heavily on overdetermination in order to reach their conclusions may be in trouble. But the thrust of the present criterion is that we have no reason to introduce a causal property when it is incapable of making a difference to the causal powers of its possessor; overdetermination does not come into it. We should not postulate the existence of properties that can only do the work some other property already does; that is poor economizing.

¹² We should not say that a property fails to be powerful just because it does not (or cannot) produce manifestations in isolation; most manifestations are the result of many interacting powers, but to be powerful each property must contribute to those manifestations. ¹³ Emergent extrinsic powers would be novel, but they run into other problems. See below. ¹⁴ Nor is this a case of causal exclusion. Jackson, Prior, and Pargetter (1982: 255), Kim (1993: 53).

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Further note that the novelty criterion is not to be confused with much stronger principles concerning existence more generally, such as the Eleatic principle. According to the Eleatic principle, everything that exists must make a difference to the causal powers of something. This has its origins in Plato’s Sophist, where the Eleatic Stranger proposes that the contribution of causal powers is the ‘mark of being’.¹⁵ I have made no universal claims about what is required for existence, and said nothing about what sorts of standards we ought to hold properties to in general. What I have said is specific to powers. I am making the very reasonable suggestion that every power that exists be such as to make a difference to the space of causal powers—nothing more general is here claimed or intended. My negative argument against extrinsic powers relies on the above criterion. I now consider four cases in which extrinsic properties might be thought to arise. (i) Directed. Perhaps the most plausible scenario in which we might claim that an object has an extrinsic power is one where the relation that supports the extrinsic power depends on the intrinsic powers of the objects in question. The scenario might look like this: the deadbolt lock on my front door has the intrinsic power of opening for keys of kind K, and the key in my pocket (a key of kind K) has the intrinsic power of opening locks of kind L, which my front door deadbolt lock just happens to be. But as well as those two intrinsic powers, the lock and the key also have the following extrinsic powers: the lock has the extrinsic power of opening for the key in my pocket, and my key has the extrinsic power of opening my front door deadbolt.¹⁶ Let us call these ‘directed’ powers, because the extrinsic powers point at (are ‘directed at’) instances of the general intrinsic power type. Note that in the imagined case, neither of the extrinsic powers is identical with either of the intrinsic powers that support them. Had either been identical, it could have been argued that the extrinsic powers were obvious candidates for a clean reduction, and therefore that admitting them into the ontology would be largely innocuous. But they are not. If we focus on just the key and its extrinsic power, it may be the case that my key has the power to open locks of type L, but this is not the same power as my key’s power to open my front door deadbolt, even though the deadbolt lock on my door is a lock of type L. How do we know that the two powers are distinct? Because if the lock on my front door was changed, my key would lose the extrinsic power to open my front door deadbolt without losing the intrinsic power to open locks of type L. Hence, we need to take seriously the question of whether extrinsic powers like this warrant inclusion in our ontology. Consider my key’s putative extrinsic power of opening my front door deadbolt, as opposed to its intrinsic power of opening locks of kind L. The two powers are nonidentical, but the extrinsic power depends on the intrinsic power in the sense that without the intrinsic power, the extrinsic power would not exist.¹⁷ That means that any ontology that includes the extrinsic power must include the intrinsic power as ¹⁵ Armstrong (1997: 41). See also Graham Oddie (1982) and Colyvan (1998). My objection is therefore more specific than that which Armstrong (1978: 82–3) raises against abundant properties. Likewise for Heil (2003). ¹⁶ Both Shoemaker (1980) and McKitrick (2003a) discuss similar cases. ¹⁷ We might also say that the latter is the salient part (a partial ground) of the former. Fine (2012).

   well. We have already agreed that the intrinsic power is a perfectly good property. Further, all the manifestations that the extrinsic power would be for have already been accounted for by the intrinsic power (they form a proper subset). Therefore, because the intrinsic power is already present, and there is no case where the extrinsic power is present and the intrinsic power is absent, there is nothing left for the extrinsic power to do. There is no manifestation the extrinsic power is capable of producing that would not be identical to one of those that would already be produced by the intrinsic power (for exactly the same conditions). In other words, the extrinsic power fails to satisfy the novelty criterion, and thus we have a good reason against admitting powers like this.¹⁸ The extrinsic power’s failure to satisfy the novelty criterion explains why they should be bounced at the door of the ontology club: there are powers enough already inside. But what if these extrinsic powers could earn their keep some other way, some way that is not strictly causal? That is, perhaps we can have a different—non-causal— reason for admitting extrinsic powers. One possible reason is that my key’s power to open my front door deadbolt is more salient to me than is its power to open locks of type L.¹⁹ It is the former I care about, not the latter. Granted, it is of some moment to me that my key should have the power to unlock my front door, but this is a fact about me and my interests, not the key or the way the world is. In fact, I care a great deal about being able to unlock my front door, and very little about other similar L-type locks the manufacturer may have produced that would also open for my key. But the space of my concerns makes no difference when it comes to deciding what properties the key possesses. Including the extrinsic property in our ontology offers no additional explanatory force in the relevant context.²⁰ Any explanation the extrinsic power can offer is matched by the intrinsic one, but the reverse does not hold. The intrinsic power of the key is capable of different manifestations with different partners (all those other locks that have escaped my interest); but the same cannot be said of the extrinsic power.²¹ Hence, that extrinsic powers of this sort might be more salient than some of their intrinsic cousins does not constitute an adequate reason to admit them into our ontology. (ii) Collective. Many hands make light work. Contrast trying to lift a piano on your own with doing so aided by a rugby team. The power that the latter has, and the former lacks, is a collective power to lift a much greater weight. And each of us has such collective powers extrinsically. We might therefore claim that I have the extrinsic power to lift a piano, but no intrinsic power to do so. Should we admit extrinsic powers like this?

¹⁸ Recognize that if we were to admit extrinsic powers in scenarios like this, then for every intrinsic power we include in our ontology, we must also admit at least one—but probably innumerably many— causally redundant, non-explanatory, extrinsic powers. After all, there may be many locks of type L. ¹⁹ McKitrick (2003a: 168). ²⁰ I here dismiss that the ease of description the extrinsic power might offer over the intrinsic powers (especially with regard to specific why questions) constitutes a genuine increase in explanatory force. ²¹ Nor must the range of possible manifestations be restricted to just other locks of kind L: one and the same intrinsic power will be capable of different manifestation types with different interaction partners. See §4.2.

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The answer, unsurprisingly, is no. But the reasons are more complicated than one might expect. Let us start with the easy case. Assume that I can lift 200 pounds, unaided. Pianos are not in the class of objects weighing 200 pounds or less, and so I cannot lift them. Now assume that the rugby players can each lift 200 pounds, and so we can collectively lift the 1200-pound grand piano with ease. There is no question that the team and I can collectively lift far more than I can on my own. But do we really need to postulate the existence of an additional power in order for this to be so? Surely not. The collective power is nothing more than the sum of the individual powers we all possess; in no way is it novel. Individual powers to lift are additive, in the sense that the total weight a group can lift is just the sum of what the individuals in the group can lift. Not only do we not need an extra power here, none is involved. That was the easy case; now let us complicate things a little. What if some days I travel with my rugby team entourage, and others I do not? We know that alone I lack the power to lift pianos, and so it might be handy (assuming you need a piano moved) to know if today is a day that I have the extrinsic power. This is handy information indeed, but it is highly contextual information that belongs on the disposition ascription side of the fence, and not that of the fundamental powers. To say that I have the extrinsic power to lift pianos on Thursdays and Fridays merely expresses some additional information about context on those days (specifically, that the rugby team will be with me). But it is not a new power. In fact, the powers I possess are such that I can lift a grand piano every day; I just need to have the right manifestation partners with me to succeed, be it a rugby team or a crane. That sounds like I am cheating. If I were to advertise my (Monday) power to lift grand pianos, I would be considered a fraud. But the cheat is in how we ascribe dispositions, not what properties I possess. My properties are such that one of them (probably many) can combine with other powers had by objects external to me for a jointly produced manifestation type that is the lifting of a piano. (This assumes—as we ought to—that the external objects include the local gravitational field and so on.) This property is an intrinsic power: it cannot be exercised without those other powers present, but its instantiation in no way depends on those powers now existing.²² It is misleading because it gets confused with another power, or with a disposition ascription. There is another power I could have, of the superman calibre, which is the power to lift grand pianos without assistance. This is also a power to lift grand pianos, in combination with other powers had by objects external to me, for a jointly produced manifestation. It differs from the first in that the range of other objects and powers required for the manifestation to be produced need not include rugby teams or cranes, and is less sensitive to gravitational force.²³ Hence the cheat is that we are accustomed to thinking that ‘the power to lift grand pianos’ names only the latter power, and not the former.

²² Causation is highly context-sensitive, as we will see in Chapter 6, but the having of this property is not. Even if the rugby team gets lost in the Andes, I would still have the power to lift grand pianos with the rugby team. And if the rescue mission fails I will never again get to manifest that power (that particular type of powers-based causation will have no further instances). ²³ I stress need not. Supermen can still lift pianos with the help of rugby teams.

   That is where the matter of disposition ascriptions comes in. The former power is a power to do many things in a great many contexts. When we ascribe dispositions to objects, we hold fixed a large portion of those contexts. We also tend to start from some manifestation type φ, and work backwards in saying that the object has the disposition to φ. Hence, we take the manifestation type that is the lifting of pianos, hold fixed the local gravitational force, hold fixed the absence of cranes and rugby teams, and then arrive at the highly contextual disposition ascription power to lift grand pianos. No such disposition ought to be ascribed to me. That is why my above claim about what powers I possess is considered fraudulent, and why we roll our eyes at folks who claim they can lift pianos unassisted, when we learn that the piano is a toy, or is on the Moon.²⁴ The eye-rolling will only get worse when I tell you that utter weaklings also have the power to lift grand pianos. To wit: they can also lift pianos with help! Without further explanation, this would start to sound farcical, but bear with me. First of all, there is the lesson just learned: this sounds a lot worse than it is, because we are accustomed to naming and ascribing dispositions relative to context, and we easily confuse the power that weaklings have to lift pianos (one that can only be exercised in contexts of help or low gravity) with one that can be exercised in a much wider (and help-free) range of contexts. Secondly, though it sounds like I am confusing an intrinsic power with an extrinsic one—Willy the weakling is intrinsically weak, but extrinsically strong (when backed by the rugby team)—that is not the case.²⁵ What Willy can do alone, and what he can do with help, are both facts about Willy that depend on the properties he has. Willy’s properties—his powers—are such that they result in heavy liftings in the right conditions. But they do not have to have been that way. How many pianos can Willy lift with the help of a team of Supermen (the ‘real’ kind, that come from outer space)? Plenty, right? Yes, plenty—but only because Willy’s properties and those of the Supermen can jointly produce lifting manifestations. Had Willie had quite different powers—for instance, had Willy been injected with kryptonite—then no number of Supermen could have helped Willy lift the piano. Willy’s powers must be what I will call ‘complicit’ with the powers of the Supermen. I will have more to say about complicity shortly, but the basic point is that of power agreement. Powers, in groups, form constellations, and constellations are what bring about manifestations. Willy’s powers are part of any constellation that he participates in. We rightly note that Willy’s usually weak powers are not difference-makers when it comes to lifting pianos with help (when included in the constellation, Willy’s powers lead to manifestations type-identical with those that would have been produced in his absence, modulo Willy himself), but they are part of that constellation nonetheless. And they are part of that constellation if the manifestation that results is a lifting of something heavy, the lifting of something light, or a kryptonite-fuelled non-lifting. For a power to be complicit is for it to be part of a constellation without being a difference-maker. Thus, Willy does have the power to lift grand pianos, and it is ²⁴ Schrenk (2009). I disagree that one should be able to jump here, just because one could jump there. It may involve the same cheat. ²⁵ Compare with Lewis (1997).

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important that we recognize his having it, but we should not ascribe to Willy the disposition to lift pianos, and we should tread carefully when talking of this power. When all is said and done, calling Willy’s power the ‘power to lift grand pianos’ is a bad idea.²⁶ All of this complicated talk about lifting pianos comes with a moral: powers are not in fact additive at all, it just seems that way when dealing with disposition ascriptions (and then only some of the time).²⁷ We said in the easy case that my lifting 200 pounds helped by 5 rugby players meant we could jointly lift 1,200 pounds. That was correct. But what Willy and the Supermen show is that the apparent additivity was just lucky. The real story is that Willy, Supermen, rugby players, and I all have some powers. And those powers can collectively produce manifestations. Some are liftings of pianos, some are not, and many of the manifestation types those constellations can produce are type-identical. But the path from powers to manifestations is not one of addition. It is a brute fact about any constellation type that it produces the manifestation type it does, and that is the end of the story. Sometimes you get the manifestation you would expect from a group of powers, and this will appear additive, but sometimes you get less (kryptonite), and sometimes you get more (as with catalysts).²⁸ If you are still clinging to the thought that this is additive, that is okay, as long as you keep clear that it is lifting you mean (a context-sensitive disposition ascription undergirded by many powers), and that this does not have general import. If we take things down to the fundamental level, the brutality might be easier to swallow. Nothing prevents there being kryptonite or catalyst-style cases at the fundamental level. And all of this adds up to the claim that we have no need for extrinsic powers of the collection. (iii) Protective. The third kind of case is what I call ‘protective’ powers, named after the now familiar angel and glass it protects. That was a masking case, wherein the glass and angel together seem to have different powers than those of just the glass or angel taken alone. Also included in the class of protective cases are those in which the external objects and powers appear to enhance the powers of the object in question. In other words, if the protective angel has a change of heart and vows that the intrinsically unchanged glass will now break in even those cases when it normally would not (such that the glass now warrants the disposition ascription ‘super-fragile’), I will still call it a ‘protective’ case. Are there novel extrinsic powers to be found in the protective cases? Again, the answer is no. When the angel vows to protect the glass, we would surely want to revise the dispositions we ascribe to the glass, but it is unchanged intrinsically. It is in a new and atypical context, but that is all. And as we just learned, the glass

²⁶ For all the reasons just stated, plus the fact that the very same type of power property will have very different manifestations it is capable of producing (in different contexts). We could still name powers this way, but they would be hopelessly complicated, as they would include every manifestation type the property could produce in every possible constellation type it is part of. ²⁷ Powers are thus not something we should model along the lines of vectors, pace Mumford and Anjum (2011). ²⁸ Catalysts increase the rate of chemical reactions.

   has among its powers various complicit powers which make it such that they, along with the angel, produce non-broken manifestations when dropped or struck. The glass has always been such that in certain circumstances it will not break if dropped onto a concrete floor. Those circumstances are non-typical, but their being nontypical does not make them new or novel. Hence, there is no need to posit an extrinsic power of stability that the glass acquires when the angel makes the vow. Again, it may be useful for us to amend what dispositions we ascribe to the glass, because those are context-sensitive and the context has changed, but nothing in the scenario has acquired any new powers. These particular constellations (involving the powers of the glass, the powers of the angel, the powers of the concrete floor, and so on) are not ones that produce broken glasses. The same is true when the angel comes to hate the glass and makes it super-fragile. There are no new powers the glass obtains, just a shift in context and an eventual shift in what dispositions we ascribe to it. The powers of the glass are still complicit, even if those same powers would result in normal fragility, absent the angel.²⁹ The relevant power of the glass—that which contributes to its breaking when the angel hates it, and not breaking when the angel loves it—might even be the same power. (Cue eyerolling.) Powers can produce different manifestations in different constellations, and these are very different constellations indeed, but that is no barrier to the same power of the glass being involved. (It should be clear enough now why ‘fragility’ is unlikely to be a good name for this power.) Surface features aside, it turns out that the protective cases are just a version of collective cases. At the level of disposition ascriptions, we see the two as different, as follows: collective cases generally add to the dispositions we ascribe to the target object, whereas protective cases typically supersede the dispositions we ascribe to the target object. But at the powers level there is no difference: both are context-free constellations that give rise to specific manifestations. Just as with the above, there is no need to posit any extrinsic power to explain what is going on: the intrinsic powers of the glass and the angel (and the floor, and gravity, and so on) are all we need to account for the manifestations that obtain. We may be tempted to think of the disposition ascriptions as justifying the introduction of extrinsic powers, but these are nothing more than convenient and context-sensitive ways of picking out subsets of manifestation types that the relevant powers can produce. They are not, therefore, novel, and so not worthy of introduction. Interestingly, William Bauer argues that mass—a property typically thought of as fundamental and intrinsic—might be more like the protective case than we typically assume. Need we be worried? Let us start with a familiar case, that of weight, to see why not. Weight is extrinsic because it is context-sensitive: the weight an object has is a function of the mass it possesses in a gravitational field. I weigh far less on the Moon ²⁹ If you are worried about complicity, consider a two-angel case, where the glass-hating angel outranks the glass-lover. The glass-lover’s vow will not be satisfied, because the hated glass will not be complicit with protection. (Actually, the power in question would be complicit with the constellation involving all three, but thinking of the glass as non-complicit with the glass-lover is easier if you see the glass-hater as previously rendering the glass non-loving-complicit.)

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than I do at home, because the Moon’s gravitational field is much weaker than the Earth’s. Following the argument above, we would appeal to the mass of the object (seemingly an intrinsic power) and the intrinsic powers of the field (or the object generating the field) in denying that we need posit any new extrinsic power of weight. All the work weight can do is already accounted for. But what happens if mass is itself extrinsic? According to Bauer, ‘the mass of any fundamental particle, a, is generated by a’s immersion in the Higgs field’.³⁰ The Higgs field is a giant energy field that permeates the entire universe. And apparently, if you were to subtract the Higgs field from the universe, then you would also remove the masses of fundamental particles.³¹ If this is correct, then mass is extrinsic, just like weight is. It might sound like it is time to worry, but Bauer gives us the way out. It is plausible to characterize the Higgs field as a particular, and hence it—and its intrinsic powers—parallels the role of the gravitational field when dealing with weight. That is half the battle. But we find a similar parallel on the particle side too. In order for a particle to be endowed with mass, says Bauer, it is necessary that it possess some property that allows for this. Bauer dubs this property Fm, and though we are not in a position to say much about Fm, it would appear to be an intrinsic property of the particle, and also a power. Hence, there is some underlying power that makes particles field-complicit, and these powers, along with those of the field, jointly produce manifestations we associate with mass. Again, if the mass-bearing object was not what we would think of as Higgs field-complicit, then it would pass through those fields without any difference-making (it would still be complicit, just not in an interesting way.) Thus, we are yet again in a position to account for mass without the need to introduce an extrinsic power into our ontology, as we already have the intrinsic powers that do the work.³² (It follows that more belongs on the disposition ascription side of the fence than perhaps we had first assumed.) (iv) Emergent. I have argued that the most compelling cases of would-be extrinsic powers are not something we should include in our ontology. We have seen cases in which the powers involved seem to target an object, combine with others, or get superseded by something outside them, and it has been shown that they all involve collections of intrinsic properties working together to produce manifestations. Thus, they do not require extrinsic powers, as none of the would-be extrinsic powers is novel. But there is a fourth case we ought to consider before moving on. The fourth case would arise if the extrinsic powers in question were entirely novel, in the sense that they do not ultimately rely on underlying intrinsic power(s) in order to exist or to be efficacious, as the others would. Let me quickly dismiss two sorts of putative emergent powers. In the mouths of some, emergent properties are properties that depend on a base of lower-level properties, but are only novel to the extent that they are unexpected. In other words, the powers of objects a and b are fairly well known, but the combination ³⁰ Bauer (2011: 89). ³¹ Jammer (2000). ³² Bauer suggests that Fm might itself give way to some other property. That would be fine; we would then learn more about what is fundamental. A potentially more troubling scenario—that in which the extrinsic powers are fundamentally ungrounded—I consider next.

   produces manifestations unlike what either produces independently. Given that the manifestations a constellation produces need not be additive, powers like this need not concern us. The same goes for what get called ‘radically emergent’ powers. The manifestations produced by a constellation need not be traceable from the manifestations of the component powers taken individually. But there is a different sort of emergent case worthy of our time. What I have in mind are what Rom Harré calls ‘ultra-grounded’ powers. If there are such things, they would not run afoul of the novelty criterion, and we might be forced to give up on the claim that all fundamental powers are intrinsic properties.³³ Harré’s cases of putative extrinsic powers arise from his interpretation of Mach’s work. For the most part, we have been considering would-be extrinsic powers that arise from an intrinsic power base. The generative direction has thus been roughly upwards, with the extrinsic powers grounded in fundamental intrinsic properties beneath them. What makes the Mach/Harré cases interesting is that they reverse the order: the micro-properties are grounded in macro-level properties (properties of the universe as a whole). According to Mach, many of the mechanical properties we ascribe to the objects in a system are had only relative to the rest of the system. Mach asks whether mass (inertia) might be like this, too. Building on this, Harré asks if we could reasonably ground ‘the powers of the simplest beings that theory requires and experiment sustains, in the properties of the whole universe’.³⁴ In other words, the system—the universe as a whole—has some set of properties, and those are what is fundamental. The intrinsic properties of the particles then would be shadows cast by the universelevel properties. So are there powers like this? Could there be? The short answer is that I am not in a position to respond with an unqualified ‘no’, but I remain sceptical that any powers are, or could be, ultra-grounded. Regarding the empirical question, there is a telling lack of evidence that there are powers like this.³⁵ That is defeasible of course, but without any good reasons for thinking that there are powers like this, I am reluctant to start admitting them, or taking them too seriously. What about the mere possibility of ultra-grounding? There are two worries here. The first is that powers form networks that capture their essences, so what is possible is not simply what is imaginable, but whether there is such a type of power in the network. This means that it is harder than usually appreciated to be a possible but non-actual power. Consider again the case of weight. Weight is context-sensitive, but it is not ultragrounded, because it depends on a property of the object as well as the gravitational field. Ultra-grounding requires that the ways the object itself is contribute nothing. I am hard-pressed to make sense of this. How can ultra-grounded powers be powers of those objects if the objects do not work with them; where is the complicity? In all cases where something outside the object-with-the-extrinsic-power plays an important role (as with the fragile glass, weight, and so on), it has to be the case that the ³³ Harré (1986: 295). See also Harré and Madden (1975). ³⁴ Harré (1986: 296). Harré interprets Mach’s suggestion as relying on universe-level categorical properties, but let us ignore this feature for now. ³⁵ Molnar (2003: 133).

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object is itself in possession of powers that work collaboratively with the external powers. Absent such complicit powers, the particle does not inherit the powers of the universe; it is just ghostlike. Perhaps the problem here is not that the only powers are properties of the whole universe, but that this looks like it is the only object, too. If that is the case, then all powers are intrinsic to the one huge object. We get the result I want, but at a cost: the objects we had assumed were the ones in possession of the intrinsic powers are not objects at all. They are shadowy objects with shadowy powers. The only object is the universe, and all its powers are intrinsic. So, ultra-grounding is only a problem if these universe-level properties are still properly properties of the smaller objects, but it is not clear that this is the right way of interpreting this picture. Furthermore, though it is anecdotal evidence against ultra-grounding, Harré himself is sceptical about the possibility. His reconstruction of Mach’s thinking sees the development of a largely conventionalist framework, and so does not commit itself to the reality of the powers mentioned, and is built on a framework of categorical properties of the universe as a whole. Hence, it is far from clear that there is any serious threat here.³⁶ At the end of the day, I am hard-pressed to wrap my head around such cases. I suspect that any view of powers that requires we take this possibility seriously will find itself swimming against the tide of intuition; this constitutes a reason to be suspicious of powers of this sort, even if not a particularly strong one. In the end, I do not think we should expend much energy worrying about ultra-grounding, and should reject it along with all other ways that extrinsic powers might get into our ontology. We should not hire properties to do work we have already hired other properties to do. That the world might leave adequate logical space for the existence of extrinsic powers does not alone constitute a sufficient reason to countenance them in any serious ontology. On the assumption that there is a plurality of objects in the universe, extrinsic powers are not welcome, because there is no work for them to do.

4.2 Multi-tracking It was Ryle who first introduced the distinction between single-track powers, those restricted to the production of a single type of manifestation, and multi-track powers, those capable of being manifested in a variety of ways when met with different stimuli.³⁷ Though Ryle’s examples of the latter focused on mental capacities, contemporary advocates of multi-track powers (‘multi-trackers’) extend the notion across the class of physical powers, arguing that many or all physical powers are capable of being exercised in more than one way. I count myself among the multi-trackers. Here is a straightforward example. Consider the three-dimensional shape of a lump of sugar—its cubicness—and assume, for argument’s sake, that this is a power.³⁸ In virtue of the cube having the shape it does, it can fit through certain sorts of ³⁶ Harré (1986: 295). ³⁷ Ryle (1949: 43–5). ³⁸ If there are such things as fundamental properties of shape, I take them to be powers; Chapter 5 explains why. It is debatable if cubicness would be among them. Heil (2005: 350) employs a similar example.

   openings, but not others. It will also cast specific sorts of shadows, resist tumbling down inclined planes, stack neatly with other cubes, make certain impressions in soft clay, and so on. All of this it can do—and a great deal more to boot—in virtue of its cubicness. This is what it is for a power to be multi-track. Of course, the lump’s cubicness cannot do all these things all on its own. It only brings about those manifestations in concert with other powers. But that does nothing to undermine the claim that it is the selfsame property doing all these different things as part of different constellations. Change the circumstances in which a cubical object finds itself, and there is every reason to think that the resultant manifestation will change, too. Not every manifestation need be different, but even if one is, the power is multi-track. I argue that all powers are like this, and that each is for many, many different manifestation types. More on this in the sequel. For now we might want to ask why anyone would want to deny that powers are multi-track. The answer concerns the individuation of powers. If you can restrict powers to a single manifestation type, or even identify powers with a specific counterfactual conditional, then it might be easier to pick out powers. I reject both accounts of power individuation, at least to the extent that either would capture all of a power type’s essence. And as we saw in the previous section, picking out powers by a single manifestation type can be misleading, in addition to being mistaken. But even if you believe that a power should be individuated by its potential manifestations, that alone does nothing to prefer a single manifestation type to a range of manifestations, and so is no reason to opt for single-tracking over multi-tracking. E. J. Lowe defends single-tracking, focusing on the case of magnetism. Lowe asks us to consider if it is at all plausible that magnetism, the power to attract ferrous metals, should also be the power to do something else.³⁹ He says it could not; not, that is, if we have correctly characterized its essence as the power to attract ferrous metals. Hence, according to Lowe, where the manifestation type φ is a singular manifestation type, and we have correctly characterized the essence of a power P as the power to φ, it follows that P is a single-track power. As we have seen, the essence of a power is constituted partly by what it is a power to do. Thus, Lowe is in reasonably safe territory when he claims that if we are correct in characterizing the essence of magnetism as the power to attract ferrous metals, then magnetism is a single-track power. But surely the real question is not whether a power whose essence is the power to attract ferrous metals is single-track or not, but whether that is the essence of the power at all. What reason could we have for thinking we have discovered the power’s essence? Simplifying matters greatly, our awareness of powers typically comes from our having observed some activity or behaviour φ in which an object (or instances of an object type) habitually engages in certain contexts, from which, working backwards, we ascribe to the object(s) the power to φ.⁴⁰ Because we have worked backwards from ³⁹ Lowe (2010). Lowe probably means ferromagnetism, not magnetism, but for ease of presentation I follow his lead. ⁴⁰ As indicated, this is a simplified characterization of how we ascribe powers. Power ascriptions are more complicated, in part because powers themselves are. In short, the identity conditions for powers require more than just what they are powers to produce. The above characterization better characterizes

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the object’s φ-ing, our concept of the associated power is that of the power to φ. And as far as our concept of the power goes, there is nothing more to it than its being exclusively the power to φ. We might even say that this captures the essence of the concept. But does this also capture the essence of the power? Here is one reason (albeit an erroneous one) why we might think that we have figured out the essence of the power in question, and why we might therefore be tempted to think it is a single-track power. Because the power in question was picked out via its possessor’s φ-ing, it stands to reason that the power’s essence is properly characterized as being the power to φ, and further that the power is single-track. In other words, we have correctly characterized the power because the features of our power concept can be applied directly to the world. For example, in a case like magnetism, ‘magnetism’ is the name for the power we ascribe to various objects in virtue of their having attracted ferrous metals; ‘magnetism’, therefore, just means the power to φ, where φ-ing is attracting ferrous metals. It follows that magnetism is a single-track power.⁴¹ However, an important shift takes place when we not only ascribe this power to an object, but further claim to have fully characterized the power in question. We may be right to ascribe to the object the power to produce manifestations like φ, but nothing warrants the further belief that the power in question is restricted to producing φ-type manifestations. The mistake comes from thinking that genuine powers must be in direct correspondence with our power concepts. But the world— including those powers that populate it—is not beholden to our understanding of it, nor to the ways in which we conceptualize powers. This error is further disguised by the way we name powers. The magnetism concept is achieved via reverse engineering, and is thereby restricted in our understanding to just the one manifestation type. Imagine, as is our tendency, that we name the power property responsible for these behaviours ‘magnetism’. We now illicitly project onto that power our concept of magnetism, in virtue of the power’s carrying that name. We limit what we take the power to be capable of because we associate with its name a specific manifestation type. But no such association is warranted, and nothing about our grasp of the concept warrants our treating it as having captured the essence of the power so named. We had assumed—for the sake of argument—that magnetism was an object’s power to attract ferrous metals, but what if our first approximation was off the mark? What if magnetism is also the power to induce an electrical current? Is it not reasonable to think that magnetism might also be the power to do that? Lowe’s response is that this should merely direct us to think more clearly about how we describe the manifestation type that captures the essence of magnetism. What we need

how we ascribe dispositions (which are often reverse-engineered, and thus functional in this sense). But I am sceptical that even disposition ascriptions are single-track, for reasons regarding conditions of manifestation and context-sensitivity. See Vetter (2013) and Glowala (2015). ⁴¹ This error is committed—implicitly—in the thinking of a number of single-trackers; I have in mind Jackson, Prior, and Pargetter (1982), Prior (1985), and Psillos (2006). I suspect the real culprit here is the failure to distinguish powers from dispositions—the latter, unlike the former, not being tied to any specific metaphysical framework.

   to find, he says, is a description of the manifestation type that ‘covers in a unified way all the supposedly “different” things that the power is a power to do’.⁴² If we are unable to come up with any unified description, Lowe advises we give up on the thought that this is just one power we are dealing with, and conclude that the case involves two or more powers. He adds that magnetism might in fact be one such case: the disparate effects of magnetism might be due to a group of different but related powers. However, as Glowala and Vetter both argue, there is more to the identity of a power than those manifestations it can produce, even if we (mistakenly) take potential manifestations to be a primary determinant of power type.⁴³ Casting this in terms of our power concepts, the magnetism concept is not captured by the manifestation type alone, however unified. It must also include the relevant interaction partners and contexts in which those manifestations are produced. Hence, two different powers might be for the same manifestation type, but would be nonidentical if they did not produce instances of that manifestation in identical contexts. Thus, having exactly similar manifestation types is not sufficient for power identity. In homier terms, there are many ways to skin a cat, so even if ‘cat skinning’ is a sufficiently unified class of manifestation types, there would be no single-track power whose essence was that of being the power to skin cats, because many different powers would have this as their manifestation (given various interaction partners and contexts.) Consequently, even if the relevant science affords a unifying description of the manifestation type for magnetism, this is not, by itself, an adequate reason for treating it as single-track. According to Lowe, if we are unable to locate a suitable unifying description, then we should treat the distinct manifestation types as picking out distinct powers. But what possible reason—short of single-tracking itself—could be given for doing this? It might be convenient to limit our power concepts to single manifestation types, and capturing them under specific counterfactuals offers a certain tidiness, but this is artificial. Powers do whatever they do; they are not beholden to our preferences. Moreover, Lowe suggests that a criterion of identity is supposed to be a principle that gives the identity conditions for entities of kind K in ‘an informative or nontrivial way’, but again this gives us no reason to prefer picking out powers by a single manifestation type rather than many.⁴⁴ Even if we agree that locating a suitable unifying description is sufficient for thinking we are dealing with a single-track power (we should not), it does not follow that in the absence of such a description we are forced to treat the non-unified manifestation types as picking out distinct powers. Our best guess as to which is the right account is ultimately up to us, and we have us much reason to treat them as many single-track powers as we do one multi-track power. That said, Lowe objects that if we side with the multi-tracker, we may be at risk of losing all useful individuation of powers: Once we allow that powers may genuinely have multiple manifestation-types which don’t fall under any unified description, it becomes unclear why we should think that a single object may

⁴² Lowe (2010: 11).

⁴³ Vetter (2013), Glowala (2015).

⁴⁴ Lowe (2010: 8).

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have many different powers rather than just one—a power to do all the things that it can do. And that would render the notion of power a rather feeble and trivial one.⁴⁵

Lowe suggests that multi-tracking is a slippery slope. At the end of that slope we find ourselves without the distinctions between powers, forced instead to speak of the ‘super-power’ each object possesses that explains all the object is capable of. I do not find the prospect of a super-power ontology attractive in the least (despite conceding its consistency), but nor is the suggestion that multi-tracking is a slippery slope at all compelling, and so we need not be concerned. Multi-track powers provide a natural explanation for clustering (see below), but only certain powers cluster. That is why we should think that objects have many powers and not just one. Unless science prompts us to think that all powers (all the relevant powers anyway) travel together, we have no reason to fear (or postulate) super-powers. All else being equal, there is no (non-question-begging) reason to be found here in support of single-tracking. We are at a stalemate. Where the single-tracker sees many powers, the multi-tracker sees just one. Indeed, single-tracker Alexander Bird argues that we can treat any putative multi-track power as a collection of single-track powers.⁴⁶ But the reverse holds, too, so why choose multi-tracking? The first reason I offer is that certain abilities are always found clustered together. ‘Clustering’ can be defined thusly: for (context-specific) manifestation types α and β, where α is non-identical with β, the power we pick out by the description ‘the power to produce α’ and the power we pick out by the description ‘the power to produce β’ are clustered just in case the class of objects with the power answering to the first description is identical with the class of objects with the power answering to the second. The phenomenon of clustering is strictly neutral between single-tracking and multi-tracking (it is an open question if the power answering to the description ‘the power to produce α’ is identical with the power answering to the description ‘the power to produce β’). But what best explains their always being found together? The answer will vary according to the specific case, but one natural response is that they are one and the same power responding differently to different stimuli (and thus answering to both descriptions), and this is why we find them together. To be clear, I am not suggesting that clustering phenomena ensures we are dealing with a multi-track power. But to the extent that we are interested in making best guesses about the natures of powers, we should be open to multi-tracking.⁴⁷ Multi-tracking offers a good—and natural—explanation of clustering.⁴⁸ Here is the second argument I offer in support of multi-tracking. In the previous section I raised the concept of complicity. Complicity, recall, is a matter of power agreement; it is one way of thinking about the roles that powers play in contributing to manifestations. The intrinsically fragile glass was complicit with the actions of the protective angel, such that it did not break when dropped or struck. Now, it is ⁴⁵ Lowe (2010: 11–12). ⁴⁶ Bird (2007a: §2.2.1). ⁴⁷ Mellor (1974: 175), channelling Nagel (1961), promotes multi-tracking as a good principle for individuating properties. ⁴⁸ Single-trackers might reply that an essentialist theory of natural kinds could also explain clustering; to wit, those powers are found together because they constitute the essence of some kind (Lowe 2006, Oderberg 2007). However, this response demands the irreducibility of kind-essences, which is rather contentious (Boyd 1991).

   certainly possible that the relevant power of the glass is a single-track power whose only manifestation is that of non-breaking (when struck, under angelic protection). But that is a very odd power indeed. Does it not make more sense—is it not far more economical—to think that this is one of the rather uninteresting contributions of a power that can do lots of things? Consider briefly just how much causal complicity is going on in the world at all times. This is a staggering amount of complicity! Do we really want unique powers for them all? I suggest we should not, and that all powers are multi-track. There is a different way one might defend single-tracking, not yet considered, that relies on a distinct account of manifestations. On this alternative conception, a power produces the same manifestation every time it is exercised, but different effects result from different combinations of manifestations. These single-track manifestations go by the name ‘contributions’.⁴⁹ This single-tracking view neatly handles the fact that the same power can be involved in numerous constellations for the production of diverse states of the world, by pushing back the effects. However, it is the introduction of that extra step that makes this account ultimately unattractive. For starters, as powers are almost always exercised in large if not huge constellations, the contributions made by specific powers are rendered unknown and effectively unknowable.⁵⁰ Perhaps this ignorance is (barely) tolerable, but it makes tracking powers near enough impossible, and their identities mysterious. Second, it adds an ontological element to a causal model that was already sufficiently complicated. On the picture I endorse, constellations of powers produce states of the world; the formation of constellations constitutes the conditions under which the powers are exercised, and the resultant states are the manifestations of those powers. But if an exercised power produces a contribution, and those contributions are distinct from effects (which themselves arise from the interactions of many contributions), then we seem to have causal interactions at multiple points, and the threat of a regress looms large. After all, it takes the interaction of powers for each interacting power to produce its manifestation (a contribution), but now all of those contributions must interact to give rise to an effect (where rarely, if ever, will the effect be type-identical with a contribution), which sounds like a second kind of causation. Worse yet, it makes contributions sound like they too are powers, such that every effect is the result of powers giving rise to powers giving rise to powers, and so on. That is intolerable. I suggest that this is not the way to be a single-tracker, and not an account of powers-based causation worth adopting. It might be thought that the problems with single-tracking come down to the way they tend to be individuated. For instance, Heil writes that, in ‘identifying dispositions solely by reference to their manifestations, we are naturally led to suppose that different kinds of manifestation signal different dispositions’.⁵¹ I do not deny that this is a contributing factor, but nor do I think it is fully to blame. There is, after all, nothing stopping us picking out powers by way of multiple manifestation types.

⁴⁹ Molnar (2003) defends this view, as does Mumford (2009b). ⁵¹ Heil (2010: 69).

⁵⁰ See McKitrick (2010).

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Consequently, rejecting single-track powers does not require that we also reject the somewhat intuitive (if ultimately flawed) method of individuating powers by way of their manifestations, or at least, that this should play some role in power individuation. I am simply promoting caution concerning expectations as to whether they line up one-to-one. As for what the real culprit is, I think it has more to do with our conceptions of powers being allowed to overstep their boundaries and dictating what the world is like than it does anything else.

4.3 Fit, Holism, and Blueprints We have seen that powers are intrinsic properties. This concerns the way that powers are had by the objects that instantiate them, but says nothing about what determines their identities. We have also seen that powers are capable of producing a range of different types of manifestations. This says something about the specific nature of a power type, as part of its identity is given by the types of manifestations it can produce, but it does not say everything. Something more is needed for a power type to be individuated. It is to that matter we now turn. The account of power individuation I defend is an atypical form of power holism, or what sometimes goes by the name ‘causal structuralism’.⁵² Power holism is the view that the identities (natures) of power types are determined by their places in a hugely complicated structure. That structure is made up of a series of relations holding between: the power types; the sorts of manifestations each power type is for; the other power types that must be instanced (and in what configuration) for those manifestations to arise (constellations); and the constellations by which the power type may be produced. There are a number of adherents of holism among the friends of powers—perhaps the most notable being Bird, Mumford, and Tugby— but mine departs from each of theirs in substantive ways, despite the obvious similarities.⁵³ The most striking of these differences concerns the existence of the structure itself. That is because the holism I defend—surprisingly—does not demand that the structure, or the relations that form it, be genuine existents. That might sound a little odd, given the role the structure plays in fixing the essences of the powers. But it sounds a little less odd if you think of this structure in one of two possible ways. Topdown structuralism starts with a series of properties not previously individuated.⁵⁴ One then builds the structure on top of them, individuating them in the process. Bottom-up structuralism works the other way. Every property is previously individuated, and has built into it a map or blueprint of all the other property types and what sort of manifestations it will produce with various sets of them. One can then generate a ‘structure’ from the patterns of potential manifestation types each property type can produce, but the structure need not, strictly speaking, be instanced at ⁵² Hawthorne (2001). ⁵³ See Mumford (2004), Bird (2007b), and Tugby (2013b). I suspect that Martin (2008) is likewise inclined, but his views on the matter are harder to discern. Martin speaks of powers as forming ‘lines’ or ‘nets’ (1993b), which he says form ‘holistic nets’ (2008: 46), but no elaboration is offered. ⁵⁴ ‘Previous’ is to be read metaphorically, as it concerns determination, not time.

   any time. The ‘structure’ is projected by the blueprint each property shares, which is just to say that the blueprint is ontologically prior to the structure. (Top-down structuralism reverses the priority.) As a bottom-up (blueprint) structuralist, one does not need all the power types in the structure to be instanced. I will get to this in due course; just be warned that when I speak of the ‘structure’ the powers form, I am speaking quasi-metaphorically. I motivate this structural holism by way of a puzzle concerning the collaboration of powers. If you consider a power property in isolation, then there is a serious metaphysical question concerning its ability to coordinate with other powers. This is the foundation of powers-based causation: powers interact with other powers to jointly produce manifestations. But when the powers first find themselves in these circumstances they do not need to await further instruction; they do not need something outside them to tell them how to coordinate with powers of different types, and nothing then comes into being that makes this so—they just act, without prompting.⁵⁵ What affords this coordination? What explains it? How does the power ‘know’ to do exactly what it does, with just those powers with which it is arranged, when it finds itself in a constellation? How do powers instantly collaborate to jointly produce a manifestation? How did it know ahead of time, before those other powers happened along? And how did it know what it would have to do, even if that exact constellation type never arose? As we shall see, the puzzle and its solution motivate the model of power individuation I endorse. I call this built-in coordination a matter of ‘fit’: powers ‘fit’ together for the production of mutual manifestations. To fail to have the correct fit is to describe an impossible situation. The operations of the powers cannot permit anything less than perfect congruence, but the fact that powers have the appropriate fit for one another is not something yet accounted for. The very possibility of reciprocal powerbased causation demands nothing short of perfect harmony on the part of the interacting powers, but nothing we have seen yet regarding the identity of powers is sufficient for the manufacture of that harmony. That is the problem of fit. Let us consider the problem more closely. Central to the intrinsicality of powers is a kind of independence. This sets up part of the problem, as it makes clear that the having of powers—as intrinsic properties—in no way depends on any other contingent objects. We have also seen that a power type is partly individuated by the set of potential manifestation types it supports, making the connection between the power and what manifestations it is for necessary. Its importance in developing our problem is that what the intrinsic powers are for (that is, the manifestations they are capable of producing) is some specific set of determinate manifestations. A power’s potential effects are written into it; this alone is unproblematic, however, powers produce manifestations in causal cooperatives. The other side of the puzzle comes from this reciprocal nature of power-based causation. In typical cases, powers-based causation is a matter of powers (often had

⁵⁵ By contrast, Armstrong’s necessitation relations (1983) that causally connect his categorical properties seem to come along after the fact to resolve this worry. That does not sound as bad when combined with eternalism, but it is otherwise a bit unsettling.

, ,  

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by distinct objects) working together to create manifestations: it is a mutual affair.⁵⁶ Even prior to interaction, powers must line up with one another in order that causation be possible at all. They must be built for mutual and harmonious interaction, even if specific interaction types never occur. If all causation was noninteractive, or if powers were relational, or indeterminate, there would be no problem of fit. It is precisely because the having of the properties and what they are for is independent of their causal interactions that the question of fit arises. An analogy might prove useful. Consider a jigsaw puzzle. The primary task when working on a jigsaw puzzle is to position the pieces so that they form a united whole—typically some image or other. The matter of jigsaw-puzzle completion is literally one of fit. The image of the completed puzzle only emerges if the pieces admit of what we might call a ‘harmony of shape’, and that is exploited in their being joined. The harmony that jigsaw-puzzle pieces enjoy mirrors that of the powers. Like the puzzle pieces, they too must admit of the appropriate fit for one another in order to produce manifestations. They must stand in the right kind of relation to one another—that of being for the same manifestation. Now consider how jigsaw puzzles are made, in the ‘created’ sense as expected of toy companies, rather than put together. What allows for fit in the case of jigsaw puzzle pieces? That is simple enough: they are created by cutting up a picture. When you start with a complete image and cut it into pieces, it is no surprise that the pieces admit of the right kind of fit for one another. But imagine what would happen if jigsaw-puzzle manufacturers divided the task of creating pieces of a single jigsaw puzzle among a variety of different labourers, without providing each with any indication of what the final image was to be, and without permitting collaboration. We simply task them with making one puzzle piece each, and provide no further instruction. What are the odds that the pieces could ever be put together? I have seen some mighty hard jigsaw puzzles in my day, but this one takes the cake! Not even puzzles as simple as those intended for young children, having only four or five large pieces, could be made this way. The odds that our puzzle makers could get their pieces to coincide are astronomically slim. You simply cannot make a jigsaw puzzle that way. And yet that is the case with our powers as presently understood: they are intrinsic, and so do not enjoy the ease of collaborating that relations might afford; they have their effects necessarily, and so what they are for cannot vary or be assigned on the occasion of interaction; and yet the theory has it that they must come together harmoniously for the production of mutual manifestations. That any manifestation should occur is like the completion of a most improbable jigsaw puzzle, but anything less than completion is unthinkable. On no model of powers can the success of causal interactions be purely random. Causation is ubiquitous; holding out for luck in any shape or form simply will not do. We cannot tolerate a world without fit. It is in this last regard that the analogy between fit for puzzles and fit for powers breaks down. In the case of puzzles one can imagine getting incredibly lucky and having the pieces fit, but a of lack fit for powers is impossible, as it is not luck that sorts the possible from the impossible. Might it be the case that fit is a local ⁵⁶ See Chapter 6.

   phenomenon, such that despite a lack of total fit, on those occasions that token powers fit with one another, a manifestation results? (By analogy, the jigsaw puzzle cannot be completed, but this and that piece fit together.) The short answer is that a lack of fit for powers is impossible in the token case, so local fit fares no better. For example, imagine a rock with the power to smash a particular martini glass when it strikes it with a certain force, where the powers of the glass are such that it emits a loud ping (without breaking) in just those same circumstances. Now imagine that we strike the glass with the rock with exactly the force in question. What happens? Does the glass smash (as was the rock’s power), does the glass remain intact and emit a ping (as was the glass’s power), or does nothing occur, because the two powers do not fit? The answer: none of the above. Here is why. Clearly the manifestation cannot be a smashing, as that runs counter to the manifestation the glass’s power is for (the glass cannot both produce and not produce a manifestation). The manifestation it is for (in that constellation) partly determines the identity of the relevant power—it is essential to it—and so there is no flexibility with regard to what manifestation it can produce in this instance. Conversely, the manifestation cannot be a loud ping, because the power of the rock is no more capable of contradictory manifestations than those of the glass, and its prescribed manifestation is likewise essential to it. What about no manifestation at all? The suggestion that a lack of fit could mean no manifestation is produced comes from the mistaken thought that when things do not change, there is no causation involved. There are many scenarios that produce rather boring static manifestations that merely maintain the status quo, but even this requires powers with the right fit for one another.⁵⁷ And in any case, something will occur, and what it is cannot be an accident, or all causation would be accidental. And what would determine the accidental outcome? This only moves the problem; it does not resolve it. With the problem of fit before us, let us turn to the solution. As I have indicated, I take the solution to be that powers are properties whose natures are determined holistically: powers are structured in terms of each other. In order to provide the required fit, powers must be engineered so that they always match. How can this be done? One way is to cram all the information about every other property into the power, thereby ‘building’ powers according to the plan—a plan that includes what kind of manifestation would result from each and every possible constellation. In keeping with our jigsaw analogy, this is nothing more than having our individual labourers build their particular puzzle piece from a blueprint. Working from a blueprint, it is hardly surprising that the puzzle pieces should fit together, even if they are constructed separately. If each labourer knows the shapes that the other puzzle pieces and her own puzzle piece are to have, then getting them to line up presents no difficulty at all. The result of packing all this information in to the powers is that each property then contains within it a blueprint for the entire universe (not only as it is, but as it could have been). Each power property has within it organized plans for every possible circumstance in which it might find itself. These plans constitute ⁵⁷ For more on the notion of static powers, see Chapter 7.

, ,  



instructions for what manifestation is to be produced in each circumstance. Fit is thus provided by the internal blueprint each carries. The notion of an internal blueprint gets us pretty far along the path to a solution. However, in order to generate the blueprint, the other powers in the blueprint were already established or fixed. But given that their natures must be determined in the same fashion, we face the same problem again. We have nowhere to start, and the possibility of a vicious regress looms large. But we can avoid this problem if the determination of powers is not engineered piecemeal, but rather all at once. What we need is a blueprint that reflects the causal structure of all the power types: we need power holism. In order to understand power holism, we first need to get clear about what ‘holism’ means. ‘Holism’ has been defined a number of ways for different purposes, and so I will briefly state what I do not mean by the term. ‘Holism’ is sometimes understood in terms of the clumsy aphorism that ‘the whole is more than the sum of its parts’. This can be refined in many ways, but in each we find the familiar thought that features of the whole emerge from, but do not reduce to, or cannot be explained by, features of the constituent parts. Thus, in the philosophy of physics, holism is sometimes taken to be the thesis that the properties of position or spin can only (properly) be attributed to a system, and not to those particles that make it up. And in moral theory, it can mean the anti-particularist claim that reasons are altered by their context.⁵⁸ What these interpretations have in common—and therefore what makes them of no use presently—is that they concern the individuals that can instantiate the properties. But our interest is in the nature of the properties themselves. Similarly useless are versions of holism that understand it as an explanatory or purely epistemic notion; what we require is a metaphysical conception, but not one that takes the existence of constituents to depend on that of others, or where the holism results in relational properties. What we need is a notion of holism according to which constituents determine their natures collaboratively, through a sort of collective engineering. Of the range of extant holisms, what is sometimes called ‘semantic holism’ comes closest. Here is one version: ‘the specific, determinate meaning of each belief depends on the specific, determinate meaning of all other beliefs with which it is arranged in a system of beliefs: if the meaning of one constituent of a system of beliefs changes, the meaning of all the other constituents changes as well.’⁵⁹ This has all the features I want to replicate. First, there is no suggestion that any belief depends for its existence on any other. Second, the determinate meaning of a belief depends on all other beliefs in the system. Third, changes to any belief result in changes to all beliefs. Fourth, there is no suggestion that beliefs are relational in virtue of gaining their determinate meanings this way. Mutatis mutandis, this is the model of holism to be applied to the powers. All powers within a system contribute to the nature of all other powers, such that each is set up for the appropriate fit with one another, but no power depends for its existence on any other, nor are they relations. Powers are thus capable of fit because they are determined collectively. ⁵⁸ Healey (1991), Dancy (2000).

⁵⁹ Esfeld (1998: 374).

   Given the way I have constructed the problem of fit, it makes sense that the powers that make up a system of powers—and therefore that collectively determine each other’s natures—are the powers that combine to produce manifestations (if and when they do). That is how I envision power holism, and as far as resolving the problem of fit is concerned, this is enough. So, if you build them together, you can explain how they fit together. Now it is time to see what is built. To understand the holist structure of power types, it is easiest to start with a connected structure, that of the constellations and manifestations that bear the causal relations. Doing so requires us to get ahead of ourselves just a bit, because it makes use of the powers-based picture of causation. A constellation, recall, is a state of affairs composed of one or many objects and their power properties, in a specific spatial arrangement.⁶⁰ That constellation type stands in an asymmetric causalpotential relation to another (typically complex) state of affairs type that is its manifestation. (It might be that this particular constellation type and that particular manifestation type never have instances, but there is nevertheless a relation of potential causal production between the two complex state of affairs types.) This is our basic causal unit, and we will use many of these units to construct a structure. Picturing the ball-and-stick models used in molecular modelling might help—you remember high-school chemistry, right?—the sticks are our asymmetric causal manifestation relations, the balls states of affairs. (Keep in mind that we are dealing with types.) Every constellation is itself either the manifestation of some other constellation, or a complex state of affairs that arises from a series of such manifestations. In other words, in addition to the ‘stick’ leading away from a constellation (towards its manifestation), there will be one or more ‘sticks’ that lead into it. And those sticks will arise from constellation balls which in turn have sticks leading into them, and so on. In the other direction, our initial manifestation will be a complex state of affairs, and it, too, will have some manifestation that it is for. And so we have another stick leading from it to another ball. And so on. And so on. Here things start to get tricky, and our chemistry model is not going to be quite as helpful. For starters, one might wonder how big these states of affairs are going to get. Take the initial manifestation type: it has a manifestation it produces, but is there a yet more complex state of affairs of which it is a part, and does that have a distinct manifestation type that it is capable of producing? The question is really a disguised question about the nature of causal locality. In Chapter 6, you will see that I typically envision these states of affairs as large; this is a far cry from our standard picture of how large a space causal interactions cover, but it is still much smaller than everything that exists at any given time. This sounds unattractive, but keep in mind that we are dealing with fundamental properties here, and that appearances are not all they are cracked up to be. Let us assume that this worry can be assuaged, one way or another. What we get is an expansive ‘molecule model’ of causally connected state of affairs types. ⁶⁰ I argue in Chapter 7 that a constellation can be a simple state of affairs involving just one particular and one power, but the overwhelming majority will be complex states of affairs involving numerous powers.

, ,  



The picture so far has seemed rather flat, in the sense that it is compatible with a ball-and-stick model that heads forward, backward, left, and right, along the same plane. But if things continued this way we would be in trouble, as we would be unable to fix any point in the structure, and therefore unable to piggyback the identities of the powers on it. To that end, we will need to see some looping back. That is, we need there to be manifestations that have as their manifestations states of affairs that appear ‘earlier’ in the structure. Again, if we assume a limited number of power types exist, then this is to be expected. In fact, there will be many such ‘loopings’, with many states of affairs having as their manifestation an earlier constellation (or part thereof). (Try building that with your chemistry kit!) Note that no constellation will ever have more than one manifestation type it is for: there is only ever one asymmetrical causal relation running out of a constellation, even if many are running in. Once the structure starts looping, the overall shape and asymmetrical connections serve to individuate the states in the structure. There is, as yet, little more to the identity of a given state of affairs in the structure beyond its position in the structure, but—in usual circumstances—this will suffice.⁶¹ The states of affairs are constructions out of (most importantly) sets of powers, but as those powers are not yet individuated, we need to rely on the unique positions the states occupy in the structure in order to individuate those states. These states are picked out by such uninteresting facts as S₁’s being the state that gives rise to S₂ (that is, S₂ is S₁’s manifestation), and that S₁ is the state that can be produced by S₁₁ or S₁₆ (to which it stands as manifestation). S₂ is, in turn, that state which can be produced by S₁ or S₉, and is capable of giving rise to S₃. And so on. Are there any dead ends? In other words, are there any states that stand in the manifestation position but are not themselves capable of producing further states? Given that we are operating within a powers metaphysic, the answer is no. Those states are complex states of affairs composed of objects bearing power properties, and any state which can arise will have some state that it can produce. The only exceptions would be those manifestation states that are utter voids (should there be any). It would seem, prima facie, that the world is capable of producing voids now and then, but as voids there would be no powers present to produce anything further. (On a dualist power theory, the possibility of a pure categorical state arises, and it, too, would be a dead end. I argue against dualism in Chapter 5.) We have a causal-potential structure built of states of affairs and asymmetrical causal relations between them. The individuation of the powers will make use of this structure, and will involve the development of a second structure. To avoid confusion, I will refer to this second structure as the ‘blueprint’. The states of affairs that compose the causal-potential structure are themselves composed of objects bearing power properties. Given that the objects have no direct causal role to play—their causal participation is via their powers—they drop out of the picture (at least as far as power identity is concerned). Hence, even though a given ⁶¹ Bird (2007b), building on the discussion of graph theory in Dipert (1997), shows how even very simple structures can be built that serve to individuate the elements in them. See also Tugby (2013b). It is worth noting that Bird’s elements are properties; as constellations, mine add internal arrangements that contribute to their individuation.

   constellation might involve two objects standing in a specific spatial relation, we can ‘see past’ the objects and look directly at the powers. The result is a spatial arrangement of powers. It follows that each state in the causal structure can be understood as a collection of many powers. Now we piggyback the identity of the powers on the causal structure, to give each power its blueprint. Take state of affairs S₁, and assume that it is composed of five powers. Each of those—call them ‘A’, ‘B’, ‘C’, ‘D’, and ‘E’—is a power that has as one of its manifestations the state of affairs S₂. A, then, is (at least) that power that produces S₂ when appropriately arranged with B, C, D, and E. A is also one of the powers that makes up S₁, and part of what is produced by S₁₁ and S₁₆. All this information goes into the blueprint that fixes A’s essence, and is what provides the instructions for A regarding what to do when it finds itself in those circumstances. And though they play no part in any sort of reduction, it ought to be clear form this picture how A’s instantiation makes true (brings with it) certain counterfactual conditionals of the form: If A is appropriately arranged with B, C, D, and E, then A through E will jointly give rise to state of affairs S₂.

This gets us part of the picture, but we are not yet all the way to having individuated A. That is because our naming so far has been artificial. A is just one of the five powers that constitutes S₁, and one of the five that jointly produce S₂, and so on. But so are the other four. And though neither is identical with any other, we do not yet have the metaphysical resources to differentiate A from B, or any of the other powers in S₁.⁶² That is where multi-tracking comes in. S₂, like S₁, is composed of powers. Only this time let us assume it is composed of four powers, and we shall not name them. Each of the four is such that it is a power that is: part of S₂; part of a state brought about by S₁ (and perhaps other states); and such that, with three other powers, it will jointly produce S₃. Now, it might be the case that one of the powers in S₂ is also one of the powers in S₁. Given that powers are multi-track, it follows that there are at least two (though likely very many) different manifestation types any given power is for. This means that any given power will appear in two or more constellations. Those need not be S₁ and S₂, but there is no harm in our treating it as if it is. Therefore, assume that this is the case, and that the power appearing in both is A. That means that A is the power such that it is: part of S₁ and S₂; part of the states produced by S₁₁ and S₁₆; such that if it is appropriately arranged with B, C, D, and E, then it and they will jointly give rise to S₂; and such that if it is appropriately arranged with the other powers that make up S₂, it will (with them) give rise to S₃. The blueprint that determines A’s essence now starts to come into view. Piggybacking on the causal-potential structure given by the constellation/manifestation pair types, each power type’s blueprint is the full set of states of affairs of which it is a constituent, along with all those counterfactuals in which it figures (both when it is all or part of a constellation type and all or part of a manifestation type). This huge

⁶² The problem here is the metaphysical problem of individuation, which need not provide any help with such epistemological problems as our ability to reidentify powers.

, ,  



blueprint structure not only serves to fix the identity of a power, it is what ensures that each instance of a power has complete instructions for what to do for every scenario in which it might find itself. We thus fix the identity, and solve the problem of fit to boot! Before ending this section, I want to briefly say a little more about the blueprints. The first point concerns the extent to which the blueprint structure is integrated. On the model of powers I prefer, every possible state of affairs that can arise is written into the powers that would constitute them. Does this mean that every power can have every other power as a reciprocal partner? Perhaps, but it is also reasonable to think that the pathways on the causal-potential structure serve to keep certain property types apart. (This is a prescribed set of states, not a recombinatorial ‘anything goes’, and so some imaginable states may not be genuinely possible.) Even if some are kept apart, the blueprints will nevertheless generate a shared structure in which every power is related to every other, either directly or indirectly. (After all, if A has in its blueprint that it produces S₂ with B-E, then given how B’s nature is fixed, A is indirectly connected to the powers in the states that B can generate, and so on.)⁶³ But we could also have a model of powers that is far less interrelated. For instance, Alexander Bird defends a single-track picture of powers according to which many power types are not connected—directly or indirectly—to all others. Is this conception of powers a threat to power holism? The short answer is no—but it generates two forms of power holism. On the first conception, every power is connected to every other; by analogy we might think of the powers in that system as forming a ring.⁶⁴ Call this ‘strong’ power holism. On the second conception, we have multiple systems, and no system shares any power with any other. We thus have multiple rings, rather like the Olympic rings (only no ring contacts any other). Call this ‘weak’ power holism. Weak power holism is as much a form of holism as strong power holism, despite the latter’s being more inclusive. Within each of the smaller rings of weak power holism we still find a series of powers that has its nature determined by its power partners, yet the rings of one colour have no contact or connection with the rings of any other colour.⁶⁵ This makes for a strange view of reality, as the different-colour rings would be like ghosts to one another—causal systems that pass through each other without any possible contact or awareness—but strange is not impossible. And just as with the strong version, the weak version provides a response to the problem of fit. If weak power holism is the response, then what needed to fit was not any power with every other, but smaller subsets of powers. But the difference is only one of degree. However, weak power holism faces a second problem of fit, as each potential manifestation must be such that it does not coincide with, rule out, or come into contact or conflict in any way with, the potential manifestations of any other system

⁶³ This has an interesting consequence: knowing the full essence of a property gives one knowledge of all properties. ⁶⁴ This is not to suggest that a ring has anything like the appropriate architecture to map this type of holism; its application here is just for contrast. If anything, the shape is more like a giant, many-pointed star. ⁶⁵ A related discussion can be found in Bostock (2003), though he rejects the possibility I consider.

   of powers. Hence, I cannot help but think that weak power holism is largely unstable, and ultimately ends up collapsing into its stronger cousin. This is a reason to prefer thinking of powers as forming a comprehensive system. Nevertheless, regardless of the number of systems involved, the problem of fit arises, and a version of power holism comes to the rescue. Blueprints serve to fix the identities of powers, but there is more to the essence of any given power type than what is given by its blueprint. That is because I take powers to have dual natures, part powerful and part qualitative. That means that one can, in principle, track powers across their instances according to their qualitative aspects. Based on what has already been said about blueprints, identity fixing via qualitative aspects sounds like overkill. And if that was the reason they were posited, it might well be. But that plays no part in my defence of mixed monism, as we will see in the next chapter. Nevertheless, to the extent one can track qualitative similarity of powers, one can track power types. This should not, however, lead one to think that this makes the identity of power types epistemically transparent. Truth be told, it does nothing to improve the epistemic situation at all. Just as the pseudo-mathematical causal-potential and blueprint structures offer an account of power identity without epistemic illumination, the presence or absence of exactly similar qualitative aspects is not something to which we have any direct form of access. That is because the only way we have of tracking such similarities is through the effects they have. But the qualitative aspects of properties are not powerful. They are, of course, part and parcel of properties with powerful essences, meaning that we can track them through their powers, but that was something we could already do. Hence, we are no better off. I have just a few more points to make about blueprint holism. Next is that Matt Tugby argues that powers theorists ought to be Platonists; holism—of what may or may not be instantiated power types—only reinforces this conclusion.⁶⁶ If we understand Platonism as the thesis that there can be property types that lack instances, then I do not find this conclusion at all troubling. But if it is taken to imply something more—say, that all instances of properties are numerically identical—then I lose my grip on how this connects to blueprint holism. As far as this second thesis is concerned, I am open to both universal and trope accounts of properties (§1.5), and tropes would avoid this.⁶⁷ In fact, closer inspection of blueprint holism suggests that it fails to fall neatly into any of the traditional (properties-friendly) solutions to the problem of universals. Case in point, the blueprints project a structure whose constituents are property types, and those types need not have instances. That favours a Platonic form of realism. But then again, blueprints are internal to the essences of spatiotemporally instantiated properties: without those property instances there would be no blueprints. This implies a version of naturalism, and thus leans towards immanent (Aristotelian) realism. But there is no reason to assume that spatially or temporally distinct, type-identical property instances are numerically identical, and that speaks ⁶⁶ Tugby (2013a). ⁶⁷ This might require that there are both tropes and universals, which will make some folks unhappy. I think the mixture is tolerable, if each is properly construed.

, ,  

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against traditional realism in all forms. It is thus far from obvious that blueprints require us to adopt Platonism. The second point about blueprint holism concerns the impact holism has on how we get to think about counterfactual scenarios involving property types. We are wont—owing to the ever-present neo-Humean proclivities I warned us of in Chapter 2—to think of what things might have been like had this or that property been different. Under the chop-and-change freedom of neo-Humeanism, there is no problem with detaching properties from their causal profiles and imagining worlds with more or less of them. But we are no longer dealing with neo-Humean accounts of possibility or properties. And we no longer have such freedom. The identity of a power is given by its blueprint, which dictates its place in the structure of powers. Therefore, we cannot imagine a possibility wherein that property (one that has the identical essence) exists in a world where the set of property types differs. If a single property type is removed from the structure, the structure is different, and so, too, are the properties in it. Fellow holist Mumford captures this point neatly: ‘change one property and we change all the properties.’⁶⁸ But do not think that the properties can in fact change. Their essence is determined by the structure. If the structure changes, they do not change: we are then talking about different properties. We are, of course, free to do this. We can talk about different structures that might have existed, and the different powers that would make up those structures. None of them would be the power properties that make up our world, but they may be counterparts that are similar in many respects. Those with very minor differences to their causal profiles would be very similar indeed, but would still be powers with distinct essences. The take-home point here is that power holism makes power properties largely unsuitable for neo-Humean style thinking about possibility. It is, thus, a good thing that the friend of powers has her own way of approaching it. Finally, are the would-be causal relations of the causal-potential structure (the sticks) identical with the laws of nature? One could go either way with this. Fellow structuralist Alexander Bird envisions the relevant features of his structure as having more or less this role, but Stephen Mumford takes the opposite route, seeing his structure as the basis for a ‘lawless’ world.⁶⁹ My blueprint holism is compatible with either, but neither strikes me as quite right. The potential causal relations in which the constellations stand could well be seen as picking out individual laws, and so it seems mistaken to think that the world is lawless (on at least one common interpretation of ‘law’). But the laws we tend to discover—and hence those we most obviously call the ‘laws’, and which appear in textbooks—are unlikely to be identical with the stick laws of the structure. The stick laws capture potentials, whereas the popular laws are reverse-engineered from the actual states that obtain in the world. The popular laws are thus those that supervene on the mosaic the stick laws create. The likelihood of divergence between the two makes me think it is ultimately unwise to think of the stick laws as being the laws of nature.⁷⁰

⁶⁸ Mumford (2004: ch. 11, note 3). ⁷⁰ I revisit this issue in Chapter 10.

⁶⁹ Mumford (2004), Bird (2007a).

5 The Powers Ontology: Monism and Dualism 5.1 Against Monism My metaphysical project is born of a powers ontology, and thus starts with the assumption that at least some fundamental properties are powers. Consequently, the neo-Humean categoricalist ontology (according to which all fundamental properties are categorical) has already been put aside. That leaves us with three types of fundamental ontology that countenance fundamental powers.¹ Two of the three are monistic, claiming that there is only one category of fundamental property types. Power monism, also known as ‘pandispositionalism’, is the ontology on which all fundamental properties are purely powerful powers. Mixed monism also has just one category of property, but the properties have natures that are at once powerful and qualitative. Hence, unlike the power monist, the mixed monist believes there is more to the essence of a property than just its powerfulness. Dualism departs from both forms of monism, despite sharing something with each. Like the power monist, the dualist holds that there are fundamental power properties fully exhausted by their powerful nature. But she rejects the claim that all fundamental properties are like this. Here she sides with the mixed monist in thinking there is more to the space of fundamental properties than given by powerfulness alone. But unlike the mixed monist, she puts the qualities in their own category of fundamental properties. I have indicated that my favoured ontology is a form of mixed monism. I justify that preference in the three sections that comprise this chapter. In this first section I argue against power monism. In the second I argue against dualism. The third section puts some flesh on the bones of the mixed view I endorse. Power monism is the conjunction of two theses. (1) All fundamental properties are powers. (2) The essence of a power is exhausted by its ability to bring about those manifestations it is capable of producing. That is, there is nothing more to a power property than its powerfulness. The first thesis distinguishes power monism from dualism; the second distinguishes it from mixed monism. Our present concern is

¹ Strictly speaking there are six fundamental ontologies: the absent three combine mixed properties with either or both of the pure property types. As these ontologies are largely unmotivated, violate simplicity, and do not play by the rules, I mostly ignore them. (Powers plus mixed properties are considered under the banner of ‘b-type dualism’ below.) The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

 

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with the conjunction. I argue that there must be more to our fundamental ontology than the conjunction affords, and thus that the conjunction is false. My argument against power monism is related to one familiar in the powers literature. That familiar argument—known as the ‘regress of pure powers’—is that power monism leads to a vicious regress.² According to the most popular form of the argument, the identity of a power type is fixed by the manifestation types it is capable of producing, but as those manifestations are themselves composed of nothing but further powers (whose identities would, in turn, be fixed the same way), no identities ever get fixed, and power monism is incoherent. If successful, the regress would be seriously damaging to power monism. Fortunately for the power monist, that is not the case: the regress is not vicious, because the identities of the powers can be fixed collaboratively, via a structure.³ But there are other worries in the neighbourhood of the regress, and it is with one of those I am most interested.⁴ Let me start by rehearsing the (identity) regress, especially as it applies to the model of powers I have developed. As we have seen, a power type’s essence is determined by its blueprint, which is a kind of internalized structure dictating what manifestations it can produce, and what sorts of constellations can produce it. Now let us ask what a specific power type’s essence is like. The answer comes from looking at the natures of the other powers with which it might interact, and the manifestations it can produce. So far so good. But now consider just those manifestations it can produce. If all properties are powers, then manifestations are either more powers, or they are states of affairs whose main constituents are powers. Either way, their distinguishing features will be powers. Now the worry starts to emerge: the specific nature of the first power is given in terms of other powers, but those other powers must rely on yet more powers to determine their natures. And those further powers must do the same. The threat of a regress seems very real. And it would be, were we unable to fix the identity of all powers holistically. Now consider a nearby issue; not that of identity, but of change. The regress should have us worried (temporarily at least) that the concept of change within the power monist’s universe would be intolerably vacuous. Consider: we start with some state of the world that is (at base) some object’s having some power or other. Now imagine that this power is manifested and this results in the object losing that power and gaining another. In what does this change consist? It seems like there is nothing more to the change than the bare fact that one property has been replaced by another. Now add another manifestation, and another. All we have is a switching in and out of powers; there are purportedly no changes at all.⁵ Like the identity regress, I believe that the challenge offered by the no-change regress can be met. In fact, just like its predecessor, a formal response is available. But ² Swinburne (1980), Foster (1982), Blackburn (1990), Holton (1999), Bird (2007b), Engelhart (2010), Tugby (2014), and Ingthorsson (2015) all discuss the regress in its various forms. ³ See Bird (2007a: ch.6), who appeals to the individuating structures of graph theory. This parallels the same strategy employed in Chapter 4. ⁴ I think of my argument as building on the regress, drawing out an aspect that was perhaps its target all along. But no harm comes from treating it as a unique version of the regress. ⁵ As Armstrong (1997: 80) puts it, objects are ‘always packing and never travelling’. See also Molnar (2003: 173–81).

   :    we might nevertheless balk at the suggestion that the challenge of the no-change regress has been met entirely satisfactorily. And it is in that lack of satisfaction that we find the argument against power monism that I want to press. As I say, the no-change regress has no bite. Power types form a structure. The instantiation of parts of that structure involves the exercising of powers and the production of manifestations. The changes from states involving one power to those involving others are, therefore, real changes that result in the instantiation of bona fide different powers. Powers are real properties; replacing them with new powers is a difference. This is change all right. And it is change we can perfectly well represent by tracking movements along the causal structure. As Shoemaker writes, it ‘is agreed on all sides that the possession and acquisition of powers produces changes in what properties are instantiated in the world’.⁶ These are legitimate changes, and thus the challenge of the regress has been met. But on the heels of this objection comes another, and it explains why the above response might seem inadequate. We have formally recognized change in the shape of one property replacing another, but these are shallow changes. There is nothing interestingly different about the states before and after the change. If all change were like this, then our world would be lacking in character. And our world—as best we can tell—is not characterless. We want more to the nature of change. To be clear, the worry here is not that these changes are not changes at all, nor that this picture is incoherent. The problem here is that the world just described does not seem anything like our world. The ‘changes’ in the example are so minimal—so merely formal—that it is impossible to see them as supporting the richness of quality our world appears to embody. It thus looks like we need more than just powers to get some of that character back.⁷ A science-fiction vignette might help illustrate the problem. Imagine a world plucked from the pages of Orwell’s Nineteen Eighty-Four, wherein an ominous company known as ‘Dystopian Railways’ has taken over rail travel . . . You awake from what seems like a very long sleep to find yourself in an underground railway station. Looking around, you see that every surface is gleaming white, from the tiles on the walls and floor to the counters in the convenience shop. There is not a person in sight: the trains, the toilets, and even the stores are all fully mechanized. You look for an exit, only to discover that there is none to be found. You are a prisoner: the only way out is to take one of the trains. The trains themselves are unmarked and exactly similar. You hop on the third of the three trains available in search of an escape. The ride is short. You disembark in hope, but that hope is quickly lost when you see that this station is identical to the last. The layout is all too familiar, as is the gleaming white and the lack of escape. For a moment you wonder if the train had looped back to where it started, but you see that this station serves four lines, not three. You had arrived at the first line. You quickly grab a snack and depart once again, this time taking the second line. The ride seems longer than the first, but the result is much the same: another exactly similar station with no means of

⁶ Shoemaker (2011: 8). ⁷ This is inspired by Blackburn’s (1990) presentation of the regress. It is in the same vein as Heil’s complaint that a pure powers world generates a ‘holism that is devoid of content’ (2003: 108).

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escape but the waiting trains. You hop on yet another train, and then another, and another. There are hundreds of stations, maybe thousands, and none from which you can escape. Years go by, and the railway system that is your prison becomes navigable, despite the similarities. You are currently in a station that serves three lines. There are many such stations, but this is the only one that is connected to stations with exactly two, four, and five lines, respectively. The stations themselves—like all the stations—are perfectly alike, but this is the only one that leads to stations with just that number of railway lines. Many of the stations have the same number of lines, and many lead to, and come from, stations with the same number of lines. But every station is only so many stations from enough differences that you have been able to generate a map.

As darkly entertaining as it is to imagine whittling away the time in this lonely dystopian purgatory, there are points to be made. The point here is that the railway system helps us envisage a perfectly coherent, yet utterly characterless, world. What distinguishes one station from the next is its place in the network of railway lines: you can map the system. And moving from one station to the next is a legitimate change. Yet there is nothing inherently identifying about any of the stations. As it happens, the stations have more going for them than do the powers of property monism. The stations have vending machines and bathrooms, even if they are all exactly similar. This is some minimal degree of character, despite not being sufficient to distinguish one from another. But the powers of power monism do not have even this. By way of analogy, all they have (all they are) are lines coming in and lines going out. They have no character at all. And that is where the objection lies. Could our world—a world so seemingly rich with character—have none at all? Could our world be nothing more than characterless points that get switched in and out for one another? Surely not. The world must have some character, some quality, and thus so, too, must our ontology. I have formulated the objection in terms of power monism’s lack of character, but I interpret C. B. Martin as raising a parallel concern when he speaks of the need for— and problem of—physical qualia.⁸ Martin sees the need for qualities alongside (better, internal to) powers. ‘The image of a property as only a capacity for the production of other capacities for the production . . . , etc., is absurd, even if—indeed, especially if—you are a realist about capacities.’⁹ Martin is fond of defending powers on the grounds that the objects that have them are not in pure act, but he finds it absurd that as powered objects they are not in act at all. Similar in spirit if not in form, Blackburn questions how objects in the power monists’ universe can occupy space, asking how we can think of objects as located in space if all their properties are directed towards potential future states (themselves directed towards future states).¹⁰ It does not matter if most of what an object is about concerns various ways it might be in the future; it still must be some way or other at each moment it exists. And these ways cannot be powers. It looks like being—as hard

⁸ Martin (2008: 77). See also Peter Unger’s (2006) solution to the ‘mystery of the physical’ in terms of (spatially) extensible qualities; I believe we three are barking up the same tree. ⁹ Martin (2008: 61). ¹⁰ Blackburn (1990).

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as that might be to define—demands that there be more to objects than their causal readiness.¹¹ So what is it, at any given point in time, that accounts for the existence of these objects? This is not to ask what makes the power real when it is not manifesting (which some neo-Humeans have asked by way of criticism); the power itself can do that.¹² I am asking what it is for the object to be in existence, whether or not its powers are manifesting. Powers—as pure powerfulness—can be nothing more than pure potentiality, but concrete particulars cannot. There must be some actuality to a concrete particular, however limited. And whatever this is, even if it is somehow packed into the notion of property bearing itself, cannot be the powerfulness of a power. Character, being, and physical qualia all point in the same direction: a world of pure powers can do a great deal, but it falls short of making a world like ours. Hence, the need arises for something more, something that is not purely powerful. I claim that this additional aspect is categorical, at least to the extent that it is not, in and of itself, powerful. It is a non-powerful aspect of the world. But there is an extent to which calling it ‘categorical’ is also misleading, as there is no way a quiddity could do the work we require of it. Recall that under the standard neo-Humean versions of categoricalism, categorical properties are quiddities. These are properties whose essences have nothing more to them than identity and difference. Quiddities gain causal profiles in certain contexts—such as the presence of laws—but these profiles are contingent. The powers, by contrast, have their causal profiles essentially, and are genuine causes of their effects. But consider: if powers alone are insufficient for qualitative character or spatial occupation, why should properties with merely contingent causal profiles fare any better? It would have to be something about the essence of quiddities that helps. But throwing primitive property identity into the mix does not do us an ounce of good. That a property P is P and not Q does nothing at all to help resolve our current problem. Hence, categorical properties as quiddities cannot provide the solution. What we need is something that has gone missing from the debate altogether: it is the genuine qualitativeness of qualities.¹³ When most of us were first introduced to the philosophical concepts of powers and dispositions, they were contrasted with the sorts of properties that were thought to be more familiar.¹⁴ The familiar properties were the reds and blues and greens of the world; the heft and solidity of things; their shapes and sizes. These properties constituted some part of the robustness and vivacity possessed by the objects we found familiar. The redness and blueness, we later learned, had as much to do with our visual and representational systems as they did the object. Science eschewed the colours, and soon after so did we. But learning that objects are not drenched in colours like coats of paint does not remove the need for something qualitative in objects. Likewise, learning that solidity largely concerns how an object will interact with other objects on impact, or even that being solid is a ¹¹ Similarly, Jackson (1998: 24) asks ‘what it is that stands in the causal relations’? ¹² The question is raised by Psillos (2006), and answered by Marmodoro (2010a). ¹³ See also Hildebrand (2016). ¹⁴ The familiar properties are supposed to be known by their ‘canonical description’ alone. Putnam (1979: 316).

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matter of being more like a cloud of bees than being free of gaps, does not, on its own, license the shift towards a world free of qualities. That quidditism has common sense on its side might be the greatest hoax of recent metaphysics, but that a world of all and only pure powers can give us what is familiar is not far behind. The neoHumean’s categorical properties are in need of qualitative character just as badly as are their monistic power counterparts, and therefore both should be rejected. The reds and blues of yore were contrasted with the suspicious ‘threats and promises’ of dispositionality.¹⁵ Some of us have since come to recognize the powers present in much of what was familiar, but not all of the old picture has gone away. We still want something of that old picture back, and powers alone cannot deliver it. Mere identity and difference also do nothing to help—that is not what is familiar about the familiar. Primitive identity cannot give us back the character and robustness we seek. Down with power monism, down with quidditism, and bring on the character-giving non-powers! Not so fast, say the power monists. Perhaps, when all is said and done, there is nothing more to character and quality than a widespread illusion. Having learned a lesson about the nature of colour, we should be willing to concede—albeit begrudgingly—that some of the world’s character may be illusory. But we should draw the line at the thought that it is nothing more than an illusion. Maybe our experience of the world as richly qualitied boils down to little more than the switching out of powers. But that little more makes all the difference. There must be some sort of difference between the changing states of the world that is not captured by one state’s ability to bring about further states. And that little more takes us beyond power monism.¹⁶ The same holds even if we thought that all quality should be relegated to the mental. It has long been held that the qualitative nature of colours—like the other secondary qualities—might exist only in our experience.¹⁷ Could all character be like this? Assume, for the sake of argument, that this is true. This would still not remove the need for character; it would only limit its place in the world. Character would not be found in fundamental properties except, we would assume, when those properties are parts of the complex constellations that constitute brains. This gives character a location, but it does not eliminate it. Furthermore, we would also need a story about how character emerges from non-character. I doubt such a story is forthcoming, as qualitative character is not a sort of activity.¹⁸ But it might be a mistake to even entertain this possibility. Granted, power monism is a thesis about the fundamental properties, and (strictly speaking) all the objection shows is the need for character in the world. But micro-substances need to have adequate being and legitimate change as much as any other objects do, and no ¹⁵ Goodman (1983). ¹⁶ The experiential case here described is metaphorical to the extent that we are dealing with microphysical substances. My ontology is not as friendly to macroscopic powers as the case requires, but the point still holds. ¹⁷ Descartes has to shoulder a lot of the blame for this. ¹⁸ I might hold, for example, that minds or life are activities, and so can emerge from non-living elements. But qualitative character is not like this; it seems like you need to put character in if you want to get character out.

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macro-quality could account for this. Further, if everything else relies on the fundamental level, or that is all there is, then relegating the qualitative character of the world to some upper level, mental or otherwise, would be a non-starter. Might it be objected that properties are purely powerful, but the substances that have them—the stuff in which the properties inhere—is what has character? That sounds prima facie plausible, but this is not a response the power monist can give. If substances, considered apart from the power properties they possess, are what have the character, we end up with dualism. For what is it for the substance to have (nonpowerful) intrinsic character, but for it to be certain qualitative ways? And what are those ways but non-powerful properties it possesses? Properties are understood as ways that objects are (§1.5). Here those ways are what give a substance its character, and if they are understood to be distinct from the power properties, then we have two types of fundamental properties. That is dualism. In closing, it is worth appreciating that the need for qualitative character and being is not a knock-down argument against power monism. But the power monist owes us an answer to the question of how we get character and being in the world; that she lacks the resources to provide one licenses our rejecting the view. There needs to be something more to the world, and this something more has to be fundamental. As it is non-powerful, it makes sense to sometimes continue to speak of it as categorical. But it is not—whatever it is—a mere quiddity. It would, of course, be good if we could know or say more about the natures of these mysterious qualities, but no description is forthcoming. We are on the wrong side of the Kantian predicament: knowledge of the qualitative character in and of itself is beyond our access and beyond our ken. In fact, once you appreciate how much of what we find familiar in a property concerns what it is liable to do, you will see that it is all but impossible to think about the natures of properties in any significant way without resorting to causal profiles. Hence, the need for humility about qualitative character is not just prudent, but unavoidable. But that humility need not lead us into quidditism.¹⁹

5.2 Against Dualism Power monism combines the thesis that all properties are powers with the thesis that a power’s essence is exhausted by its powerfulness. The argument just considered has as its conclusion the rejection of this conjunction. Based on the need for qualitative character, there must be more to the fundamental ontology than purely powerful powers; how do we include this something more? Two answers are available to us: dualism and mixed monism. The dualist rejects the first conjunct of power monism, taking the existence of non-powers at face value and making a distinction between the types of properties that exist at the fundamental level. The mixed monist, on the other hand, rejects the second conjunct, incorporating the non-powerful natures into the powers themselves. Here I consider the dualist response.

¹⁹ Lewis (2009). See also Langton (1998).

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If dualism is true, then in addition to the powers there are other properties, equally fundamental, that are not like the powers. We thus have two types of fundamental properties. We can think of the argument for dualism as having two steps: the first is motivating the need for non-powers; the second involves rejecting mixed monism. I will hold off discussion of the second step until the next section, and will assume, for the time being, that any properties we add to the ontology are of a distinct type. That shifts the focus back to the motivation. We have already seen one kind of motivation in the need for character. A second type of property could fill precisely that role. But proponents of dualism tend to find their motivation elsewhere. For instance, dualist Brian Ellis argues we should countenance categoricals alongside powers because of the causal roles he believes we need them to play, most notably that of influencing the sorts of manifestations produced by powers. He lists such things as structures, arrangements, distances, orientations, and magnitudes, as examples of properties to which causal powers are sensitive, but which are not powers themselves.²⁰ George Molnar offers a near-identical motivation, stressing that there are non-power properties to which the powers are sensitive, and that impact the sorts of manifestations the powers produce.²¹ In both cases the additional properties are included in order to answer a specific need that powers alone cannot meet. This is as it should be: properties are theoretical posits, and should only be countenanced when there is work for them to do, and when nothing already in our ontology is up to the task. For convenience, and in order to include any nearby motivations we may have overlooked, let us classify these motivations under two general types. We can think of the first—the need for qualitative character—as one sort of non-causal role for which non-powers might be introduced. (Though we are currently unable to specify other non-causal roles that a second type of fundamental property could be asked to perform, it would be imprudent to rule out the possibility of future metaphysical or scientific classified ads.) The second class of motivations are those that would have us introduce extra properties in order to perform certain causal roles, as Ellis and Molnar suggest. I believe the non-causal motivation is well founded. The causal motivation might be, too. However, unlike the non-causal motivation, the causal motivation leads to a form of dualism that is untenable. In fact, unless the properties the dualist brings in to satisfy the causal motivation also serve to satisfy the non-causal one, the resultant form of dualism collapses into monism. In effect, the two motivations generate three different versions of dualism.²² All take powers to be one type of fundamental property, but they differ in that the second type: (a) satisfies just the causal motivation; (b) satisfies both the causal and the non-causal motivations; (c) satisfies just the non-causal motivation. I am going to argue that the sort of dualism that results from the inclusion of a-type properties—call it ‘a-type dualism’—is unstable. That argument will take up the bulk ²⁰ Ellis (2009, 2012). ²¹ Molnar (2003: 164). ²² Or pluralism, if one has multiple motivations but cannot employ the same properties in those different roles. I ignore this in what follows, as it ultimately makes little difference.

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of this section. Having done that, I then argue that b-type dualism is stable, but it results in an ontology too much like mixed monism to be worth serious consideration. That leaves only c-type dualism. I conclude that serious debate between the dualist and the mixed monist should concern whether or not to adopt c-type dualism versus properties with complex essences. a-type dualism. The motivation behind a-type dualism is that the additional properties have causal roles to play: we need non-powers because they influence manifestations. Consequently, any a-type property must be such that it is causally relevant. That is the first premise in the argument against a-type dualism. The next premise is that a-type properties cannot be causally relevant without being causally operative. This is not a general claim about causal relevance being tied to causal activity, it is specific to a metaphysic of powers and the nature of powersbased causation. In order for an a-type property to be causally relevant it would have to be capable of interacting with the causal powers. This is what the sensitivity Ellis and Molnar call for adds up to. Were the powers not sensitive to the a-type properties, the powers would be blind to them. The a-type properties would thus be causal ‘ghosts’ (like the properties of the disconnected rings discussed in §4.3), and could have no influence on manifestations. Hence, the addition of an a-type property to a constellation of causal powers would have to result in a distinct manifestation type from that which arises without it. This just is what it is for a property to be causally relevant on a powers metaphysic: a property must be a potential differencemaker, and this is how differences are made within the framework. For illustrative purposes, it might help to think of the potential for differencemaking anthropomorphically, borrowing the Ellis/Molnar sensitivity metaphor. Powers can ‘sense’ one another; that is, powers are responsive to the presence and absence of other powers. This is a built in sensitivity they have for one another (as captured by the blueprints), and this is part of how they produce manifestations.²³ It follows that if a-type properties are to be similarly capable of difference-making, then the powers must be sensitive to them. If the powers were not sensitive to the presence of a-type properties, then the a-type properties would be ghostlike, and therefore not capable of being causally relevant. However, once it is appreciated what it takes for powers to be sensitive to a-type properties, the distinction between causally relevant properties and causally operative properties disappears.²⁴ Talk of ‘sensitivity’ is just a handy way of expressing the fact that powers, by their very nature, are such as to produce specific manifestations when arranged with other powers. This is the essence of a power. Now let us ask what is required for the powers to be similarly sensitive to a-type properties. The answer is that the powers must have this as part of their natures as well: the sensitivity to a-type properties must be likewise built into them. It must, in other words, be included in the power’s blueprint. That is the next premise: in order for any property to be

²³ This is purely metaphorical. Real sensing would be an act on the part of the power that precedes manifestation production, but the actual process is but a single step from constellation to manifestation. ²⁴ Armstrong (2005: 313) briefly suggests a similar worry to that which I develop here.

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causally operative, it must be ‘written into’ the blueprint of any powers with which it could interact.²⁵ But here is where we run into trouble. If the nature of the power is to be sensitive to the presence of a-type properties, then this is part of the power’s essence. Therefore, the power is necessarily such that it will respond, in whatever way it does, if there are a-type properties present. But this means that a-type properties are as much a part of the structure that determines the essences of the powers as the powers themselves. They are in the power’s blueprint. Moreover, this sensitivity must run in both directions: the a-type property must be such that it can be sensed. We thus find that a blueprint is written into the a-type property too. And given that there is nothing magical about the nature of powers-based causation—a constellation gives rise to a manifestation, which is itself a constellation—it turns out that the a-type properties just are powers. In short, the reason that any causally relevant a-type property must also be causally active is because there is no way of difference-making within a powers-based account of causation without being a power. Could this conclusion be avoided if we took the relations between the powers and the a-type properties to be merely accidental?²⁶ That is, perhaps it is essential that powers are connected to other powers in the nature-determining ways that they are, but their connections to a-type properties could be merely contingent. It turns out that this cannot hold, as it runs afoul of the assumption that powers are the causal doers, and that their natures (or their actions) are either the laws of nature, or ground whatever supervenient laws we might countenance. If the objection were to hold, we would have laws of a different type—neo-Humean laws—holding between those same powers and a-type properties. But this is an untenable mix. It would require powers to have causal profiles that are part necessary and part contingent, and thus their causal profiles could not help fix their identities. And that is if we were willing to tolerate such a radically uneconomical ontology that has not just one primitive causal modality, but two. Combining powers and neo-Humean laws makes for a prima facie unappetizing mix, and perhaps we could get past that. But we cannot get past its being incoherent. In order to accommodate these additional laws, the structure of powers would have to be designed such that the manifestations of the one could not possibly preclude the other. Thus, they would have to work hand in hand, or else the two could simultaneously generate non-identical states of the world at the same time and place, which is impossible. But avoiding this impossibility means making it part of the nature of the powers that they produce such-and-such manifestations when a-type properties are present. And if it is part of their natures, then these are not accidental or contingent relations they bear to the a-type properties. And thus we end up with the connections being necessary once again. (We could, alternatively, keep the connections contingent by making all of them contingent, but then we would wind up with all properties having contingent causal profiles, which is neo-Humeanism.) Consequently, the

²⁵ I have cashed out sensitivity in terms of my blueprint terminology, but the argument in no way hangs on this. ²⁶ As suggested by Brian Ellis (2012: 21).

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a-type properties are properties that bear essential causal connections to powers, and are properties that bring about certain manifestations as parts of constellations. In other words, they would be unwelcome at Hume worlds, as they are now powers, too. It turns out that if we start with a model of powers, there is no halfway house for atype properties: they cannot get in on the act—causally speaking—without being powers. For the sake of clarity, it is worth rehearsing the argument against a-type dualism via a more ‘colourful’ illustration. Imagine we have the following items at our disposal: a pegboard, a collection of coloured pegs (some red and some blue), and some rubber bands (also some red and some blue). The red pegs will represent power property types, and the red bands will represent the necessary connections between the red power pegs that reflect the natures of the powers. In other words, the combination of red pegs and red bands gives us a representation of the causal structure we saw in Chapter 4. In and of themselves (that is, without the red rubber bands), the red pegs have no natures. Only when we add the red bands—and form a giant interconnected red-rubber-band web between the red pegs with them—do the red pegs gain their identities. Once we have that all-red pegboard structure in place, we have power monism. The blue pegs will be our a-type properties. Like unbanded red pegs, there is nothing to the blue pegs, taken in isolation. The blue rubber bands serve as the neoHumean counterpart to the power theorist’s red bands. In other words, we use blue bands to represent the contingent laws of nature that connect the blue pegs. If all we had on the pegboard were blue pegs and blue bands, we would be looking at a neoHumean world. Back to the all-red pegboard of power monism. If dualism is true, then we need to add blue pegs to the representation, in order to capture not only their presence in the world, but the fact that they influence the space of potential manifestations. Start with just one, as that will make the first point as well as would adding many pegs. Add a blue peg to the board, but do not place the peg inside any of the red bands; have it off in a free corner instead. No bands connect the blue peg with any of the reds: right now this is a causally ghostly blue peg. Why reject the ontology this picture represents? Quite simply, there is no point adding one or many a-type properties to the world if they can play no causal roles. The ontology as described is coherent, but nothing is achieved vis-à-vis the a-type motivations by adding a ghostly blue peg. If these blue pegs are going to have a role to play, then they need to be hooked up with the powers. They need to be causally relevant. On our pegboard that means they must have rubber bands connecting them with the red-peg powers. But being hooked up by bands also means that they are going to be causally operative. Being ‘banded’ is being ready to go for causal action. The bands of the pegboard are representative of the modality that makes the world tick, after all. But now we must ask: what colour bands do we use to connect the blue pegs to the red pegs? Start by trying the red rubber bands, and stretch a few bands around the red pegs on the board so that they are now connected to the blue pegs. Given what the red bands represent, the blue pegs are now part of the causal structure, and are capable of causal difference-making. However, there is a problem. Recall that the red pegs are

 

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not, in and of themselves, much to talk about. What gives each its identity is that it is exactly that peg in the structure that is attached by a bunch of red rubber bands in exactly the way it is. But attaching the blue peg to the red pegs raises two issues. For one, it changes the nature of the red pegs to which it is banded. The red peg now has a new identity. (Given that the blue peg would have always been part of the world, this is okay; the ‘change’ just needs recognizing. This just is part of the red peg’s blueprint.) But there is a real problem stemming from the second issue. Consider the blue peg, now attached by red bands to red pegs. What about it makes it any different than the red pegs? As far as the distinction between categorical properties and powers goes (§3.3), the banded blue peg now just is a red peg. Red power pegs are connected to other red pegs by red bands; so is the blue peg. Those red bands indicate necessary connections between the red pegs. They are identity-giving, and they are what dictate the manifestations that will arise when these constellations form. The blue pegs now have all these features. Moreover, the blue pegs are part of the structure of properties. Hence, if you change a blue peg you change the structure, and therefore the identities of all the pegs, reds included. Blue pegs thus have their causal profiles essentially; their identity is determined by their place in the structure. Long story short, incorporating the categorical blue pegs via the red bands of necessity removes any difference between the red pegs and the blue pegs. Dualism imagined thusly is unstable: it turns the a-type properties into powers, and thus collapses a-type dualism into monism. If using red bands removes the distinction between the red and blue pegs, then what about connecting the blue peg to the reds with blue bands? Blue bands, recall, represent contingent neo-Humean laws: they attach to pegs, but are not identitygiving and could have been otherwise, or absent. (Ignore for the time being the Lewis vs Armstrong question of whether blue bands in action necessitate their effects; I will get to that shortly.) Let us go ahead and hook up the blue peg to the reds via blue bands. What is wrong with this picture? At first blush, perhaps nothing. But now consider the laws of this world. It is more than a little odd—and certainly ontologically extravagant—that we have two systems of laws in operation in the world the pegboard represents. Some laws are associated with the red bands, others with the blue. Some are necessary, others could have been different. This is an unusual powers/neo-Humean hybrid ontology. And it is most unattractive. That is reason enough to condemn this pegboard model and the ontology it represents, but things only get worse. Consider just the blue bands and the contingent laws they represent. Are they non-oomphy Lewisian laws, the sorts of laws that merely supervene on the arrangement of properties, but do not produce effects? If yes, then what are the different states of the world on which they supervene? It would seem odd to have the world merely occupy different states at different times, given that there are powers at work, and the powers do that job already. It looks like the blue bands ought to be shadows cast by the red bands. So, on that view the blue bands are not really laws at all. But now the blue pegs are not causally relevant. They are at best causally relevant*, which is to say that they are of no causal relevance, but they impact which supervenient laws obtain, simply by popping up here and there. But causal relevance* is not causal relevance, so this does not get us what we need. In fact, even

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  :   

if you allow that blue pegs are free to pop up when and where they like in order to generate this picture (uncaused, of course), their ‘poppings’ must cohere with the fully caused states given by the powers and their exercising. Thus, the random poppings cannot be random at all. The caused and uncaused states of the world must cohere, because the caused states act of necessity. Hence, the actions of the blue pegs must fit with those of the red, and the blue-bands-as-Lewisian-laws view breaks down. Try thinking of the blue bands as Armstrongian instead. Red bands necessitate their effects, and now so do the blues. So far so good. But what prevents a blue band from dictating some state of the world that the red bands prohibit? The universe cannot be in causal disagreement with itself, so the blue bands must mesh with the red ones. We have a new version of the problem of fit (§4.3). And getting that fit demands compliance between the red bands and the blue bands. The only way to generate that fit is to build it in (coincidence is not up to the task). But if we are building the system of bands so that the red and blue bands can all gel in perfect causal harmony (and both necessitate their effects), then we have again lost track of how the blue and red bands differ. They all seem red. Let us take stock. Undetached blue pegs are ghostly, and so they do not satisfy the a-type desideratum. Hooking up the blue pegs to the reds via red bands converts the blue pegs into red pegs, and so is an unstable form of dualism. But hooking up the blue pegs via blue bands renders the blue bands red, and so it is unstable, too. Given the fundamental ontologies these are supposed to represent, it follows that getting the a-type properties to be causally operative breaks down into power monism. And that means that a-type dualism is not a form of dualism worth having. By way of an objection, should we be wary of absences? Prima facie, absences constitute a counterexample to the claim that (within the powers ontology) being a causally relevant property means being a causally operative property. If we remove a power from a constellation, we get a different constellation, and therefore the possibility of a different manifestation arising. Hence, absences can be causally relevant, but they are not powers, and so not causally operative. It is true that absences are not powers, but nor are they properties, and so there is no worry here. An absence is the lack of a property, and lacks of properties do not cause anything. How then can absences be causally relevant? A more detailed answer appears in Chapter 6, but the brief response is that the causal relevance of absences is parasitic on powerful causation. We can contrast what manifestation would arise when a given property is present with that which would arise in its absence, and therefore come to appreciate the significance of a given power. We can then explain the difference in terms of the absence, despite the fact that absences never cause anything. Hence, absences can be causally relevant without being causally active. But they are no threat to the argument, because they are not properties, and thus not causally relevant properties. I do not claim that everything that is causally relevant ends up being a power, only that a-type properties do. What about locations, or better yet, relative locations? Locations, it would seem, could not be powers, and yet seem to be causally relevant. Could our a-type properties be locations, and thereby escape the above argument?

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First of all, how can we be sure that locations are not powers? Answer: because powers have their locations contingently, whereas locations do not.²⁷ It could be that locations are things that have powers (though I doubt it), but it cannot be the case that the locations are themselves powers. And this accords with common sense: powers are had by objects, and those objects are at various locations. It is thus the objects and their properties that are powerful, not the locations at which the objects are found. Given that location is not a power, why think that it is causally relevant? Powersbased causation is a matter of collections of powers working as constellations to produce manifestations. The identity of a constellation is determined not only by the powers it includes but also by the way in which those powers are arranged. The same set of powers is capable of producing different manifestations when differently arranged. Even the Laplacean demon would have to know the relative locations of the powers in order to tell us how the world will unfold.²⁸ Consequently, location— or, more correctly, relative location—is causally relevant.²⁹ So locations are not powers, and yet they are causally relevant. And I have argued that a-type properties must be powers. What should give? It seems clear enough that relative locations are causally relevant. (Different arrangements can mean different manifestations.) And though less clear, it also seems to be the case that locations are not powers. (It would be hard to hold onto the principle that different locations result in different effects if the locations themselves are powers.) I suspect the error in this line of reasoning is in thinking that locations are properties at all. In fact, the most pressing case concerns relative locations, and those do not fit neatly into the picture of properties as ways that things are. So what are they? It could be that locations are not properties per se, because they are properties of properties. That is, locations might be second-order properties: locations are the properties powers have of being at some location or other. This would mean restricting the claim that all causally relevant properties are powers to just the first-order properties, but this seems harmless enough. However, this runs counter to the assumption that it is objects—and only objects—that are capable of bearing properties. A better answer is that locations are parts of states of affairs, and have no peculiar being in their own right. A state of affairs is a matter of some particular having some property or properties. If we include locations, then token states of affairs would be the matter of some object having some property or other at some location or other. Relative location would then supervene on those states of affairs that obtain. It follows that the causal relevance of locations—relative or otherwise—falls out of the fact that constellations are states of affairs. Thus, a-type dualism cannot be saved. b-type dualism. The collapse of a-type dualism is born of the fact that a-type properties satisfy only the causal motivation. If those properties had some other role to play, such that they had more to them than just their causal profile, then perhaps the collapse into power monism could be avoided. Having those properties play those ²⁷ Ellis (2009: 109). See also Molnar (2003: 164). ²⁸ Molnar (2003: 162). ²⁹ The same set of powers arranged in the same way would (presumably) not produce a different manifestation if the whole constellation was relocated.

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  :   

additional (non-causal) roles is what gives us b-type properties and b-type dualism. How does this impact the argument of the previous section? As far as the causal aspect is concerned, substituting b-type properties for a-type properties leaves the above argument largely unchanged. The connections the powers bear to the b-type properties would still result in either necessary connections between the powers and the b-type properties (and that both are part of the blueprint structure), or an inconsistent hybrid account of laws. However, the inclusion of the non-causal motivation adds something to the b-type properties that prevents a complete collapse. The final structure—that which sees the red power pegs banded to the b-type blue pegs with red bands—is very much like power monism, but with one important difference. Whereas all the properties are causally operative properties that bear necessary connections to one another, the b-type properties differ from the pure powers in that their essences are not exhausted by their place in the structure. In fact, they have complicated essences of the sort one finds in mixed monism: part power, part qualitative character. b-type dualism is, thus, a slightly unexpected form of dualism, but it is stable. What else can be said about b-type dualism? b-type properties are not, by any stretch of the imagination, categorical properties. As far as the distinction in §3.3 is concerned, these properties count as powers because they are powerful properties. But they are not pure powers, and they lack the trademark characteristics of categorical properties. That makes this dualism a little strange. On the one hand, we have pure powers, whose essences are captured by their place in the causal structure. But on the other, we have properties that are powerful, but whose essences come from their place in the structure and the qualitative character they possess. This is not to suggest that either type of property is strange; what is strange is why anyone who believed in the existence of b-type properties would bother with anything but just them. If some of the properties are powers with qualitative character, why not have them all be that way? Monism is tidier and more parsimonious. That is the primary criticism that should be levelled against this form of dualism. Once you have b-type properties, there is no longer adequate reason to hang on to the purely powerful powers. b-type dualism is not unstable, but it does not seem to offer anything beyond a monism of just b-type properties. In fact, when we recall that properties are theoretical posits, having purely powerful powers alongside the b-type properties is an unmotivated ontological extravagance. The b-type properties are all we need. And that means that b-type dualism comes in second place to b-type monism, and b-type monism just is the mixed monism I endorse. c-type dualism. The a-type dualist’s properties cannot earn their keep causally without that same dualism collapsing into monism. b-type dualism is stable, but that stability comes at the cost of undermining the motivation for having two types of fundamental properties, rather than just one. In both cases, the argument leans on the causal role these properties are required to play, arguing that achieving this end within the powers metaphysic gives us either just one type of property, or the need for just one. A natural response is to drop the causal motivation, leaving only noncausal roles for the second type of properties to play. These are the c-type properties. There are, for all we know, a variety of non-causal roles that c-type properties could play. But for the time being, satisfying the need for qualitative character is the only one

 

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we have in our sights, and so we will continue to think of it as the archetypical noncausal role that the c-type properties could play. With that in mind, let us ask what c-type dualism would be like, and consider what troubles, if any, might befall it. It is an explicit feature of c-type properties that they not have any causal roles to play. This means that the resultant c-type dualism sidesteps most of the difficulties faced by the a- and b-type dualisms. But despite having no causal role to play, it need not be the case that c-type properties fall entirely outside the causal structure. In fact, there are two ways that c-type properties could be added to the ontology without occupying a causal role. In the first scenario, the c-type properties are ghosts: the powers are blind to the presence or absence of c-type properties. They just appear in the world at random locations. On the second scenario, the c-type properties do not influence what manifestations arise, but they nevertheless constitute parts of manifestations. That is, they are caused, but they are not causes. Let us start with the ghostly case. Properties are ghostlike when the world’s causal properties are blind to them. That blindness boils down to a complete absence of sensitivity: when the c-type properties are present, the powers produce their manifestations as if the c-type properties were not present. This is not simply a matter of not making a difference. A power is only a difference-maker if adding it to a constellation makes for a constellation whose manifestation type is not identical with that which would otherwise have obtained. But even adding a non-difference-making power to a constellation makes for a new constellation. Ghostlike properties, by contrast, cannot make even this minimal difference. A constellation remains unchanged regardless of what ghostly properties are added or subtracted. They simply do not constitute parts of constellations, and therefore fall outside the causal structure of the world. I argued above that a-type properties could not be ghosts, because they will be unable to play the causal roles for which they are posited. But no such restriction applies to ghostly c-type properties. Nor is there any need for coordinating when or where ghostly c-type properties appear, because they do not and cannot interfere with the actions of the causal powers. Hence, ghostly c-type dualism is not incoherent. It is, however, undesirable. Consider the role that these c-type properties have been introduced to play. They are there to add qualitative character to the world. Can they do that without being causes? That they could seems plausible. After all, any causal jobs we might believe should be associated with the character could be done by the powers. It thus seems that the mere instantiation of the c-type properties would suffice. But now consider the nature of change. It seems like the world not only has qualitative character, but that the character changes over time. Again, ghostly c-type dualism is up to the challenge: all we need is that different c-type properties get instantiated at different times. But it is in the nature of those changes that the undesirability of ghostly c-type dualism arises. Those changes are random changes. Different c-type properties pop up in various locations over time. The randomness is not strictly problematic, but do we really want those changes to obtain independently of the changes brought about by the powers? Recall that the neo-Humean’s changes are a matter of random properties appearing at different times and places. Part of the attraction of the powers metaphysic is

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  :   

that changes are governed by the actions of the powers. But ghostly c-type dualism denies the power theorist that feature. Changes in qualitative character could be utterly random, but it is far more attractive, and far more in keeping with the spirit of the powers metaphysic, that those changes be under the control of the powers. And that means abandoning the ghostly version of c-type dualism in favour of a dualism in which c-type properties are included in manifestations. In order for changes in qualitative character to fall under the control of the powers, the c-type properties must be such that their instantiation is governed by the actions of the powers. The best way to do this is to make the c-type properties parts of manifestations. A manifestation is a (probably complex) state of affairs brought about by a constellation of powers (see Chapter 6). This is typically a matter of some object having some properties. Nothing prevents some of those properties being c-type properties. Those can be some of the ways that the object is; they can be those that give the state character. Manifestations are states of affairs, and those states either are, or are part of, the constellations that produce the next manifestation. How can the c-type properties be part of the manifestations without then being part of the constellation, too? That answer is one of forward-looking blindness. Powers produce c-type properties, but are blind to them as far as the operations of constellations are concerned. Is this a good version of dualism to have? It seems to be so. It gets us the qualitative character we want, and it gets changes in qualitative character as dictated by the powers. And it does this without the c-type properties coming out as powers (or quasi-powers) themselves. That said, they are not quite categorical properties in the sense discussed in Chapter 3 either. They bear necessary connections to powers, and are part of the blueprint all powers possess. They thus have their identities fixed, in part, by their place in the structure. This is a necessary connection, and so it renders these properties unwelcome at Hume worlds. Hence, it no longer appears that they could be categorical, as we currently understand categoricity. But they are not parts of causes, and do not have internal blueprints themselves. It is this last regard that makes clear that they are not powers: c-type properties are not powerful, and this is surely the most important condition for a property’s being a power. Powers and ctype properties have some of the features of powers in common, but not all, and not that which matters most. So should we adopt c-type dualism? I still say no, but not because it has any deep faults.³⁰ It just seems like it comes second place to a monism that takes properties to be powerful properties that also have qualitative character. It is to that view I now turn.

5.3 Mixed Monism I have argued that an ontology of purely powerful powers falls short of the mark when it comes to filling the world with qualitative character. It is similarly silent on ³⁰ Perhaps the threat of an increasingly large number of causal dead ends brought on by the possibility of quality-only c-type manifestations should give us pause for thought?

 

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the question of how it is that physical objects occupy space. (These objections might boil down to the same thing; even if not, a single solution could be offered for both.) Hence, I have claimed that something more must be added to the powers ontology beyond purely powerful powers. We have also seen that there is no room in the powers ontology for a second type of property whose instances are not powers and yet are causally relevant. We are left with two options: the first option is c-type fundamental dualism, wherein we have purely powerful powers and c-type manifestation-bound properties that give qualitative character. The second option is that we combine the two types into just one, and have a single type of property that is at once both powerful and character-providing. That second option is mixed monism, and it is the ontology of powers that I prefer.³¹ The properties of mixed monism are properties that live a double life. That double life is at once powerful and qualitative, and both aspects constitute the essence of the mixed properties. On the one hand, these properties are the basis of causation, and account for all manifestations. That is the powerful side, the side that is captured in the blueprint and the causal structure. On the other hand, these properties contain the qualitative character that the world requires. This allows them to occupy space, and play the non-causal roles we require of them. There is consequently ‘something it is like’ for an object to have these properties.³² Neither aspect is such that it can be understood in terms of the other, nor can one aspect be reduced to the other. Both sides are equally fundamental. It is clear enough that a property’s being dual-aspect requires a union of the powerful and qualitative within a single property, but it is not obvious what that boils down to. First things first, it is not a matter of dual-aspect properties being conjunctive properties formed out of two other properties. That is a thinly disguised form of dualism. Nor is it the case that dual-aspect properties promote higher-order properties that are powers and categoricals: nothing said here rules out that possibility, but that is not the way in which the dual nature of the fundamental properties is configured. Dual-aspect properties are composite, but not composite in the way that tables are composed of molecules, such that they could in principle be removed. They are composite in the way that concrete particulars include properties but are not just collections of properties. It is, to be sure, an abstract form of composition. The two cannot come apart, and the two are not properties in their own right, but they jointly comprise the same property. They are the two aspects of a power property’s essence. A return to the pegboard might be in order. Recall what happened when we added the a-type blue pegs to the structure, and hooked them up to the red pegs via red bands. They were part of the structure, but had no independent character, rendering

³¹ Views in the same neighbourhood include: Martin (1993a, 1993b), Martin’s contribution to Armstrong, Martin, and Place (1996), Heil (2003, 2012), and Jacobs (2011). ³² Talk of ‘what it is like’ is typically reserved for discussions of consciousness and qualia. I allude to those debates in an effort to evoke a possible way qualitative character might be, but this is not intended to suggest that character is experiential or mental.

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  :   

the blue pegs indistinguishable from the reds. They were thus powers. But something interesting happened when we replaced the a-type blue pegs with b-type blue pegs. Causally speaking, the set-up was much the same: we had a collection of pegs, all banded by red bands. This meant that all the property types were connected by necessary causal potentials, and that each property type carried in it a blueprint. Every property was thus essentially powerful. But the blue pegs were more than this, and thus remained distinct from the reds. The reds were pure powerfulness, but the blue pegs had an essence that went beyond this. They were red-banded into the structure, giving them a powerful essence, but they had qualitative character, too, meaning that their essence was richer than that of the pure powers. An interesting dualism resulted. The argument levelled against that (b-type) dualism was that it lacked sufficient motivation. The purely powerful red-peg properties were postulated as part of the powers metaphysic, and the motivation for the powerful-yet-charactered blue-peg properties came from the need for qualitative character combined with the need for causally interactive properties. But once one has dual-natured blue-peg properties, the need for power-only red pegs goes away. These blue pegs can play that causal role, too; a distinct type of property is not required. The ontology that results from eliminating the red pegs is mixed monism. There is just one sort of property: btype blue pegs, bound to each other in a complex network of red bands. Take away the superfluous pure powers, and b-type monism just is mixed monism. The mixed monism defended here can be contrasted with a number of nearby views of powers found in the powers literature. The first of these is the dual-aspect view C. B. Martin once proposed (he later dropped it in favour of the identity theory, which I consider below). Called the ‘limit view’, properties were conceived of as dualnatured ‘Janus-faced’ properties, with features recognized as both qualitative and powerful.³³ Which aspect you saw depended on your perspective, as one finds with the duck/rabbit image and other optical illusions. Moreover, to speak of the property as either a power-less quality or a quality-less power was to speak of the property as approaching a limit—though according to Martin no property could exist at either limit. Some properties were highly qualitative and only slightly powerful; others were largely powerful and only thinly qualitative; the majority fell in the middle. My mixed monism embraces the two-facedness of the limit view, but I balk at the suggestion that any property would be largely one way or the other. It seems that the limit view gets something right—to the extent that properties are amalgams of both qualitative character and powerfulness—but what reason is there for thinking that a property is more powerful than any other, or that one has more qualitative character than powerfulness, or the reverse? On the structural picture of powerfulness, a power acts as prescribed in whatever states arise. All powers are like this, and so there is no sense to be made of any power being more powerful than any other, nor of more of the property having an essence that was more powerful than not. The addition of qualitative character is similarly unquantifiable. There is no amount of quality that a property can be said to have, and no way to say that the essence of one type has more

³³ Martin (1993a; 1997).

 

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or less qualitative character than any other. One could, of course, conceptualize properties this way, but that is a feature of us and our thinking, not the properties themselves. Another form of mixed monism, also later dropped by its main proponent, is Mumford’s neutral monism.³⁴ According to Mumford, all properties are amenable to both a dispositional description and a categorical one. Strictly speaking, however, the properties in question were essentially neither. This is the powers counterpart of Davidson’s anomalous monism, which took the physical and mental to be two ways of characterizing properties that were strictly neither.³⁵ Like its predecessor, neutral monism runs into problems concerning how these neutral properties answer to the descriptions they do, despite being neither. But we need not pursue that here; the present mixed monism is clearly not neutral. The powers are properties with essences determined by their locations within the structure and their qualitative character. They satisfy descriptions of both sorts because they are of both sorts, not because they are neither. A similar difference is what distinguishes the present view from Jacobs’s truthmaker form of mixed monism, despite their many similarities. On Jacobs’s account, properties are qualities that ‘make true’ a series of counterfactuals; this being his preferred take on what it is for a property to be powerful.³⁶ While it is agreed that powers will serve as the truthmakers for ever-so-many counterfactuals, that is not the way in which the powerfulness of a power is here understood. That said, Jacobs rightly sees the two accounts as very similar, even referencing my blueprint account in the use of his own: ‘the totality of counterfactuals some property is sufficient to make true serves as a sort of causal-modal blueprint for the property.’³⁷ I think this reverses the order: counterfactual truthmaking is a consequence of the blueprint, not constitutive of it, but this is clearly a disagreement between neighbours, if ever there was one. The neighbour on the other side of my mixed monism is the identity theory, championed by Martin and Heil independently and collaboratively.³⁸ According to the identity theory, the qualitative just is the powerful, and vice versa. There is only one type of fundamental property, and it is what you get by identifying the powerfulness of powers with the qualitative. Read as one sort of identity claim, there is no difference between the identity theory and the view now under consideration. On the present view, one and the same property is at once powerful and qualitative. That is a tolerable form of identity. But characterizing the view as one that literally identifies the powerful with the qualitative—that is, where it is not just the case that the same property is at once both, but where the qualitativity is the powerfulness—has the potential to be misleading (or worse), and thus is not the route we ought to go.³⁹ Consider: the identity of a mixed-monist property type is fixed along two different dimensions. There is the blueprint structure it possesses, as well as whatever qualitative character it has. Our pegboard world represents these in terms of red bands for ³⁴ Mumford (1998). ³⁵ Davidson (1980). ³⁶ Jacobs (2011). ³⁷ Jacobs (2011: 15, note 18). ³⁸ Martin and Heil (1998, 1999), Heil (2003), Martin (2008). ³⁹ Heil (2003: 111) makes what looks like the literal identity claim.



  :   

the former, and blue pegs for the latter. It is true that one and the same peg is both that which is a blue peg and that which is banded by red bands. Here the identity is informative. But it is not at all informative to imply that being red-banded is the same as being a blue peg; these capture different features of the pegboard models. On the face of it, any such identity claim would be false. If we think about the ontology in terms of the motivations that justify the postulation of the properties, we find that the red bands are what satisfy the causal motivation, and the blue pegs are what satisfy the need for qualitative character. Yes, one type of property satisfies both desiderata, but we should stay away from the suggestion that the desiderata are themselves one and the same. They are not. And if we read that identity at face value, we would be left saying something that sounds conceptually confused. I, thus, suggest we avoid speaking as if the powerfulness of a property just is its qualitative character. On my view, the two jointly compose the essence of mixed properties, but the two are not identical. Martin and Heil respond to the appearance of conceptual confusion by stating that the identity (like many a posteriori identities) is ‘surprising’, and further that seeing the property as one way or the other is a matter of ‘partial consideration’.⁴⁰ Again, discovering that Superman and Clark Kent are the same guy is surprising, but undeniably palatable. And one can think of that guy as having super strength while ignoring his skills as a reporter (and vice versa) without inconsistency. But the same identity cannot be claimed of the descriptions ‘being a superman’ and ‘being a mildly nerdy bespectacled reporter’. We should not think of those as being the same thing, even though the same thing can answer to both. Partial consideration—Locke’s term for the ability to think of some entity without thinking of it in its entirety—is no help here.⁴¹ For one, partial consideration would seem to be a distinctly mental act, and thus invites the objection that something about the essence of a power depends on mental activity, human or otherwise, which no one here takes to be the case.⁴² Second, thinking of a power as purely powerful can be achieved through partial consideration, but the same does not hold of pure powerfulness itself. Finally, partial consideration is, anecdotally, a matter of considering something in part, suggestive of something that is complex, not identical. In the spirit of avoiding confusion, I suggest we steer clear of identity. If the relationship between powerfulness and qualitative character is not that of identity, then what is it? Armstrong and Molnar each ask of the mixed view whether the connection between the qualitative and powerful is necessary or contingent.⁴³ Molnar argues that if it is merely contingent, then there is nothing stopping a property being entirely powerful or entirely qualitative. Yet he claims that if it is necessary, then the qualitative part would be essential to every manifestation, and we would not need the powerful side at all. (I admit to not understanding why Molnar believes this. Molnar is suggesting that qualitative properties would somehow be enough for causation, but within the powers metaphysic this is false.)

⁴⁰ Martin and Heil (1999). See also Heil (2003: 112). ⁴¹ Locke (1979). ⁴² Jacobs (2011). See also Molnar (2003). ⁴³ Armstrong (1997), Molnar (2003).

 

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Molnar’s objection misses its target, but is still worthy of consideration. A merely contingent connection would allow for the possibility of pure properties, and that is an unacceptable consequence in a monistic ontology. Hence, there is no choice but to take the connection to be necessary. But this is what we would want regardless. Both the causal structure and the qualitative character serve to fix the identity of the power property types, and hence the two sides are connected necessarily. No such property could fail to be both powerful and qualitative. But that does not render the powerful aspect obsolete: Molnar’s objection is simply mistaken. The need for a ‘causalmaking’ feature of the ontology must be satisfied, and that requires the powerful aspect of the properties. The only way to replace the power component would be to bring in extrinsic causal features such as laws—and that is just to reject the powers ontology in favour of a neo-Humean alternative. Necessity is thus unproblematic. Armstrong replies that this results in what he dubs an ‘untransparent’ necessity.⁴⁴ This he contrasts with the ‘transparent’ logico-mathematical and analytic necessities. But the problem he raises is really nothing more than the lack of conceptual fit between the qualitative and powerful. We have already seen that we should avoid speaking in terms of the identity of the powerful and the qualitative. One and the same property can be both, but what is character-providing in a property is not its powerfulness. Returning to the call for transparency, there is no denying that the necessary connection between character and power gets no clearer once it is understood, but that does not constitute a serious objection. If it was, it would generalize to all discovered necessities, but it is simply not the case that necessities must be transparent, nor that they are any better for being so. Necessarily, water is H₂O. What is at all transparent about this? Like many necessary truths, it had to be discovered. Rather than the lack of transparency’s being an objection to necessities, it ought it be expected. Such is the nature of theory, postulation, and discovery. It is in response to this objection that Martin and Heil describe the identity of the qualitative and the powerful as ‘surprising’. Following suit, we may think of the necessary connection between the qualitative and powerful aspects as surprising, like so many other learned necessities. This raises an important point. When talking of mixed properties, we must do our best to avoid any neo-Humean impulses we might have learned. Armstrong’s worry is born of a Hume’s Dictum-inspired piece of neo-Humean reasoning. A similarly inspired problem is raised by Peter Unger.⁴⁵ Unger describes a simple causal scenario of various objects and powers, then considers what would happen if one object were to change one of its qualities, but not any of its powers. The scenario is perfectly conceivable. But it only constitutes a counterexample to the mixed view if we: (i) take seriously the importance of conceivability in guiding possibility, and (ii) permit neoHumean-style chopping and changing recombinatorialism. Neither belongs to the powers metaphysic, and so there is no counterexample to be had. Possibilities are afforded by the space of powers, and hence the conceivability of the scenario is not enough to describe a genuine possibility. We can imagine the two coming apart, but we can also imagine water having been something other than H₂O. The necessity is

⁴⁴ Armstrong (2004a: 141).

⁴⁵ Unger (2006: ch. 3.).

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  :   

not one that follows from the concepts alone. This is why it is surprising, and why we are able to imagine them being separated. It is thus a consequence of the powers metaphysic that Unger’s scenario is conceivable but not possible. (Of course, what is metaphysically possible is (partly) determined by the systematic metaphysic with which one operates; Unger and I can thus agree to disagree, but his objection is not an objection when considered within the powers metaphysic.) The relationship between the two sides of the mixed monist’s properties is a surprising necessity. Knowing that each power property type has its own blueprint, and that the blueprint determines its unique location in the causal structure, one might wonder what role the qualitative character has in fixing the power’s identity, and whether those qualitative characters are similarly unique. As far as identity goes, the power needs no more than its blueprint. But it has more than its blueprint, so what it needs for identity should not be what directs our thinking in this matter. There are additional desiderata in play. If we were only concerned with what we needed, we could find ourselves seeing the qualitative character as superfluous, and merely complicating the issue. But that is not the reason we take powers to be this way, and so we are not subject to that worry. Instead we are free to hypothesize about the possible roles and ways that the qualitative character can be involved. It is in that spirit that I suggest that the qualitative character is unique to each property type, and thus individually capable of fixing the identity of each. Hence, each property type is a matter of some uniquely charactered property having a unique place in the structure. As far as sufficiency goes, every property has its identity fixed twice over. But sufficiency is not at issue: each property type is thus that property with exactly that causal profile it has, and exactly that qualitative character it has. It follows from this proposal that there are many qualities, much as we might have expected. After all, their job is to give qualitative character to the world, and though this might be minimally achieved by just one or a handful of different qualitative types, that hardly seems like an adequate basis for real character or real change. This is why we should reject the suggestion that we could make do with just a single quality type: just one would not provide sufficient qualitative diversity for change.⁴⁶ We need a plurality, and this proposal gets us exactly that. I have argued for the need for some sort of qualitative nature, but have said nothing about that nature beyond the metaphysical role it plays. That is because nothing more can be said. Our access to the world is forever indirect, fed to us via powers. Hence, we might get lucky in imagining what exactly the world’s qualitative character is like, but for the most part it lies beyond our epistemic reach. Most of what we can say, beyond the motivation itself, tends to be negative. For instance, we have already seen that the need for qualitative character cannot be satisfied via the ‘everyday’ qualities we took to be pre-philosophically familiar. It turns out that the ‘everyday’ are not familiar at all. If anything is at all familiar about them, it would be the effects they have. It could be that the qualitative character we need is one and the same as whatever unfamiliar properties lie at the heart of what we mistakenly took to be familiar, but who is to say?

⁴⁶ Pace Schroer (2010).

 

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Avoiding the familiar means that it is probably unwise to think of the mixed properties as what Jacobs and Heil call ‘powerful qualities’.⁴⁷ Properly understood— that is, as meaning that every property is both powerful and has qualitative character—the name is unproblematic. But it misleadingly conjures up an image in which the everyday properties are the qualities, and that they are what is powerful. That is not the picture we are after, and so that is a term perhaps best avoided.⁴⁸ The last matter of the mixed ontology concerns its closest competitor. We saw in the section on dualism that c-type dualism—wherein c-type properties were parts of effects but not themselves causal—satisfied our desiderata without running into trouble. Why should we prefer mixed monism to c-type dualism? The reasons are not pressing; both are perfectly good views. Ontological economizing gives a slight lead to mixed monism, but that probably is not enough to convince a fan of dualism to change her allegiance. Why include things in your ontology if you can (reasonably) do with less? There is certainly no loss in going from two types of property to one. Again, this is unlikely to move a dualist, but perhaps those entering the fray without prior commitments can see it as a reason to opt for mixed monism. The same could be said about the fear of semi-ghostly properties.⁴⁹ Folks who were content to postulate epiphenomena or causally inert qualia are unlikely to get the heebie-jeebies from properties that have no causal role to play, but on the whole one ought to avoid such properties if one can. There are thus perhaps only the weakest reasons to prefer mixed monism to its nearby dualist counterpart, but for my tastes that is enough.

⁴⁷ Heil (2010), Jacobs (2011). ⁴⁸ I think Heil and Jacobs would agree with me, but certain examples, such as the powers of the redness of a cape (Heil 2010: 70) or mental qualia (Jacobs 2011: 19), make it worth spelling it out. ⁴⁹ Pace Ray Parker Jr (1984), I am afraid of ghosts, and think we all should be.

6 Powers-Based Causation 6.1 Causation and Causal Concepts We have seen the parts of the powers ontology; now it is time for the powers metaphysic to take shape. We start with what the powers do best: the heavy lifting in a theory of causation. The incredibly brief account of powers-based causation is as follows: causation is the exercising of powers. Collections of powers, in specific arrangements (constellations), give rise to manifestations. The collective powers are the causes, the manifestations the effects. The rest of this chapter fleshes out the details. However, before we do that, it is important to make clear exactly what this account of causation hopes to achieve. On the positive side, it is intended as an account of the fundamental causal relation as it holds in the actual world. That is, it assumes that there are aspects of the world that are responsible for the later states of the world, and seeks to provide the mechanism behind this phenomenon. It thus assumes that there is genuine causation in the world; the world is therefore what some call ‘oomphy’.¹ States of the world give rise to further states—they produce them. This is oomph. Powers will be employed in an account of how this oomphy causal relation operates. What you will not find in this chapter is an attempt to figure out what the folk mean when they use the term ‘cause’ or its many cognates. Behind this common usage is (presumably) a folk concept of what causation is. It is not clear that this concept is well-defined, or if there is any agreement regarding how it is understood. But that is not a problem that will trouble us, as I will not be offering an analysis of our everyday concept of causation. Let me explain this further. A significant portion of the contemporary causation literature concerns our folk concept.² This literature is centred on us and how we conceptualize the world, and aims to provide an analysis thereof. The goal is to unpack what we mean or intend when we utter words like ‘cause’. A successful analysis would provide a set of necessary and sufficient conditions for the correct application of the terms in the causal family. This is inherently interesting, but completing this task will not itself tell us anything about what causation is, beyond how we think or talk about it. However, that task may give way to a second task—one of a worldly or metaphysical nature— ¹ Or at least I do. ‘Oomph’ is not well defined. It is clear enough that necessary causal relations (as given by powers or Armstrongian laws) count as oomphy, and that mere regularities, contiguity, and counterfactual dependence—common components of many neo-Humean accounts of causation—are not even close, but it is unclear if tending or some other middle-ground connections are sufficiently strong. I suspect they are not. See Schrenk (2009) and Kutach (2014). ² Lewis (1973a), Collins et al. (2004), and Hall and Paul (2013). The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

   



which asks if there is any fully natural relation corresponding to our concept. In effect, this question asks if our concept picks out anything real in the world, to the extent that there exists a relation that more or less corresponds to our concept, and is natural (in the sense of existing independently of—or prior to—our concept). This is what Jackson calls the ‘location problem’.³ This is a perfectly respectable strategy, and useful to philosophy. So why avoid it, and what do I hope to do instead? Moreover, how can we hope to say something about the nature of causation without having located an analysis? As I will explain in the rest of this section, I am not convinced that this concept-first strategy is the best in this case. Moreover, even without completing the first task, we do not have a hard time recognizing a worldly relation as a causal one. There is a phenomenon of change. I am starting with the assumptions that it is a causal phenomenon, and that it requires explaining. An analysis will emerge—one that appeals to the parts of the powers ontology—but the primary aim is that of explanation. The analysis, to the extent that it is one, will deal only with causation like that.⁴ It comes after the phenomenon, and is not the product of an examination of our folk concept. But it nevertheless constitutes bona fide progress regarding the nature of causation. I believe that starting an investigation into the nature of causation via the analysis of our folk concept is a strategy best avoided. Here are the reasons (which I further explain below). First, there is evidence against there being a single, unified causal concept. Hence, we have a reason to be sceptical about our uncovering an analysis of the causal concept. Second, even if there is a single causal concept, we might be worried that this concept is not adequately divorced from other nearby concepts, and so there is no way to locate anything that corresponds to it in the world. Third, there are features that belong to our concept that are (arguably) divorced from the world, but it would be a mistake to interpret that as meaning that there is no genuine causal relation, rather than its indicating something about our concept. Here is some background on the claims just made. Firstly, we ought to be sceptical about the prospects of offering a unified analysis that captures all the things we as folk count as causal.⁵ Consider, for instance, the matter of whether our causal concept takes causation to be transitive. That is, if a is a cause of b, and b of c, does it follow that a is therefore a cause of c?⁶ Some examples would have us believe it is. You hit a ball with a bat, and the ball hits a passer-by on the arm, breaking her arm. It seems natural to say that your hitting the ball caused the injury. After all, had you not hit the ball, there would have been no injury. It seems just as natural to say that toppling that first domino is the cause of the last one falling, and that your hitting the median caused all the subsequent damage of the four-car pile-up. So, causation is transitive, right? Not so fast. Now imagine that our passer-by is an avid tennis player. Not wanting her injury to keep her from her favourite pastime, she opts to play with her much

³ Jackson (1998). This two-task strategy is at the core of the Canberra Plan. ⁴ I offer an account of what in the world explains this causal phenomenon. The analysis—if you can properly call it that—appears above: causation is collections of powers (constellations) giving rise to manifestations. ⁵ See Hall (2004) as good evidence that this is the case. ⁶ Hall (2000), Hitchcock (2001).

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- 

weaker left hand. She is good enough that she wins her match, but by a narrow margin, not the huge margin she typically enjoys. She played with the weaker hand owing to the injury, but it is unreasonable to claim that your hitting the ball was the cause of her winning. So, causation is not transitive, right? One could try to resolve the mismatch, but there is no problem here if we concede that we may have different things in mind when we speak of causation. One concept—perhaps many—take causation to be transitive. But others need not. And if we have many causal concepts, then there is little to be gained by hammering out the conditions of each so that we can then go looking for which line up with the world. The same goes for other features we sometimes attach to the causal relation, such as asymmetry, probability raising, temporal direction, and so on. We can find examples which seem to convince us that these features are part of our causal concept, but also others that would have us draw the opposite conclusion. Rather than trying to unify this mess by arbitrarily excluding features and prioritizing others, we can do justice to all our intuitions if we allow for many (probably incompatible) causal concepts.⁷ The second difficulty is connected to the first. It is that our causal concept(s) are not well divorced from our concepts of blame and responsibility. Take a case where a lawmaker accidentally generates a legal loophole that would permit a chemical company to pollute some region. We might well hold the lawmaker responsible for the resulting pollution, owing to her legal misstep. Is the lawmaker thus a cause of the pollution?⁸ The answer depends on whom you ask. Some will take the responsibility to be sufficient for having been a cause, or that the lack of prevention makes it a cause. Others might claim that causes require direct positive input. (If you are not feeling the tug of intuition, run back the example under the assumption that the lawmaker acted intentionally, having accepted a large bribe.) Is there a right answer to the causal question? And even if there is, should it be one that can be so easily manipulated by our moral considerations? There does not seem to be any easy way to neatly tease apart these concepts, and so I doubt we can make our causal concept amenable to a unified analysis. Third, our concept of causation looks like it is committed to causation by absence, but it does not appear that any genuine (fully natural and worldly) causal relation obtains in these cases.⁹ Consider: the process of firing a gun (by pulling the trigger) is a matter of causation by disconnection, which is a type of causation by absence.¹⁰ In pulling the trigger one removes the sear, which was preventing the spring from expanding. Firing a gun is thus the removal of a preventer, an example of what is known as ‘double prevention’. Disconnection as double prevention falls under our folk causal concept. It is—as far as our concept is concerned—a perfectly good case of causation. But the two states do not stand in a worldly causal relation, not, at least, as far as production and oomph are concerned. (More on that below.) Hence, our concept and the causal relation in the world come apart. We could try to convince ourselves that causation by absence is not part of our concept, but that project is sure ⁷ Lombrozo (2010), Rose and Danks (2012). One can get a sense of this conceptual mess by consulting the literature on causation coming out of experimental philosophy. ⁸ This follows Knobe (2003). ⁹ Livengood and Machery (2007). ¹⁰ Schaffer (2000a).

, ,  



to fail. So, should we be sceptics about causation? That seems like an unwarranted response, especially given that there would still appear to be some sort of causal connection in the world.¹¹ A better suggestion is that we stop trying to make the two cohere. We can do that either by recognizing that the world need not line up with our causal concept, or by taking on multiple causal concepts, and recognizing that the world does not line up with that (or those) causal concepts that include causation by absence. Either way, it undermines the strategy that would have us do conceptual analysis first. Finally, it might be suggested that once we have an account of what fundamental causation is, that account can be used to generate an analysis. In a sense, this is correct: there will be something that ‘causation’ will mean according to the account on offer. That is (roughly), whenever and wherever a constellation produces a manifestation we have a cause and an effect. But that account would be quite restricted—it will not, for example, include transitivity or causation by absence— and so whatever that analysis was of, it would not be the general folk causal concept (or not amenable to many of them, if there are many). Do we have any need for such a restricted analysis? If we do, it is the analysis of the natural fundamental causal connection. Perhaps the other uses could be considered metaphorical or analogical, derived from the fundamental case. The reader is invited to understand causation thusly, but I leave the details up to them. In any case, should this be construed as an analysis at all, it is an analysis of just one of the causal concepts we as speakers are prone to recognizing.

6.2 Mutuality, Reciprocity, and Constellations It is part of the standard picture of powers that they lie in wait until the right sort of conditions arise. Supposedly, when those conditions arise, the powers become active and reveal themselves by producing a manifestation. Conceived thusly, the stimulus is an action or event that kick-starts the action of the power; it instantly spurs the dormant power to life. We see this feature of the standard picture reflected in the proposed conditional analyses. According to those would-be analyses, a power is not just the power to produce some manifestation m, it is the power to do so in response to some stimulus s. As previously argued, the SCA and other similar analyses fail.¹² But there are more problems with the standard picture than just this; in this section, I rehabilitate the notion of stimulation by offering an alternative understanding.¹³ ¹¹ One could insist on scepticism about causation. But that would only invite the response that there is causation* in the world: a genuine relation of production. ¹² E. J. Lowe (2011) argues that the conditional analysis of power ascription is doomed to failure in any form, because it relies on this mistaken stimulus-driven conception of powers-based causation. ¹³ The first step towards a rehabilitated notion of stimulation comes in recognizing that there is an important class of powers that have nothing that could count as a stimulus. Hence, the picture of powers as always requiring stimulation in order to produce manifestations is mistaken. Some powers, like those associated with radioactive decay, are insensitive to external conditions. It is an important discovery that not all powers require stimuli, but one whose consequences I leave for the next chapter. For now, the rehabilitation of stimulation in powers-based causation will stick with the more familiar cases. See Lowe (2011) and Williams (2014).

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- 

Let us consider what constitutes a stimulus condition for a power. A stimulus, we have said, is whatever triggers the power so that it produces a manifestation. If salt is to manifest its solubility, it must be immersed in a solvent, such as water. Being immersed in water is, thus, a stimulus for the salt to go into solution. But the salt would not go into solution if that water was already beyond the point of saturation, or if the water somehow lacked the causal features it typically possesses. On the mistaken understanding of stimuli, the stimulus acts as if it is a cause of the power’s producing the manifestation. This is mistaken in at least three respects: (i) not only does it falsely suggest that the stimulus is a cause unto itself, it (ii) suggests that it acts prior to the power acting, and also that (iii) the power, once stimulated, acts alone to produce the manifestation. Placing the salt in the water is not some event that causally triggers the salt’s solubility; rather, it is a necessary condition of its going into solution. Putting the salt in water does not cause the manifestation, it is what is necessary for the manifestation to come about. As Lowe states, it is a misconception to suppose that being in water is some condition which functions, or even could function, as a cause of the manifestation of water-solubility whenever that disposition is manifested—together, perhaps, with other causes. And yet it seems clear, this is precisely what being in water is understood to be by those who regard it as the ‘stimulus’ of that disposition.¹⁴

The manifestation of water-solubility is that of being dissolved by water. It is not a prior event of immersing the salt in the water that is required for the salt to go into solution, but its continued immersion in (non-saturated) water. Hence, there is nothing that acts as a stimulus in the sense of a causally efficacious event that is prior to the manifestation. It might be conceptually prior that certain conditions obtain in order for the manifestation to be produced, but that is not nearly the same. Being in water is, thus, not a cause of the salt’s exercising its power. Nor does the immersion in water serve as a cause that acts prior to the salt’s acting. These are the first two mistakes listed above. [I]n reality what is called the ‘stimulus’ is not aptly so-named at all, since it can’t stand in a causal relation to the ‘manifestation’, being in truth only a logically necessary condition of the latter.¹⁵

So, what does the stimulus in fact do? The answer lies in the third mistake, that of thinking that after its stimulation the power produces the manifestation on its own, without the stimulus. Powers do no such thing. The power works with the powers of the stimulus to produce the manifestation together. Let us shift now from the mistakes to the lessons. The first lesson of powers-based causation is that the production of manifestations is a mutual affair. The second concerns the reciprocal nature of powers-based causation. Lesson 1: Mutuality. The mutuality of causal action—whether it results from powers or not—is not an unfamiliar notion. Recall Mill’s observation that when assessing

¹⁴ Lowe (2011: 25).

¹⁵ Lowe (2011: 30).

, ,  

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causation we need to consider the total cause.¹⁶ Our tendency is to focus on a single salient feature of the cause, treating it as the cause and simultaneously downgrading the importance of the other factors involved.¹⁷ And yet without those other factors, ‘the’ cause could not have produced the effect. We say that it is the rock that broke the glass. The rock is the subject, it is the one we are interested in; the glass is merely the object of the rock’s action. But when powers are the source of causal action, the rock does not act upon the glass, the powers of the two act together. It follows that it was a mistake to single out a single feature and treat it as the cause in the first place. All aspects of the cause are involved. This is the essence of mutuality. Martin writes: I have been talking as if a disposition exists unmanifested until a set of background conditions is met, resulting in manifestation. This picture is misleading, however, because so-called background conditions are every bit as operative as the identified dispositional entity. A more accurate view is one of a huge group of disposition entities or properties which, when they come together, mutually manifest the property in question; talk of background conditions ceases.¹⁸

Perhaps the worst offenders of singling out causes are those who speak in terms of ‘active’ and ‘passive’ powers, where the ‘active’ powers are the causal doers, and the ‘passive’ powers idly acquiesce. Similar connotations follow from distinctions like ‘agent’ versus ‘patient’, and ‘triggering conditions’ versus ‘standing conditions’. Inasmuch as these distinctions are intended to be epistemic, they are innocuous— we might reasonably prioritize certain aspects of the cause over others. But as metaphysical distinctions they are dangerous, because they falsely suggest that some part of the cause has dominance over the rest. This bias is most obvious in the case of agent and patient; it conjures up images of human agents acting freely as prime movers and forcing the surrounding world to comply. But this implication of causal inequality cannot be permitted. The powers of the water contribute as much to the salt’s going into solution as do the powers of the salt—there is no metaphysical sense in which any power involved is any less than any other. It is a case of cooperative powers all around. A rehabilitated understanding of stimulation replaces the picture of the stimulus acting before the power with that of them both acting together. Together they produce the manifestation. How do they do this? The answer is simple: the powers of the one act with the powers of the other. Part of the reason that the standard understanding of stimulation is so mistaken is that it treats the stimulus as if it were an entity of a different kind. The stimuli are no more than other powers that are needed for all the powers involved to produce a manifestation. The only sense in which it is different at all is when considered from an epistemic or explanatory perspective. If we focus on just one power and just one manifestation, we can ask what is required for that power to bring about that manifestation. Those ¹⁶ J. S. Mill (1967: Book 3, ch. 5). See also Mackie (1965). ¹⁷ Lewis (1973a: 159): ‘We allow a cause to be only one indispensable part, not the whole, of the total situation that is followed by the effect in accordance with a law.’ ¹⁸ Martin (2008: 50).

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powers that need to be added count as the stimulus for the target power. But of course the reverse is true, too. The target power is just as much the stimulus for the other powers as they are for it. Hence, though we often speak of a single power and its manifestation, this is only part of the story. Powers are multi-track, and so there is never just one manifestation that a given power is for (§4.2). But even looking at just one manifestation type, it is still mistaken to speak of that manifestation as if just one power is the only one really responsible for its production (even if this is of practical use). For most of the manifestations we are interested in, the manifestation is produced by many powers acting in concert. When a power is appropriately arranged with other powers, those powers jointly act to bring about what is their mutual manifestation. But this does not make it incorrect to say of each of the powers involved that it is for that particular manifestation—no more than saying that the I-90 highway will get you to Cleveland; it does, but so will the 77, the 71, and the 80—it just omits some relevant information. Each of the powers that make up a constellation is, thus, for the manifestation that they collectively produce. And that brings us to the second lesson: the production of manifestations is reciprocal.¹⁹ Lesson 2: Reciprocity. What properly deserves to be called the ‘stimulus’ is nothing more than some set of powers required for the target power to produce (with them) some specific manifestation. But the same is true for every power in that set. What counts as the stimulus thus depends on what perspective we take on that set. But this helps demonstrate another way in which the stimulus is not special. What it provides, in terms of bringing about the manifestation, is no more or less than is provided by the target power. They all act together, and they all act equally. The basic idea behind reciprocity is that manifestations are an egalitarian affair. Producing manifestations requires the coordination of two or more powers, but neither dominates the other. It simply does not make sense on this account of powers-based causation for one power to dominate another. The manifestation is the product of their working together; none does more lifting than any other. There is no quantifying a power’s contribution: that set of powers produces that manifestation, and that is the end of the story.²⁰ Beyond balance, reciprocity demands that powers complement one another. That is, just as the salt must have a power to dissolve, the water must have the power to dissolve the salt. Consider the smashing of a martini glass by a rock. It takes more than just the rock and its powers—you need a martini glass and all its powers, too. This is not just to say that the breaking of the glass is a manifestation that requires both objects to be present (though that should not be ignored); both objects must have the appropriate powers. If the two objects are not appropriately powered, or lack the powers for that kind of manifestation, then some other manifestation will occur. We should expect that if either the rock or the glass had different powers, then a different manifestation would typically result. But this is no threat to reciprocity, it ¹⁹ The terminology here, that of ‘reciprocity’ and ‘mutuality’ as applied to the causal action of powers, is due to C. B. Martin (1993a). See also Heil (2003) and Martin (2008). ²⁰ Well, almost the end of the story. Arrangements matter, too, and particulars (indirectly, despite our seeing past them).

, ,  

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merely recognizes that objects can vary in the manifestations they are capable of producing. Whatever manifestation the rock and glass give rise to is a product of the powers of the rock and the glass, powers that work together to produce what they do. This is the case if their mutual manifestation is the shattering of the glass, the rock’s bouncing off, or even the shattering of the rock. Let me be clear about what is being claimed here. I am not saying that the manifestation two (or more) powers produce cannot be surprising or unexpected: that is an epistemic matter. What I am saying is that mutual manifestations require complementary powers. (They must have the right fit, as we saw in Chapter 4.) Each must manifest powers that are for an identical manifestation. Consider what the alternative would mean: the glass manifests its power to shatter, and the rock manifests, what, some power for which the manifestation is not the glass’s shattering? No sense can be made of this. The only powers the rock can manifest are those that fit those of the glass. Hopefully by now we are past the mistaken notion of stimuli, at least as it applies to powers-based causation, and can move forward with the account. This brings us to the final step regarding stimuli. Taking the two lessons together we see that the only thing that can properly count as a stimulus is constituted by the presence of other powers. The salt exercises its power to go into solution only when met with a solvent that has the reciprocal power of dissolving the salt. These two powers—the solubility and the power to dissolve—are reciprocal partners. However, we should not be misled into thinking that powers are operative only in pairs: the vast majority act in large groups. I therefore speak of the circumstances under which powers are exercised as ‘constellations’. It is to them we now turn. A constellation is constituted by a collection of powers. When a constellation obtains, the powers that constitute it jointly act to bring about their manifestation. But constellations are not mere collections of powers. Not only must a power be in the vicinity of the requisite reciprocal power partners to be exercised, those partners and it need to be appropriately arranged. And nowhere are arrangements more important than in the astronomical constellations from which the notion has been lifted. From around here, and to the naked eye, stars all look pretty much the same. And so even though we can sometimes pick out a star or group of them based on absolute locations in the night sky, relative positions tend to be the most useful guide. Hence, practically speaking, arrangements are the most important feature in differentiating astronomical constellations. It is thus unsurprising that arrangements (relative positions) are an essential feature of astronomical constellation identity. Power constellations are not limited to difference of arrangement alone, because individual powers are not so easily mistaken for one another. But it would be a mistake to overlook the importance of arrangements in constellations, not least because of the different manifestations that can arise from the very same set of powers when differently arranged. For instance, the lighting of a match requires more than just having a match along with a striking surface and some oxygen—that combination of powers can produce many manifestations—it requires that the oxygen enfold the match as it is rubbed along the surface and the red phosphorus is heated by the friction. Moreover, it might be that there are very few different types of power properties, making the differences in their arrangements all the more significant.

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- 

Another key feature of constellations is the powers they exclude. Beyond their arrangements, the addition or subtraction of powers to or from a constellation results in a distinct constellation, and therefore the potential for a distinct manifestation.²¹ Just as Scorpio would no longer be Scorpio if you added an extra star, constellations change when you add extra powers. Consider Superman’s lifting a rock, versus his attempting to do so with some kryptonite thrown in, and you should get the picture. It matters that the kryptonite was not there in the first place. Hence, the negative space within a constellation is just as important to the constellation as the powers that are present. Just as the egalitarian nature of powers-based causation eschews metaphysical interpretations of agent and patient, once we recognize that there is nothing more to causal antecedents than the obtaining of a constellation of powers, it follows that there is nothing metaphysically deep to be found in the concept of a stimulus. As we have seen, stimuli, strictly speaking, are of no metaphysical significance, despite their use in helping us navigate the world. We say of the salt that it will dissolve if placed in a solution, and go on to treat immersion in the solvent as the stimulus of the salt’s power. But the powers of the salt work hand in hand with the powers of the solvent. Hence, the powers of the salt are just as much a stimulus for the powers of the solvent as the reverse. All that is really going on—metaphysically speaking—is that the constellation obtains. And that is all that is required. However, from a pragmatic standpoint, it is useful to be able to speak of the rest of the constellation (constellation minus solubility) as the stimulus under which the salt will go into solution. We might even highlight other aspects of the constellation as having greater pragmatic significance, and there is no harm in doing so. For instance, we probably care most about the powers of the solvent, and not the ambient temperature or state of pressure, despite the fact that these powers play a role. Hence, when thinking of stimuli we focus on an aspect of the constellation in relation to the rest. We think of bringing the rest of the constellation into place alongside the target power as ‘triggering’ the target power, but all we have done is brought about an instance of a constellation. This is a harmless abstraction, at least as far as knowing what sorts of powers an object has, or in what sort of constellation a power will produce in this or that manifestation. We have seen how talk of active and passive powers falsely suggests some of the powers act on the others. But it is also misleading in that it gives the impression that some of the powers are active at all. There is simply no good sense in which some powers are active and others inactive. Inasmuch as we can say that any is active when they produce a manifestation, they all are. But we should nevertheless avoid speaking this way, because there is no time at which a power is ‘switched on’ to a different sort of state.²² Powers exist, and when they meet with the right constellations, they give rise to manifestations. This, as we shall see, is a very brief occurrence. Consequently—beyond the fact that there is no place in the ontology for a power ²¹ I say the potential for a difference in manifestation because there is no reason to rule out different constellations having the same manifestation type. There are, after all, many ways to skin a cat, and all of them result in skinned cats. ²² Pace Marmodoro (2017).



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to be anything other than instantiated or not—there is no time for powers to be in an altered state.²³ We might, for convenience, speak of a constellation’s occurrence as an ‘activation’ of one or all of the powers involved, but that is only to contrast that case with those times the powers involved are not in that constellation. But when we are being more careful we should never speak as if ‘being active’ captures a genuine way that powers can be. In fact, there is something quite odd about thinking of a power as having a different status like this. This is not a matter of its being instantiated or not—that sort of change in status is familiar enough; this is an instantiated property having different ways that it is, owing to what powers it is partnered with. Though we can contrast the potential with the actual, instantiated powers are always actual, and so having them change in status when active cannot be their becoming actual. Inactive powers are not unreal powers, which means that change in status must be a property of the power properties. I, for one, can make little sense of powers bearing properties like this. I want to make a final point regarding constellations and their role in powersbased causation. That is that the model is to be taken at face value. Instances of various constellations obtain, and they give rise to their manifestations. That is the full picture; it is not a metaphor designed to give way to some deeper analysis. There are other accounts of powers for which this is not true. For instance, there are accounts of powers in the literature which start out looking like this one, but we are then told that the manifestations result from energies or forces.²⁴ If it is energies or forces that are responsible for causal production, then the powers are not genuine powers at all. And when presented with such accounts, we are moved to ask how these energies and forces are supposed to work, and it does not appear that they work in the same way the powers were supposed to. The details need not concern us, but it is worth stressing that for the present account there is nothing behind the curtain: all the causal magic is right up front for all to see. States of the world—none other than the arrangements of powers that are the constellations—give rise to the later states of the world that are their manifestations. Talk of states of the world giving rise to states of the world provides a nice segue into the next aspect of powers-based causation. That is the nature of the manifestations themselves. We have heard plenty about the properties that produce the manifestations, but less about the manifestations. I said in Chapter 4 that I took them to be states of affairs. In the next section, I defend that claim, but en route to that conclusion many as yet unmentioned features of powers-based causation will come to the fore.

6.3 Manifestations Examples taken from the powers literature indicate that manifestations fall into one of the four following ontological categories: properties (fragility results in being ²³ It will turn out, as we see below, that an instantiated power is one that cannot help but instantly produce a manifestation. Hence, though there is no active state of any power, every instantiated power is ‘active’ in the minimal sense that it is now producing a manifestation as part of a constellation. ²⁴ See Molnar (2003) and Ellis (2012).



- 

broken); states of affairs (flammability results in something’s being combusted); events (solubility results in dissolving); or processes (gravity results in acceleration).²⁵ If number of appearances in the literature is anything to go by, then the event category boasts an early lead, but I suspect that this has as much to do with the popularity of certain examples as it does anything else (pass the solubility, please). With some simple reorganization, the options can be reduced to two. Paradigmatic events are four-dimensional entities with a temporal extent, but under one popular analysis an event is nothing more than the exemplification of a property at a time.²⁶ Understood thusly, there is little difference between an event and a state of affairs. And though a property exemplification is not merely a property, any manifestation that is a property will entail that property’s being exemplified at a time, and so the difference for our purposes is minimal. Hence, we can lump these three together in a group we will call the ‘brief ’ or ‘instantaneous’ manifestations. The other group will house the longer events and the processes. Processes are a special class of events: they are protracted, four-dimensional, and structured events, composed of many states and shorter-lived events. (This ordering is imprecise and victim to straightforward counterexamples, but this will not matter in the long run.) I hold that manifestations are states of affairs. The result of a power’s being exercised is that some state of the world obtains. However, as the categories within the brief group are quite similar, my biggest concern is with the brevity of manifestations. Hence, my primary aim is to argue that manifestations belong in the brief group. We ought to reject any view that treats manifestations as entities of any significant temporal extent: they must be very short-lived. To help us get the cognitive juices flowing, let us focus on a specific sort of power, namely that of something’s being poisonous.²⁷ Though there are more nuanced ways of understanding what it is to be poisonous, for present purposes the colloquial definition should suffice: something is poisonous just in case it has the power to cause death when ingested in specific quantities. Now consider the following vignette: Two brothers, Angus and Malcolm, are hiking in Australia when Angus is bitten by a highly venomous tiger snake. His foot swells up at the location of the bite, and Angus starts to sweat as his breathing becomes laboured. Luckily for him, Malcolm is no stranger to snakebites, so quickly splints and binds the area, thereby limiting the flow of venom. Nevertheless, a small amount of the potent neurotoxin in the venom begins to work its way through Angus’s system, and he starts finding it harder and harder to move. Malcolm resorts to carrying Angus, and in

²⁵ Regarding the nature of manifestations, Molnar (2003) speaks of them as being events, Williams and Borghini (2008) treat them as states of affairs, Mumford (2004, 2009b) and Bird (2007a) opt for powers, Vetter (2015) for properties, and Ellis (2001), Chakravartty (2007), and Handfield (2008a) for process types. ²⁶ See Kim (1973, 1976). ²⁷ If you are anything like me when it comes to thinking about powers, you might be hesitant to treat being poisonous as the sort of power that belongs in your ontology. In fact, if you are exactly like me, you will flat out deny that there is any such power, claiming that something’s being poisonous is a useful ascription of potential object behaviour that is broadly derivative of the genuine powers, and therefore not powerful itself (it is probably a disposition). I am aware of the pitfalls we might encounter by directing the discussion in this way, and the worries arising from the case of poisons in particular. I attempt to assuage those concerns in due course.

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due time arrives at a local emergency ward, where an anti-venom is administered. Angus recovers, and has little to show for his encounter beyond a minor wound and an exciting tale.

The mechanics of the case might sound familiar. That is because it is an antidote case of the sort that Alexander Bird raises in response to David Lewis’s revised form of the conditional analysis.²⁸ The case is relevant to our present concern because of what we can learn about manifestations when they go awry. The antidote throws a proverbial spanner in the manifestational works, and once we have figured out how to deal with that, we will have learned some important lessons about manifestations. So, what has gone ‘wrong’ here, and what should we say about it? The sense in which the poisoning case has gone wrong concerns its failure to have resulted in Angus’s death. The poison was ingested in sufficient quantities, but Angus lived to tell the tale. There is no point saying that the venom was not poisonous, or that the relevant power was missing, because the scenario makes clear that both were the case. They are, after all, why Angus required treatment, and why he suffered paralysis. Nor is it the case that the relevant power failed to meet with the appropriate conditions for its manifestation. Angus lacks any natural immunity to tiger-snake venom, and we can safely assume that he had not previously done anything to make his body otherwise unsusceptible to its deadly effects. The power was present, as were the conditions for its manifestation, and hence the problem must lie with the manifestation itself. What can be said about that? On the one hand, it seems perfectly reasonable to say that the manifestation did not come about. This is the assumption Bird makes in claiming that antidote cases undermine the revised conditional analysis: the power remains and the object receives the appropriate stimulus, but the expected response does not arise.²⁹ And this seems obvious enough: Angus’s death was prevented by his taking the antivenom. But, on the other hand, there is something altogether too clumsy about saying the manifestation did not come about. There is a perfectly reasonable sense in which the manifestation did come about. To flatly say it did not suggests that the poison did nothing at all. But that is mistaken: Angus suffered some degree of paralysis in addition to sweating and laboured breathing. Had Angus been immune to the venom, we could state unreservedly that the manifestation did not come about, but saying the same of the anti-venom case obscures the contrast between it and the null reaction of the immunity case.³⁰ What we want to say—one way or another—is that the manifestation both did and did not come about. Finding the best way to say it will help us better understand manifestations. Long-winded manifestations 1: Processes. A natural proposal is that manifestations are processes. According to Handfield, the manifestation of a power ‘typically—perhaps always . . . involves a process’.³¹ If the manifestation associated with being a poison is a process whose terminus is death, it is understandable why we would want to say both that the manifestation came about and that it did not. ²⁸ Lewis (1997), Bird (1998). ²⁹ Bird (1998: 228). ³⁰ That is ‘null’ in the sense that it does not produce any change. ³¹ Handfield (2010: 106). Ellis (2001: 124) maintains much the same, claiming that the display of a power is ‘a certain natural kind of causal process’.

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- 

Processes—protracted, structured events—paradigmatically involve a series of changes. Here the final change is that of changing from living to being dead. That change has not come about, and this explains our intuition that the manifestation failed to obtain. However, some portion of the process has come about (changes have taken place, just not the final one), and this is what is behind our thinking that we did get the manifestation after all. Approaching manifestations this way also provides us with the resources to capture how the anti-venom case differs from the immunity (null) case: the former involves a series of changes brought about by the poison, whereas the latter does not. At a first pass, this proposal seems kosher; but not all is as it first seems. If manifestations are processes, then when the right constellation of powers obtains, we get a process. But this is somewhat vague. There are many ways in which this might result in a process (to wit, if a series of briefer events line up the right way), but which fall short of any single manifestation being a process. For manifestations to be processes it cannot be that a process merely supervenes on whatever else takes place. The manifestation cannot, as Handfield states, merely involve a process: the manifestation must be a process. But now it is no longer clear how this helps us with the anti-venom case. What was initially attractive about treating this case as a process was that processes are structured entities, and their cleavages allow us to distinguish partially completed processes from those that run to completion or never start. But now this is denied us once more. Manifestations as processes is an all-or-nothing affair: the processes either come about or they do not. It is their structure that makes them appealing, but this proposal undermines that feature. If we are to exploit the cleavages, we need a means of accessing them. That is, we need manifestations to be shorter so they can ‘add up’ to processes. To reiterate, it may well be the case that the exercising of powers ‘gives rise to’ processes, in the sense that certain processes supervene on multiple powers producing manifestations over time, but this is not the same as some single constellation manifesting a process. That would not allow for the cleavages we seek to exploit. For illustration, consider a long line of dominoes, stood on end and ready for toppling. We tap the first, and watch as the line topples. The toppling of the entire line is clearly a process. What is being denied is that the manifestation of the relevant power (or powers) of the first domino is the process that is the toppling of the rest. But surely, you say, that process occurred because the first domino was toppled. It was responsible for the rest falling over—it was the cause of the process. Yes, the toppling of the first could figure in an explanation of why the rest fell, and yes, it was responsible, to some extent. But not because its manifestation is the process. Its manifestation is the toppling of the second domino. That is the state of the world the powers of the first bring about. And the powers of the second will result in the toppling of the third, and the third the fourth, and so on. If the manifestation was the entire process, then we would yet again be unable to say what the powers of the first have done when an intervening spider stops the toppling of dominoes after the 3,356th domino has fallen, but long before the last has. Furthermore, though it is possible to interpret ‘getting the right constellation of powers required for manifestation’ as indicating something about the diachronic

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distribution of powers, this is a mistaken reading in this instance. Assume, for argument’s sake, that being poisonous is the sort of power that has to be present throughout a process in order for the process’s terminus to be reached.³² (That is, we deny that being poisonous is the sort of power that can start a ‘chain reaction’ through some initial interaction, but can thereafter be absent.) This means that if the poison meets with the right power partners along its temporal timeline, a certain process will unfold, resulting in death. It would then be tempting to say that the manifestation of the power was the process, partly because the process arose from the power’s having met the right partners along the way. But for manifestations to be processes, the right constellation must be some set of powers appropriately synchronically arranged with the target power, such that the full process springs forth—en bloc—from that constellation. If there are many such meetings, then a process will arise, not because any one power has as its manifestation a process, but because processes supervene on ever-so-many meetings and manifestations. The objection to treating manifestations as processes is that this would require that processes come as package deals, and it is clear from Angus’s survival that they do not. This means that there is no hope of salvaging the manifestations-as-processes proposal by appealing to partial or incomplete processes. Not, that is, without making them very brief, but that would move us into the brief manifestations category, and we are considering the long-winded ones. But might something be gained by thinking of processes differently? That is, we are treating the manifestation of poison as death. But what if the power in question was not for that process in toto, but something more mysterious, such as a contribution to the process? For instance, according to Molnar, the manifestation of a single power is a ‘contribution’: many contributions combine to give rise to the processes we observe.³³ This suggestion is not without its merits, but it will not help us here. Treating manifestations as contributions to processes breaks the processes up, but it breaks them along the wrong dimension. Contributions would be abstract parts that combine to form processes, but the cleavages we require are breaks along the temporal dimension. Unless contributions are understood as carving processes temporally, they are of no help. And it is clear that is not how they are understood. Processes are prima facie attractive for our purposes because they are causally structured entities.³⁴ The cleavages are causal cleavages, meaning that a process is a causal chain. A process is thus a series of causes and their products, extended along the temporal dimension. Given that we are operating within the powers ontology, the causal links are the exercising of powers. Hence, processes give way to a structure of powers and their exercising, and so it cannot be that powers have processes as their manifestations. Despite rejecting the proposal, it remains the case that we can, loosely speaking, describe powers as having processes as manifestations. But do not trick yourself into

³² If the target power is not present throughout, then the presence or absence of later powers cannot be relevant to its manifestation. ³³ Molnar (2003: 195). See also Mumford (2009b: 104). This proposal runs afoul of other concerns; see McKitrick (2010) for further discussion. ³⁴ Handfield (2010: 111).

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- 

thinking that manifestations are processes just because it is true that processes are manifest when powers are exercised. Powers are ‘process initiators’, in the sense that their manifestations determine the constellations from which the next manifestation will be produced. Statements about powers giving rise to processes come out true, but not because powers have processes as their manifestations.³⁵ Ceteris paribus, a constellation will favour an end state, many steps down the line.³⁶ But these processes can be interrupted, blocked, or diverted. Knocking over the first domino sets us on a path towards the last, but no power has the whole path as its manifestation.³⁷ We can use this to describe the nature of objects. It would prove useful in science—and more generally for navigating the world—despite failing to pick out the actual powers that do the work. Case in point: dried out hunks of clay are brittle, but what makes this true is not that they have a power of brittleness, but that they have some set of powers that (if allowed to produce their manifestations through sufficiently many iterations without being disturbed) would give rise to a series of constellations and manifestations on which a process like crumbling would supervene.³⁸ Long-winded manifestations 2: Events. What about events? When it comes to finding the right category for manifestations, the events category is the default response: folks often speak of the displays of powers using the language of events. We are told that powers manifest themselves in dissolvings, stretchings, burnings, shatterings, breakings, meltings, and the like. But events come in all shapes and sizes. If they are sufficiently brief, then they belong in the brief group. So, what about the rest? The process category was unfit for manifestations, because the right processes are structured entities. Lengthy events are similarly structured, composed of ever-somany steps, and so they fare no better. Should we be concerned about medium-sized events, those that are neither very long nor very short? Look at the list of examples that makes the events proposal attractive: dissolvings, shatterings, and so on. Every one of the examples belongs to the structured half of the events category. Consider just dissolving: the dissolving of the salt in the hot water is not a one-step event, but rather the product of a series of interactions. We can see that it is structured because it is interruptible: there are cleavages in the event where the later parts can be blocked or prevented. Interruptibility is the hallmark of structure, and all the paradigm examples of events bear it.³⁹ That leaves us with only the brief manifestations. Brief manifestations 1: Events. Treating powers as having short-lived manifestations allows us to say everything we want to about interruption cases, without being forced ³⁵ If those statements concern what processes a given power would give rise to, then they would only be true ceteris paribus. You cannot fix which powers a given power will come into contact with over time (not without a laboratory, anyway). This is another reason to reject the proposal (and is the basic fact that fuels much of the debate over the conditional analysis of power ascriptions). ³⁶ Note that we can best make sense of these ceteris paribus requiring features of processes if we see the processes as sequences of exercising powers. ³⁷ See §10.2. ³⁸ E. J. Lowe (2006: 140) argues that the manifestation of brittleness is ‘essentially a process’. If ‘brittleness’ names a power, then this is strictly false, but it can nevertheless be truly predicated of driedout hunks of clay, in virtue of the powers they do possess. ³⁹ More on interruptibility appears below, and in §9.3.

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into error. We should embrace the fact that the exercising of constellations of powers gives rise to processes (or long events), but not because the manifestation of a power is itself a process, but because manifestations can be lined up, and those are processes. To the extent that my aim was to argue that manifestations must be short-lived, we have come that far. From this point onwards, the task is that of selecting which of the remaining categories best suits the class of manifestations. The reason we should reject the brief manifestations-as-events proposal is not a deep one. On some analyses of events, an event can be very brief indeed. This is not simply a matter of reducing the time involved from that of a soccer match to a sugar cube’s dissolving, but getting right down to events that are near instantaneous. For instance, if an event is a matter of some property being instantiated at a time, or some change in property, then some events can be incredibly brief indeed.⁴⁰ What is wrong with manifestations finding a home here, with events like this? As indicated early on, this is an account we should be happy enough with, and we should treat it as a close runner-up to states of affairs. I nevertheless suggest we pass on it because it has the potential to mislead us. Consider the events category as a whole: some events are structured (in the sense we have been discussing), others are not. The manifestations-as-events proposal is motivated by examples that the brief manifestations cannot live up to. Simply put, paradigm events are structured, but manifestations never are, and so we have a mismatch. The significance of this mismatch can be reduced if manifestations constitute a mere subset of the category of events, but we can only claim this if we are willing to admit events into our ontology that are not causally relevant and that supervene on the genuinely causal events, which we might not all be willing to do. Nonetheless, if there is a mismatch, it makes the manifestations-as-events proposal misleading, and that is reason enough for us to look elsewhere. Brief manifestations 2: Properties. Why not properties then? Mumford describes powers-based causation as the ‘passing around of powers’.⁴¹ Read literally, this would entail that manifestations are properties. A ‘fragile glass manifests itself in breaking, for instance, and the pieces now have a power to cut’, something the pieces previously lacked.⁴² However, virtually every example we have considered, regardless of the category it seemed best suited for, included not only properties in the manifestation, but some property bearer. It is the glass that is shattered, the salt that is in solution, and the rubber band that stretches. We need not deny that the exercising of powers gives rise to properties (further powers), but why think the manifestation ends there, with just the properties? The manifestation of the glass’s fragility does not result in the power to cut simpliciter; it is the pieces of glass that have this property. It would be a serious mistake to treat manifestations as nothing more than properties. This proposal has another unsavoury consequence: treating manifestations as properties cuts objects out of the causal nexus. Whatever you take objects to be, it is hard to deny that their comings and goings are a causal matter. When something comes into ⁴⁰ See Kim (1976) for an analysis of the first sort, and Lombard (1986) for the second. ⁴¹ Mumford (2009b). It is not clear that Mumford endorses the literal reading, appearances to the contrary. ⁴² Mumford (2009b: 98).

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- 

being or ceases to be, it is the result of powers being exercised. (As is their continuing to be, as we will see in Chapter 8.) But unless one is willing to endorse the incredibly unpopular thesis that ‘existence’ names a property, then either there has to be an independent and non-powers-based account of the causal story here, in which case our powers theory is not the whole story, or objects are a part of the manifestations powers produce. Only the latter is reasonable, and therefore we should let the powers do all the work.⁴³ That is what they were built for, and a significant part of why the existence of theoretical entities of this sort were postulated in the first place. Letting them do their jobs means making substances part of manifestations, and that means treating manifestations as something that includes them, such as events or states of affairs. Brief manifestations 3: States of affairs. If manifestations are states of affairs, we get to keep what is attractive (and intuitive) about thinking of them as events or properties, while avoiding the worries that arise from each. We also get a tidy way of capturing our intuitions about causal processes, allowing us to explain them entirely in terms of constellation–manifestation pairs (without inviting the problem of interruptibility). Return to the poison case, and our initially troubling desire to say that the manifestation both did and did not come about. We can now see the manifestation for what it really is, and why it was we were so keen to assert something impossible. The ingestion of the poison is a matter of the power of the poison interacting with a constellation of other powers within the body. That resulted in another state of the body’s constituents, which in turn resulted in another. Many iterations of constellations are followed by yet more constellations. If left alone—if nothing else is added to the constellation—then the series of constellations will eventually give rise to a state of affairs of Angus’s being dead. But the expected sequence of constellation– manifestation pairs is mucked with when the antidote is added. This new reagent adds new powers, thus generating a new (and thus unexpected) constellation in the middle of the process. That constellation has a different sort of manifestation, and shifts the process in a new direction—one that does not lead to death. We are free to see the processes as a whole as supervening on the exercise of powers, and I recommend that we do. But note that no process ever really starts or ends; it is just one little constellation and then the next.⁴⁴ Some sequences of manifestations we track, others we do not. A process we see as derailed is really just an expected sequence that continues in an unexpected direction. No wonder some friends of powers speak as if all powers-based causation is a network of interacting processes.⁴⁵ And now we know how that can be so, by treating manifestations as they ought to be understood. ⁴³ Not even the bundle theorist can avoid this conclusion. A manifestation could not just be properties; it would have to include the compresence relation that binds the properties, too. (Constellations see through objects to the powers they possess, but objects are present regardless, and they must be present in manifestations.) ⁴⁴ More correctly, the sequence of constellation–manifestation pairs never ends. Identity conditions of the supervenient processes mean that they will have starts and ends, but these artificially carve up the actually endless sequence. ⁴⁵ See Mumford and Anjum (2011) and Heil (2012). It also explains why many friends of powers have waged a war against the necessity of powers-based causation. If you took manifestations to be processes, you would often run into interference.

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Of course, this new appreciation of what manifestations are and how processes emerge has something of a minor cost. Recall that we tend to name powers by way of the manifestations they can produce. Though something like this could still hold, it would not line up with our standard ascriptions. Poison (properly understood) can result in death if ingested; not because that is its manifestation, but because it sets up a sequence that leads to death if not mucked with. Hence, most of the powers named for their effects are not named for their manifestations at all, but for states that come at the end of a sequence. That is why it is convenient to have a pragmatic understanding of powers as process initiators (even if this is not strictly correct), because it is useful to track states that obtain when powers are manifested, even if they are not produced directly by those powers. Hence, though it might be a minor cost of any view that treats manifestations as brief that standard ascriptions are rarely identical with genuine power properties, those ascriptions nevertheless remain advantageous for science, because they are born of real powers. I have more to say about manifestations, but that I leave for the next section. I close this section with the following lesson from the poison case: powers do not take time to do their work. They do it as quickly as they can. That is not to require that they do it instantly. It might happen to be instant, but it need not be. It takes exactly as long as is needed, but there is no space for interruption, not even in principle.

6.4 Necessity and Neighbourhoods An important feature of powers-based causation is that powers produce manifestations as a matter of necessity. This is a worldly necessity, not a logical one. That is to say that when a power finds itself in those circumstances that ‘stimulate’ it—more correctly, when a given constellation obtains—it cannot help but produce its manifestation: its effects must occur. It is, thus, impossible that a constellation obtains, but the manifestation which that constellation is for does not then arise. This facet of powers-based causation is not complicated, but it is controversial. Consequently, this section spends more time defending the proposal from objections than it does spelling it out. Can more be said about this necessity? On the typical philosophical understanding of these things, the necessity in question would be metaphysical necessity, but that is not particularly enlightening in this case. On the standard hierarchy, the strongest necessity is logical/mathematical necessity. This is the necessity by which two plus two gives four, and by which all bachelors are men. This has as much to do with the meanings of terms as it does anything else. At the other end is nomic necessity, which is a matter of obeying the laws of nature. This is the weakest of these three forms of necessity. According to it, the pressure of a closed system must co-vary with the temperature, and it is impossible that the system should suddenly turn into a duck. Metaphysical necessity falls somewhere in the middle. It permits the system’s turning into a duck, but not that the system never was a system. Colloquially this type of necessity is analysed as truth in all possible worlds. Hence, to say that constellations produce their manifestations as a matter of metaphysical necessity is to say that every time that constellation type arises (in all worlds that it does), it will produce an instance of the same manifestation type.

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- 

As I say, this is not all that enlightening. For starters, worlds talk is a poor way of unpacking notions within the powers metaphysic. But worse yet, if a power’s blueprint is taken as giving the fundamental laws of nature, then to say that a constellation must produce the manifestation it does is just to say it acts in accord with the laws of nature. This makes it sound like the relevant necessity is nomic necessity. But given that the laws themselves could not differ, it seems to be a metaphysical necessity; the two notions collapse into one. In fact, if one knew everything about a given constellation—the locations of all the properties and their internal blueprints (imagine the Laplacean demon slipped you a crib sheet)—then one could deduce the manifestation that would follow. That sounds rather like logical necessity. So, thinking about necessity in this way does not tell us much more than that the manifestation must follow. But perhaps that is enough. We have some intuitive grip on necessity, and if that helps us understand the force with which constellations produce manifestations, then so be it. The standard interpretations are spelled out using aspects of the neoHumean metaphysic, making them ill-suited for our needs. But it is unclear if there is any benefit to offering a powers-based analysis of necessity, given the bruteness of the constellation–manifestation connection. In the interest of moving forward, understanding the productive force of powers in terms of neo-Humean metaphysical necessity is of some use, even if doing so involves a cross-metaphysic conceptual confusion. It is, at least, an illuminating confusion. Shifting gears a little, one can rarely appeal to necessity in causation without raising worries over real-world probabilities. If the instructions are determinate— that is, for some specific manifestation type—then necessity seems a natural enough fit. But what about indeterminate powers, those whose manifestations are stochastic or probabilistic? It hardly seems like those could be necessitated. Appearances aside, that remains the case.⁴⁶ What is necessitated in stochastic cases is not a single manifestation type, but a prescribed disjunction of manifestation types. What a constellation produces is one within that range. (Those states must be restricted to those that are independent of, or cohere with, those produced by neighbouring states.) We might liken the case to the throwing of a six-sided die. Assume, for the sake of the example, that die throws are stochastic. It is nevertheless necessitated that the throwing will produce one of six outcomes. We thus have a necessitated disjunctive state. Here the proportions of each are equal: the throwing necessitates possible states with a probability of one in six for each. (If you are worried about the die landing on its edge or corner, then up the number of states to twenty-six, but now the probabilities will be just shy of one in six for each of the sides, and infinitesimally small for the edges and corners.) For the most part there has been a working assumption of determinateness. I continue to assume that in what follows. Why think that the connection between constellations and the manifestations they produce is necessary? A not particularly forceful response, but worthy of mention

⁴⁶ Assuming there are powers like this, and that what we take to be stochastic is not in fact an empirically impenetrable set of constellations.

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anyway, is that this is the standard position concerning causation; this is oomph. Most folks (not in the grips of a theory) take the causal relation—as enacted by powers or otherwise—as necessary. That is, they think that if you line up the world a certain way, you get a specific result and no other. This can be seen in their behaviour. If the expected result does not come about, they do not question the causal relation. They instead go looking for what causal factor they might have missed. Is there something involved in the set-up that had gone unnoticed, they ask? And if nothing turns up, they revise what they take that set-up to have as its effect, still employing the same sense of necessity. A better reason is that nothing short of necessity has the oomph required to get us from one state of the world to the next. To see this, imagine something weaker than necessity were to play the same role, such as strong inclination. Strong inclinations— even the strongest of them—do not get you from one state to another. Just ask a procrastinator! As much as one state may be ready, willing, and able to make the move to the next, that alone will not do it. It needs an extra push. But the extra push will not help if it, too, is nothing more than a strong inclination. Piling on strong inclinations can give us a state of incredible readiness and willingness, but it does not get the job done. A room full of like-minded, strongly inclined procrastinators gets us no closer to a result than does just one. What more is needed? A doer. Not a woulddoer, or a wants-to-doer, or a will-doer. A doer. And a doer is something that makes that step come what may. Perhaps inclinations are the wrong sort of substitute for necessity. What about strong tendencies? Well, if this just means that something frequently produces manifestations, then that is beside the point. We need to know how it does it on each occasion that it does: we need the tendency explained. If the answer is that something tends to produce some manifestation because it strives to do so, we are back to inclinations. But what else could it be? At the end of the day, something needs to get us from inactivity to activity, but all the wanting, striving, aiming, and intending in the world cannot help us take that step. It is said that the road to hell is paved with good intentions, but I beg to differ: no amount of intending paves any road. We should think of the necessity in terms of instructions for the actual world. The necessity tells the world in one state to take on the next. It tells the world what orders to execute. But if those instructions are vague, in the sense that they leave room for no response at all, then we leave space for the universe to be cast into impossibility. It simply cannot be that the universe hits a state for which it does not have full instructions for what to do next. The instructions need not be for changes—they could be to leave things just as they are—but they need to be complete, and they need to be exact.⁴⁷ Nothing short of necessity can ensure that the instructions will be fulfilled. And nothing but necessity has the modal force to get us from one state of the world to the next.⁴⁸ Let us turn to the objections. ⁴⁷ More on this point in §7.2. ⁴⁸ Does this make everything necessary? By no means: each transition from constellation to manifestation is necessary, but the sequences that many such constellation–manifestation pairs result in is not, because other powers might get added from elsewhere.

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- 

Mumford and Anjum (M&A) and Schrenk have argued that metaphysical necessity is not up to the task of connecting a power with its manifestations.⁴⁹ Employing the same devices used in rejecting attempts to analyse disposition ascriptions in terms of counterfactual conditionals (finks, masks, antidotes), they argue that any process a power elicits could be frustrated by way of interference or prevention, and thereby blocked. For example, striking a dry match against a rough surface will generally lead to its lighting, but as anyone who has attempted to do this can attest, a strong gust of wind can prevent the match from lighting, despite the striking having taken place. Hence, they argue that even in the presence of its stimulus, the power’s manifestation is not ensured, and so the claim that powers necessarily bring about their manifestations is undermined.⁵⁰ We are asked to consider some power P whose nature it is to produce effect E in circumstances C. Schrenk provides the example of a uranium pile that has the power to chain-react catastrophically when it reaches critical mass; M&A opt for a match that has the power to light when struck. If it were the case, they claim, that powers produce their manifestations (when triggered) as a matter of metaphysical necessity, then we should be ensured of the outcome every time the power finds itself in circumstances C. But a stimulated power might fail to produce its manifestation if some sort of antidote is quickly administered. For instance, the chain reaction is prevented if boron rods are inserted into the uranium pile. The boron rods absorb the radiation, and the catastrophic chain reaction is prevented. Similarly, the match could fail to light if a gust of wind picks up at just the right moment. The argument envisages the scenario as involving a process that leads from one event (the stimulation of the power) to another (the manifestation). It follows that there is some non-zero temporal duration to the process as a whole which runs from time t₀ to some later time t₁. It is this temporal extent that permits the possibility of interference (here an antidote), and that gets exploited in blocking the path to the manifestation. What supposedly drives these counterexamples is the fact that necessity is monotonic. That is, M&A claim that if the connection between the stimulated power and its manifestation is metaphysically necessary, then it must be the case that the manifestation will obtain regardless of what is added to P. Hence, if P necessarily leads to E in C, then just as long as P is in C, E must come about, even if we follow C by immediately administering the antidote. M&A go on to use the monotonicity of necessity to generate the ‘antecedent strengthening test of necessity’: whenever A necessitates B we get a true conditional of the form: if A and φ, then B, regardless of what value φ takes. The test is carried out by inserting different values for φ and assessing its truth (by accessing our intuitions regarding the situation that would make true A and φ and seeing if we think B would result). If not, then A does not necessitate B.

⁴⁹ Schrenk (2010), Mumford and Anjum (2011). Though not identical, Schrenk’s argument against necessity is similar enough to M&A’s that I treat them as one. ⁵⁰ Mumford and Anjum (2011) offer an alternative to necessity in terms of tending: powers do not ensure their effects, they tend towards them. Tending is a new modality.

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Most of the putative counterexamples to necessity that Schrenk and M&A employ involve what I shall call ‘late’ preventers. A late preventer is something that acts after the stimulation occurs—stopping or diverting the process—and thereby prevents the manifestation from coming about. Such is the case with the boron rods in Schrenk’s reactor example: the rods are inserted during the process to prevent the catastrophic outcome. A late preventer exploits the time a power’s process takes—following stimulation—to go through to the completion of the manifestation.⁵¹ By contrast, an early preventer is something which blocks the process at the outset, such as a neutralizer stirred into the poisoned wine before it is drunk, or if poisoned wine is refused by someone who correctly anticipates that it contains poison. However, unlike late preventers, cases of early prevention cannot be used as counterexamples to the necessity thesis. A case would not be a putative counterexample if an early preventer were to prevent the appropriate constellation from obtaining. Recall that the proposed necessity holds between a stimulated power (a constellation) and its manifestation. Thus, the only potential counterexamples to necessity are those in which the constellation obtains but the manifestation for that constellation does not result. No one denies that powers can go unmanifested in a particular circumstance; whether a power gets stimulated is a contingent matter. What is at issue is whether they must necessarily produce their manifestations when appropriately stimulated. Hence, potential preventers can already be in place, but if they are to serve as counterexamples, they cannot prevent the stimulation of the power; they must act later. For instance, the antidote already in the system of the prognostic poison victim stops the poison from killing her by stopping the process the poison initiates once ingested. The case is therefore a legitimate candidate counterexample to necessity. By contrast, if she refuses to drink the poisoned wine, then the case is not a candidate counterexample, because the power was not appropriately stimulated. This point warrants repetition. To count as a stimulation, not only must there be some power P that is the power to E in C, C must obtain, and it must obtain with P as one of its constituents. In terms of cause and effect, genuine counterexamples are those in which we have a cause but no effect. This will prove important to the rescue of necessity. In fact, in order to get clearer about what does and does not count as a counterexample, it is worth pausing for a moment to consider how powers are exercised. This allows us to better appreciate what would count as a genuine counterexample. In light of the discussion of constellations, it ought to be clear that some of the putative counterexamples Schrenk and M&A employ are not counterexamples at all. Consider the striking of a match and its lighting manifestation.⁵² It is claimed that in otherwise optimal lighting conditions, the addition of a factor like a gust of wind would prevent the lighting and thereby undermines the necessity. But striking a match in a gust of wind is not the same as striking a match without a gust present. A gust of wind—really just a simplified way of talking about the movement of everso-many particles—gets counted in a constellation. Or, more correctly, it carries with

⁵¹ Manifestations are not processes, and so this should already raise suspicion. ⁵² Mumford and Anjum (2011: 55).

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it a host of powers that contribute to the constellation. Allowing ourselves the convenience of speaking of the gust and not just its powers, a constellation that includes a gust is simply not the same as one that does not. Adding a gust of wind is adding extra elements to the constellation, and thus there is no guarantee that it will produce the same manifestation as a gust-free constellation would. Therefore, as the circumstances under consideration are not those in which a power is met with the appropriate stimulation, it does not count as a counterexample to necessity. All it shows is that one and the same power can manifest itself in a variety of different ways with different partners. The same goes for any putative counterexample with the same structure. One can see this more generally with the antecedent strengthening test of necessity. We cannot fill in just any value for φ, because most values for φ constitute a replacement of A. The ‘test’, therefore, is largely misleading.⁵³ We should now have an adequate sense of what it takes for a case to constitute a genuine counterexample to the claimed necessity with which a power produces a manifestation. To wit, it must be a case wherein a power helps constitute the appropriate constellation, but it nevertheless fails to be about the manifestation which that constellation is for. That means that the only cases we need to worry about are the late preventers. So, how can late preventers be avoided? Recall from the previous section how thinking of manifestations as processes leads to problems when those processes do not reach their termini. Because manifestations are mistakenly thought of as arising (or arising in full) only at the end of a process, we can envisage something that acts during that process to prevent it from running to completion. However, just as was done above, we can look at any process in a more fine-grained sort of way and see that it is a series of steps. And because it is a series of steps, we can make sense of something—an interferer—that would change the direction of the process, such that the original terminus is not reached. Hence, recognizing that a process is nothing more than a series of constellation– manifestation pairs gets us much closer to necessity. To see how, let us think about these steps in the process more carefully. If the process is such that it can be interfered with or prevented, then it has to be the case that it is interruptible. If it could not be interrupted, no matter what, then nothing could interfere with it (and Schrenk and M&A are without an argument against necessity). Are there powers with uninterruptible manifestations? The powers of micro-entities appear to be, but assume, for the sake of argument, that they are not.⁵⁴ Consider just those powers whose manifestations are putatively interruptible in the sense just outlined. How is it that they can be interrupted? The answer is that they are composed of a series of smaller steps, and that those can be made to do something other than lead to the terminus. And this only makes sense if the interrupter is operating causally on the powers and objects involved. The possibility of interruption—interruptibility—is nothing more than the possibility that the process ⁵³ Moreover, if asked what would happen if you tried to light a match in a gusty breeze, you would happily agree that it would not light. This is necessity at work: the necessity of a non-lighting state for gusty constellations. ⁵⁴ The powers we typically ascribe to the midsized objects certainly do not appear to be, unlike their micro counterparts. Handfield (2008b).

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is diverted. In other words, the process here is a series of much shorter states which are causally connected with one another, like a line of dominoes. Interruption shifts the path of the falling dominoes. Now recall that causation boils down to the exercising of powers. As the steps in the process are causally connected (as is required for them to be interruptible), what we have is not a single constellation whose manifestation is a process, but very many constellations (one after another) whose manifestations are the brief states that make up the larger process. Unlike that larger process, the shorter manifestations are not interruptible, and so avoid the anti-necessitarian worries. Moreover, if they are interruptible, it is again because they are composed of yet smaller steps of causally connected states (constellation–manifestation pairs), and we can continue to break these down until we get uninterruptible manifestations. Hence, once we get down to the level of genuine manifestations (and not the level of the process), they can no longer be mucked with. That is, they are necessary. Thinking of powers this way allows us to evade the objection to necessity, but what should we then say about the typical powers we ascribe to midsized objects that result in much longer processes? The answer is that these powers will not be real powers at all. They will be powers in name only: rough and ready accounts of how things tend to occur in the world. After all, we recognize ‘powers’ of this sort because we see processes of a certain kind unfold. But these processes need not always run to fruition, as we have seen. They are composed of many iterations of constellation– manifestation pairs, and the reason we find the longer processes to be largely reliable models of the world is because if you line things up in the right way, you typically get the outcome you anticipate. Longer processes are like lines of dominoes: if you knock over the first, you will typically see the last topple in due course. Each toppling sets things up for the next; left alone it generally plays out as expected. But because it is made up of ever-so-many steps, you can block the process at any stage by adding to, taking away from, or re-arranging one of the constellations. You cannot prevent constellations from manifesting, but you can manipulate which constellations obtain, and thereby change what manifestation will arise. Manifestations arise as a matter of metaphysical necessity, but the processes that supervene on the sequences of manifestations do not. Once we come to see our common power ascriptions—familiar ones like solubility, fragility, flammability, and so on—as handy and reliable but imperfect ways of gesturing at the real powers at work, we are well on our way to avoiding the sort of concerns that have been raised about necessity. And once we come to see those processes as supervening on sequences of fast acting constellation–manifestation pairs, necessity for manifestations is restored. But one worry remains. In responding to the anti-necessitarian I relied on an important fact of powersbased causation: it is that non-identical constellations of powers have (potentially) non-identical manifestations. In many cases, similar constellations will have similar or type-identical manifestations, but no promise is made that if the constellation differs even slightly, then the outcome will be the same. This is significant in the argument I have presented, as it allows the necessitarian to argue that cases of putative early preventers are not potential counterexamples because they are cases in which exactly similar constellations do not obtain. But what if a constellation were

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to obtain—in toto, and properly arranged—as a proper part of an even larger constellation? Given that these larger constellations constitute additions to the powers in the smaller constellations, the argument has been that this is a new constellation, and so the new constellation determines the manifestation. But just how big are constellations then: is the state of the entire universe at a time a (the?) constellation? The worry is that we have rescued necessity at the cost of locality. Superman tries to lift a large rock; this is a simple task for him, and lift the rock he does. But now take every part of that constellation—in the identical arrangement— and place it in some larger space. Add to that larger space a chunk of kryptonite. We now have a new constellation, and its manifestation is a non-lifting. Both constellations, as presented, ought to produce their manifestations necessarily. But given that the first is embedded in the second, we can only maintain the necessity if we also adopt a principle to the effect that larger constellations trump smaller ones. So far, so good. Bigger constellations trump smaller ones that are proper parts of them, and necessity is maintained. But now we might start to wonder just how big constellations have to be. Imagine, for instance, that the kryptonite is eight metres to Superman’s left. On the assumption that kryptonite counters Superman’s super strength at that distance, then the constellation must be big enough to include both. Now further imagine that there is a substance that counters the kryptonite (anti-kryptonite), and that a chunk of anti-kryptonite is eight metres to the left of the kryptonite. Surely the active constellation includes it, too, and so we get bigger again. The manifestation of this constellation is a lifting, and though this manifestation matches the first, we cannot merely revert to the first, as the kryptonite and anti-kryptonite are important constituents of the constellation. I think we can see where this is headed. Worse yet, even if there is no kryptonite present, had it been present, it would have resulted in a distinct constellation and a distinct manifestation. Hence, even in the first case, the area that the constellation covers is extremely large, even if it is not otherwise occupied. Schrenk and M&A both anticipate—and ultimately reject—what might be achieved by increasing the size of the stimulus (constellation) in this way. M&A call this the ‘∑-strategy’.⁵⁵ The general idea is that one might be able get around the problems that the possibility of prevention produces by adding more and more to the stimulus (constellation) so that it includes remote factors, and even negative factors, like the absence of a potential interferer. We pack all of this into the super-structure that is ∑, and then ask if that would necessitate its manifestation. Unsurprisingly, M&A claim it would not. They raise four objections to this strategy. They are that: (1) one cannot legitimately appeal to negative factors as causes, however complex ∑ might be; (2) it would be most unlikely that constellations like ∑ could ever recur; (3) even if ∑ packs in a huge amount, there is still the possibility that something outside it serves as a preventer; and (4) insulating ∑ from further preventers can only be done artificially by fiat, and thus is question-begging. We have already seen that the first objection is a non-starter. The negative space of a constellation is as much a part of the constellation as are the positive parts. The

⁵⁵ Mumford and Anjum (2011): 64. Schrenk’s ‘hyper mosaics’ are much the same (2010: 733).

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negative factors are not causes—only the powers in the constellations produce anything—but negative space is key to constellation identity.⁵⁶ The second objection is similarly toothless: that identical constellations are unlikely to recur (if that is in fact the case) is not the most desirable position to be in epistemically, but it is no threat to necessity. But even epistemically it is far from troubling: nothing prevents similar enough constellations from producing similar enough manifestations, and that is sufficient for scientific knowledge. That leaves us pinched between the third and fourth objections. We can meet the third by making the constellation all-inclusive, but doing so runs afoul of our intuition that causation is a (largely) local affair. We can push back by trying to restrict the size of constellations, but the threat of artificiality looms large. Is there a balance to be found? Let us call the region that determines a constellation its ‘neighbourhood’. The task then is to determine just how big neighbourhoods must be—or if you prefer, just how small we can get them—without compromising necessity. First off, note that our intuitions regarding the locality of causes (the size of neighbourhoods) are not nearly as restrictive as we initially take them to be. Though on the one hand we take causes to be quite local (for instance, my typing on a computer involves just me and the computer), we are nevertheless perfectly willing to accept that outside factors impact the outcome (consider that same typing, with a giant electromagnet not too far away). This is not intolerably non-local, but it shows that our intuitions regarding causal spheres of influence are naturally large. Secondly, though I employ science-fiction examples for illustrative purposes (like kryptonite), the powers ontology and the account of powers-based causation are intended as a model of this world. We think of neighbourhoods as quite restricted because that is how they seem to be. Why not assume, then, that it is not the nature of power properties to act over large distances? This is an account of natural properties: if the natural properties of our world have specific spheres of influence, then these spheres and the spaces between them are what determine neighbourhoods. This might sound ad hoc, but we ought to be guided by the world in these cases. Philosophically this is hard to establish—no principle presents itself—but it appears to be what is at work in the world. It is a pragmatic approach. (Notice how naturally we assumed in the above examples that the electromagnet was ‘not too far away’ and that the kryptonite was effective ‘at that distance’.) Being guided by the world may give us locality, but then again it may not—and this is something we ought to be fine with. If quantum entanglement (the instantaneous influence of particles on one another over large distances) turns out to be as described, then perhaps we were wrong to have ever thought that causation is a local matter. We are happy to allow that massive bodies exact causal influence over huge distances—this might all be done via the powers of intermediary particles, gravitons, forces, or chunks of spacetime, acting locally—but then again it might not. Would it be so strange to learn that powers at vast distances were in fact part of what ⁵⁶ We can speak as if these lacks and absences make causal contributions, but at the end of the day these are mere façons de parler. It was not the absence of the boron rods that caused the uranium pile to chainreact catastrophically when it reached critical mass, but the powers of the radium atoms. See §6.5.

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we took to be quite local interactions, especially if these distant powers made only infinitesimally small differences to the sort of manifestations that result? We tend to think of tiny pockets of the world as causally isolated from the rest, but nevertheless allow that the right sort of power—however distant—could still influence the outcomes of that pocket. If we think of neighbourhoods as being vast, but treat most powers within them as rarely resulting in distinct (or much distinct) manifestations, we could harmlessly capture this intuition. Perhaps our localized thinking was mistaken all along. We screen off parts of the world and test them in the laboratory, conducting experiments that are slightly artificial in this regard, but we have now come to see the artificial as the norm. We take our screening-off to be a real screening-off in the world—we interpret these tiny portions of the world as primary, making larger portions artificial. And though we might be right, we might just as well be mistaken. The fact is, our intuitions about locality are pretty meagre, and could easily be mistaken. Right or wrong, we can get neighbourhoods of interacting powers that would fit the bill—however big the bill— and preserve necessity. If it should turn out that our sense of locality is off the mark, and neighbourhoods are truly expansive, then as long as distant powers make little difference to local affairs, we could still make use of local-like interactions, through talk of quasineighbourhoods and quasi-constellations. Just as processes supervene on genuine powers-based causation, and are not themselves necessary, quasi-constellations would be subsets of genuine constellations that are largely stable and traceable, and thus amenable to science, despite lacking the necessity of the genuine constellations. Distant powers might be included, but if they tend not to be difference-makers with respect to the manifestations that result, ignoring them would be harmless. But large or small, the neighbourhoods will be determined by the true nature of powers—and so the worry about locality is not nearly as troubling as it first seemed.

6.5 Absences and Transitivity I started the chapter by saying that causation by absence and transitivity belong to our folk concept of causation, and are no part of the powers-based account. But rather than just writing them off, powers-based causation is all the stronger for explaining how causation by absence and transitivity can be understood by an account that nevertheless omits them. This section is thus a translation manual of sorts, at least as far as those two features of our folk concept(s) are concerned. It is common for us to speak as if an absence—a lack of something, or something’s not being present—can itself be a cause. We say, for instance, that the lack of water caused the plant to die. On the powers-based account of causation, absences cannot be causes, properly speaking, because an absence of a causal power is not itself a power. Only powers can be causally active. But that is not to claim that absences cannot be difference-makers, nor is it to claim that absences cannot be causally relevant. However, unlike powers, their causal relevance is not born of their doing anything: nothings cannot do anything, causal or otherwise. So, is there real causation by absence? Nothing doing. The supposed causal roles of absences are entirely parasitic on actions of the powers. In fact, their folk-causal relevance is an epistemic

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matter: the absences are explanatorily relevant (meaning that they are apt to appear in explanations), but the folk tend to lump these in together. Hence, it is because absences can be causally relevant in this way that we are prone to thinking—albeit mistakenly—that absences can be causes. So, how can absences be causally (explanatorily) relevant? The answer comes from contrasting the manifestations that arise when the constellations are altered with those that would have otherwise arisen.⁵⁷ We have already seen how different constellations can give rise to different manifestations. Consider a case where a change in constellation would have this result. For instance, if we assume that, to live, a plant needs water, sunlight, soil, and nutrients, we can imagine some set of constellations of the relevant powers that will result in a healthy plant. For simplicity, I will treat the water and so on as if they are themselves powers. Now, compare what happens when all those powers are present (and properly arranged) with what happens when they are not. If we have water, sunlight, soil, nutrients, and a plant, the plant lives. But a constellation without water results in the plant’s death. More correctly, it results in a less healthy plant, but in so doing it initiates a process that terminates in the plant’s death. Now compare the two constellations and their manifestations and ask what difference the water makes. Pretty clearly if the water is present, you get a lifeproducing constellation and a ‘lifey’ manifestation. If the water is absent, you get an unhealthy-producing constellation and an unhealthy state of the plant. Just considering those two options, you can toggle back and forth and see that the presence of water makes a difference, as does its absence. The absence of water is a differencemaker because it results in a different constellation for a different manifestation. And this is how—and why—absences are causally relevant. Absences speak to constellation identity—they are relevant to what constellations arise—and so are capable of difference-making without doing anything at all. Of course, not all absences in all cases will be difference-makers. Removing a power necessarily results in a different constellation, but not all differences in constellation mean a difference in manifestation. For example, the presence or absence of a garden gnome beside the plant in our example will not change the manifestation. (Unless we are all horribly mistaken about the causal powers of garden gnomes.) That is not to suggest that cute garden statues lack powers, nor that those powers are not part of the constellation. They are, but the powers are not differencemakers in this scenario, and therefore are not causally relevant. That covers causation by absence. What about transitivity? We often think of causation as being transitive: when a causes b, and b causes c, we say that a is thereby a cause of c. When we set a Rube Goldberg machine in motion, that initiation is the cause of the first action, and each subsequent one, right through to the end. But powers-based causation is not transitive. If constellation c₁ gives rise to manifestation m₁, then the powers that make up m₁ (perhaps with other powers, but maybe not) will comprise c₂, and c₂ will give rise to m₂.⁵⁸ But it is not the case that c₁ is the cause of m₂, because m₂ is not c₁’s manifestation. Hence, we do not have ⁵⁷ For a discussion of absences in powers-based causation as applied to diseases, see Williams (2007). ⁵⁸ There is nothing wrong with c₁ being type-identical with c₂, and m₁ being type-identical with m₂, but assume the present case is not like this. I discuss the type-identical case in §7.3.

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transitivity. What we need to translate that feature of our folk picture into powersbased causation builds on the discussion of processes. Powers-based causation is not transitive, but it has the next best thing. Actually, it may have something even better: sequences of constellation–manifestation pairs. These sequences give us anything we could want out of transitivity. If a certain constellation obtains, then through its manifestation it sets up the world in such a way that specific types of later states become more probable. We can thus appeal to early constellations in explaining why much later states obtain, by pointing to the steps that lead from one to the other. No constellation is directly causally connected to any state but that which it produces, but constellation–manifestation steps can take us much further downstream. Hence, the powers-based model of causation has no problem capturing what lies at the heart of transitivity. But it can do better, too. Think about the connection between early constellations and late manifestations. Many of the objections to necessity seek to exploit the temporal gap between them when arguing that the latter need not follow from the former. And they are correct. They are mistaken when they claim that constellations do not produce manifestations as a matter of necessity; but they are correct to the extent that processes can be mucked with. The traditional model disguises this fact by allowing the causal relation to bypass the intermediaries. According to it, a is not merely connected to c via b, a is a cause of c, just as it is a cause of b. Hence, a is a cause of both b and c. And even if we never have any doubts about a’s necessarily producing b, doubts creep in when we ask if a must necessarily cause c (and things only get worse with d, and e, and f ). This is the price of transitivity. The sequencing of powers-based causation should thus be preferred to transitivity for letting us look down the causal line without allowing us to jump the line. We get to have our cake and eat it, too. There are other ways that the concept of causation, as understood by the folk, differs from what is defended here. By now you know enough about powers-based causation to see how many of those features are epistemic abstractions from the core of powers-based cases, and so there is no need to labour the point. This brings to an end the discussion of the standard cases of powers-based causation. Next up is more causation, but now things are going to get a bit weird.

7 Causal Oddities 7.1 The Causal Sideshow The previous chapter presented the basic model of powers-based causation. The sense in which it is basic does not concern its simplicity, but the types of situation it covers. It is the model of how powers are exercised in common causal scenarios, wherein a number of objects produce a change in the world. The current chapter discusses the features of powers-based causation in unusual causal scenarios, those that are outside the mainstream discussions of causation. The standard literature is rife with billiard balls striking one another, houses with broken sprinklers burning down, baseballs smashing windows, and dozens upon dozens of expert rock throwers engaged in acts of vandalism. These cases are interactive, they are dynamic, and they are change-producing. But if that was the main attraction, then we are now on to the sideshow, complete with all sorts of causal freaks, curios, and oddities. Proceed with caution! The unusual kinds of causal scenarios are not designed to be exhaustive: there might well be others that have been overlooked. Perhaps they will join the troupe and feature in the causal sideshow in the future. The ones included here have stolen the spotlight because of what they add to the picture of powers-based causation, and because they provide a backdrop for what follows. I also make no claim to the effect that these cases are completely distinct; nothing prevents these cases from overlapping with the others. So, what are these unusual cases? The causal sideshow consists of five grotesque acts. First of all, we have eerie cases of causation in which the effect is not a change. Sometimes—perhaps often—powers give rise to states of the world that do not differ from how things were beforehand. Why do we need powers to keep things as they are? The answer, it turns out, is that it takes a lot of effort to maintain the status quo. Keeping things as they are is a matter of spooky powers producing static manifestations. The second act follows quick on the heels of the first. Imagine powers so strange that they are identical with their effects. Not even the Siamese twins can riddle out how these powers can be both cause and effect, yet these powers force us to reconsider what is possible as they give rise to none other than themselves! The third aberration involves causation in which there are no circumstances that stimulate the production of the effect. Stare in wonder as manifestations are produced without stimulation! Stimuli are nothing more than other powers that jointly constitute constellations (§6.2), but what happens when those other powers go missing, and yet we still get manifestations? Maybe in some of these ‘stimulus-free’ The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

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scenarios we have simply overlooked the stimulation, but in other cases there is nothing to be found. Beware! The fourth weirdo case concerns the number of objects involved in the production of a manifestation. Gaze in astonishment as a lonely object brings about states of the world unassisted! Sometimes—perhaps quite often—cases of causation are restricted to a single particular. This could be some or all of the properties of an object working with one another, or it could be single properties within an object acting alone. This is the wonder of immanent causation. Lastly, the fifth deviant case arises when effects bizarrely take place at the very same time as the causes that produce them. This is the freakish phenomenon of simultaneous causation, and like the other four acts, it is a wonder to behold.¹ So roll up, roll up, one and all, and enjoy the show!

7.2 Static Manifestations There is a strong belief that difference-production is a necessary condition of causation. That is, it is standardly held (or assumed) that change or changes must obtain if causation takes place. Here is Lewis, presumably speaking for us all: ‘We think of a cause as something that makes a difference, and the difference it makes must be a difference from what would have happened without it.’² We likely ought to agree that if a cause makes a difference, then it must be a difference from what would have been the case had the cause not acted. But must it be that all causes bring about differences in the world? I suggest they do not. Let us agree to understand a change as follows: Change: a change has taken place just in case for any object x and property F, x is F at time t₁, but it is not the case that x is F at some distinct time t₂, where t₂ is earlier or later than t₁.³

This principle is intended to apply to the loss or gain of intrinsic properties (the most direct changes), but extends to mere Cambridge changes, too (purely relational and thus indirect changes, such as one’s becoming an uncle when a sibling has a child). Though the latter are not typically the sorts of changes we take causes to produce directly, they are nevertheless changes that obtain in virtue of other directly caused changes, and we want to be as charitable as possible to the claim that change is a necessary product of causation.⁴ To claim that change is a necessary condition of causation is to require that a change must obtain if causation is to have taken place. For clarity’s sake, note that it does not follow from the principle that all changes are the result of causation. That is a perfectly reasonable claim—and one that I endorse—but not currently at issue. Thus, the point considered here is not that for every change there is cause, but the reverse. That is the principle that should be rejected. I said (facetiously) that Lewis speaks for us all. Obviously that is not the case, but there is no denying that the principle is commonly held. I shall argue that the ¹ Spoiler alert: the final act is a hoax. ² Lewis (1973a: 557). ³ Geach (1969). ⁴ That said, pace McTaggart (1908), because the definition requires a property change, temporal difference alone will not count as a change.

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principle has no place in the powers metaphysic. As a realist about causation, I think it has no place in causation simpliciter, but the neo-Humean’s understanding of causation differs so much from that of the powers theorist that we should leave room for those who want to build their accounts around the principle (or have it as central to one such understanding, should they be pluralists). First, I seek to undermine the commonly held intuition that causation requires change. I do that by considering three reasons why we hold this to be true, and find them all wanting. That should help to dislodge our intuitions. Second, I attempt to show that a powers-based causation, wherein some powers have manifestations that are not changes, is desirable. Here are three reasons why we might believe that causation requires change. (1) This is an essential part of how we understand causation—it is a central aspect of our concept. (2) Causation is a relation between events, and events are changes; therefore causation must produce changes. (3) Something about our engagement with the world—either for survival or knowledge—demands manipulation and mastery of the world, and this tracks change. I deny that the three reasons stand up to scrutiny. There might be different reasons why we have this belief about causation, but if they resemble these three, then I should have done enough to demonstrate that our intuitions are misguided. Let us start with (1), the claim that we understand causation as requiring change. Talk of a single causal concept is problematic, but assume, for argument’s sake, that we can get past that. We can see that (1) is false by considering a very well-balanced tug of war. The team on the left is matched pound for pound with the team on the right, and for a long stretch of the competition the flag in the middle remains unmoved, despite the effort of both teams. This non-change in the position of the flag is produced by the causal work done by the two teams. The rope is not accidentally stationary, nor is there any lack of effort on the part of either team to pull the rope in their direction. It just so happens that the force exerted by the one team is perfectly matched by the force exerted by the other. The scenario counts as causal, because there are significant forces being exerted by both teams, but no change is produced. The same result can be achieved by any balance of forces: my computer is attracted to the floor beneath it, but the table keeps it in place. A local tug of war takes place, but without eliciting any change. Virtually any example of so-called ‘simultaneous’ causation can be offered as a counterexample to the claim that causation requires change.⁵ For instance, two playing cards leaned against one another are the cause of each other’s continued standing, as a result of their being appropriately powered to do so. Simplifying things slightly, their leaning against one another is the cause of their continued leaning against one another. Likewise for the book resting on the table, and the stable bridge under heavy traffic. The tugging of the teams causes the flag to remain stable. The leaning of the cards each causes the other to be stood. The solidity of the table causes the book to remain motionless. All are common instances of causation, and none of

⁵ So called because it is not really simultaneous. See §7.6 below.

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them involve change. If the belief that causation requires change has any basis at all, it is not because it is central to our concept. Like the tug-of-war flag, some folks will remain unmoved, despite the obvious force to do so. They will claim that these are not causal scenarios, citing the lack of change as their evidence. But this stubbornness is unfounded. The forces of the tugof-war are present throughout. If they are balanced for only brief moments in an otherwise back-and-forth match, should we say that there were many causes interspersed by non-causal instants, even though the very same forces that account for the causes are present at all times? Surely not. And are we forced to say that the forces that hold molecules together are not causing this? Again, this is mistaken. Others might object that one person’s changeless tug of war is another person’s flurry of lower-level changes. That is, one might insist that the genuine causes here are at a lower level, and that those all involve changes. But do they? And can this strategy always be relied on? Granted, a human tug of war is grounded in microchanges, even if the result is a tie. And we should agree that those micro-changes are caused. But once we get all the way down, who says that fundamental tugs of war cannot also result in stalemate? There should be no barrier to two fundamental entities holding one another in place just like playing cards do. (Not to mention what a lonely particle can do.) But even if the science tells us otherwise, the point here is that our concept does not demand that it be so. And that is what is at issue in reason (1). Reason (2) is based on two contentious claims: that the causal relata are events, and that all events are changes. Some accounts of causation understand causation as a relation between events, and so agree with the first claim, but just as many do not. The powers-based account on offer here is amenable to an event-based description, but states of affairs are preferred. Other candidates for the causal relata include facts, properties, objects, aspects, features, and situations. Under none of these other accounts would it follow that causation requires change on the grounds that events are changes. There are, then, many ways to undermine the second reason, based on the causal relata alone. Even if you think that causal relata belong to the events category, there is still no requirement that effects must be changes. On one popular analysis of events, an event is a change.⁶ But there are equally good, and equally popular, analyses, where this is not so.⁷ We should not—of course—care about what is popular, whether it helps our case or not. The real question is whether we ought to believe that events are changes. Is there any good—and independent—reason for thinking that they must be? It would not seem so. Even if many events involve changes, must all? I lack the space to enter into that debate here, but it should suffice to note that it is an open question.⁸ Casati and Varzi argue that the question of whether events must involve changes is purely stipulative, and thus lacking in metaphysical import, and so perhaps the ⁶ Lombard (1986). Lombard asserts this without argument. ⁷ Kim (1973, 1976) treats events as the instantiation of a property at a time, Quine (1985) takes them to be the material contents of four-dimensional regions of spacetime, and Lewis (1986c) classes of regions, just to name a few. ⁸ See Steward (1997) and Simons (2003).

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question is not even all that significant.⁹ I am unable to fully close the door on (2), but keep in mind that endorsing the principle that causation requires change this way requires a very specific view regarding causal relata, and a similarly restricted view about the nature of events. Moreover, even if our concept of causation is one that relates events, and even if our concept of events is that they are changes, this alone has very little force beyond teasing out our use of a narrow concept. We can just as easily reply that there are neighbouring concepts of causation* and event* which do not carry those features. And causation* will be incredibly similar to causation; so much so that there would be little reason to hang on to the latter concept. We have wandered too far into conceptual analysis. That was a necessary evil of considering why we might have thought that change was required for causation, but now we can step away. Even if change is part of our standard concept, that does not mean that real causation in the world is likewise restricted. We should not let conceptual analysis push us around, especially if it is mistaken! Lastly, there is no denying that we track changes in the world, nor that changes are epistemically perspicuous, as is claimed in (3). Further, it seems reasonable to think that change-tracking benefits us as a species. Tracking changes is important, and continues to be important in our learning about the world. But how we might learn about the world, and what we might more naturally pick up on about the world as we navigate it, do not dictate the nature of causation. For all we know, we might only be getting half the causal story. Ignoring the unchanging status quo while remaining alert to changes seems a much better cognitive survival strategy than the reverse, but in no way does it dictate that the status quo cannot itself be caused. Whatever the reason we came to think that causation requires change, that is a belief we should now be prepared to give up. If our causal concept has been developed on the basis of misleading intuitions, then so much the worse for our concept; it makes the possibility of realism about that sort of causation all the more remote. But we are interested in real causes in the world, and so it is time to get past these common beliefs and intuitions. Perhaps there is some better reason that we have come to hold this belief about causation. I contend that the bias in the literature towards treating causation as essentially change-producing lacks a substantive philosophical motivation, and so there is no point labouring the issue. It will thus serve us better to shift from attacks on the possible foundation of the principle to what causation would look like if the principle were rejected. Consider the interactions of two qualitatively identical particles. Among the powers of each will be many powers whose manifestations are for states that differ substantially from the constellations that produce them. That is, the particles will have lots of powers that can produce changes, or what we can call ‘dynamic’ manifestations. There are bound to be many constellations into which these two particles can enter, and perhaps for quite different sorts of manifestations. For simplicity, let us stipulate that most of those dynamic manifestations will involve the particles repelling one another.

⁹ Casati and Varzi (2008).

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Now ask: what happens when the particles find themselves arranged such that they do not repel one another? Do not say ‘nothing’, because nothing would mean that there were no particles at all, or anything else. That is surely not what would result. (Though if it did, it, too, would be a dynamic manifestation—that of both particles ceasing to exist.) A better answer is ‘more of the same’, or ‘as you were’. But this instruction—boring as it may be—is nevertheless an instruction for what to do in those circumstances. It is the recognition that, for some range of constellations, the manifestation that is produced is a state that is qualitatively identical to that which preceded it. To ‘remain as you were’ is to respond positively to the command; it is not a change, but nor is it uncaused or insignificant. Powers embody an infinite set of commands or instructions for what actions the bearer must carry out under those conditions. (If this sounds fantastical, note that much of it will involve type identities.) This is a fully interrelated system, such that every power has instructions for what it will do in any constellation. Some of those constellations will be for changes, but many will not. Failing to include instructions for what to do when changes are not the outcome is equivalent to a blank region in the list of instructions. It is a failure to account for all possible situations in which the powers might be found, and it is therefore intolerable.¹⁰ Unless our causal model is intolerably gappy, we need causal scenarios in which the output is the status quo. For convenience, let us call the non-change manifestations ‘static’ manifestations, in contrast with the ‘dynamic’ manifestations that are, or include, changes. In the previous chapter, I gave an account of causation in terms of powers and their manifestations, assuming that a theory of causation ought to explain the mechanism of change. But I believe that it is also the job of a theory of causation to explain nonchange. Fortunately, the account of powers-based causation can be extended to include the production of static manifestations, too. Returning to our two particles, having a complete causal system for them requires instructions for dynamic manifestations like repelling, but also for static manifestations that leave things as they were.¹¹ Without static manifestations and the powers to produce them, our particles have incomplete sets of instructions. Consider an analogy: we can imagine a situation in which a golf pro gives a set of instructions to someone golfing for their first time, explaining which clubs to use for a particular hole. The golf pro tells the neophyte golfer: ‘At the tee box use the driver, on the fairway use a 7-iron, and on the green use the putter.’ To this the golf pro adds

¹⁰ This situation might be likened to that of a computer program, where a highly specific set of instructions dictates what output the machine should produce for each input. For many of those inputs, the machine will have no difference in output, and this should be understood as the machine acting in compliance with the program. In the case of a computer, the ‘stay the same’ output may not require a specific line of coding telling it to do nothing for that input—but this is only because computers are constructed so that they ‘stay the same’ unless some other output is triggered. This is no different than the default setting I discuss below. ¹¹ It is not enough to reply that this region is merely indeterminate—for indeterminate instructions are still instructions. It might be the case that some powers are probabilistic, but this would still require that each constellation has a prescribed manifestation, even if that manifestation is a range of states. The exact manifestation is thus not determined, and so is indeterministic in this sense, but the constellation cannot be one for which there is no instruction at all.

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that the pitching wedge can be used if the ball is near the green but not quite on it, or if the ball ends up in the rough. Then, while playing the hole, the student finds her ball has fallen into a sand trap. Which club should she use? If the golf pro fails to tell her which club to use if her ball lands in the sand, then the golf pro has not really done her job. The instructions she has given are incomplete: they are insufficient for covering all eventualities that could arise when the student attempts to play the hole. It does not take much to imagine an incomplete golf lesson, but can we imagine that the instructions that govern causal interaction should be similarly incomplete? And even if we can, do we really think the universe is built that way? Again, we ought to say no. Assuming that the causal network cannot include instructionless regions, then our particles must have instructions for what to do when not repelling one another. If carrying out these instructions does not require a change, then we have static manifestations. At this point some readers might happily admit that the universe should come complete with a full set of instructions, but still doubt that anything like static manifestations are needed to fill up the gaps. Instead, they might prefer to think that the stability is just the result of a default setting for the universe, such that if no action is put in, or no power is manifested, then everything just remains the same. On this view, existence and stability are just part of the default setting; the exercising of powers would always produce change. On the face of it, this default view looks like an alternative to that on which there are causes for non-changes. However, closer inspection shows that this purported alternative is nothing more than a law-based version of the powers-based account. The constellations that produce static manifestations have merely been replaced by a physical law description. That law is expressed as if it is somehow prior to any other causal structure that might be at work within the world, as if it were more fundamental as a background condition, or a precondition on the very construction of a world. However, without an explicit statement that things within a world will stay the same when not under the influence of other laws, there is no reason that they must stay the same, and no reason that they will. Once that is understood, it is clear that this default setting is nothing more or less than an overarching physical law that ensures the stability of the universe when not undergoing change—and is something that would have to be differently accounted for within the powers metaphysic. This will clearly differ from what a law-toting neo-Humean might provide as far as her response, but as much as we are concerned with accounting for non-change, and doing so causally, the two are in agreement. Though it may look like the default setting constitutes a denial of non-change causes, it is in fact just more of the same. I have been arguing for static manifestations on the basis of admittedly abstract cases, involving general inactivity and the continued existence of objects. But there are homier cases, too. Consider properties like shape or hardness, or many of what have historically been called an object’s ‘primary qualities’. For properties like shape, there is a continuum regarding an object’s power to stay that shape. At one extreme we have objects whose powers are such that under no conditions can they maintain their shape. At the other extreme we find objects so strongly powered for the maintenance of their particular shape that there are few circumstances under

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which that shape could be lost. The difference is that which we find between a balloon and a bowling ball. A child’s balloon is such that numerous constellations result in a change in its shape. Poke a balloon with your finger and the shape changes. Bowling balls, on the other hand, are much more resistant to change. For a wide range of constellations, a bowling ball will keep its current shape. (Good thing, too; a bowling ball that could not keep its shape would be useless!) These cases—these nonchanges—are perfectly common. And once we start to appreciate the work that goes into the status quo, we are that much closer to powers with static manifestations. Now consider the structural stability of a water molecule. These molecules are hugely important to life as we know it: without their structural stability, there is no saying what life would be like.¹² The structural form of water molecules is due to electrostatic attraction between the hydrogen and oxygen atoms. Structural form is essential to the nature of these molecules. Now ask, do we honestly think that the structural stability of water molecules is a product of chance, or worse yet, of blind luck? Part of what it takes to count as having a structure is to have mechanisms in place for the maintenance of that structure (in many, though clearly not all, circumstances). The mechanism boils down to the work of the powers: the electrostatic attractions are powers that produce—and maintain—the structure. Just like the stability of bridges, maintaining molecular structure comes down to the powers of the component parts. They can be broken apart—a dynamic manifestation—but a picture according to which they are previously idle misunderstands structure and electrostatic attraction. If your aim is to master the world around you, then change and manipulation might be all you need care about. But they are not all that is. And it is the task of the metaphysician to explain what is: how it came to be, how it continues to be, how it evolves, and the like. Change is part of that package, but it is not the whole package. And though many a metaphysician might limit their focus to just that of explaining change, this no more makes the problem of explaining non-change go away than ignoring social injustice makes it go away. The status quo is part of what exists, and thus it is a proper topic of concern for the metaphysician, and so it warrants explanation. But does it warrant a causal explanation? My claim is that the explanation of change accounts for non-change, too, and therefore we ought to explain the status quo causally. Of course, it does not follow from the need to explain non-change that all change and non-change phenomena must be captured under a unified theory, but a democratic treatment of the phenomena will have (at least) that parsimony as an advantage over the alternatives. A single causal model that can handle change alongside non-change is attractive for reasons of simplicity, elegance, and parsimony. Like the scientist, the metaphysician wants to explain as much as she can with as little theory as possible. Those who are not attracted to my powers-based account of non-change are thus free to propose another explanation, just as long as they actually do. That is not to claim that the facts of non-change cannot be brute, but if one adopts a brutal theory of non-change, one has to pay the cost of doing so. Any theory

¹² Or anything else, for that matter.

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will have its primitives—those parts of the theory, or features of the ontology, that are incapable of further unpacking—but when and where one does so affects the attractiveness of one’s ontology and one’s metaphysic. If a metaphysician wants brutality, so be it, but recognize that this is a substantive response to a substantive question. A brute account is still an account. I happen to think we can do better than brutality, and thus a fully integrated causal model is attractive. I think the case against the principle we started out with has been satisfactorily made: causes can have non-changes as their effects. This should be accepted as a basic datum of causal phenomenon, and needs to be recognized whatever one’s preferred ontology and causal metaphysic happens to be. Hopefully I have convinced you of at least this much. But it is possible I have yet to convince you that powers-based causation can satisfy this desideratum. After all, if there are static manifestations, then there are constellations that have as manifestations states that are qualitatively identical to those that would produce them. And you might be sceptical that this can be the case. The next act deals with this worry.

7.3 Powers as Identical to Their Manifestations If we have effects that are non-changes, then we are going to have causes that are identical to their effects. It might well be objected that powers cannot be like this. For instance, E. J. Lowe claims that a power, P, is never identical with its manifestation-type, M. This is obviously true of token powers, since types cannot be identical with tokens. But it is also true of power-types. Clearly, even though a power can be a power to acquire another power, a power cannot be a power to acquire itself: it cannot be its own manifestation-type.¹³

We might capture the general claim that powers cannot be identical to their manifestations as follows: [PP]A power P cannot have as its manifestation the power P.

Lowe obviously thinks that PP is not just plausible, but true. I respond below, but let us first note that, taken at face value, PP indicates that powers have as their manifestations properties, and I have argued that this is the wrong ontological category for manifestations (Chapter 6). Powers are constituents of manifestations, and though they are perhaps the most salient constituent of them, they are not manifestations unto themselves. Manifestations are the havings of properties; they are states of affairs. Hence, on the face-value reading, PP comes out as true, due to its mistaken understanding of the nature of manifestations. But it is clear that there is more to the spirit of this objection than a vacuous truth based on a confusion, and thus it warrants a more careful response. (For convenience I will follow PP in speaking of the power P as if it were the manifestation and not just part of it, but the correction should be assumed.)

¹³ Lowe (2010: 12).

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As Lowe indicates, PP is ambiguous between type and token readings. As no token power can be strictly identical to a power-type, we can dismiss any version of PP that would fill in the first occurrence of P with a token power, and the second with a power-type. That leaves us with two types of disambiguation of PP: those that are token-token, and those that are type-type. Here is one of the token-token disambiguations: PP1 Token-Token: a token instance of a power P₁, instantiated by object a at time t₁ and at location l₁, cannot have as its manifestation the existence of that same token instance P₁ by a at t₁ and l₁.

Here the sense of identity is a strict one. PP1 claims that no power token can have as its manifestation the exact power token that it itself is. PP1 is true, and for an obvious reason: PP1 is nothing more than a corollary of the strict claim that nothing is the cause of itself. No token power can be such that it is strictly the cause of itself (because nothing is), and hence it cannot be the case that a token power has itself as its potential manifestation, and so we should have no problem joining Lowe in accepting the truth of PP1. But PP1 is only one reading of PP. Dropping the problematic part of PP1—that which restricts the manifestation to the identical token—would allow for a more sensible manifestation of the power. No token power can be strictly identical to a power type, so we cannot have a token-type version of PP. But any token instance of a power can be identical to another instance of that same power-type when both are instances of the same power-type. That is, two token powers can be type-identical. Hence, we get: PP2 Token-Token: a token instance of a power P₁, instantiated by object a at time t₁ at location l₁, cannot have as its manifestation the existence of some token instance P₂ (where P₁ is typeidentical with P₂) by some object b at t₂ and l₂.

Unlike PP1, PP2 is not trivially true, if it is true at all. Standard readings of PP2 will rule out the cases covered in PP1—those wherein P₂ is strictly identical with P₁ and instantiated at the same time and place—on the grounds that the times and locations are distinct, but just in case anyone is concerned that the one might be contained in the other, let us stipulate that PP1-type cases are excluded from PP2. Now let us ask if PP2 is true. To put the question in more digestible terms, we are asking if a property, had by some object, can be the cause of some other object’s having a property of that same type (where the properties are powers). The answer is surely yes. But let me hold off on the explanation ever so briefly, to deal with some potential dissention. One reason I can imagine someone endorsing PP2 is because they interpret the specific time and location of the manifestation as essential to the manifestation, and further hold that such fine-grained manifestation types are unlikely. While it is not impossible that a power is for such a highly circumscribed manifestation, this scepticism strikes me as well placed. It would be quite surprising to learn that there were token powers that had as their potential manifestations not instances of powers had by some object at some time and place, but that were necessarily for the having of that power by a specified object at a similarly specified time and place. One would be hard-pressed to see these as powers of the same type at all. Hence we should reject the

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suggestion that times and locations are essential parts of manifestations, and treat them as contingent.¹⁴ Understood thusly, PP2 claims that no instance of a power can be the cause of that same type of power having an instance at some other time and place. If the non-essentialist reading of PP2 is rejected, and hence it is accepted that any token power can have as its manifestation a token power of the same type, then there should be no reason for thinking that a power-type cannot be such that its manifestation is that very same power-type. It cannot hold for every such case, as evinced in PP1, or as might be thought to arise if t₂ is much later than t₁, but many other cases are admissible (and not at all suspicious, like the essentialist version of PP2). Hence, we have no reason to endorse PP3: PP3 Type-Type: a power type P cannot have as its manifestation the power type P.

Time for the explanation. Here is the reason why we ought to reject PP3 (and the non-essentialist reading of PP2). Consider the case of viral infection. The concern over viral infections is precisely that viruses exhibit the repetition of power-types highlighted in PP3: a virus v₁’s token power to duplicate itself d₁ (an instance of the power-type D) is a power-type shared by all those duplicates it produces, and so on for any further duplicates they might produce. This is how viruses spread within a host. Granted, we tend to think of viruses in terms of the entity itself, but this is typeidentical property production nonetheless. The same is true of the passing of energy: when a billiard ball strikes another it passes on that power of motion to the latter, which it, too, can do for the next. Nothing seems more common to causation than that an object with some property should cause some other object to come to possess a property of just that type. The production of type-identical powers is incredibly common. Hence, with the exception of cases like PP1, PP is false. We have no reason to worry that—as a matter of principle—powers cannot be identical with their manifestations. But can we do better, and avoid even the PP1 cases? After all, some of the clearest examples of static manifestations require that we have powers whose manifestations are the same powers had by the same particular. Are the relevant cases perhaps too close to PP1? They are close, but they are not the same. I have argued that effects need not be changes. It follows that a primary factor in distinguishing exactly similar powers from their manifestations (causes from effects) must be spatiotemporal. Given that the power, and the constellation of which it is a part, is spatiotemporally separated from the power in the manifestation, the two tokens can be distinguished. Therefore, we can reasonably claim that the token powers had by the constellation are distinct from those had by the manifestation.¹⁵

¹⁴ That is, absolute locations are not essential parts of manifestations, but this does not apply to the relative locations of the powers in the manifestations. ¹⁵ This is not a strange suggestion in the least: trope identity is based on spatiotemporal distinctness (see Campbell 1981 and 1990, and Schaffer 2001), and even realists about universals recognize differences in instances based on differences in the times and locations of their appearances, owing to their bearers (Armstrong 2010).

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The model I have in mind is adapted from one suggested by David Armstrong, concerning the laws of nature. On the metaphysic Armstrong endorses, singular instances of laws occupy much the same niche—at least as far as singular causes go— as do powers in the powers metaphysic. There are plenty of differences to be sure, but the relevant similarities are great enough that we can borrow some of the thinking behind Armstrong’s solution. According to Armstrong’s early account, a law is a second-order universal—a relation—that holds between two first-order universals. Using the language which is common when speaking of laws, Armstrong tells us that if it is a law that ‘All F’s are G’s’, that is because there is a contingent relation between F’s and G’s such that something’s being an F necessitates its being a G. He symbolizes this as N (F,G). What prompted Armstrong to refine his view are laws like Newton’s first law of motion: the law that an object at rest will remain at rest, and an object in motion will remain in motion, with the same speed and direction, unless acted on by an unbalanced force.¹⁶ Using his typical notation, Armstrong would be forced to say there are laws of the form N (F, F), whereby something’s being an F (in motion) causes it to be an F (in motion). We have—on the early view—a universal that bears a nomic relation to itself. This is precisely the sort of worry we have been considering. Armstrong’s fix is to change the theory by rethinking the relata. No longer is it the case that laws are relations between mere universals; now they are relations between states-of-affairs types. Though it sounds odd to say that being in motion causes being in motion, there is nothing odd about saying that something’s being in motion is the cause of something’s being in motion, even when the ‘something’ refers to the same object in both cases. (It is so far from being odd that generations of us have been reciting Newton’s first law since we were children, and no one has had a problem with it yet.) Armstrong goes on to suggest a reformed symbolization for his laws, but all that matters for present purposes is that we appreciate the significance of the shift from relations between universals simpliciter to universals understood as states-of-affairs types. (Trope theorists can follow suit, or take a shortcut by claiming that tropes can be individuated by temporal separation.)¹⁷ Importing Armstrong’s suggestion into the powers metaphysic gives us a version of PP that differs minimally from PP1, but does so in a way that avoids the objection. PP4 Token-Token: a token instance of a power P₁, instantiated by object a at t₁ at location l₁, cannot have as its manifestation the existence of some token instance P₂ (where P₁ is typeidentical with P₂) by a at t₂ and l₁.

Whereas PP1 relies on our intuition that nothing can be the cause of itself, we should have no similar intuition regarding properties of an object at one time being the cause of that same property type being instantiated by that very same object at a later time. (And if these are universals, ‘they’ are the selfsame property, not just exactly similar tokens.) There is nothing odd about saying that some object has the shape it does ¹⁶ The core of the early view was first presented in Armstrong (1978), and later refined in (1983). The new view appears in (1997) and (2010). Newton (1687). ¹⁷ See Schaffer (2001).

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now because it had that shape immediately prior to now. This principle is, after all, at the core of Newton’s first law of motion. At this point we should have no problem agreeing that there is no support for the general claim that powers cannot have themselves as manifestations. And so there is no reason to object (on these grounds) to static manifestations either. That brings down the curtain on the second act of the causal sideshow.

7.4 The Case of the Missing Stimuli The third unusual case involves causation in which there are no circumstances—or at least no obvious ones—that stimulate the production of the effect. We have already seen (§6.2) that the concept of stimulation of powers is purely pragmatic. We thus understand ‘stimulus’ in a restricted and rehabilitated way, to refer to the need for specific constellations to obtain for specific manifestations to be produced. Nevertheless, though the concept of stimulation has no metaphysical bite, we are still at liberty to focus our attention on a given power and to track what other powers must be present in order that certain manifestations result, thinking of the latter as the stimulation of the former. Furthermore, many accounts of powers and dispositions (and many analyses of them, too) treat the presence of a stimulus as the essential feature in accounting for a power’s shift from dormancy to active production of a manifestation. For some, responding to stimuli is the earmark of powerfulness or dispositionality. Hence, whether the matter is pragmatic (as it is here), or metaphysically robust (as with other views), the lack of stimuli should be of interest. There is perhaps no example more famous or straightforward in this regard than the simple conditional analysis of dispositionality. Recall: [SCA] Something x is disposed at time t to give response r to stimulus s iff, if x were to undergo stimulus s at time t, x would give response r.¹⁸

In fact, even as analyses like this give way to complicated offspring, the importance of stimulation remains unchanged.¹⁹ And though my understanding of powers is well removed from that of the SCA, it, too, has a role for stimulation, albeit a rehabilitated and pragmatic one. Hence, it really is the stuff of freak shows if all of a sudden powers are producing manifestations without stimulation of any kind.²⁰ And yet that seems to be the case. The β-decay of radium atoms, for instance, appears entirely insensitive to external conditions. Manipulating a radium atom’s external conditions has no effect whatsoever on the probability of its decay. For powers that produce manifestations like this, there does not seem to be anything that counts as a stimulus, or anything that could count as a stimulus. The same is true of those powers that are permanently manifesting: gravitational attraction of massive bodies is constantly manifested under all conditions. It does not seem as if it responds to some state of the world and then ¹⁸ Lewis (1997). ¹⁹ Lewis (1997), Choi (2006, 2009). ²⁰ E. J. Lowe (2011) argues that the conditional analysis of power ascription is doomed to failure in any form, because it relies on this mistaken ‘stimulus-driven’ conception of powers-based causation.

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exerts gravitational force. It appears to act without input. It, and all powers like it, do not appear to have stimuli. Granted, it may turn out that in some of these scenarios we have overlooked the stimulation (and that a proper redescription of the case will bring it back in), but in other cases it looks like nothing at all is required. (And even if you are operating under an unreformed understanding of stimulation, it is still missing.) The standard form of manifestation for powers is that of mutual manifestation of reciprocal powers. As was argued in Chapter 6, the powers of the salt work with those of the solution (they form a constellation) for the manifestation that is their collective effect. Likewise for the striking of a match: it is a coordinated effort that includes the powers of the match, the surface, and the enfolding oxygen. The correct causal picture is thus egalitarian: powers act together for whatever they jointly produce. But the picture of powers-based causation as driven by constellations of cooperating powers is built for cases of powers that operate in the presence of other powers. What happens to the model if not just some, but all, of those other powers are absent? In other words, what happens to powers-based causation in those cases where the stimulus is missing? This is the bizarre case of the missing stimuli. Let us look at the cases more closely, then figure out how to accommodate them within a theory of powers. Assuming, that is, that there is any need to deal with them at all. It might be replied that, appearances aside, these cases are not causal at all. Case in point, Ellis and Lierse dub the properties in cases like this ‘propensities’, and they claim that causation is not involved in the action of propensities.²¹ They base that claim on the grounds that the missing-stimuli cases lack the interaction they believe is required of causation. Such cases are not causal, it would seem, precisely because the reciprocity of powers-based causation is absent. I find this response mystifying. Do propensities not start out with states of the world that then give rise to others? And is this not exactly what powers-based causation looks like? Perhaps the claim is not meant to be a deep one. That is, perhaps ‘causation’ is a term reserved for cases of interactive production, and these cases, though otherwise similar, are distinguished by their lack of interaction. They are instances of causation*. We should do what we can to avoid battles over the use of terms, but to the extent that we might already be in one, the burden here seems to be on those who would deny that gravitation and particle emission are causal. These cases look to be just as causal as their interactive cousins. They are states of the world that produce later states of the world. Unless one has a positive proposal regarding propensities that differs in kind from that of powers-based causation, then there is no need to separate them. Moreover, if they are not causal, then what are they? Dubbing them ‘propensities’ as opposed to powers is of no use at all; it merely passes the causal buck. When the exercising of powers is the mechanism of change, why should we allow that changes take place without powers being involved? If such changes fall outside the scope of powers, then either we have changes in the universe that just are—brute changes—or we have more than just powers at work. Why have powers account for most, but not all, of the world’s changes? It is needless multiplication of

²¹ Ellis and Lierse (1994: 40).

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entities to postulate properties that resemble powers—but are not powers—and have them work alongside the powers. It is similarly profligate to bring in brute changes. (In fact, in light of the considerations in §5.2, we should be sceptical about the stability of any such system.) It is thus preferable to treat all changes as the result of powers, and therefore to think that powers are at work in these missing stimuli cases.²² Let us start with the ‘insensitive’ powers—like the decay of radium atoms—which manifest at some time or other within a large stretch of time, but without there being any clear reason for their having done so at the precise time they do. Once we correctly understand stimuli as the matter of a constellation obtaining (and therefore dictating which manifestation obtains), it is far from obvious that all insensitive cases genuinely count as cases in which the stimulus is missing. As C. B. Martin indicates, the powers that cooperate for the production of manifestations need not be instantiated by distinct particulars. Hence, though typical constellations include powers stretching across multiple objects, nothing prevents a constellation from having powers instantiated by just one particular. Armstrong’s case of the previous state of a thing causing its own successive state without having any reciprocal disposition partners is a case of an entity that exists in and for itself, absolutely independently of everything else (including electromagnetic and gravity fields of force, etc.). Even so, it is not an example of a total lack of reciprocal disposition partners. A previous state x of a thing a at t₁ has innumerable reciprocal dispositional partners in other states of a at t₁ for the continuance of state x of a at t₂.²³

What could stand in the way of powers within a single particular working together as an object-bound constellation? Two scenarios come to mind. They are, firstly, that there are objects with just one power property; and, secondly, that the many powers within an object participate only in constellations that include external powers. The first scenario should be rejected on the grounds of naturalism. Objects with just one power are creatures of fiction; they are not the natural objects of our world. And even though the substances of the micro-physical realm are beyond our direct experience, reason tells us that each will be many ways, not just one. As for the second scenario, it seems equally natural to think that the numerous powers that objects have would work together to produce manifestations. In fact, it seems like this is the most natural way to conceive of the power properties of a particular operating. If one has any trouble at all imagining this at the microscopic level (not that you should: there is mutual interaction in even the simplest of particulars), there can be no denying that the homeostatic processes that underlie the life processes of complex biological individuals are exactly like this. Furthermore, the model of powers-based causation—neighbourhoods of interacting powers especially—makes it incredibly unlikely that powers within an object could not have constellations including just them. Many powers will participate in constellations without being differencemakers (recall the notion of ‘complicity’ from §4.1); exclusion is thus improbable. ²² There is, of course, nothing preventing missing-stimuli cases from being for non-changes, too. They do not require a special treatment. ²³ Martin (2008: 91).

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Therefore, we should hold that powers within a particular are capable of forming constellations just as much as powers within and without. Most constellations, of course, will include powers of the surrounding area: independence from gravitational fields and the like is hard to achieve. But we are considering insensitive cases, which, by all lights, are manifestations produced without the powers of the surrounding area. It could turn out that the surrounding powers are involved, but that their presence or absence does not result in different manifestations. For the sake of argument I shall assume that the external powers are excluded. Thus, the claim is that some—perhaps all—of the insensitive cases are not really missing stimuli at all, but rather cases where the constellations are restricted to the powers properties of a single object. (They are instances of what is known as ‘immanent causation’, which is discussed below.) The only thing ‘missing’ are powers from external objects, but that does not pose any sort of problem with regard to the model of constellations of powers producing manifestations. However, appreciating that the lack of external stimuli does not entail the lack of stimuli simpliciter does not solve all the mysteries here. To wit, it does not tell us why radioactive decay occurs at some time rather than any other, and it does not cover the limit case of insensitive missing stimuli. The first of these is easily handled. Why some time and not another? These are stochastic powers. If we build into the power a randomizing factor, then at each passing moment it can manifest that power, but only once (and with low probability) will it decay. Recall that stochastic powers are not powers that manifest randomly. They are powers—just like the others—that produce a manifestation when the right constellation obtains. But unlike the others, the manifestation is itself disjunctive, selecting between two (or more) possible states, with some probabilistic distribution between them. In this case it might be that the manifestation prefers a non-change to that of emitting a particle at a ratio of ninety to one. The constellation always produces the selection, and the state is produced accordingly. What about the limit case of missing stimuli? That is, what about constellations with just one power? In these cases, what we have been calling ‘stimulation’ (really just powers working together) cannot possibly obtain: reciprocity is impossible. Let us call these ‘unilateral powers’, precisely because they operate on their own, without cooperation. So, what does the powers-based model of causation have to say about unilateral powers? Firstly, powers that operate entirely on their own are going to be very rare indeed. So rare, in fact, that we might easily be convinced that there are no such things. After all, think about how hard it would be to find a power that exists without other powers in its neighbourhood. Can there really be a neighbourhood of one? Remember that relevance is a largely epistemic matter, and so a non-issue here. That is, even if the inclusion or absence of a power in a constellation makes no difference to the manifestation that obtains (and so would tend to be ignored in scientific or explanatory contexts), it would still be part of the constellation. So, what we are asking is not whether there are cases where other powers in a constellation make no difference to the manifestation produced, but if there are constellations that include no other powers at all. These would have to be incredibly rare. They would be so rare that Martin is convinced that the only circumstance in which we could

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possibly find what we are calling a unilateral power ‘would be that of a perfectly simple and irreducible single state’, which he bitingly suggests only God could exhibit.²⁴ I am not sure they must be quite this rare, but let the record show that unilateral powers are very rare. For the few that there are, the story is far less complicated than one might have guessed. Properly understood, stimulation is nothing more than certain constellations obtaining: there is nothing operationally distinct about the simplest constellations. Unilateral powers thus produce manifestations in constellations that have just that one power property. The constellations are peculiar in terms of their size, but size does not matter when it comes to powers-based causation. Some constellations will be huge, whereas others consist of just one power, but they all act exactly alike with respect to giving rise to manifestations. Therefore it turns out that there is nothing special to unilateral manifestations beyond the number of powers involved. They are special to the extent they are beyond the class of typical causal cases, but deep down they are just more of the same (well, less really). Permanent manifesters—such as gravitational attraction and the like—are themselves similarly banal. These powers manifest without pausing and without requiring the sort of stimulation we have now come to see as confused. Constellations obtain, and their manifestations follow. Nothing about the picture of powers-based causation stops this from happening over and over again when similar or identical constellations obtain. What is a permanent manifester? It is any member of a class of constellations that repeatedly give rise to manifestations that are themselves states that give rise to identical (or near enough identical) manifestations. To this we might add that these tend to be ‘robust’ manifestations, meaning that there are apparently very few powers that can be added to these constellations that do not result in similar enough manifestations. But they are not all that special, just not the middle-of-theroad case of powers-based causation. In the end, what seemed like very odd cases of powers at work now appear much less so, once we understand stimulation and powers-based causation correctly. The case of the missing stimuli has thus been solved. As a final word on missing stimuli and unilateral powers, I want to point out that the powers in question need not be special in another sense. Unilateral powers are conspicuous in their ability to produce manifestations in the smallest possible constellations, but there is no reason to assume that powers capable of this cannot also be exercised in larger constellations. Our powers are multi-track powers, producing different manifestations in different constellations. Unilateral powers can go it alone, but that does not mean they do not also play well with others.

7.5 Immanent Causation The fourth case of unusual causation is that of immanent causation. Immanent causation takes place when both the cause and the effect are attributed to the same particular. This is contrasted with transeunt causation, in which the causation is not ²⁴ Martin (2008: 91).

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restricted to a singular particular. Examples of the former include such things as locomotion, inertia, homeostasis, radioactive decay, and, perhaps more controversially, persistence. The notion of ‘immanent causation’ has its roots in a distinction found in Aristotle’s Metaphysics, between scenarios in which the result of some exercise is actualized in some entity apart from the agent, versus those in which the actualizing remains within the agent. Similar distinctions can be found in the medieval period: Aquinas writes of a distinction between making—wherein an activity is transferred onto something external—and doing—where the effect of the activity stays within the agent.²⁵ But it is a slightly more recent use that we will consider here. In the third part of his 1924 Logic, W. E. Johnson defines ‘immanent causation’ as ‘the causality in which the cause occurrence and the effect occurrence are attributed to the same continuant’, which he contrasts with ‘transeunt causation’, wherein ‘the cause occurrence and the effect occurrence are referred to different continuants’.²⁶ And Hermann Lotze—in his 1884 Metaphysic—refers to the immanent causal process by which ‘state a¹ of a thing a begins to bring about a consequent state, a², in the same thing’, contrasted with the process whereby ‘the same a¹ sets about producing the consequence b¹ in another being b’.²⁷ The basics of immanent causation are simple to grasp. Any cause and effect restricted to the actions of a single object will be instances of immanent causation.28 Consider Newton’s first law of motion. As Johnson tells us, for ‘the movement of a particle from A to B during an interval of time followed by a movement of the same particle from B to Y, the law or formula in accordance with which the nature of the former movement determines that of the latter exhibits immanent causality.’²⁹ The law here is one that maintains the direction and speed of movement from one moment to the next, assuming nothing intervenes. (Told in terms of powers, the story is much the same.) A similar story can be told for radioactive decay. The decay is self-directed: it is causation from within that solitary object alone. And numerous biological processes—especially those essential to life—occur within the entity too. Immanent causation abounds. So, what can the powers theorist say about immanent causation? As it happens, we have already come to terms with a powers-based account of immanent causation, albeit under another guise. Because immanent causation involves powers within the causal line of a single particular, the relevant constellations include powers only from within that one particular. They do not have anything that counts as an external stimulus, and hence they are a breed of missing-stimuli cases. As we saw when dealing with missing stimuli, powers-based causation includes cases where numerous powers of the same object work collaboratively to produce a manifestation. And when the manifestation is similarly limited to just that particular,

²⁵ Emmet (1984). ²⁶ Johnson (1964: 128). ²⁷ Lotze (1884: 88). ²⁸ The stage theorist holds that objects—properly speaking—are incredibly brief. Hence, any plausible union of stage theory and immanent causation (an attractive mix, according to Hawley 2001 and Sider 2001) would have us relax one or the other’s understanding of objects over time. As this is not a complicated task, I will ignore this caveat from here on in. ²⁹ Johnson (1964: 128).

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we have powers-based immanent causation. In the limit case—that of just one power acting alone—we have a decidedly simple constellation, but the mechanism of powers-based causation is the same as when there are multiple powers involved. Thus, the main question of the powers-based version of immanent causation has already been answered. Immanent causation is nothing more (nor less) than the following: Powers-based immanent causation: we have an instance of powers-based immanent causation just in case the powers that comprise a constellation are all had by a single particular x, and the manifestation produced by that constellation is a state of affairs composed of just x and its powers.

Powers-based causation incorporates immanent causation without modification. There are constellations, and they produce manifestations; the model is effectively blind to what possesses those powers, and simply produces whatever it does when those obtain. It does not count objects. So, the cost of accepting the reality of immanent causation is incredibly low, as it demands nothing new of our theory. (One wonders why it is thus worth mentioning at all, but the benefits will be reaped in the next chapter.) For the time being, I want to close this section with a discussion of perspectivalism. That is because perspectivalism is significant to some of the best-known, and most developed, early accounts of immanent causation, but does not find a home in the powers-based account. According to Johnson, we can treat a causal scenario as either a case of immanent or transeunt causation, depending on the way in which we couch the scenario. Processes which are immanent to a whole system of interacting continuants may always be regarded as entailing transeunt causality between the parts of the whole system. This aspect of causality is familiar to the student of Physical Science. Or—to express the same principle in converse form—if we primarily conceive of interaction between parts of a system as exhibiting transeunt causality, we may (without contradiction) express our formulae in terms of causality immanent to the whole.³⁰

Thus, on Johnson’s account, as long as we are willing to switch between considering objects qua whole and qua constituent, we can treat the causal process in terms of either. Whether a case counts as one or the other thus depends on what perspective we take on the individuals involved, and our willingness to treat various fusions of objects as objects themselves. Assuming we are quite liberal in this regard, Johnson would thus approve of treating most instances of transeunt causation as immanent causation when the perspective shifts towards greater generality. Lotze himself endorsed a form of monism in which the entire universe is treated as a single object, and thus all instances of causation could count as immanent.³¹ To the extent that we are willing to treat systems of interacting objects as larger objects, perspectivalism allows us to treat cases of transeunt causation as cases of immanent causation, and vice versa. But the translation does not always hold: a lot

³⁰ Johnson (1964: xxiv).

³¹ Lotze (1884: Book I, ch. VI).

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hangs on the extent that we are willing to permit perspectival shifts. For example, someone who denies that the world is gunky will deny that immanent causation inside the smallest objects is a matter of yet smaller objects causally interacting. Conversely, a truly radical monist should deny that the parts of the ‘one’ (the ‘blobject’) are objects, and thus would hold that all causation is immanent and none is transeunt.³² One might even hold that simple objects in a non-gunky world engage in immanent causation, yet deny that they form interacting networks. As Lotze indicates, Leibniz’s monads were like this: tiny particulars that moved around and enjoyed internal causes which had effects on only themselves, but which never interacted with one another. And finally, if our ontology is ‘flat’ (in the sense that the simples never compose any object), then interactions between the simples cannot be treated as internal to a larger whole, as no such whole exists. Shifting perspectives are also amenable to hybrid views: most causation, says Lotze, is a mixture of immanent and transeunt causation.³³ Interestingly, Johnson claimed that purely immanent causal processes ‘perhaps never’ occur within the happenings of a single physical object.³⁴ If Johnson’s claim is interpreted as a practical one, referring to the fact that objects are almost always in the company of others, and thus that they typically interact, his claim is halfway believable, but as a general principle it appears to be false. Consider an abstract case. Radical monists more or less have to accept that there is immanent causation (the only way out is to reject causation outright), because there is just one object. There is a simple formula here: monism plus causation makes for immanent causation. This would suffice to undermine Johnson’s claim. But further imagine we are dealing with physical simples, and that there is just one. And imagine that this lonely object is moving, perhaps in a straight line—or that the object is spinning, or losing energy, or growing increasingly larger then shrinking again. Or even imagine that it is just floating there on its own. The same monistic conclusion ought to follow: if there is any causation for that one simple, then it must be immanent causation. One could reply—quite reasonably, perhaps—that lonely particles are a philosopher’s fiction. It seems easy enough to imagine such a scenario, but little follows from that, even if the thing we had in mind was enough like a particle to count as one after we had subtracted the world around it (which is doubtful). (Recall that imagination is not much of a guide to what is possible on the powers metaphysic.) So let us bring back all the other particles into our imagining. Now consider the moving, spinning, shrinking, growing, and so on that our never-actually-lonely particle gets up to. Some of those might involve interactions with the other particles (and so are transeunt), but surely not all of them. If one particle were to send another spinning off in some direction, its continued spinning and moving in that direction will be a case of immanent causation, even though its initial spinning was not. As would the actions of a near enough lonely particle, which is at some great distance from the others. So, what impact does this perspectivalism have on the powers-based account of immanent causation? The short answer is very little, at least as far as genuine

³² See Horgan and Potrc (2008) for a defence of ‘blobjectivism’. ³⁴ Johnson (1964: xxv).

³³ Lotze (1884: 90).

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causation goes. First off, if the world is comprised of but a single huge object, then all causation is immanent. Second, if the world is composed of ever-so-many microscopic objects (as many of us believe) then we have immanent causation and transeunt causation, but there is nothing perspectival about it. As we have just seen, there can be constellations and manifestations restricted to the same microparticular (immanent causation), but there might be other constellations constituted by powers across a host of particulars (transeunt causation). What we should deny is that the objects involved in the latter ought to be treated as a particular such that any case of transeunt causation is also a case that is immanent to the fusion-formed particular.³⁵ Here is why. In Chapter 4 (when arguing against extrinsic powers), I appealed to a non-redundancy principle for the postulation of powers. Put briefly, this ‘novelty’ principle requires that any powers we postulate add to the set of potential manifestation types, on the grounds that powers are theoretical entities, and there is no need to posit powerful properties whose work is already being done. By extension, there is no need to posit powers of the fusion-formed particular that are anything over and above those of the micro-particulars that are its parts. In fact, we should not posit additional powers beyond those of the micro-particulars, precisely because they would violate the novelty principle.³⁶ Given that the fusion-formed particular has no properties of its own (so to speak), it can never properly be the case that the powers involved are the powers ‘had by it’, and thus the case is not (properly) one of immanent causation. Thus, we should deny that cases of transeunt causation can be cases of immanent causation, or that which a constellation–manifestation pair happens to be is a matter of perspective. For those who do not shy away from impropriety, there is a little more wiggle room to be found. The powers of the fusion-formed particular are not powers had by it, but they are all had by its parts; thus if one wants to treat this as a case of immanent causation, one can do so without much trouble. It is not such a case, but it is very much like one. The same can be done in the other direction. The true monist has no transeunt causation, properly speaking, but there is no harm in treating constellations constituted by powers had by distinct parts of the blobject as if they were powers had by different objects.

7.6 Simultaneous Causation I promised you a fifth category of unusual causation, but now that I have your money, I can tell you that you have been swindled. There is no simultaneous causation; it is a hoax. Sorry, no refunds. But fear not. You may not get to see effects that freakishly obtain at the same time as do their causes, but the cost of entry was not a total waste: the lessons herein will help protect you against the snake-oil merchants out there who will have you believe that simultaneous causation is genuine. (Be warned: many of those who seek to deceive you are friends of powers, too.) ³⁵ Assuming, that is, that the manifestation is similarly restricted to the fusion-formed particular. ³⁶ None of this is to deny that fusions exist, only that they have novel powers. See §10.2.

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What is simultaneous causation? Simultaneous causation—were such a thing to exist—would be causation in which the cause obtains at the same time as the effect it produces. Most famous among fans of simultaneous causation is Kant, who believed it to be quite common. His preferred example concerns a ball sitting on a cushion: the ball causes a depression in the cushion.³⁷ The ball’s causing the depression, and the effect that the is depression itself, are simultaneous, claims Kant. We should all agree that if this counts as simultaneous causation, then simultaneous causation is very common indeed. But does it? Before answering, we should see how causal simultaneity has recently arisen among friends of powers. First up is C. B. Martin. Though not put in terms of simultaneity per se, Martin takes manifestations to be identical with the coming together of the cooperating powers that produce them. This means that what counts as the cause could not arise before or after what counts as the effect (they are the same!), and hence they are simultaneous. [T]he coming together of the disposition partners is the mutual manifestation; the partnering and the manifestation are identical. . . . the partnering is the manifestation.³⁸

Next in line is John Heil, denying that the actions of the powers obtain prior to the production of the manifestation. He claims that the standard temporal sequence we would expect in a causal scenario is missing, at least for the case in question. You take two playing cards and prop them up against one another so they stand upright on the table. The cards—with the help of the table—are mutually supporting: they remain upright. The cards work together with the table (and the gravitational field) to produce this result. But their working together and the result are not sequential.³⁹

Lastly, we have Mumford and Anjum, who speak explicitly in terms of simultaneity, and dedicate a full chapter to it. Causes, they claim, are simultaneous with their effects: effects begin as soon as the powers are appropriately arranged, and sometimes those causes continue—alongside the effects—until the terminus is reached. Causation is thus an unfolding process whereby a turns to b. . . . The combined powers of the cause, such as the solute and the solvent, become the effect – a substance held in liquid suspension – as part of what it is to be those powers.⁴⁰

These examples are compelling, to be sure. So, why should we deny the existence of simultaneous causation? Chief among the phenomena that theories of causation are built to explain are changes in properties instantiated by objects. It would therefore be shocking if an account of causation ruled out the possibility of change. But if a cause perfectly overlaps its effect in time, then the rejection of change is precisely what follows. If the very powers that jointly give rise to the manifestation must themselves be the manifestation—as Martin indicates—then change is impossible. No powers can be lost or gained as a result of those selfsame powers interacting. It follows that this model is untenable.

³⁷ Kant (1933: A203). ³⁸ Martin (2008: 51). ⁴⁰ Mumford and Anjum (2011: 119).

³⁹ Heil (2012: 119).

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Perhaps the changes we should be looking for are not elsewhen (because there is no elsewhen for simultaneity) but elsewhere? That is, simultaneous causation could be compatible with change if the effect differs in its spatial location from the cause. However, not one of the four cases on offer has anything like the required picture of spatial separation. These are all causes that are spatially coincident with their effects. The location at which the solvent comes into contact with the cube is that which also gets sweeter. Do not resort to thinking that Kant’s ball-and-cushion example escapes this complaint: properly understood, the case involves an interaction between the powers of the ball and those of the cushion. Moreover, imagine that we have spatially distinct but simultaneous states of affairs, where one is the cause of the other, as the case requires. It is hard to make sense of this at all, but worse is that the constellation state would have to somehow prevent the earlier states at the location of the manifestation state from giving rise to their manifestation. I am hard-pressed to see how the inconsistencies would be avoided. Simultaneous causation cannot be squared with the account of powers-based causation I have presented. So, what is going on in these cases then, if not simultaneous causation? The answer is that states of the world (constellations) are giving rise to states of the world (manifestations). They do so very quickly, and they can often give rise to manifestations that are very similar (or type-identical) to those that produced them, but the manifestation does not obtain at exactly the same time as the constellation does. In short, take the lessons from Chapter 6 concerning the speed with which manifestations are produced and how long they last, combine those with the lessons regarding static manifestations from this chapter, then throw in the rehabilitated sense of stimulation, and you have all the tools you need to deal with so-called ‘simultaneous’ causation, without any actual simultaneity. The mix I have prescribed is a far cry from the standard models of causation. Kant could therefore be forgiven for his mistaken treatment of these cases, and should be credited with noticing that they differ importantly from the everyday examples. Similar credit goes to the friends of powers referenced above. They are finding cases that are common in nature but ignored in the discussions of causation. And, given the contrast class in terms of neo-Humean models of causation on offer, there is a sense—albeit a rough one—in which we might say there is simultaneous causation. To be clear, we should deny that simultaneous causation exists. On a proper understanding of simultaneity, the constellation and the manifestation would have to perfectly overlap in time, and this cannot occur. Simultaneity, thus understood, is not worth taking seriously. But something like it—something slightly metaphorical—could enhance our picture of causation. Consider what happens if we ignore the constellation–manifestation pairs, and zoom out just a little. For instance, consider placing a sugar cube in a hot solution, and think about the process of its going into solution and the outcome of that process.⁴¹ Little by little, the sugar cube gets smaller as it dissolves, and the solution

⁴¹ The example is the one used by Mumford and Anjum (2011) in their defence of simultaneous causation.

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gets sweeter. The dissolving of the cube—considered at the level of the cube as a whole, and not of the numerous constellation–manifestation pairs—is a protracted process. The increasing level of sweetness and saturation is a protracted process, too. And though the two processes might not admit of perfect overlap, at most points in the process the sugar cube’s dissolving is simultaneous with the processes of increased sweetness and saturation. Hence, from a certain perspective, there is simultaneity here; it is what we might call ‘wide-scope simultaneity’. Of course, getting to this perspective pulls us too far back to be dealing with causation proper—the time frame is too great to be a matter of powers exercising—but at the level of processes we can appreciate how talk of simultaneity is something of a step forward, especially for those drawn to event-based causal theories. After all, if our only way of thinking about the sugar-cube case was in terms of all the sugar having dissolved or none, then we could do a lot worse than seeing the effect as simultaneous with its cause. But we are not stuck interpreting the case as all or nothing, and therefore have better options available to us. We only get simultaneity if we think of the manifestation of the dissolving as the entire sugar cube’s being dissolved, not this or that part of it. The simultaneity is of parts of the cube, getting us closer to the final state we seek, which is many manifestations down the road. If we focus on just the smallest part of the sugar cube’s exterior, then when it has gone into solution we can say of the whole cube that it is partly dissolved. This takes zooming out to the wide scope, allowing us to have constellations and manifestations obtaining at the same time. If we zoom in on the process, the simultaneity is lost: the dissolution of the outermost molecules follows very shortly after their immersion. At no time are the very same molecules both dissolved and not dissolved. At no point does a manifestation of increased sweetness and saturation obtain at the exact time as the constellation that produces it. Each manifestation is the product of a similar—but slightly less sweet—constellation. That portion’s going into solution was not simultaneous with its cause, but it was immediate, if not instantaneous. The process is, therefore, a series of brief (nonsimultaneous) steps like this—molecules now in contact with the solvent and then quickly dissolved—that give us the overall process which we treat as (wide-scope) simultaneous. When the chips are down, there is no genuine simultaneous causation, just multiple constellation–manifestation pairs. This brings the causal sideshow and the discussion of eerie causation to an end. Please exit to the left, where a discussion of powers-based persistence is waiting for you.

8 Persistence Explained 8.1 The Problems of Persistence temporal parts are caused to exist by previous temporal parts. Sider, Four-Dimensionalism (2001: 217)

The present powers metaphysic is starting to take shape. We have seen the powers that form the core of the ontology, and put that ontology to work in a theory of causation. The next application takes us into the realm of persistence. It is all but a basic datum of our experience that all sorts of objects, familiar and unfamiliar, continue to exist over time. I existed this morning at 6.45; and I still exist now, at 3.18 in the afternoon. It is a safe bet that I will still exist five minutes from now. The same is true of the things I have seen or interacted with in that time period: my family, my car, my computer, my phone, and so on. Likewise for the many molecules and atoms of which the above are composed. Persistence is ubiquitous; explaining how it is so is at the heart of the problem of persistence. As the title of this section suggests, there is more than just one problem answering to that name. There are, in fact, quite a few connected problems in the general persistence ballpark, distinguishable by subtle differences, and requiring different solutions. We will look at three such problems, with the aim of clarifying the details of one in particular, to which a uniquely powers-based solution will be offered. That problem concerns how individual objects persist—microphysical objects in particular.¹ That is, powers will be employed in an explanation of fundamental object persistence. The problem of how objects persist has received very little attention to date. However, that fact is less surprising once one appreciates that the sorts of assumptions the neo-Humean metaphysician makes about objects make it hard to raise coherent questions about the ‘hows’ of existence. When presented with a mosaic, questions naturally shift to how to track objects through the image, rather than what explains the coming to be of this or that state. The neo-Humean takes states of the world to be pre-existing, loose, and separate, and hence only sees the need for an account of how they attach to one another, not how they came to be. This is, thus, another occasion when the problems and solutions available to the metaphysician

¹ §10.3 provides a brief discussion of macrophysical persistence. Recall from §1.5 that I defer to physics regarding the nature of the fundamental entities. I will further help myself to the assumptions that they have identity conditions and are property bearers. If neither turns out to be true, then there might not be any microphysical persistence at all. The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

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differ according to their chosen metaphysic. Explanations of persistence are rarely considered, consequently the first sections of this chapter are dedicated to setting up the explanatory problem, which I call ‘the problem of pluck’. Much of the rest of the chapter is spent solving the problem. But doing so demands we first get clear about some of the problems of persistence, how they differ from one another, and how they differ from that of pluck. One form of the problem of persistence—the one that has historically gained the most attention, and that swamps all others in the contemporary literature—concerns how it is that individual objects survive through change. Part of what it is to persist is to be the same thing at different times, under some understanding of what it is to be that thing. Hence, persistence is a matter of relevant sameness. But experience tells us those objects we take to persist over time—those objects we see as being the ‘same’ objects at both 6.45 and 3.18—undergo changes through those same stretches of time. How can something, some one thing, change, yet still be the same? On the face of it, for something to stay the same as it undergoes change sounds paradoxical. And yet we believe this happens all the time. Squaring sameness with change is the problem of change, and is the most common version of the problem of persistence. The tension between sameness and change becomes all the more acute when we consider a well-accepted principle of identity: the indiscernibility of identicals (hereafter ‘II’). II states that for any objects α and β (where α and β are different names for what could be the same object), if the object denoted by α is identical to that denoted by β, then any property possessed by α must also be possessed by β. II is not to be confused with its converse, the identity of indiscernibles. Whereas II is the historically uncontroversial principle that numerical identity entails qualitative identity (because every object must have all the same properties as itself ), the identity of indiscernibles is the highly controversial principle that exact similarity of properties entails numerical identity.² If we consider objects only at a given time (synchronically), II looks to be an obvious truism. But once we consider the identity of objects over time (diachronically), II gets us in trouble. After all, II tells us that in order for α at some time t₁ to be the same persisting object as β at some other time t₂, α and β must have all the same properties. This renders change impossible. If it turns out that the only way objects can persist is by avoiding change, then either our intuitions about persistence are mistaken, or II is false. Either way, something must give. A more specific version of the problem of change concerns the instantiation of intrinsic properties. David Lewis presents the problem thusly: Persisting things change in their intrinsic properties. For instance shape: when I sit, I have a bent shape; when I stand, I have a straightened shape. Both shapes are temporary intrinsic properties; I have them only some of the time. How is such change possible?³

The issue here is not simply one of change (it is not merely the case that persisting objects have non-permanent intrinsic properties), it is that the changes they persist through involve the instantiation of incompatible intrinsic properties: no object can

² See Black (1952), Ayer (1954), and Zimmerman (1997b).

³ Lewis (1986a: 203–4).

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be both bent and straight. Moreover, no object can be both bent and straight at the same time, and yet the passage of time permits the instantiation of contradictory properties. How this can be so is the problem of temporary intrinsics.⁴ Much of the contemporary literature on persistence is concerned with the problem of change, especially as it pertains to intrinsic properties, but change is merely one aspect of the problem of persistence. A second problem of persistence concerns the question of what persistence consists in, known as the ‘tracing problem’. This is the problem of finding some criterion by which the careers of objects can be traced through time. (This is the ‘can’ of metaphysical fact; it may not be of much practical use for object reidentification.) For example, consider some object named α at some specific time t₁; that is, α-at-t₁.⁵ Now consider some object named β at some later time t₂ (β-at-t₂). The tracing problem asks what it would take for α-at-t₁ to be the same object as β-at-t₂. That is to say, what is the criterion by which these two would constitute parts of the same persisting object, or, if you prefer, moments in the career of the same object? Providing the right criterion gives us a means of tracking or tracing the career of the object through time. Though connected to the problem of change, differences between it and the problem of change can be made clearer by considering standard answers to the former. Three positions dominate the problem of change literature. They are perdurantism, stage theory, and endurantism. Perdurantism is the view that objects persist by ‘perduring’; that is, by being composed of temporal parts. A ‘temporal part’ is a shortlived part of an object, considered along the temporal dimension. Just as objects can be divided into spatial parts (the top half of the table versus the bottom; the left and right hemispheres of your brain), by analogy they can be divided into segments of their lifetimes (the first two minutes of your life; the butterfly’s larval stage; the year your leaf-blower spent in my garage). The thought is that objects have these parts just like they do the spatial ones, and that to persist is to be made up of many such temporal parts. More often than not, perdurantism is combined with an eternalist account of the ontology of time, resulting in what is known as ‘four-dimensionalism’.⁶ According to the eternalist, all times (past, present, and future) are on equal ontological footing. There is nothing special about the present: the times before now, and after now, are just as real as now is. Just like ‘here’ points to where we are spatially, but locations extending away in all directions are no more or less real, ‘now’ is a term for the present moment of utterance—it is an indexical that points to one time, but not to a special time qua ontological status. Combining eternalism with perdurance gives us the picture of perduring entities as ‘spatiotemporal worms’, which explains why perdurantism is sometimes called ‘worm theory’. One gets worms by circling groups

⁴ Hawley (2001:16) rightly indicates that changes in extrinsic properties can be just as troublesome. ⁵ This is to be read as ontologically neutral: ‘at-t’ and ‘at-a-time’ do not here imply any commitment to an account of time or persistence. They merely indicate that we are speaking about some object and the way it is or was at some given time. ⁶ But be on the lookout for other nearby uses: see Rea (2003) and Hawley (2015). Perdurantism does not commit one to eternalism, but they make for a more comfortable pairing than combining perdurance with any other view. The same holds for endurantism and presentism.

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of temporal parts that combine to form persisting entities, much like you might circle the letters in a word-search puzzle to pick out a word. Like the perdurantist, the stage theorist holds that persistence is a matter of temporal parts forming fusions. For present purposes we can lump the stage theory in with perdurantism, as the difference between them makes little difference for contrasting the problem of change with other problems of persistence. Perdurantists claim that subject terms—such as ‘chair’, ‘person’, and ‘molecule’—refer to persisting entities (collections of object stages), not the singular stages. Stage theorists, on the other hand, take our object terms to pick out the temporal parts—the ‘stages’. These referential differences often align with claims regarding ontological priority: to wit, perdurantists take fusions to be fundamental, whereas stage theorists give priority to the stages. But both agree that persistence crucially involves temporal parts, and this is what distances both from endurantism; it is also why we can safely treat them together. Endurantism is the rejection of perdurantism. Some would describe it as the rejection of temporal parts, but as we can have a neutral reading of ‘temporal part’, it would be better to say that endurantists deny that persistence depends on temporal parts. As a positive depiction, endurantists claim that objects persist by enduring, which is described as an object’s being ‘wholly present at every moment that it exists’. I am unsure just how this phrase is to be understood, but when endurantism is combined with presentism (according to which only the present time exists) to make ‘three-dimensionalism’, it makes sense that all of a persisting object is located right there in the present.⁷ Unlike perdurantism, wherein persisting objects are temporally extended worms, the endurantist picture of persistence sees the object move in its entirety through each passing moment, leaving nothing behind, and with nothing ahead. As standardly presented, perdurantism and endurantism do not constitute solutions to the tracing problem. Turning them into solutions requires adding something to each. Within a perdurantist account of persistence, tracing boils down to which ‘worms’ can be formed by uniting the various temporal parts. Perdurantist tracing is thus a matter of diachronic composition, and comes in weaker and stronger varieties. On the weaker side, tracing can be just a way of picking out privileged fusions: a perdurantist might permit the fusion of any temporal parts in the formation of a persisting object, but claim that only those fusions satisfying the tracing criterion count as the familiar objects. Stronger versions bring composition and the tracing criterion closer together, claiming that only those collections of object stages that satisfy the tracing criteria count as fusions, and hence as persisting objects. Within endurantist accounts, tracing tracks the movement of persisting objects from one moment to the next. As the three-dimensional object moves through time, it traces a particular path; the tracing criterion allows us to follow that path. Another way of presenting the distinction between perdurance and endurance is in terms of a disagreement concerning how ‘identity’ should be understood when applied diachronically. If we consider the relationship between a-at-t₁ and a-at-t₂

⁷ See Crisp and Smith (2005) for how ‘wholly present’ might be understood.

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(understood neutrally), endurantism is the view that a is identical in each case: what connects the parts of an object’s career is nothing less than identity. Perdurantists claim that something weaker than identity—‘gen-identity’—is what connects the various parts of a.⁸ Hence, perdurantism is the view that a-at-t₁ and a-at-t₂ are not strictly speaking the same object, but that some connection holds between them such that each makes up a moment in a persisting object’s career. Though understanding endurantism this way offers a built-in solution to the tracing problem (strict identity tracks objects over time), it does little to help with the problem of change. Showing how objects can instantiate inconsistent intrinsic properties requires indexing the properties to specific times. According to the perdurantist, incompatible properties are instantiated by distinct temporal parts (a-at-t₁ is bent; a-at-t₂ is straight), and thus perdurantism is built to deal with change. But the endurantist needs to say something more. She has two options at her disposal. The first is that intrinsic properties are not intrinsic at all, but are instead disguised relations that objects bear to times (bent-at-t₁; straight-at-t₂). The second option tenses the copula: there is no being bent or straight simpliciter; one is-at-t₁ bent and is-at-t₂ straight. It follows that the problem of change and the tracing problem, though both problems of persistence, are not one and the same. We have seen two problems of persistence, but it is the third that takes the spotlight here.⁹ That third problem is the problem of pluck.

8.2 Pluckiness Something is said to be ‘plucky’ when it shows resolve in the face of difficulty. Objects, by and large, are existentially plucky. That is, even when faced with difficult scenarios, they continue to exist. Like a Timex watch, objects take a licking, and keep on ticking. They are plucky. They are plucky through change, but they are no less plucky when they continue to exist unchanged, even as change takes place around them. The problem of pluck is the problem of explaining how objects continue to exist, as such, regardless of change. As the literature makes clear, it is no small feat to say how things can stay the same through change, but there is no less challenge to be found in the sheer phenomenon of persistence. Meeting that challenge is the problem of pluck. Consider the scenario we saw previously, concerning α-at-t₁ and β-at-t₂, and the question of whether the two are parts of just one persisting object. It is the differences in the properties of α and β that stand in the way of our treating them as the same. This is because we are thinking about the sameness of objects in terms of II, and the differences rule out a straightforward application of it. But consider a case without changes, perhaps one in which we are already satisfied that the object in question is the same object at different times. What we have now, when we consider a case of numerical identity of a-at-t₁ and a-at-t₂, is a very different problem indeed. The ⁸ Sider (2000). ⁹ This is not to suggest that the powers metaphysic cannot offer solutions to the tracing problem or problem of change, but they tend to be too much like the standard solutions to warrant much discussion. I offer a brief primer in §8.5.

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question is no longer how a can be the same throughout changes—that question does not arise. The question is now: how can a exist at two distinct times at all? What accounts for the fact that it is able to exist at different times? Even without changes, this problem is difficult enough; changes only make the problem harder. What the question calls for—not addressed in either the problem of change or the tracing problem—is an explanation of how objects persist. How is it that objects continue to exist, rather than just winking out of existence? That is pluck. If you are worried that this does not sound like a distinct problem, or are having a hard time seeing the problem for what it is, the following comparison might help. Imagine someone asks you how to get from one place to another. Or better yet, imagine having a conversation with someone requiring physical therapy for a spinal injury, who is relearning how to walk. They ask you how to get from one place to another. The answer you give is not in terms of the directions you take (as we would typically offer in response to how to get from a to b), but how to move from one place to another. To say that you have to start in one place and end at another, having occupied all points between, will not help this person in the least, despite being factually correct. Nor will it help to provide them with a map. That is not what is at issue. The question is not what it is to have moved from one place to another, not a matter of what constitutes moving, nor an analysis of what movement consists in, but a question of how this occurs. What is needed is an explanation of movement. E. J. Lowe puts the point thusly: [T]here is a distinction to be made between explaining a tomato’s persistence and saying what that persistence—the tomato’s ‘diachronic identity’—consists in. . . . I take it that what is involved here is the quite general distinction between providing a causal explanation of the occurrence of a phenomenon and saying in some revealing way what that phenomenon really is—disclosing its ‘real essence’. (Compare the distinction between saying why lightning occurs and saying that what lightning is is an electrical discharge.) . . . To be in a position to say in what a thing’s persistence consists is, in more familiar terminology, just to be able to supply a criterion (or ‘principle’) of diachronic identity for that thing, and, more generally, for things of its sort.¹⁰

Having made the distinction, Lowe is clear that he nevertheless thinks the two concerns are intimately related, which they surely are. He then goes on to deal with the problem of what persistence consists in, leaving aside the explanatory question. What the problem of pluck concerns—and what is typically absent in discussions of persistence—is the explanation of the existential side of the problem of persistence. For the most part, contemporary discussions of persistence ignore this existential aspect, assuming that the various objects-at-times that their theories range over are had for free, as if whatever defence is needed for those objects-at-times is not their concern. But the existence of the objects-at-times cannot fall outside of the scope of any complete theory of persistence. Persistence is concerned with the identity of objects—this is too intimately tied to their existence for an explanation of existential aspect to be ignored. Theorists who deal with persistence often act as if their

¹⁰ Lowe (1998: 108).

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endorsement of a given theory of time grants them the freedom to sidestep the explanatory question. This is most often the case for perdurantist accounts of persistence, because perdurantists tend to be eternalists, but the question arises for endurantists as well. Regardless of one’s views on time, questions of persistence should not be limited to just the problems of change or tracing. This way of thinking—according to which persistence and existence are distinct problems—perhaps results from the secular spin put on medieval and modern-era accounts of persistence. In times past, explanations of persistence and existence often went hand in hand, with God pressed into service as explanation for the existential aspect and persistence coming along for free.¹¹ With the move away from the medieval era came a move away from God as sustaining all the universe, and explanations of existence were effectively excised from theories of persistence. But removing God from the picture does not entail that we get existence for free; nor does it give us licence to stop asking the hard metaphysical questions. Once we reunite the various aspects of the problem, we can see that the problem of persistence concerns not just which objects count as the same objects, but how objects can exist at different times at all, and how they can do it with or without undergoing change. In the end, it is desirable if an account of persistence is sensitive to what produces the various objects at times, rather than ignoring the need to explain persistence. Just as answers to the problem of change need not be answers to the tracing problem (and vice versa), neither sort of answer tends to be an answer to the problem of pluck. For instance, even if we assume that perdurantism is true and objects are composed of temporal parts, we still have no explanation of persistence. What we have is a specification of the explicandum: the explanation needs to tell us how it is that objects are spatiotemporal worms with temporal parts, but that explanation is absent.¹² Endurantism draws a similar blank regarding pluck. That objects are wholly present at every moment of their existence tells us nothing about how this is so. That said, it should not be taken as a criticism of either view that they fail as solutions to the problem of pluck. They are not, after all, designed to be solutions to that problem, nor are they offered as such. The same holds for proposed criteria by which objects can be traced through time. If, for instance, being the same object over time requires that its stages satisfy the same sortal concept—that is, they must be the same sort of thing, such as being a cat or chair—then you have a handy way of connecting the dots.¹³ But it can only connect the dots, it cannot provide them, or tell you how they got there. It may well be suggested, especially by fans of the first two problems of persistence, that the question of pluck is not really a problem at all. It is, they might say, a pseudoproblem: the sort of question upon which no light can be shed. But this is to mistake philosophy for science. Metaphysics deals with the non-empirical aspects of our world. It is the task of metaphysics to deal with problems like this, even if the sciences offer little help. It is a real problem, and a hard one at that. And recall that our medieval forebears were in no way dismissive of this problem. They saw the need to

¹¹ Winkler (2011), Kvanvig (2014). ¹³ Wiggins (2001).

¹² Oderberg (1993: 112) raises a similar concern.

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explain persistence. The philosophical landscape has evolved since their day, but the problem remains. Why might someone deny that there is a real problem here? Beyond knee-jerk reactions to the unfamiliar, one might think the following: if four-dimensionalism is true—eternalism in particular—then there is no work left to be done in explaining the presence of the temporal parts. They might further note that the truth of fourdimensionalism needs defending, and so there is honest metaphysical work to be done there. And even when that job is done, the metaphysician needs to provide tracing criteria, and so there are two perfectly respectable tasks for the metaphysician to tackle. But there is no need to explain how or why the temporal parts are there, because those come for free with the truth of eternalism. It is true that eternalism gets us objects at times, but it is ultimately a theory about time, and not offered as an explanation of the existence of the objects or stages therein. As Lowe indicates, the explanation is likely to be causal. Having the parts is not the same as having an explanation for the continued existence of the parts. Recall the mosaic metaphor used in Chapter 2, and imagine you have that mosaic before you. You can look at it, you can trace patterns through it, you can even circle collections of tiles and call them ‘worms’, but you do not yet have anything like an explanation. The explanation concerns the nature of the relationships between the tiles (either individually or in groups) that dictate the pattern. You might envision this as an overlay: a clear plastic sheet we put over the mosaic that shows the connections between the tiles we could not previously see. This overlay describes the manifestation relations that groups of tiles bear to one another. (For the Armstrongian, the overlay describes the laws; the neo-Humean has a blank overlay that represents the fact that the pattern is random and brute.) Hopefully this will help you appreciate that even if you have very different ideas about the nature of the causal relata, there is nevertheless a place for robust causal connections in the fourdimensional manifold. What might be harder to appreciate is that the overlay represents metaphysical rules that are prior to the mosaic yet not temporally prior to it. I believe this to be a product of our experiencing the world in time. The present feels very real (and indeed, could be) and this makes it easier to think of causes as things that obtain in the present and that produce the next present. But those causes are still there even when all the world is before you, and even if there is no present. That all times are on equal ontological footing does not mean there cannot be (or are not) robust causal relations between the states. Adopting eternalism does not require one to reject theories of causation wherein states are causally necessitated by one another, and where some of those states explain the presence of other states, precisely because they are responsible for them. Armstrong saw this clearly, and was a proponent of both eternalism and a robust account of causation.¹⁴ And so there is a problem of explaining persistence even if you have already signed up for eternalism or fourdimensionalism.¹⁵ ¹⁴ Armstrong (1997). ¹⁵ Further ‘evidence’ can be found in the intelligibility of the standard creation story of Genesis 1. (This pushes the bounds of artistic licence, but bear with me.) On the first day, God is said to have created the

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This then is the primary problem of persistence to which the powers ontology shall be applied. But what of the solution? We will get to that shortly, after a little set-up. The set-up requires that we (1) set our sights on exactly the right target, and (2) develop a notion of ‘object stage’ that is neutral with regard to three- and fourdimensionalism.

8.3 Setting Sights and Setting Stages As stated, the problem of pluck is perfectly general, and can be raised for persons and pets as much as for molecules, computers, corporations, and minor-league baseball teams. But dealing with all those cases—not to mention the pluckiness of artworks and art houses, numbers and numerologists, sets and sensibilia, and so on—is more than one could hope to cram into a single book. Space alone demands we cull the herd. And cull we will, but not simply because space is at a premium. Here are two reasons that the account of persistence on offer will not (yet) be extended to other objects, and why it should not be generalized (not, at least, without exercising extreme caution). First of all, the primary focus in this book is with the fundamental physical objects, whatever they turn out to be. The discussion has been largely about their powers and their causal interactions, even if there are lessons to be gleaned about the entities they compose and macroscopic causation in general. The application of powers to the problem of pluck is no different: the focus is on the pluckiness of the physical simples. I am proposing an explanation of how it is that the fundamental physical entities persist. So, what are those things? The short answer is they are whatever our best physical sciences come to tell us are the fundamental existents; I leave it up to science to fill in the details. It does not matter for the theory what exactly they turn out to be, just as long as they are the fundamental physical ‘atoms’ from which all else is composed, and they are property bearers. If we find out that at bottom the universe is made up out of intersecting fields, then it is the fields that have the powers, and it is the fields that persist. Furthermore, the account appeals to the powers of the microphysical entities in question. Not much has been said about the powers of macroscopic objects, but when the discussion has gone that direction, it has been largely negative. I discuss this in Chapter 10, but the short story is that the powers we ascribe to the macroscopic entities are not genuine powers; they are indirect gestures at the constellations and possible manifestations the microscopic powers take on. This means that accounts of how macroscopic entities persist should not appeal directly to macroscopic powers, as, strictly speaking, they are not legitimate powers. This does not render an indirect account of macroscopic persistence in terms of powers impossible, but it could not be modelled on the account of microscopic persistence without modification.

heavens and the earth. With that task complete, He then took another five days adding to His creation until it met His satisfaction. Only on the seventh day did He finally rest. But if eternalism rules out robust causation, then card-carrying four-dimensionalists might wonder if they were severely overbilled. By their lights, God’s work was done after the first day, and He fraudulently charged for an extra five days.

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Secondly, there are good reasons for our being pluralists about persistence. That is, it seems that there is no ‘one size fits all’ answer to the problem of pluck. And if there are different solutions to the problem, then the present solution will not have general import, and there is no point treating it as if it does. Why think that persistence requires different solutions for different sorts of entities? Part of the thinking behind this pluralism comes from the ties that the problem of pluck has with the tracing problem. Start with an obvious case: consider what it takes to track a platypus over time, versus tracking the number 7. Both persist (or so we might assume), but whatever properties a thing has to have in order to count as the same platypus tells us nothing about what it takes to be the number 7 at any time. Now move to a putatively easier case: what can the criteria by which we trace a platypus tell us about tracing humans? Again, not much. Some facets of the account might translate, but surely not all. And that answer is the same even when we compare how we trace platypuses versus echidnas. Both are species of egg-laying mammals, but what it takes to trace a platypus through time will not tell us everything there is to know about tracing an echidna. Now consider a smaller example, that of a water molecule. A water molecule is made up of two hydrogen atoms and one oxygen atom, where each of the hydrogen atoms is covalently bonded to the oxygen atom in a roughly v-shaped configuration. Assume that hydrogen atoms and oxygen atoms persist by way of appropriate causal connections between their stages. However, just because the atoms persist in this way and are the material constituents of the molecule, it does not follow that the water molecule must persist in the same way, or that it persists just because those constituents do. Common sense tells us that the bond structure has to be maintained, which the mere persistence of its parts does not provide. In fact, persistence of exactly those token parts is probably not necessary for the molecule to persist. What counts as sameness for water molecules might be as simple as sortal continuity: the water molecule counts as the same molecule as long as it continues to fall under the kind water molecule, even if the atoms that make it up switch in and out. It is therefore prudent that we not carelessly extend what may work for physical simples to physical composites, or to such complicated entities as humans or echidnas. It might be replied that the explanations in one case would not always be useless in others. After all, platypuses and echidnas are both evolved biological creatures and egg-laying mammals, and so it stands to reason that something about the explanation of how both persist will involve some sort of biological story. That is correct—but it will not be the same story, and it will have nothing in common with the stories of how numbers or artefacts persist, nor how gods or molecules or baseball teams do. On the assumption that the number 7 persists, no part of that explanation will be biological. Nor will it be in any way physical, as with molecules. Baseball teams might involve a biological element—they are made up of humans, after all—but that cannot be the whole story, nor even the part that would seem to matter. And though the explanation of how the Mona Lisa persists is going to have a physical component, it, too, will not be the whole story. This has the convenient by-product of insulating the present solution from certain objections. For instance, a lot of our thinking about persistence is driven by our responses to thought experiments. We might ask, for example, if divine replacement

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of a person’s body constitutes a replacement of that person, or whether the same person can persist through such an ordeal. This helps us tease out our intuitions about the conditions for persistence, or at least what matters to us about persistence.¹⁶ But how we respond to these thought experiments can shift dramatically when the object in question changes. We have intimate knowledge of ourselves, and might worry that our impressions—from the ‘inside’—would rule out survival in the case of divine replacement. But we have no such relationship with water molecules, so might be perfectly content with molecules surviving similar replacement. The point is that not all persistence is equal, nor is our thinking about it. Hence, a certain thought experiment that generates intuitions about persistence may not apply to all cases. (And that is if the case can generate consistent responses at all, about which we might be sceptical.)¹⁷ The thrust of the last few paragraphs is that the account of persistence on offer is intended to explain the persistence of basic physical substances only. If it turns out that the explanation at the lowest level is suited for those above it, so be it, but confidence in the appropriateness of the account should go down considerably as the degree of complexity goes up. That covers the first part of the set-up; our sights are set. Now on to the second part, the setting of stages. We saw, in Chapter 6, that powers-based causation underlies change in the powers metaphysic. But to have explained how changes occur is not to have solved the problem of change. That problem is a very specific problem concerning the instantiation of incompatible properties at different times, and it is not my intention to offer a solution to it. As such, I will not be weighing in on whether objects persist by having temporal parts. My justification for not doing so comes from the fact that the powers metaphysic is compatible with all the standard responses to the problem of change: powers work just as well with temporal parts as they do with enduring entities.¹⁸ Powers are perfectly comfortable if there are temporal parts, and no less so if there are not. The powers metaphysic is neutral in this regard. With that in mind, the rest of this section presents a neutral way of talking about objects at times that can be used in discussing the problem of pluck (and can be paired with the standard solutions to the problems of change). In order to do that, I develop the notion of an object stage.¹⁹ Right up front I will indicate that this should not to be confused with the stage theorist’s notion of a stage, though the two clearly have a lot in common. For the stage theorist, a stage just is a very short-lived temporal part. The notion of object stage to be employed here can be conceived of as corresponding to stages, or to brief temporal parts more generally (and indeed should be, if one is working with the stage theory or perdurantism), but can just as easily describe enduring objects at some specific point in their career.

¹⁶ Perhaps none is more famous than Williams’s (1970) memory-switching cases. ¹⁷ Berniunas and Dranseika (2016). Then again, our scepticism might be misplaced: Nichols and Bruno (2010) find that intuitions in support of psychological accounts of personal identity are quite robust. ¹⁸ Pace Mumford (2009a), who would have you believe that powers are better paired with endurantism. See §9.3 for my reply. ¹⁹ In the spirit of Shoemaker and Swinburne (1984).

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To get clear on what is here meant by ‘object stage’, let us start with what Kripke called the ‘holographic state’ of the world.²⁰ The holographic state is the snapshot which captures the nature of all objects and their properties for any instant (a zeroduration temporal slice). We can liken this state to what you would find if the whole history of the universe was one long movie captured on film, and you considered just one frame in that film. The frame is an enormous, three-dimensional slice that includes the entire state of the universe at that moment. Now consider one of the objects in that frame. This state of the object is what is here meant by an ‘object stage’. (Well, almost: there is a wrinkle below.) Put together all such stages for that object, and you get the full extent of that object’s career. The precise ontological status of these object stages will vary according to the models of time and persistence one prefers, but are interpretable within each. For example, perdurantists and stage theorists will take them to be roughly identical to their understanding of the basic temporal parts, whereas presentist endurantists will see them as what exists on the knife-edge of the present (or what once existed, or will exist, on the knife-edge of the present, and that are only fictional or abstract for times before and after that knife-edge). Here is the wrinkle. That state of the object—the object stage, at just that temporal instant—may or may not be sufficiently thick as to instantiate powers, or to be the sort of state that will then produce a manifestation.²¹ That is, powers might not be properties that can be instantiated by perfectly instantaneous objects. (You might be worried that this is the case if you are worried that the possession of powers is like the having of certain thoughts, thoughts too temporally extended to be had at instants, or some similar worry.)²² If they cannot, then the object stages will not be instantaneous. They will be thicker, temporally speaking. How much thicker? Exactly as thick as they need to be to instantiate powers, and no more.²³ They need to be thick enough to instantiate powers, and thus thick enough to be causally significant (that is, capable of being constellations or spatial parts thereof). It might be the case that the causally significant states are instantaneous; there is very little for us to go on here, and so the issue is best left open. It is, after all, relatively harmless for us to allow the object stages to be non-instantaneous, if that is what they need to be. In any case, make these states just as thick as they need to be such that they are causally significant states. If, by analogy, that takes several frames of the film, then so be it. (They will also be of uniform thickness. That is, whatever ‘width’ the instantiation of powers demands of their bearers will not vary between power types. If this were not the case, we could have problems of coherence: not only might powers fail to correctly line up with each other in the formation of constellations, there could be manifestations produced that were incompatible with the out-of-sync powers.)

²⁰ Kripke uses this term in a series of 1978 lectures entitled ‘Time and Identity’. See Shoemaker (1984). Given the relativity of simultaneity, the holographic state is probably a useful fiction. ²¹ Or will have produced a manifestation. I hereafter ignore the shifts in locution required to capture the appropriate status of the object stage relative to what, at that exact moment, does or does not exist. ²² See Brink (1997). In the case of thoughts, one might deny that these are intrinsic properties of person stages; see Hawley (2001: 65). The same response could not be used here. ²³ This point gets more discussion in §9.3.

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As you have likely noticed, speaking of ‘object stages’ has a perdurantist/ stage-theoretic ring to it. This is, however, no objection to our treating the notion as fully neutral. It just happens that we are short of ways to capture objects at various moments in their careers that do not sound as if we are taking those moments to be parts of four-dimensional entities. But we can hardly allow the four-dimensionalists to hijack what is a perfectly good way of speaking about objects at times. A threedimensionalist is at liberty to speak of objects at times, even if she might believe those times to now be unreal. More surprisingly, it could be that greater opposition to the neutral notion of object stage comes from the four-dimensionalist camp, precisely because it comes too close to their notion of a temporal part without necessarily being identical. This problem could arise if the object stages come out ‘thicker’ (of greater temporal extent) than some folks take temporal parts to be. But being thicker—if indeed they are—is not a serious problem. For starters, not all proponents of temporal parts take them to be instantaneous. C. D. Broad and Russell both denied that temporal parts could be instantaneous, yet understood persisting objects as composed of temporal parts.²⁴ And Lewis and Heller—four-dimensionalists par excellence—both embrace non-instantaneous temporal parts.²⁵ Second, one of the primary reasons for thinking that temporal parts are instantaneous (by those who do) can be traced back to the theoretical need for temporal parts to be able to satisfy possible changes. Case in point, Hawley argues that temporal parts must be instantaneous on the grounds that they must be short enough to accommodate possible—and not just actual—changes an object could undergo.²⁶ When understood within the neo-Humean metaphysic, this need produces a demand for instantaneous temporal parts. Thinking about this in terms of a vast mosaic of point-like property bearers, the range of possible changes comes out as fine-grained as time itself, and thus the temporal parts need to be instantaneous. But within the powers metaphysic the need is met differently. We can thus agree with Hawley that temporal parts need to be short enough to accommodate all possible changes. That is how persisting objects can instantiate not just those incompatible properties they in fact do, but those they could have done, during stretches of time where they persist unchanged. But accommodating possible changes does not itself require that temporal parts be instantaneous, only that they be as short as the account of change requires them to be. For a neo-Humean, that account permits instantaneous differences in the state of the world. As no state is required to be spatially or temporally located next to any other (à la Hume’s Dictum, see §2.2), you can have anything popping up at any time. However, when change involves the exercise of powers, the possible changes will require object stages that align temporally with the time powers require of their bearers to be instantiated. Within the powers metaphysic, there is no conceptual space for the exercise of powers to fail to line up with possible changes, because they

²⁴ Russell (1915), Broad (1923, 1925). ²⁶ Hawley (2001: 48–53).

²⁵ Lewis (1976: 77) and Heller (1990: 11).

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are the source of the possible changes. Hence, whereas neo-Humeans will reasonably claim that temporal parts can be as short as zero-duration instants, their motivation for thinking this gets cashed out in a way the friend of powers does not endorse. And so the thickness of the power theorist’s temporal parts could be thicker, even if it turns out that they are not. Hence, there need not be any worrisome near-miss mismatch between object stages as here understood and temporal parts as understood within the powers metaphysic. To reiterate, if it turns out that constellations have to be relatively temporally thick in order to be able to produce manifestations, then that is the thinnest that an object stage can be. And though we can imagine a possible change in properties during that interval (at the halfway point, say), what we have imagined is not a legitimate possibility. What is possible—as far as change is concerned—is dictated by the operation of the powers. And so regardless of how thick or thin the object stages turn out to be, they remain as finely grained as possible change, thereby satisfying the desideratum by which the neo-Humean object stages come out as instantaneous. One might worry that this could compromise translation between the object stages as here understood and the notion of temporal part. But it should not, as those temporal parts (and that is if they are shorter, which they might not be) are still present. As far as the powers theorist is concerned, those parts can still be there, only some of those parts (or groups of them) are aligned with the causally significant states; the others are innocent mereological abstractions. When it is powers that are responsible for change, they will dictate which are the significant states and temporal parts. If there are temporal parts between the object stages, such that the world is carved into states smaller than those dictated by the mechanism of change, those smaller states will be causally insignificant. We can compare this innocent notion of temporal part with its spatial analogue. There is a perfectly natural sense of (spatial) ‘part’ that corresponds to the material occupants of any given spatial region. Consider a random circular region within my chest cavity. Anyone ought to admit that such a part exists. As I am suggesting of the temporal case, few would be willing to admit that these parts have properties unique to them, have sortal predicates that apply to them, or, most importantly, are in any way causally significant (independently of whatever respectable parts they might overlap), and so on. But these are parts, even if not interestingly so. I take it that any intervening parts or states found between the object stages that make up the constellation–manifestation pairs would be parts or states of exactly this sort. But all this, recall, might be for naught. There is no reason why operational constellations could not be had by instantaneous stages; we are simply covering ourselves in case the facts happen to be otherwise. As a final word about the neutral use of ‘object stage’, there are folks who deny that there is anything ontological at stake in the debate over the existence of temporal parts. They claim the debate is purely verbal. Right or wrong, this anti-debate position would be a non-starter if those for and against temporal parts lacked the means to speak about what the anti-debate folks claim is the same thing.²⁷ It would

²⁷ Miller (2005), Lowe and McCall (2006), Hirsch (2009, 2011).

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thus be odd if we were not allowed to employ a neutral notion. But even for those who take the ontological credentials of the debate seriously, there are no good reasons to reject a neutral terminology. Thus, we should be safe talking about object stages without committing ourselves to the existence or denial of temporal parts. In the mouth of the perdurantist, ‘object stages’ will sometimes (if not always) refer to temporal parts, likewise for the stage theorist; when the endurantist speaks, they will be the states of objects at times.

8.4 Sensible Three- and Four-Dimensionalism Ted Sider tells us that the ‘sensible’ four-dimensionalist will posit causal connections between temporal parts of persisting objects that account for the existence of those temporal parts.²⁸ The current temporal parts, he says, are ‘caused to exist’ by those that came before them. This, I propose, is the best way to explain persistence.²⁹ But it is not just the four-dimensionalist who wants a sensible account of persistence: the three-dimensionalist wants her account of persistence to be sensible, too. And so it will be, just as long as the three-dimensionalist explains the continued existence of persisting objects via those same causal connections. (Recall that the threedimensionalist believes that the various object stages that make up an enduring object will be numerically identical, but though this tells us what the object’s persistence consists in, it does not explain it. That is why the causal connections are needed.) After all, though Sider speaks of temporal parts specifically, it is clear that his point has wider application, and could just as well have been expressed in terms of neutral object stages. Sensible persistence thus calls for causal connections, and the powers-based explanation of persistence is sensible in exactly this way. Current object stages are manifestations (or parts thereof ) produced by the actions of the powers of their immediately prior predecessor object stages. Hence, using the neutral framework just proposed, the explanation of persistence for three- and four-dimensionalists alike comes down to object stages giving rise to successor object stages as part of the manifestations they produce. Whether or not they constitute entire constellations or manifestations unto themselves, power-bearing object stages are a key ontological ingredient of powers-based causation. And though we routinely look past the property bearers to the power properties themselves, especially when we conceptualize constellations and manifestations, those object stages are right there in the mix. And as powers are exercised, the object stages that bear those powers give rise to further object stages because of those self-same exercisings. For the perdurantist, then, the persisting entity is identical with some fusion of these causally connected object stages. The same is true (mutatis mutandis) for the stage theorist.³⁰ And for the endurantist, though the ²⁸ Sider (2001: 217). ²⁹ It might also be the only way to explain persistence. What other relation could play this explanatory role? ³⁰ The stage theorist takes the stages to be ontologically fundamental, but persistence is nevertheless achieved via composition or a nearby relation.

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persisting entity is that which is wholly present at each moment of its existence, even as the now existing constellation gives way to the now existing manifestation, its full career spans the extent of all its object stages.³¹ And how better to do that than to have that process grounded in the series of constellation–manifestation pairs? That, in brief, is how persistence gets explained within the powers metaphysic. It is how powers give us pluck. Let us look a little closer. Manifestations are states of affairs (§6.3). That means that in the relevant cases— those that ultimately count as instances of persistence—we have manifestations that are nothing more (or less) than objects instantiating properties.³² We thus have states of the world (including various object stages) giving rise to new states of the world (including new object stages), and so the explanation of persistence is right there in the ways in which powers are exercised. The states are of whatever temporal extent is the minimum needed for objects to instantiate their power properties. That might be an instant, but could be longer. They thus line up with the neutral object stages of the persisting objects. (Of course they do—the latter was built that way!) Within those states are the various constellations that produce the manifestations. And within these constellation–manifestation pairs we find the succession of object stages that gives us the plucky aspect of persistence. In essence, once we have the full picture of powers-based causation before us, we find that we have the explanation of persistence, too. With powers-based causation we get pluckiness for free. So, how do microscopic objects persist? By having later stages created by present ones. That is it. It is, by and large, a rather simple solution, but elegant, too. But that simplicity did not come easily. It is not something you can do without the right sort of properties or the right account of causation. The solution here only gets to be simple because of the complexity of powers-based causation. Part of that complexity is what is missing in many other accounts of causation. We already know that genuine production is absent in the leading accounts of causation, and many ‘oomphy’ accounts nevertheless cut objects out of the causal story. Putting them back in is important to the present understanding of powers-based causation, and it is what makes explaining persistence a relatively simple task for the powers metaphysician. The exercising of powers gives us the constellation–manifestation pairs—and therefore the procession of object stages—on which object persistence relies.³³ That provides the core of the solution to the problem of pluck. But there are plenty of questions regarding this account and this aspect of persistence that have yet to be answered. One question concerns the sorts of constellations involved in explaining persistence, and the potential role that immanent causation plays.

³¹ Here again we are skipping over the thorny details of the varying ontological status of non-present object stages. See Bigelow (1996), Keller (2004), Bourne (2006), and Crisp (2007) for some of the options. ³² Manifestations also include such states as objects going out of existence. Those will not be cases of persistence. Nor are they really states of affairs, as here understood. We will therefore need to widen our understanding slightly, allowing that produced voids count as an outlier case of states of affairs. ³³ The problem of pluck is only one of the problems of persistence. The account on offer provides a solution to pluck, but is not—without augmentation—an answer to the other problems of persistence.

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It is one thing to recognize that we get object stages as part of the manifestations, but it is another to say what the object-stage-producing constellations are, and whether they are special in some regard. As far as their being special, the short answer—though neither completely illuminating nor completely true—is no, they are not special. Every manifestation is a state of affairs, the great majority of which are a matter of some object stage’s bearing some properties. This is standard operating procedure for the exercising of powers, and so, for the most part, there is nothing special about the constellations required for the existence of the object stages. But there are some limit cases that need a bit of special handling, as we see when we consider the size of the constellations involved. Size matters because—prima facie— persistence feels like a different beast if the powers involved are spread out over a series of different objects, rather than restricted to a single object. In other words, something needs to be said about the difference between the immanent versus transeunt cases of causation. And then there are the matters of static versus dynamic manifestations, and of cooperative versus unilateral ones, too.³⁴ Let us start with a ‘middle’ case of causation, that in which the powers of multiple objects jointly produce a manifestation that differs in type from the constellation that produced it. This is a transeunt and dynamic case, and it is perhaps the most familiar sort of case discussed in the causation literature. Consider: two microscopic objects repel one another. This is a transeunt interaction that results in the dynamic manifestation of the two objects moving away from one another. From the perspective of creating successor object stages, this case is completely straightforward. We have a constellation that stretches over two object stages, and it produces a manifestation that also stretches over two object stages. We thus have a causal explanation of the object stages we need for persistence. (But which, you might ask, is which? What makes it the case that the particle on the left continues to be the particle on the left, and not the one on the right? This is a legitimate concern, but it belongs to the tracing problem, not that of pluck. I consider it below in §8.5.) Our middle case was dynamic, but would it have mattered any to the persistence of either particle had the manifestation been static—that is, type-identical with the constellation that produced it? Not in the least: what is relevant to pluck is that new manifestations are being produced, not what powers are instanced in those manifestations. Just as we conveniently ignore the objects when we visualize constellations and manifestations, we can similarly ignore the properties when thinking about pluckiness. Part of accounting for how something can remain the same throughout change requires explicating the mechanism for change. That mechanism is the same if there are changes or not. Hence, from the perspective of pluck, explanations of change and non-change are the same. Transeunt causation is unproblematic. Let us therefore shift to a case of persistence via immanent causation, wherein the powers of the constellation are restricted to a single particular. When it comes to instances of causation, immanent causation is rarely considered the norm.³⁵ But as far as persistence and pluckiness are concerned, ³⁴ As presented in Chapter 7. ³⁵ It is an open question what portion of causation is legitimately immanent. If there is just one huge object in the universe, then all of it is.

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there is nothing unusual about this case at all. Armstrong hardly seems to find it unusual that a form of immanent causation may be involved in the way that an electron, which may be a simple particular, one having no parts, goes on existing and retains the same mass, charge and absolute value of spin while it remains in existence.³⁶

He is not alone.³⁷ Powers-based immanent causation involves the powers possessed by a single particular giving rise to a manifestation that is that self-same particular and its properties. Let us assume that the powers of the manifestation are type-identical with those of the constellation. (It is thus a static manifestation, too.) I take it that this is the sort of case Armstrong has in mind when he speaks of an electron continuing to exist with all its properties intact. Let us further assume that the relevant constellation is a cooperative one (internally speaking), involving all the powers of the object. This is the baseline immanent case; now we can complicate things a little. The first complication involves replacing the static manifestation with a dynamic one. In other words, we assume that the constellation is still made up of powers had by just the one object, but that they now give rise to an object stage that has different properties than the original. Qua pluckiness, this case is no different than the first. As long as the dynamic manifestation is one in which the object is present—that is, it is not an explosion or the like—the addition or subtraction of various properties has no bearing on the object’s pluckiness. There is an object stage in the original state, and another in the manifestation. Hence, destructive cases aside, the static versus dynamic manifestation distinction has no bearing on pluck. Is shrinking the size of the constellation similarly insignificant? Given our understanding of powers-based causation, we should expect that even in the immanent case any power possessed by an object stage will interact with the other powers had by that stage for what is a joint constellation, making the cooperative immanent causal case (more or less) the limit case. Unless we believe that fundamental particulars possess just one power (a highly multi-track super-power), then the unilateral case is off the table.³⁸ Nevertheless, it could be the case that many of the powers possessed by the object contribute to the constellation without being difference-makers. That is, it could be that their presence or absence affects only the manifestation token, not type. If there was only one difference-making power, it would resemble a unilateral power: it would be a quasi-unilateral power that brings about the manifestation that is the object stage and all its powers. We need not see this single difference-making power scenario as particularly likely, but nor can we rule out its being that case that despite the many powers an object has, it is some single power that is the difference maker vis-à-vis the object’s persistence. We might think of it this way: there are many powers that combine with this quasi-unilateral power to form constellations that produce successor object-stage manifestations. These other powers can come and go,

³⁶ Armstrong (1997: 74). ³⁷ See Zimmerman (1997a), Hawley (2001: ch 3), Balashov (2003a). ³⁸ We should not believe this. See §4.2.

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but the same manifestation will still be produced. We could even add that the presence or absence of these other powers will change the manifestation produced, as long as the persistence-relevant aspect of those manifestations—the presence of the object stage in the manifestation—continues to be produced. By contrast, the quasi-unilateral power would be a necessary constituent of any constellation that produces a successor object stage. Returning to the question, does the account of persistence in the powers metaphysic suffer if it turns out that objects possess a quasi-unilateral power whose presence is required for persistence? Not as far as I can tell. If anything, it would only serve to strengthen the account. If there is some special power involved, then persistence would largely depend on the presence or absence and actions of that power. Hence, the model is no different even if very few powers—or just one—are the key powers in the constellations. I tend not to see the quasi-unilateral power case as the right model, preferring a picture wherein many powers work together and no particular one is any more or less essential than any other. But let us dwell on the idea of a quasi-unilateral power for just a moment. For the most part, naming powers is unwise. The main reason is that there is a long tradition of naming powers according to the manifestations they can produce, and this does not square well with multi-track powers. Consider all the manifestations a power is capable of producing in different constellations, and you have a name that has no practical import (and makes the name of that village in north Wales sound downright terse).³⁹ Highlighting just one manifestation type from that large set makes for a grossly misleading name, and so is best avoided. But for this one case let us throw caution to the wind and do it anyway. If there is a special power on which persistence relies, then despite all the other things it probably does, we could do a lot worse than naming it the ‘power to persist’.⁴⁰ Objects with the power would go on existing; those without it would not. As I have said, I do not think there is such a thing as a quasi-unilateral power that objects have that (largely) explains their power to persist. A more sensible picture is one in which many powers have many manifestations, many of which result in object persistence. Hence, there are many powers whose manifestations count as instances of object persistence. If there were a single power that was the power to persist, what would stop it producing successor object stages in other objects? Or stranger yet, could pairs of objects get their persistence wires crossed and be the cause of each other’s persisting? That such a power should exist need not produce such far-fetched possibilities, but who is to say what weird and wondrous things could be the case if such powers exist? That is the story behind pluck; let us quickly take stock. Causal accounts of persistence are not, for the most part, new or unexplored territory. Sider clearly thinks that causation has a role to play in persistence, as do Hawley, Armstrong,

³⁹ The village’s name is ‘Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch’. Those without a Welsh background are cautioned against attempting to pronounce it. ⁴⁰ This suggestion gets more discussion in Williams (2005). See also Unger (2006).

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Shoemaker, Swoyer, Broad, and Russell, to name just a few.⁴¹ But the causal accounts in the extant literature—even those that employ a notion of immanent causation— typically do not deal with explanations of persistence (pluck), in that they frequently assume the existence of the object stages that they connect causally. Case in point, as friendly as Sider’s quotation in the epigraph is to my own project, he himself must take it with a grain of salt. Sider’s underlying framework is neo-Humean, meaning that the causation involved cannot be of the sort that genuinely produces the subsequent temporal parts, in the oomphy sense of production we have been using. I thus have a hard time squaring what Sider says in the quotation with other views he holds. Perhaps it was written in a brief moment of neo-Humean doubt? His picture is that of ever-so-many pre-existing temporal parts united by some sort of causal glue. To borrow Hawley’s language, causation provides ‘suitable relations’ for ‘sticking stages together’.⁴² Hawley suggests we stick the stages together with non-supervenient glue; this fares better than any supervenient alternative, but still falls well short of causing the parts to exist. It follows that views like this fail—strictly speaking—to satisfy Sider’s criterion for being sensible. It would be something of a stretch to conclude from this that neo-Humean accounts of persistence are uniformly nonsensible, but there is no denying that the neo-Humean is hard pressed to square the standard neoHumean accounts of causation with the literal ‘causing to exist’ of temporal parts by their predecessors.⁴³ By way of contrast, the powers theorist employs causation in accounting for the very existence of the stages themselves. Powers-based causation literally causes the object stages to exist—be they temporal parts, stages, or merely phases through which the objects pass.

8.5 Plucky Streaks Recall the two-particle transeunt case from above. A constellation that included both particles produced a manifestation that included two new particle object stages. This is pluckiness in action: it explains the persistence of the two particles by explaining how it is that the successor object stages come to be. But which is which? Any complete answer would take us beyond pluckiness and into tracing. In fact, a full account of powers-based persistence would require that we now go on and consider not only what it is that lets us trace persisting objects over time, but also whether or not they require temporal parts to accommodate changes in their intrinsic properties. Unfortunately, doing so would take up more space than we have. But more importantly, it would force us well into non-neutral persistence territory, as one could not hope to deal with those matters without taking on the commitments of either threeor four-dimensionalism, and that is beyond the scope of this book. It is a worthwhile ⁴¹ Broad (1925), Russell (1948), Shoemaker (1979), Armstrong (1980a, 1997, Swoyer (1984), Hawley (2001). ⁴² Hawley (2001: ch. 3). ⁴³ Perhaps the nearest rival to the powers-based account of pluck is one that uses strong (DTA) laws of nature to explain the existence of later object stages. See Armstrong (1997: 74), who agrees that ‘the actual bringing into existence of later parts by earlier temporal parts’ is a necessary condition of persistence.

 

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exercise, but one best left to the reader. Or mostly left to the reader: I will help by getting the exercise started. The tracing problem asks what it is that makes two temporally distinct object stages parts of (moments in the career of ) one and the same persisting object. If you are an endurantist, the answer is simple: it is identity. α-at-t₁ is part of the same persisting object as is β-at-t₂ because α and β are numerically identical. Hence, for the endurantist, our two-particle tracing problem is not much of a problem at all. There is a fact of the matter—a metaphysical fact about identity, not reducible to other facts about the object stages—in virtue of which they are object stages of one or the other persisting particles. Granted, this is of little practical import, but that was never the name of the game. All that tracing requires is the criteria by which object stages constitute parts or moments of a persisting object; identity is the endurantist’s response. But for everyone else there is the task of spelling out the details of the ‘gen-identity’ relation: the lesser-than-identity relation that provides the principles of unity for connecting object stages. Pluck gives the object stages, but gen-identity tells us which ‘plucky streaks’ count as existential runs or world-lines of the same object.⁴⁴ Common responses call for spatiotemporal continuity between the stages, and/or the need for the stages to be the same sort of thing (thus answering to the same sortal term).⁴⁵ In other words, two consecutive object stages cannot be separated by much of a temporal gap (probably none), nor any great spatial distance. The faster that object is moving, the greater that spatial distance will be. And they cannot be so different as to count as members of different kinds: permissible differences must be those that are irrelevant to kindness, including the changes an object might undergo during its lifetime, such as the switch from larval to adult form. But perhaps no response to the tracing problem is more common than that according to which the stages must be connected by some sort of causal relation (probably in conjunction with the other responses).⁴⁶ Our two particles (four particle stages) have that. In fact, without adding anything to the case at all, we can see that all three criteria are satisfied: the pair of particles are causally connected, they satisfy the same sortal, and they are as spatiotemporally contiguous as one could ask. But the problem remains: it is as yet undetermined which is which. There are a number of conclusions we might draw from this, but the most obvious is that the criteria on offer are not sufficient for tracing.⁴⁷ They might all be necessary (I hazard they are), but even jointly they are not sufficient. Not—at least—on the assumption that there are two persisting particles. Perhaps the mistake was thinking that there were two things here at all. Maybe we got the objects wrong. If not, something more will have to be added—some extra criterion—but I am in no

⁴⁴ Russell (1948: 487) refers to the careers of objects as ‘causal lines’, whereas others—particularly those in physics—typically speak of the ‘world-lines’ that map the position of an object over time. See the discussion in Oderberg (1993: ch. 4). I prefer to think of them as ‘plucky streaks’. ⁴⁵ See Hirsch (1982) for a defence of the former, and Wiggins (2001) for the latter. ⁴⁶ Kolak and Martin (1987: 339) write that causal accounts are defended by most ‘leading contributors to the current literature on personal identity’. We can assume this extends to non-persons. ⁴⁷ Others include: brute underdetermination about persistence; vagueness; conventionalism; and even scepticism about transeunt persistence.

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 

position to say what that is (or to say whether or not it could differ according to context). By contrast, the same problem does not arise in single-object immanent causation cases. That is not because it is a case of immanent causation, and therefore restricted to the line (streak) of a single particular, as that would be question-begging. Rather, it is because the lack of competition renders the above criteria sufficient for persistence.⁴⁸ What more could be required? This ought to be plenty of grist to your tracing mill, and more than enough to get you started on your powers metaphysic persistence homework. Let us, therefore, turn our attention to some of the powers-specific problems this view of persistence might face.

⁴⁸ Nozick (1981).

9 A Dormitive Virtue? 9.1 Objecting to Powers-Based Persistence Bachelierus: I am asked by the learned doctor for the cause and reason that opium makes one sleep. To this I reply that there is in it a dormitive virtue, whose nature is to make the senses drowsy. Molière, Le Malade imaginaire, 1673

I have argued that powers can help us explain the persistence of microphysical particulars. The account tells us how it is that objects persist, and provides a necessary (yet probably not sufficient) tracing criterion that takes us beyond the regular ‘connect the dots’ accounts of persistence by offering a story about how the dots are there to be connected in the first place. But philosophy being what it is, and philosophers being as they are, there are sure to be many readers who are sceptical about the account on offer. This chapter is an attempt to assuage some concerns about the view. These powers are, after all, being employed in ways that few would have anticipated. And if there are quasi-unilateral powers to persist, then we are talking about some very odd powers indeed. They certainly are not the typical powers of everyday discourse. The lion’s share of the chapter is taken up with considering the most general objection to the account: namely, that powers simpliciter cannot be explanatory, never mind strange powers for persistence. For instance, we can imagine someone asking: ‘Is this any kind of explanation at all? It looks far too easy . . . Where we have some phenomenon to be explained, we cannot simply say that there was a power to create it, and accept that as an explanation.’¹ This is a long-standing objection to the explanatory credentials of powers, claiming that they are mere virtus dormitiva (dormitive virtues), styled after Moliere’s joke about the ‘wise’ student who explains that opium makes one drowsy because it has the power to do so. If successful, this objection would undermine the claim that powers can be used to explain persistence. In light of this difficulty, most of the chapter is dedicated to the debate over powers and explanation to see what, if anything, can be said on behalf of the explanatory credentials of powers-based persistence. Once that objection is dealt with, I consider three other objections, concerning: how well powers fit with temporal parts; the production of object stages; and the possibility of atomless gunk. ¹ Mumford (2010). This is how Mumford responds to Unger’s (2006) suggestion that there might be powers to persist. The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

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   ?

9.2 The Objection from Dormitive Virtues In the case Molière describes, a doctoral candidate undergoes oral examination by a group of learned doctors to determine if he is worthy of joining their ranks. When asked by the doctors for the cause and reason that opium makes one sleep, he replies that it possesses a virtus dormitiva: that is, a power whose nature is to cause sleep. The doctors are most pleased with his response, and he is sworn in.² Quite some time has passed since Molière penned his famous mockery of powersbased explanations in Le Malade imaginaire, but old habits die hard. Some 300 years later we find Molière’s attitude towards powers is still the majority view, as evinced in Dennett’s remarks on the matter: ‘there can be no doubt that convicting a theory of relying on a virtus dormitiva is fatal to that theory.’³ These are hard words to swallow for any powers theorist, but for someone who employs powers in the explanation of object persistence, the sting is particularly acute. Even if we restrict the range of explanations to just the causal ones, wherein the aim is to elucidate the causal process that produced the behaviour in question, powers-based explanations are still considered poor.⁴ It follows that anyone who wants to make use of a powers-based explanation owes the objectors a response. Most of us have at least a passing familiarity with the objection behind Molière’s joke. But responding to the objection demands a more intimate knowledge of its inner workings. Let us ask, then, what exactly is the dormitive-virtues (DV) objection, and what is so bad about it for powers-based explanations? At its most primitive, the objection complains that citing that an object possesses a disposition to φ in order to explain some activity or behaviour φ (in which an object, or instances of an object type, engages) fails to constitute an adequate explanation of why φ occurred (or why the object φ-ed). But there are a number of ways this objection can be fleshed out. Here I present three interpretations of the DV objection.⁵ The list of interpretations aims to be exhaustive but not to avoid overlap. For now, I will simply present the interpretations, leaving the responses for the next section. But first a word of caution. Though targeted at dispositions, it is clear that the DV objection is intended to apply to powers, too, or would be taken to apply, intentions aside. In fact, most objectors fail to see any difference. But here we have been working with a distinction between powers and dispositions, the former being the fundamental properties at the core of the powers ontology, the latter being something more like handy ascriptions we apply to objects, regardless of size. Hence, though the distinction is not one the objectors recognize, it is important that we do—as the ontology under consideration is one based on powers, not dispositions. Moreover, not all versions of the objection apply to powers. I will, therefore, state the objections as if

² Molière (1926). Powers were referred to as ‘virtues’ by the medieval philosophers Molière mocks. ³ Dennett (1981: 57). ⁴ See Salmon (1984) and Lewis (1986d) for what counts as a causal explanation. ⁵ Much of what I understand as interpretations of the DV objection, Mumford (1998) sees as distinct objections to powers-based explanation.

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they all apply equally to powers, but where the powers versus dispositions distinction is relevant, I will adjust the objection as needed. (i) Triviality. One central interpretation of the DV objection—perhaps the central interpretation—is that the postulation of powers to explain various behaviours is trivial. The purported triviality arises from the perceived circularity of the power ascription: it is not uncommon to arrive at power ascriptions via a process of reverse engineering, working backwards from the behaviour to be explained. Having observed some activity or behaviour φ in which an object (or instances of an object type) habitually engages, we work backwards to ascribe to the object(s) the power to φ. This ascription procedure provides no new information about the behaviour in question, and therefore, as the postulation of the power is uninformative, it is deemed non-explanatory. This objection can be levelled against powers, but only in so far as they align with the reverse-engineered ascriptions. I have warned us against identifying powers this way, but the procedure is less out of place for dispositions. (ii) Impotence. The second interpretation of the DV objection complains that postulating powers cannot be explanatory because powers are second-class properties at best, and therefore not genuinely causally operative or relevant. According to Salmon, ‘[t]o provide an explanation of a particular event is to identify the cause and, in many cases at least, to exhibit the causal relation between this cause and the eventto-be-explained.’⁶ Similarly, Lewis writes, ‘to explain an event is to provide some information about its causal history’.⁷ If the central aim of causal explanations is to elucidate the causal history of a fact or an event, then it is pointless to cite properties that fall outside the causal nexus. In Molière’s day, the distaste for so-called ‘occult’ scholastic powers was so great that powers were not afforded even second-class status. The opinion of the day was that there were no such properties, and therefore no way that they could possibly be the causes of anything.⁸ If powers cannot be parts of causes, there is no question that explanations that treat them as such should be found wanting. Even in more contemporary and seemingly tolerant ontologies, wherein powers are identified with a categorical property base in the presence of the laws of nature, the causal heavy lifting remains the job of the laws, and so talk of powers still has no place in good causal explanations.⁹ To suggest otherwise would require treating the power properties as also being causal (in addition to their categorical property and laws counterparts), resulting in what Mackie aptly dubs ‘gratuitous multiplication’.¹⁰ As ought to be obvious by now, it is far from uncontroversial that powers cannot be causes or causally relevant. But for a host of popular ontologies—neo-Humean ones especially—powers are mere shadows cast by categorical or structural properties in the glow of the laws of nature, and therefore causally impotent. As shadows are incapable of producing the effects we initially credit them with having produced, they do so in name only. Hence, if powers are outside the causal network, no mention of them belongs in causal explanations. ⁶ Salmon (1984: 123). ⁹ Armstrong (1997).

⁷ Lewis (1986d: 217). ¹⁰ Mackie (1977: 104).

⁸ Hutchinson (1991).

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   ?

(iii) Reductivism. The third and final interpretation of the DV objection is born of the mechanistic approach to explanation, according to which good explanations require a downwards shift in granularity. The phenomenon in question—and thus any putative powers-based explanation—is to be reduced. In effect, when power ascriptions are apt, the effects to be explained and the powers are both ‘black boxes’ that must be opened to be explained. We must describe the actions and interrelations of the component parts to understand the behaviours of the whole. Powersbased explanations operate at the black-box level, and therefore they cannot be explanatory. This attitude towards explanation typifies the thinking of the early modern philosophers, who were so strongly opposed to the medieval ‘virtues’ they had inherited from the scholastic tradition. At the hands of Descartes, Boyle, Newton, and others, explanation shifted in a mechanistic direction: explanation required pulling back the curtain to expose the mechanism beneath. Power ascriptions were surface-level illusions tied to nominal explanations; it was behind those illusions, in the structures and workings of the micro-components, that the real explanations were to be found. This attitude continues to dominate: ‘discovery and presentation of the mechanism is what really does the job of explanation . . . Scientific research is in large measure a search for the natures from which causal powers flow.’¹¹ According to this reductivist form of the objection, behind every cheap power ascription lies a lower level of categorical properties plus laws, and with them lies a respectable explanation. Presenting the mechanism behind (or better, beneath) powers and their effects is typically achieved via a reduction; the power and its manifestation are frequently described as nothing more than the law-like behaviours of smaller constituent entities. It is those entities, and whatever categorical qualities they possess, that explain the actions and powers of the whole of which they are part. For instance, the explanation of a sugar cube’s dissolving in a cup of unsweetened hot tea is to be put in terms of the molecules that compose the cube, and not the cube itself or its solubility. This form of the objection goes hand in hand with a general attitude concerning explanation that pushes us to examine more closely, to seek out constituents, and to be generally reductive in our efforts at explanation. This attitude is sufficiently forceful that it seems appropriate to speak of it as an impulse—the ‘reductive impulse’. It is this impulse that lies at the heart of the third interpretation of the objection. Unlike the first two versions of the objection, it is hard to see how this version applies to powers and not just dispositions. Powers are already at the base level; they are not black boxes to be opened. One might object that the fragility of a glass is not explanatory because it gives way to a more basic mechanism (and, ii–v below notwithstanding, I would agree), but the same cannot be said of fundamental powers. It is thus important that we recognize that the reductive impulse is behind this version of the objection, but it cannot be the basis of a direct form of objection to powers-based explanations (properly understood).

¹¹ Michon (2006: 143). See also Armstrong (1973: 15–16).

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Having considered the various ways the DV objection can be understood, let us turn to some responses, with the aim of determining which, if any, can be adapted to our present needs. As might be expected for an objection of this magnitude and antiquity, there are a variety of responses in the literature. I will run through the best of them, but I start with the one most appropriate to the present discussion. As we will see, it provides the most promising reply to the DV objection that can be offered from within the powers metaphysic. That is because, unlike the others, it is the one that most clearly resonates with the framework-relative, and ontology-relative, stance that has been employed throughout the book. Recognizing these restrictions, and what they mean for causal explanations in general, is key to vindicating the explanatory credentials of powers for persistence (and in explicating what is wrong with the objection). The remainder of the responses are either ontology-blind or skewed towards the neo-Humean ontology. They are nevertheless worthy of our attention, as there are ways that powers or dispositions can be (somewhat) explanatory even within the neo-Humean framework. Granted, the explanatory force of dispositions and powers is diminished when the ontology is ultimately neo-Humean, but it is important to register that they fare much better than the DV objection would have us believe. (i) Ontological relativity. Causal explanations involve elucidating those events or processes that produce the effect in question. As the constituents of that causal history are ontology-relative—that is, the causal facts reflect whatever ontology actually obtains—so, too, is causal explanation. One can see this assumption at work in the ‘impotence’ interpretation of the DV objection. Neo-Humean ontologies countenance laws and categorical properties but treat powers as second-class. Powers are therefore not proper parts of causes, and so do not figure in good explanations. But this ontological relativity of explanation cuts both ways. If the correct ontology grants powers full status as causal properties (as the powers ontology says it does), it follows that powers would be proper constituents of causal histories, and therefore that powers-based explanations that reference them would be good explanations. Furthermore, just as powers are eschewed within neo-Humean explanations, friends of powers should be similarly sceptical of categorical properties arising in powersbased explanations. They can be no more explanatory than are powers for the neoHumean (dualism notwithstanding). Let me take one brief step backwards. Which actual ontology obtains—the true ontology—is not something we know. The neo-Humean and the powers theorist offer competing and incompatible accounts regarding what they believe is the true ontology. On the basis of their respective ontologies, they also offer a metaphysic, developed using the features of their preferred ontology. Part of that metaphysic will include a story about the nature of causation (unless, of course, the metaphysic denies that causation is real). Causal explanations then utilize this story in spelling out how it is that this or that phenomenon occurs. Strictly speaking, at most one of them can be right, because at most one of them has got the ontology right. But in the meantime—while the ontological facts remain beyond our grasp—each is at liberty to offer explanations made in terms of their preferred ontology. This is the sense in which explanations are ontology-relative.

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   ?

This is worth spelling out. 1: Causal explanations involve elucidating those entities and/or processes that produce the phenomenon in question (the effect). 2: The constituents of that causal history are ontology-relative; that is, the causal facts reflect what ontology actually obtains. 3: Therefore, causal explanation is ontology-relative. A by-product of the ontological relativity of explanation is that—as a matter of fact—most attempts to explain will fail to do so, because they get the ontology wrong. If the correct ontology is neo-Humean, then any explanation that employs fundamental powers is ultimately a bad one, because it would countenance entities that do not exist. (I say ‘ultimately’ because an explanation might be useful in ways other than that of presenting the causal facts.) In the meantime, while the ontological facts remain unknown, the best we can do is to evaluate explanations relative to the metaphysic within which they are offered. Hence, a necessary condition on good explanations is that they reference all and only aspects of the ontology with which they are offered. As ought to be clear, nothing about this gives preference to neo-Humean explanations. So what about the DV objection? If the objection is raised internal to the neoHumean metaphysic, then it is a perfectly good objection. It is a plea that one satisfy the necessary condition of causal explanations just given. (Putting aside the reductive aspect I will get to shortly,) neo-Humeans should not be offering explanations that countenance powers. But as a general objection the DV objection fails. One cannot require of explanations in general that they not employ powers, as powers might well be part of the correct ontology. There are, however, further aspects to the DV objection. Ontological relativity responds most directly to impotence, but the reductive and triviality angles matter, too. If the response from ontological relativity is to work, it must be that the powers in question are not vacuous ascriptions. They must be powers posited by a mature ontological theory, arising from mature scientific work, and involving significant empirical and intellectual toil. It should not be simple reverse engineering. Nor should they be susceptible to reduction. We have been working with the assumption of fundamentality, and so that question has been largely pre-empted, but it should not be ignored. Even within the powers metaphysic, a macro-level power (if there are any) would fail to be part of a good explanation if the lower-level powers are what do the causal work. Putting it all together, if there are fundamental physical entities, and they possess irreducible powers, then mentions of power properties in the explanations of their behaviours are not replaceable. For proponents of the powers ontology (wherein powers lack a distinct non-power basis), explanations that cite powers are as good as can be given; they are the only game in town. Thus, working with the powers ontology entails that powers-based explanations can be good explanations. This response thus succeeds in vindicating fundamental powers-based explanations precisely because it relies on a powers ontology at the fundamental physical level. The commitment to an ontology of genuinely causally efficacious powers means they gain bona fide explanatory worth. This counters the triviality and impotence forms of the DV objection. Moreover, as properties of ‘partless’ physical

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entities, there is no recourse to lower-level properties that might otherwise undermine the value of the powers-based explanation. It thereby satisfies the reductive impulse, and with it the third version of the DV objection, because there is no reduction to be had. Were there reductions in the offing, then it is with those yet-lower powers that the explanations are to be found. If it is powers that do the work in one’s ontology, then it is powers that belong in explanations. Powers-based explanations are thereby vindicated.¹² This assumes, as we should, that the reductive impulse is an impulse to reduce, and not simply that of insisting we replace talk of powers with talk of categorical properties (plus the laws). That is, I am here treating the reductive impulse as ontology-neutral. It drives you to look closer at the inner workings (assuming there are any to be found), but does not dictate what sort of ontology those inner workings must have. If the reductive impulse were to run counter to this neutral assumption, it would be nothing more than the question-begging insistence that all explanations be given in fundamental neo-Humean terms. Such dogmatism should be ignored: the DV objection ought to demand reductions (when available), but remain open to whatever features might be found beneath.¹³ For what it is worth, there is (defeasible) theoretical and experimental evidence that the entities we presently take to be fundamental are structureless entities, indicating that they are fundamental.¹⁴ And further, they are described using such power terms as ‘spin’, ‘energy’, and ‘charge’. If these terms pick out the powers they appear to, then we may well have fundamental power properties in our ultimate explanations. If these terms are here to stay, then the DV objection becomes the weapon of the powers theorist. Perhaps the tables have turned?¹⁵ We can now appreciate something we were unable to see before. That is that to explain that opium causes drowsiness because it possesses a dormitive virtue is not funny because it fails to offer categorical properties and laws in the explanation. It is funny because it is a poor explanation, made so by the alternative, lower-level explanation. That is the case whatever one’s fundamental ontology. Talk of dormitive virtues gives way (eventually, if not immediately) to fundamental properties, whatever their nature. Summing up, the powers-based response from ontological relativity succeeds because it: (1) proposes genuinely causally efficacious power properties (as part of the powers ontology), and (2) blocks further reduction by locating them at the fundamental level.

¹² Mumford (1998: §10.6) offers a version of this response; Ellis (2001) implies something similar. ¹³ According to Sober (1982), at the heart of the objection from dormitive virtues is the belief that, in order to rise above triviality, a non-power basis for the power ascription must be found. If the objection is raised within the neo-Humean metaphysic, then this would be correct. But the only substantive objection is ontologically neutral. ¹⁴ Molnar (2003: 133) claims there is good theoretical and experimental evidence that there are no further reductions to be found at the (putatively) fundamental physical level. ¹⁵ Probably not: the scientific evidence is compatible with both fundamental powers and the neoHumean alternatives, even if it appears to favour the former. See Williams (2011a).

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   ?

Despite everything I have said, there are surely people who have yet to be convinced. There are plenty of ontological ‘ifs’ to consider here, and plenty of ways our ontology might fail to be as the powers theorist claims. Ifs aside, can the response from ontological relativity genuinely vindicate powers-based explanations? It might be objected, for instance, that despite the ontological facts, powers-based explanations simply cannot explain. Even putting triviality aside, powers-based explanations fail to provide the ‘quiet’—the satisfaction—we seek from explanations; they lack the ‘aha!’ that explanations are supposed to provide. Unlike their law-based counterparts, powers-based explanations do not have us saying to ourselves, ‘Yes! That is the reason that so-and-so occurred.’ It would be good if we could diagnose what is wrong with thinking like this. Without trying to understand the subjective aspect of explanation (should it prove significant here), I hazard that this scepticism derives from the widespread, enlightenment-inspired belief that properties are inert and act in accordance with the laws of nature. In other words, it is nothing but a by-product of the dominant neo-Humean metaphysic, in which case it is bias and should be ignored (as hard as that may be to do). The neo-Humean metaphysic has a strong grip on contemporary thought; perhaps so much so that it is hard to appreciate an alternative, or what explanation would be like under an alternative. Hard-headed objectors might still fail to be swayed, even if the ontology is as the powers theorist claims. One can imagine someone so wedded to a certain model of causal explanation that, when faced with this framework, she would rather say that we have no explanation at all than treat powers-based explanations as good ones. I have no answer to explanatory scepticism of this sort. It may be hard—initially at least—to think of the quiet we seek from explanations as coming from our rationally submitting to what is in fact the case. Nevertheless, this dogmatism is an inappropriate response, and a mystifying one to boot. After all, what more can a law do but relate events? If laws can be explanatory in the right ontological context, then powers can fare just as well in another: a proper sceptic is sceptical about explanations citing laws or powers.¹⁶ Or better yet, such a sceptic ought to be sceptical about causal explanation simpliciter. There is no point trying to convince the sceptic, but perhaps there are folks who would balk at scepticism, but still have their doubts about powers-based explanation. For them I offer a final attempt to bring them into the fold, by considering an unusual case of a world ruled by magic. (It might be odd to think that a magical case could somehow fare better than a powers-based case at getting doubters to ease into different sorts of causal explanations, but this case is familiar enough that it might have the desired effect. Causal explanation is ontology-relative: this applies to ontologies where the causes are magical, too!)

¹⁶ A law relates one sort of event or state type to another, telling us that the one typically precedes the other. Under the assumption of a neo-Humean ontology, providing this information constitutes a causal explanation; but why on Earth should we think that subsumption under a law makes for a good explanation simpliciter? Or that powers cannot do just as well if a powers ontology is assumed? See McMullin (1978) and Michon (2006).

    

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Most of us are familiar with Aesop’s fable about the goose that laid golden eggs. For those not in the know, here is a quick synopsis: a poor but good-hearted couple are lucky enough to find a goose that lays golden eggs. The goose periodically but infrequently produces golden eggs that the couple sells, and the previously poor couple come to enjoy much economic freedom. Their new economic status then undermines their good nature, and the previously good-hearted couple become greedy and impatient. No longer satisfied with waiting for the eggs, they cut the goose open to get the gold they assume is inside. There is no gold to be found inside. The dead goose no longer lays eggs, golden or otherwise. The moral of the story has something to do with the evils of greed or how money changes people for the worse. But let us put these maxims to one side. At least as interesting (if not more so) is the matter of the goose itself, and how it manages to produce these valuable eggs. If confronted with such a fantastical beast, we would be desperate to have its fabulous ability explained. Would it ever suffice to say—without inviting Molière’s mockery—that the goose simply has the power to do so? Could such an explanation ever be adequate? Assuming the real (magical!) details of the case have been passed down with the story, then it seems that it can. From an explanatory perspective, the couple acted reasonably in cutting open the goose: they assumed, as we would, that the goose’s power was to be explained by its inner workings, even though it turned out that the goose’s power to lay golden eggs was not reducible.¹⁷ This means that the goose’s magical power is the stopping point of explanation. The only explanation for the goose’s production of golden eggs is that it has the magical ability to do so. Here we have a virtus dormitiva-style explanation that mirrors Molière’s opium case. And yet—owing to our acceptance that in fantasy scenarios there are magical causes—this is a good explanation. What makes it so? The fundamental (irreducible) magical powers the explanation cites are the best that can be given. The magical facts are the causal facts, and they are the only game in town. Causal explanation is ontologyrelative, and here the assumption is that the ontology is magical, according to the fiction (or the fact, as it were). To see the goose’s power as explanatory in the magical causal context is to concede that point. Laws explain if the ontology has laws, magical abilities explain if the ontology is magical, and powers explain if they are the entities that do the work. Nowadays, of course, our means of investigating the goose’s miraculous ability would be well beyond the primitive methods utilized by the couple in the fable. But in keeping with the story, we have no reason to think that our modern scientists would fare any better. Just as the couple found no gold, our scientists would find no traces of gold or compounds from which gold could be extracted. When the goose is still alive and laying golden eggs, we might well find the magical explanation unsatisfactory. Just knowing that properties are magical is not quite enough, because we only satisfy the impotence aspect of the DV objection. At this stage the magical explanation could be questioned. Now consider what happens

¹⁷ With regard to their finances the move seems unreasonable: even if there was gold to be found inside, it would (presumably?) have been a finite supply, not the infinite supply the goose could produce if healthy.



   ?

when the couple decide to kill the goose. Their motives are financial, but a by-product of their greedily cutting open the goose is that the reductive impulse is satisfied. Our desire to see what—if anything—is the underlying mechanism by which the goose lays the eggs is thereby assuaged. Once we have the goose open, we learn that no additional information regarding the process is available. At that point the magical explanation is a good one. In sum, if having a causal explanation is a matter of elucidating the causal structure at work, then one is a bold-faced sceptic or a question-begging dogmatist if one continues to deny—within the right context, and after some poking and prodding— that the explanation given in terms of the fundamental entities cannot be a good explanation. Consider the objection from dormitive virtues defanged. Despite its success, the response from ontological relativity still leaves us with a few problems. One problem concerns those explanations that cite macroscopic powers or dispositions.¹⁸ (Our interest is with the fundamental powers, but this is a worry nonetheless.) Within the powers ontology, fundamental powers-based explanations evade the DV objection. But return to the good old sleeping pills. They operate via a lower-level chemical process. Hence, an explanation that refers to pill-level soporific powers fails to satisfy the reductive impulse, and so is not similarly vindicated. That does not entail that it is useless, but its vindication is limited to what the other responses (ii–v below) can afford, which can vary greatly. Should we hold out hope for something more? Recall that to be successful a powers-based explanation must (1) propose genuinely causally efficacious power properties (as part of the powers ontology), and (2) block further reduction by locating them at the fundamental level. When it comes to special science explanations, the ‘abundant’ power theorist (she who endorses powers at levels of granularity greater than the fundamental level) has no problem satisfying (1)—she is, after all, assuming that the powers metaphysic is true, and therefore that we have a largely, if not exclusively, powers ontology.¹⁹ But finding a parallel for (2) proves more difficult. She cannot simply follow the sparsist’s lead. After all, these upper-level powers are susceptible to reduction. At the very least, every macroscopic object has smaller physical entities as parts. Hence, the reductive impulse is not obviously satisfied as it is with the powers of the smallest physical entities: we are well aware that there are properties instantiated by lower-level constituent entities, and so the tendency to find upper-level powers-based explanations unsatisfactory remains. To vindicate these upper-level explanations, the abundantist needs to find a way to impart that same irreducibility to upper-level powers. It could be that some of those upper-level powers are composed of smaller objects in possession of powers, but that something about the way in which the macroscopic objects function renders their powers (or some of them) fundamental in a slightly different sense. I am unsure if this would constitute a full-blown emergence, but maybe that does not matter. Constitutive of some forms of non-reductivism is the ¹⁸ I will make some brief comments about these sorts of powers in Chapter 10. For the most part, these are not the powers I am interested in. ¹⁹ Abundantists include McKitrick (2009a, 2018), Mumford and Anjum (2011), and Vetter (2015).

    



belief that the special sciences cannot be neatly folded into one another so as to reduce all explanations to fundamental ones. If this lack of reduction could be taken one step further—to the extent that the domains of each of the sciences (special or otherwise) are treated as distinct—we could generate a framework that emulates the fundamental powers, but for each area of scientific discourse. In effect, you would satisfy (2) because no reduction would be available. I lack the space to give this nonreductive project its fair due (nor is it my project to carry out), but however successful it might be, I cannot see it as vindicating all upper-level powers-based explanations, and so the problem remains, even if mitigated. Regardless of the problems the response from ontological relativity might face when considering explanations of non-fundamental phenomenon, it works at the basic level. And that is enough for our needs. This clears the way for powers-based explanations, at least as far as the fundamental powers are concerned. But there is more that can be said in response to the DV objection that applies across the board, and so is worth a look. Note, however, that the remaining responses are concessive: they concede to the objector that there is something inadequate about powers-based explanations, despite attempting to vindicate them. I indicate the ways in which the responses are problematic or concessive along the way. (ii) Causal locus. In the absence of any causal topography, information about where to find the most salient feature of a cause is explanatory. If, for instance, an otherwise healthy man were to suddenly fall asleep at the wheel, learning that he had ingested opium is informative: it tells us that our attention should be focused on the pill and its popper. Hence a common response to the DV objection is that powersbased explanations can be useful in pointing out where the most salient features of the cause are to be found. To say that opium is somniferous drives us towards an answer, it selects a substance and says that this substance has a causal power identified by such a result. We are ready to analyse the substance and to understand how it interacts with the nervous system in such a way that sleep is produced.²⁰

Knowing the causal locus is similarly beneficial in ruling out various kinds of alternative responses. For example, knowing that opium causes sleep because of a dormitive virtue ‘rules out opium merchants administering a genuine soporific each time they see someone else take opium’, and ‘it rules out divine intervention’.²¹ For many, the benefit of knowing the causal locus is tied to the reductive impulse: it tells us where the real explanations are to be found. This does not mean that the explanation ceases to be trivial, nor that the ascribed property is now causally potent—hence, the causal locus response is concessive—but, to the extent that it indicates ‘where to dig’, it is of use. This makes clear, however, that the response belongs on the disposition side of the powers versus dispositions distinction, if it is to have any force. If the explanation is

²⁰ Michon (2006: 137). ²¹ Mumford (1998: 138). See also Lewis (1986d: 221) and Block (1989: 163).



   ?

telling us ‘where to dig’, then there has to be digging to be done. That is, there must be constituent entities and their properties to be found, and those are what will give us a fully satisfying explanation. But if you have already dug all the way down, then saying that the power is the ‘x’ that marks the spot is of no use, because you cannot dig any deeper. Thus, when it comes to powers (and not mere dispositions) the causal locus response is not going to assuage the objector, not even concessively. However, the value of this response as it pertains to dispositions is sometimes limited by the fact that the causal locus may already be known. In Molière’s scenario the question is why opium makes one sleep; hence, we have nothing to learn from the disposition-based explanation regarding causal loci. The explanation is redundant, and thus non-explanatory. It is only when we are in the dark that information about where to look is useful. (iii) Context sensitivity. According to Chakravarrty, Citing a disposition can be non-explanatory in some contexts, like that of explaining why opium causes drowsiness by citing the disposition of opium to cause drowsiness (!), but . . . there is nothing empty about affirming the existence of a dispositional property to explain manifested behaviours. Consider the physician’s answer in response to a different question, say that of why a patient feels drowsy after completing his or her midday routines. Here, ascribing a disposition to opium is not empty at all. It is an empirical hypothesis which may turn out to be false.²²

The point is clear enough: there are certain contexts—certain ‘why’ questions—for which a powers-based answer is appropriate. In those contexts a powers-based explanation can be a good one, despite failing in others. Furthermore, given that ‘why’ questions are themselves context-sensitive, what constitutes a reasonable explanation ought to also shift with the context.²³ Nevertheless, the response is concessive. The reason is present in the quotation: in order to see the value in the powers-based explanation we need to consider what the physician would say ‘in response to a different question’.²⁴ Different from what? Different from the very question we asked. (iv) Placeholding. Quine is hardly a friend of dispositions—he is downright hostile to them—but even he sees them as having some minor worth in explanations.²⁵ Terms referring to dispositions, he claims, can serve as ‘placeholders’ in good explanations, temporarily filling in gaps until permanent (non-dispositional) explanations can be found. This sort of thinking goes hand in hand with the reductive impulse. The dispositions we ascribe are part of the phenomena to be explained by lower-level interactions, but until the activities of the constituent entities are understood, the upper-level explanations will suffice, even as they employ disposition terms. Should further disposition terms appear in the lower-level explanations, these, too, will be only temporary: final explanations are to be free of any such terms. Treating disposition terms as placeholders is a highly pragmatic approach to dispositions, at once offering them a limited role in explanation while simultaneously

²² Chakravartty (2007: 125–6). ²³ van Fraassen (1980) and Lipton (1990). ²⁴ Chakravartty (2007: 126); italics added. ²⁵ Quine (1974).

    



denying them any serious ontological status. The end product is one that is suspicious of genuine dispositions, because of what one would have to concede ontologically in order that they be capable of producing effects, but at the same time approving of explanations that (temporarily) employ them. Quine gets to have his cake and eat it, too. The placeholder response recognizes that science is a work in progress, but maintains that we can still have reasonably good explanations until better ones are found. It thus wears its concessive nature on its sleeve. To the extent that the powers theorist adopts a similar attitude to the state of scientific knowledge, she, too, can agree that some disposition terms will serve as placeholders in good explanations. After all, many good explanations will have disposition terms that will later be replaced by better explanations regarding lower-level entities. Of course, if placeholding was all powers could do, then it would be game over for the powers theorist. Powers are already operating at the fundamental level, and so they cannot be temporary in the way Quine imagines. It is only if one rejects the powers ontology that fundamental powers are temporary; they would then give way to alternative explanations, such as the neo-Humean explanations that employ only categorical properties and laws. Hence, if power terms cannot have permanent places in good explanations, then the powers theorist is incapable of producing genuinely good explanations. (v) Power predication. In many reductive explanations, a disposition term is replaced by a description of a complex mechanism operating at a lower level of granularity. But sometimes that lower-level explanation makes use of disposition terms, too. Hence, the resultant explanation is not ‘disposition-free’. Consider the following explanation of why table salt (NaCl) goes into solution in water (H₂O): The crystal lattice of sodium chloride is held together by very strong electrostatic attractions between alternating positively charged (sodium) and negative charged (chlorine) ions. In water, crystalline sodium chloride dissolves into individual sodium and chloride ions because the attraction between the Na+ and Cl is greatly exceeded by the electrostatic attraction between Na+ and the partially negatively charged oxygen atom of a water molecule, and between Cl and one of the positively charged hydrogen atoms of the water molecule. Water molecules are therefore able to insert themselves between these ions; the energy needed to separate an Na+ from a Cl is more than provided by the energy released when bonds form between water molecules and these ions.²⁶

Like any good causal explanation, it succeeds by making clear the salient features of the causal structure involved in the solubility of salt. We started with a disposition ascription—‘solubility’—and ended up with the mechanism that accounts for the solubility. But we have replaced the one disposition term by others (or by terms that perhaps pick out powers): ‘energy’, ‘positively charged’, ‘negatively charged’, ‘able to insert’, and ‘electrostatic attraction’ are putatively dispositional or powerful, if not overly so. It would thus appear that good explanations can countenance

²⁶ Lange (1994: 115).



   ?

powers, if not dispositions. And if they all work this way, then the powers theorist is in good shape. Critics are bound to reply that the use of power terms in such explanations is merely temporary, perhaps thinking of power terms as placeholders: these, too, will go the way of ‘solubility’. But we cannot claim the same of fundamental powers without simply rejecting the powers ontology. We have already explored that route, and so for the sake of discussion, let us assume that the explanation above is a good explanation of solubility, and that it includes power terms. Is this, therefore, a good response to the objection, and is it good enough for the powers theorist? One reason to be sceptical concerns a question we have managed to avoid until now. That is: what is a powers-based (or disposition-based) explanation? Because I opened the discussion with Molière’s joke, we had a putative example at hand and avoided the question. But now the question is relevant. In Molière’s opium case it is clear that the explanation is disposition-based: it cites the disposition to cause sleep as the reason opium produces sleep when ingested, and says nothing else. The only salient notion in the explanation is a disposition. By contrast, the solubility explanation is more complex. It incorporates what are arguably power terms, but it does so alongside various terms that would appear to refer to structural and categorical elements. Perhaps this means that that the solubility explanation is not a powersbased (or disposition-based) explanation after all? That strikes me as unlikely. It is unclear what portion of an explanation has to employ disposition or power terms for it to count as one, but opponents respond to those terms as if just one is enough to spoil the entire explanation. That suggests that the right answer is an extreme one. Dare I say, if one’s ontology treats powers as second-class or worse, then pointing to the causal actions of a single power or disposition violates the strictures of that ontology. But conversely, the solubility explanation employs terms that putatively refer to properties other than powers, and so the (monistic) powers theorist would be within her rights to deny that it was a powers-based explanation on those same ‘bad apple’ grounds. Perhaps we do not need to decide. As far as vindicating powers-based explanations goes, even if we treat the solubility explanation as a good explanation, it does nothing to help the opium-type cases. If the relevant difference between the two is that one employs disposition terms and the other power terms, then this ought to be acceptable to the powers theorist. That might lead us to think that if the solubility explanation counts as a powers-based explanation, then some powers-based explanations are good. But I doubt the objector would allow us even that, as they can still insist that the power terms are only temporary, awaiting replacement by ‘respectable’ categorical terms.²⁷ Many explanations make use of disposition and/or power predicates, but those opposed to powers-based explanations must assume that these terms are merely temporary. Whether they are ultimately right depends on the ontological facts. Hence, given that the nature of those facts is still up for debate, the final move in the back and forth between reductions and powers will be relative to one’s ontological

²⁷ Mellor (1974).

    ?



framework. That means that powers-based explanations can be good ones, if the ontological facts are as the powers theorist claims. With that said, let us rehearse how the specific powers involved in persistence can be explanatory. The defender of powers of persistence can borrow both the ‘causal locus’ and ‘context sensitivity’ responses to the objection from dormitive virtues. Both are concessive responses, and so they cannot do much to help the situation, but it is far from vacuous to say that objects persist because of features within them, as opposed to having to rely on an omnipotent being, or denying that there is a causal explanation at all. It is also somewhat informative to know that for certain ‘why’ questions, such as ‘why does this object continue to exist?’, an answer can be given. But as we have seen, neither response provides adequate vindication of the powersbased explanation of persistence. We now know where to dig, but that is no use if there is no digging to be done, and the relevant question concerns how objects persist over time, not why they do. By way of contrast, no use whatsoever can be made of the ‘power predicates’ or ‘placeholding’ responses, as the use of powers here is not temporary. Therefore, the main response lies with the response from ontological relativity. Successfully adapting the response from ontological relativity to the case of powers-based explanations of persistence requires that we satisfy the desiderata that make powers-based explanations good ones. Satisfaction of the need for a powers ontology is easily achieved: we have been working with a powers ontology from the start. Whatever powers are involved in pluck and persistence are no less causally efficacious than any other, as the only causal activators are powers. What about reduction? That depends on whether or not the power/manifestation pairs that make up persisting individuals are ‘black boxes’ capable of further reduction. Given the fundamentalism involved, that is clearly not the case. The parts or stages of the persisting object that are connected as powered object and manifestation are not capable of further reduction. These are the smallest object stages of the fundamental entities (we can perhaps talk of even shorter-lived segments of these parts, but they are mereological fictions, and not genuine parts), and so there is no way to get any ‘closer’ to find even briefer or finer inner workings. These stages are the stopping point of reduction, and also the stopping point of causation. And thus they are the stopping point of explanation. Thus, by all lights, a causal explanation using powers for persistence ought to be a good one.

9.3 Do Powers Need Enduring Entities? Are powers better suited to one theory of persistence than another? It has been suggested that the adoption of temporal parts (genuine ones, not the neutral stages employed in Chapter 8) favours neo-Humeanism, and thus that powers are better matched with endurantism.²⁸ The claim is that the static nature of the temporal parts does not square well with the dynamism of the powers metaphysic, and so ‘a powers ontologist nevertheless has some reason to favour endurantism as sitting most ²⁸ Mumford (2009a). See also Wahlberg (2009).



   ?

comfortably with their ontology’.²⁹ If that is the case, then the powers-based account of pluckiness could not be paired with any account of persistence that depends on temporal parts. But I deny that this is the case: powers are perfectly at home with temporal parts, and thus can form a happy union with perdurantism or stage theory (and not just endurantism). This section explains how.³⁰ What is the problem supposed to be? The perdurantist relies on temporal parts to explain how persisting objects can instantiate incompatible intrinsic properties. She claims that persisting objects are composed of temporal parts, and that these parts are what instantiate the incompatible properties. Throughout its career an object might be both bent and straight, but the temporal part that is straight is not strictly identical with that which is bent; no temporal part is ever both. Though they collectively accommodate these incompatible properties, and thus collectively underdo change, the individual temporal parts are incapable of change; they are static. Change is a matter of different property types being instantiated by different object stages at different times. They exhibit change collectively, but not individually.³¹ In seeming contrast to the static nature of temporal parts, it is claimed by some friends of powers that powers give rise to processes (prolonged events that may encompass numerous changes). If we conceive of those same processes as essentially dynamic—that is, if we understand those processes as continuous events that are constantly undergoing change—then their dynamic nature seems a poor fit for the static temporal parts. According to Mumford, Change in a particular can be understood as a continuous and constant process in the sense that it contains no proper portion that is not undergoing change. While the whole process involves movement from one state, condition or property to another, each proper portion of that process also involves change. The process should not, therefore, be broken down into its static, instantaneous parts. If one tried to understand the process in that way, one would lose something of its dynamic and developing nature.³²

If, as Mumford claims, powers are tendencies to give rise to processes that are ‘continuous, dynamic, natural processes’, and further that particulars are ‘always acting’, then powers look like poor partners for perdurance.³³ In other words, the objection really comes down to disagreement about the nature of powers and how they operate; their not playing well with temporal parts is a consequence of one half of that disagreement. This is something of a departure from the way that powers are here understood; this will be evident in my response. We have already seen that the most pointed form of the objection—that according to which manifestations are processes—can be avoided. Manifestations are too short-lived to be like this, and so parts and powers are not at strict odds with one another. But the greater the extent to which we should

²⁹ Mumford (2009a: 226). ³⁰ The response is formulated in terms of perdurantism, but as the objection concerns combining powers with temporal parts, the response applies equally well to stage theory, mutatis mutandis. ³¹ This has led to the confused objection that perduring objects do not in fact change, grounded in an uncharitable understanding of change. See Thomson (1983) and Lombard (1986) especially. ³² Mumford (2009a: 228). ³³ Mumford (2009a: 228).

    ?



understand powers and their exercising in terms of dynamic processes, the less amenable they are to an ontology of static temporal parts, and that is concern enough. These two perspectives lend themselves to two ways of modelling processes. On the first—the most amenable to perdurantism—processes are drawn out events encompassing many changes, but they are dissectible into ever-so-many short-lived states, none of which itself includes change. The second model of processes sees them as continuous and impenetrable. To split them up is impossible, as the process would thereby cease to be a member of the same process type, or cease to be natural in the right sort of way, or fail to be properly understandable. If processes are best understood like this, then pairing parts with powers will not produce a very happy union. Both are perfectly good models of processes, but which better fits how we think about powers and their manifestations? We already have our answer in the account of manifestations. The possibility of a process’s being interrupted—its interruptibility—forces us into a picture of manifestations as short-lived. We thus recognize that processes are lines of toppling dominoes, built up out of the short-lived manifestations. They are sequences of constellation and manifestation pairs; states lined up one after the next. Does understanding a process in terms of this ‘domino model’ see us ‘lose something of its dynamic and developing nature’? Certainly not: to recognize a process as dissectible into ever-so-many parts does not thereby privilege those parts in terms of how we understand the process as a whole. We do not fail to see the forest for the trees when we learn that forests are little more than collections of trees. The fine-grained perspective on the process merely offers a different perspective—one that is directly in keeping with the true natures of the powers and manifestations at work—but our understanding of the process as a whole need not differ. Regardless of the ontological facts, nothing here dictates how the processes must be understood.³⁴ Worries about the dynamism of processes can be put to bed. But what happens if we go beyond the processes—down the level of constellation–manifestation pairs— and the question of dynamism is raised once again? That is, what if the pairings involve continuous (and uninterruptible) changes themselves? The answer depends on the size of temporal parts. Consider the two states of the world that constitute the constellation and the manifestation. They would seem to have to be determinate states, meaning that whatever properties are parts of those states are fully parts of those states. That is, there is no halfway house between the temporal parts that compose those states having a property and their not having a property; it is all or nothing. If the only temporal parts are those that compose the constellation and manifestation states, then there is no sense to be made of the claim that the pairs involve continuous changes. There are just two states; the world causally ‘jumps’ from one to the next. (Do not be concerned, as these are tiny jumps; bigger jumps are strictly unreal, being really nothing more than many tiny jumps.)

³⁴ Sider (2001: 211) makes a similar point.

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   ?

The only way the constellation–manifestation pair could be said to be in continuous change is if these two states were separated by a series of non-determinate states. If we think of a determinate state as the property-instantiation version of bivalence, then a ‘non-determinate’ state would be the fuzzy counterpart. I have a hard time making any sense of what these non-determinate states would be. The closest I can come to wrapping my head around them is by imagining that they are like what could once happen when you paused a video in a VCR. Digital video makes this example a thing of the past, but back in the day, if you paused a video, you rarely got a clear image. Most of the time the image on the screen was either blurred between two images, or flickered back and forth between the two. So, if we have a series of analogue fuzzy states between the constellation and the manifestation, then we could treat the pair as involving continuous change. What should we say about this sort of case? I open by registering my scepticism: I deny that there are any non-determinate states like this. But my scepticism is unlikely to be enough. After all, it seems reasonable to think that time is dense, and therefore that there will be times—and by extension, states and temporal parts— between the constellation and manifestation states. And further, if they are the states through which the world transitions from the constellation to the manifestation, then they ought to be non-determinate. I continue to prefer the picture of the world as jumping between determinate states, but I cannot deny that the picture of smooth transitioning seems reasonable enough. Nevertheless, I do not see this picture as presenting any serious problems for combining powers with temporal parts. And that is because the constellation and manifestation states should be thought of as big enough to contain these ‘intermediary’ states. Recall that the constellation–manifestation pairs are uninterruptible. This is easier to concede if time is chunky and the constellation and manifestation states are two consecutive chunks. But here we are assuming that time is dense, and therefore that there are times between the two states. However, that there are times between the two states does not have to mean that there must also be temporal parts or states, not causally significant ones anyway. We have seen that the shortest duration of an object stage is dictated by the mechanism of change; it is an open question whether these object stages will be instantaneous. Powers dictate which are the significant states and significant temporal parts; their duration is not something we are likely to know. Those could be instantaneous, and they could be consecutive, but there is no problem accommodating the possibility of intervening states, just as long as it is recognized that those intervening states are not causally significant. They are the transitional states between the constellations and manifestations, if they exist at all. That was the conclusion of the argument in §8.4: object stages could be instantaneous (they are the entities responsible for change, and hence they dictate which are the significant states), but even if they are not, there is no problem accommodating temporal parts between them. These parts are mereological fictions: innocent abstractions which can be considered in conjunction with the ontologically neutral object stages without compromising that neutrality. Only the object stages will be causally relevant. But their ‘thickness’—if that is how they are—renders them thick enough to permit the ‘fuzzy states’ of continuous change between them, if needed.

  

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The present worry arises from an alleged mismatch between the duration of temporal parts and the time it takes a power to be manifested. I have argued that the exercise of powers takes less time than the objector assumes, and that temporal parts can have longer durations than the objector assumes, making the possibility of a mismatch remote. There is, therefore, no problem mixing powers with perdurance, or any other account of persistence that accommodates incompatible properties via temporal parts. On the assumption that this was the dubious mix, I will not bother arguing that powers and endurantism make for perfectly good bedfellows. After all, there is no prima facie reason to think that powers and their exercising would have any problem being incorporated into endurantism. Powers are perfectly comfortable if there are temporal parts, and no less so if there are not. The powers metaphysic is neutral in this regard.

9.4 Creation Ex Nihilo Then again, it could be objected that the model of pluckiness I have described is too well suited for accounts of persistence that rely on temporal parts, and therefore a poor fit for perdurantism. Judith Thomson raises the following objection to accounts of persistence that rely on temporal parts in general, but it applies to the neutral notion of object stages just as well. In fact, given the nature of the causal model defended here, the objection seems even more pressing. She accuses those who employ temporal parts as having a ‘crazy metaphysic’. We can only imagine that combining temporal parts with causal powers would leave her utterly cross-eyed. She writes that, The metaphysic yields that if I have had exactly one bit of chalk in my hand for the last hour, then there is something in my hand which is white, roughly cylindrical in shape, and dusty, something which also has a weight, something which is chalk, which was not in my hand three minutes ago, and indeed, such that no part of it was in my hand three minutes ago. As I hold the bit of chalk in my hand, new stuff, new chalk keeps constantly coming into existence ex nihilo. That strikes me as obviously false.³⁵

The ‘obvious falsity’ of the view leads Thomson and her readers back to the ‘less extravagant’ endurantist account of persistence. That sounds bad, to say the least. Fortunately, there is plenty that can be said in response. A quick (but fruitless) response is that the present account says nothing about pieces of chalk or middlesized dry goods in general. And though no one as reasonable as Thomson would probably ever claim to have held a particle or wave in her hand, we can easily rework her objection so that it applies to the fundamental physical entities. On to more serious replies. First and foremost: despite what Thompson claims, I find nothing remotely false or crazy in the proposal exactly as expressed. Not only is it not obviously false, it does not seem false at all. What is wrong with a picture of the world as recreated at every moment?³⁶ What can one possibly point to as evidence that this is not the true story? ³⁵ Thomson (1983: 214).

³⁶ Winkler (2011).

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   ?

Granted, we do not experience the world as if it is constantly created anew. (As parts of that world we, too, would be subject to constant recreation.) But those same experiences deceive us constantly, especially as they concern deep scientific and metaphysical facts. Is it obviously false that the table before me is nothing more than a cloud of buzzing particles? Is that a crazy physic—and is it obviously false, too? Long story short, I have no idea that the universe or parts of it are not created anew at every moment. And though it does not seem that this is the case, we learned long ago not to stake philosophical claims on what seems to be so. The objection might gain a greater foothold if the ‘creation’ had no explanatory basis, but that is precisely what we have provided: it is not creation from nothing at all. Creation from nothing would be worrisome, but these are clearly created from something, namely the powersbased causal actions of the predecessor object stages.³⁷ Building on the first response, a second is that the causal process by which one object stage gives rise to another does not have to involve any creation ex nihilo, nor any destruction either.³⁸ Instead, the ‘giving rise to’ or production can be just as well understood as a projection through time: conservation, rather than recreation. The existence of new object stages is partly a matter of the mere passing of time, but is more importantly a causal sustaining on the part of the persisting object. Simply put, in order for the object as a whole to persist, the object stages themselves must have powers to reinvent themselves from one moment to the next. The object is involved in a perpetual state of reproduction: each object stage creating the next, moment after moment. But it need not be a matter of genuine creation or destruction: powersbased causation, especially in the immanent causation case, does not require that matter be created or destroyed. There exists stage after stage, but this need not be understood in a way that would be analogous to gods creating and destroying objects at will.³⁹ I have presented powers-based causation as akin to the toppling of dominoes, but only to aid in understanding. There is no reason that the constellation– manifestation pairs cannot be thought of in terms of perpetuation or conservation. Consider: when one (parent) amoeba splits and gives rise to two progeny, the original amoeba is ‘destroyed’, and the two new amoeba are ‘created’—but the universe undergoes no loss or gain of matter. Persistence can be similar, even where the ‘parent’ object stage only produces a single offspring. Nothing prevents powers-based causation as working with the matter already at hand, and sculpting it (or not) through the exercise of powers. This no more demands the creation of matter than does the sculpting of clay. Lastly, Sider asks—in a tu quoque reply to Thomson—why it is that enduring particles do not just stop existing?⁴⁰ What he means is that the answer to Thomson’s charge of craziness will appeal to causal connections between the stages, and that the endurantist is on the hook for the same. The endurantist owes us an answer to the question; that answer is bound to be causal. It thus turns out that both sides of the debate are going to need to appeal to causal connections. The powers theorist has the tools to satisfy that need. ³⁷ See also Heller (1990). ³⁸ See Sider (2001: 217) for the destruction case, which he quickly dismisses. ³⁹ As described by Shoemaker (1979) and Armstrong (1980a). ⁴⁰ Sider (2001: 213).

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9.5 All that Gunk According to a famous myth, the world rests on the back of a giant turtle. And that turtle, we are told, rests on another turtle. And on what does that turtle rest? You guessed it—yet another turtle. It is, as they say, turtles all the way down.⁴¹ As the account of pluckiness defended here is intended for the fundamental physical entities, there had better be a bottom turtle (or many, very small, turtles, all of the same size). That is, the theory would be in trouble if it turned out that the fundamental physical entities—the fundamental particles, fields, or what have you—are not the power property bearers, as would be the case if our world was ‘gunky’. A gunky world is one in which all the parts are themselves divisible into yet smaller parts, without end. Such a world would be a world of atomless gunk.⁴² If every move to smaller objects was followed by yet another move to yet smaller objects—to the extent that there was no bottom to the universe (it is turtles all the way down)—then it is unclear what good the theory of pluckiness would do, if any. Fortunately, there is less here to worry about than it might seem, as I do not believe ours is a gunky world. You might not find my confidence very reassuring. After all, there is no saying that I am correct. And moreover, is it not possible that ours is a gunky world, and is that alone not worry enough? In short, yes it is possible, and no, that is not enough to cause concern. That is because the sense in which it is possible that the world is gunky is a mere epistemic possibility. For all we know, the world is gunky. But as a matter of fact, it is either gunky or it is not. I am betting on the latter, and will stand or fall with the outcome of that bet, but the theory does not need to make any room for the mere epistemic possibility. If the world is not gunky, then it is not metaphysically possible that it be anything but that way. Metaphysics—or better yet, the metaphysical facts— are necessary in this sense (see §2.2). Whatever the metaphysical facts turn out to be, they could not have been otherwise. We might not know what they are, thereby leaving open epistemic possibilities about the metaphysical facts, but this does not render the metaphysical facts contingent, only our knowledge of them. (Recall that what we can imagine or dream up through acts of mental collage-making are of no significance here.) As with any good theory, there must be things it rules in and things it rules out. The current theory rules out the metaphysical possibility that ours is a gunky world. If certain things are the case, then the theory is false. This strikes me as a good thing. It is an odd practice—though not uncommon in metaphysics—to look for theories that would be true come what may. By contrast, it ought to be that an interesting theory is one that sticks its neck out and runs the risk of being wrong. (Folks doing serious systematic metaphysics rarely fail to stick their necks out.) Metaphysical theories without at least a few risky commitments are unlikely to be interesting, and are probably at most vacuously true. The world is some way or other, and its metaphysics will not be true come what may. So, why reject gunk? One reason for doing so is that it is very hard to make proper sense of what the world would be like if it was gunky. It may not be coherent at all.

⁴¹ The myth pops up all over the place. One such place is Hawking (1988).

⁴² Lewis (1991: 20).

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   ?

Though we might understand what it means for objects to be made up of smaller parts, in the way a clock is composed of pulleys, cogs, and gears, and to further understand what it means for even those parts to be made up of parts, can we really make sense of the suggestion that this can go on without end? To appreciate what is involved in each step in that reasoning is not yet to have grasped what it means for it to go on (and on) without end. As for me, the only sense I can make of legitimate gunkiness is to think of the universe as a giant, amorphous blob. It would have no smallest parts, as each is divisible into more, but only because the universe itself is just one large object. And if that were the case, we would have no problem at all. It—the blob—would be the fundamental physical entity to which the theory of pluckiness applies. And even though we might suspect that the fundamental objects are much smaller than this, for my theory, actual size does not matter. There can be one giant fundamental object or numerous small ones. (In fact, if the universe is just one large object, then the account of immanent causation in Chapter 7 will prove quite significant, as all causation will be immanent.) Another reason to reject gunk is that the possibility of gunk is not coming from the right quarters. The folks who seem most worried about the possibility of gunk are arriving at their concern via evaluations of formal theories of parthood. They are not, to the best of my knowledge, building those concerns out of assessments of the relevant physical sciences or fundamental physics.⁴³ Many theories of parthood allow that any part can have parts, and without some principle of atomicity, this leads naturally to gunkiness. But even if the formal theories permit treating any part as a whole composed of proper parts, why should we think that the physical world is similarly structured? For example, if it turns out that particles are the smallest objects of physical theory (the ‘atoms’ of physical theory, so to speak), we can still make sense of those particles having a top half and a bottom half. And even those halves will have parts too. But these are not genuine parts, in the sense that particles are composed of smaller objects that are themselves parts of physical theory. These are only parts in the mathematical sense, a by-product of the formal system. They are not parts in any sense that should concern us. Our interest is with the atoms that make up the world, however large or small they may be, not the atoms of formal mereology. Hence, we need not worry about gunk. And if the world should turn out to be gunky after all, then a theory of how fundamental particulars persist is not something we need. But at that point we would be dealing with metaphysical fact, not worries that arise because of ways things might, for all we know, be the case, despite their not being the case.

⁴³ See the list of references discussed in Varzi (2016).

10 Loose Ends 10.1 Laws of Nature We have seen a significant portion of one possible powers metaphysic, applying the powers ontology to a range of metaphysical problems. Throughout the project I have shifted the focus in the direction of the microphysical, as that is where the powers reside. But doing so has left a number of dangling loose ends, especially as they pertain to the macroscopic middle-sized dry goods and their capacities. The aim of this final chapter is to tie up those loose ends. Or more correctly, the aim is to tie up a few, and where tying would require a whole discussion unto itself, gesture at how they might be tied in future work. Thus, some of these knots are still a little loose. It is hard to have a discussion of powers without someone raising questions regarding the laws of nature. After all, an account of the laws of nature (even if negative) seems like a natural enough part of the story a metaphysic tells through its applications of the core ontology. So, what can the powers theorist—better yet, what can this powers theorist—say about the laws of nature? Let us first recall what the neo-Humean has to say about laws. According to the leading neo-Humean account of laws—the best-systems analysis or ‘BSA’ (also known as the Mill–Ramsey–Lewis account)—the laws of nature supervene on the array of perfectly natural, categorical properties.¹ The laws are those axioms of the system that capture the distribution of these properties and relations and that strike the best balance between being informative and simple. These BSA laws do not govern the locations or distributions of the properties; they are extrinsic after-the-fact laws that locate, but do not dictate, patterns in the mosaic. (By way of contrast, recall that on Armstrong’s account of laws—the Dretske–Tooley–Armstrong, or DTA account—the laws are second-order necessitation relations between state of affairs types.² Thus, they govern in the sense that these necessities dictate the property distribution, but the laws remain outside the objects and categorical properties they govern. Thus, like the BSA, DTA laws are extrinsic laws.) So, what does the powers theorist say? Here are two options one might pursue. According to Mumford, once you have powers, you no longer have laws of nature, because you no longer have the need for them.³ Interactions between powers account for the distribution of properties, and therefore underlie the generalities tracked in the sciences. To go this route is to argue that the powers metaphysic has no strict

¹ Mill (1967), Lewis (1973b, 1983b, 1986b, 1994), Ramsey (1978), Earman (1984), and Cohen and Callender (2009). See §2.4. ² Dretske (1977), Tooley (1977), Armstrong (1983). ³ Mumford (2004). The Powers Metaphysic. Neil E. Williams, Oxford University Press (2019). © Neil E. Williams. DOI: 10.1093/oso/9780198833574.001.0001

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need for laws, as the powers do the work for which the laws would be employed. Mumford calls this a ‘lawless’ account. This lawlessness stands in sharp contrast to Bird’s powers-based account of laws, in which the laws of nature supervene on the potential actions of the powers.⁴ Interestingly, the ontological framework from which Bird’s laws arise is similar to that which Mumford endorses, yet they make opposite metaphysical choices. According to Bird, powers underlie the laws, and the powers are what ultimately account for the world’s pushings, pullings, changes, and such. To this extent he agrees with Mumford. Yet the laws are not identical with the powers, he claims, because the powers are properties, and laws concern relations between events. It is the laws that give us the generalities, says Bird; they are what capture the facts regarding how the powers are exercised. He states that, Since a property P is essentially dispositional, then necessarily, if some x possesses P and receives appropriate stimulus S, then it will yield its characteristic manifestation M. Generalizing, 8x ((Px&Sx) ! Mx)—and so we have the regularity that is characteristic of the law (which may need a ceteris paribus clause). We see how the law is internal to the property—it flows from the essence of the property.⁵

Mumford defends lawlessness on the grounds that: (i) the role laws have been posited to fill has already been filled by the powers, and (ii) any laws would have to govern, yet powers-based laws are incapable of doing so. The first is the sort of manoeuvre employed here regarding extrinsic powers: do not posit theoretical entities to play a role that some other theoretical entities already perform. There is no need for laws alongside the powers. The second depends on the claim that the only laws worth positing would be those that govern. As stated, this would leave room for Bird-style supervenient laws. However, Mumford claims that if the laws are grounded by the powers (as Bird claims they are), then they would seem to be incapable of governing, because they would have to govern the very thing which grounds them. They would be self-governing, which Mumford deems problematic. Bird defends his choice to reify the laws partly on the grounds that laws are useful devices: as generalities they give us the regularities we track in nature. But the stronger reason comes from scientific practice. Many areas of science employ talk of laws, and many of those laws are well confirmed, as is, it would seem, the claim that there are laws.⁶ It can hardly be denied that tracking generalizations is central to the methodology of the natural sciences, and this makes the elimination of laws much less attractive. Moreover, supervenience putatively gets us laws from the powers for free, and so we can satisfy the needs of scientific practice without further ontological cost. That looks like a win–win situation. But what about Mumford’s concern that laws must govern, and that their being partly constituted by the powers renders this impossible?

⁴ Bird (2007a). Bird speaks of fundamental ‘potencies’, but he means by that term more or less what I mean by ‘powers’. ⁵ Bird (2007a: 196). ⁶ Bird (2007a: 198).

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Contrary to what Mumford claims, it is not clear that the only way to have laws— even those that satisfy his nomological realist desideratum—is to have laws that govern.⁷ But we can nevertheless agree that many of the intuitions behind the thought that powers are responsible for determining the locations and arrangements of properties in the world are unlikely to be satisfied by anything less than a governing conception of laws. A conception of laws as governing is thus the more desirable conception. Let us, therefore, shift our attention to whether laws that supervene on powers are capable of playing this governing role. In order to see how powers-based laws can govern, one must first appreciate that the laws are not identical with the powers from which they are derived. If they were identical, then perhaps the laws would govern by virtue of their being identical with the powers, because the latter govern. But they are not identical: the laws concern the specific ways in which the powerful nature of each power can be expressed. That expression, we have seen, is typically a matter of the power being appropriately arranged with other powers for what is their mutual manifestation. Thus, the law includes not just the power, but that portion of the power’s identity that connects the power to its constellation and manifestation types. It is therefore not the case that the powers are giving rise to laws and those laws concern only the powers. Yes, the laws will determine the distribution of powers, but they do so by being those relations that take us from one state of affairs to another. As Bird indicates, it ‘is the entities and events making up the world’s history that get explained and governed by the laws’, and those laws are not internal to the states of affairs that they govern.⁸ Thus, there is no problem having these laws govern (if, indeed, we insist that they must). As ought to be clear, the present account of laws of nature could be developed along the lines of either of these powers-based accounts. The powers are what do the work, and are what ultimately account for the distribution of properties, and so lawlessness is a live option. Adopting Bird’s realist account would take a tiny bit more work (owing to small differences in the accounts of powers), but nothing is required that is not already built in to the present account, or for which there is no natural substitute. Case in point, rather than appealing to the counterfactuals Bird uses to derive laws from his single-track potencies, one could take a law to be the portion of a power’s blueprint that connects the power to a specific constellation and manifestation type. This is, effectively, to conceptualize my multi-track powers as if they were a series of single-track powers, with each track running from power type, through constellation type, to manifestation type, and from there to laws. One could do a lot worse than thinking that these are the laws, or that there are none. Nevertheless, I find neither account completely satisfying, and prefer a third option: a hybrid view.⁹ The hybrid is motivated by reasons Mumford and Bird each offer in support of their metaphysical choices, but the result is not a simple mixture of both. It is instead a somewhat more surprising hybrid that combines fundamental lawlessness with a best-systems account. That is, it combines a fundamental powers-based ⁷ Mumford (2004: ch. 5). See Bird (2007a: ch. 9) for the reply. ⁸ Bird (2007a: 196). ⁹ This is not the sort of hybrid defended in Tahko (2015) or Hendry and Rowbottom (2009). It most resembles that of Demarest (2017), but she takes the powers to be identical with the properties instanced in her modified BSA, as discussed further into this section.

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lawlessness with a set of after-the-fact systematized generalizations. I call it the ‘Best Systems Blueprint’ account, or the ‘BSB’ for short. I take the BSB to be the best of both worlds as far as the motivations for laws go, and it is pragmatic to boot. In effect, the account is hybridized because it seeks to address two conflicting aims regarding the laws of nature, and gives two distinct responses.¹⁰ The first concerns what it is that makes the world tick: that is, what it is that explains why things are the way they are, where they are, and when they are. It is from this need to underlie the generalities that we get lawlessness. Further justification for lawlessness comes from the ‘unruly’ nature of powers and their exercising (at least as far as taming them via a relatively small set of rules goes). Assuming there are more than a handful of property types and potential manifestations, blueprints are going to be very complicated. So much so that convenient generalizations are unlikely. But this does not cohere well with the second aim. The second aim is that of doing justice to scientific practice, according to which there are simple, repeatable, and downright practical laws of nature—those which many scientists are in the business of finding. ‘Scientists certainly see themselves as engaged in the project of finding such generalizations.’¹¹ Why would we want to deny the status of law to what appear to be useful regularities emerging from the natural sciences? Hence, for the purposes of scientific practice and that of packaging the world into something more manageable, I incorporate the BSA’s supervenient laws.¹² Bird’s account is motivated—in part—by this second aim. I, too, feel the tug. But, unlike Bird, I do not believe that the sorts of laws that emerge from the blueprint structure are identical to, or can adequately replace, those that come from the natural sciences. Hence my preference for having BSA-style laws in addition to the blueprint, rather than just letting Bird-style laws satisfy both roles. With that in mind, let us focus on the blueprint side of the BSB—the fundamental lawlessness—and why I opt for it over the Bird-style alternative. Opting for lawlessness leaves a gap which the BSA fills, but why prefer lawlessness to a blueprint structure-based account of the laws? I offer three reasons. The first concerns a mismatch between the sorts of laws arising in scientific practice and those that we would get from the powers. Recall that Bird’s powers are single-track powers, expressed by counterfactuals: P is the power to M when met with stimulus S. These easily lend themselves to the sorts of generalizations found in the natural sciences. Multi-tracking is slightly less amenable to translation, but it can be done, in principle. But it gets harder to appreciate the mapping as the number of power types increases. That is, as the powers-based laws start to multiply and get more and more specific and unwieldy, the less well suited they seem as a replacement for the very general and navigable laws found in science. Then there are the stimuli. Saying that P will M in S papers over the complexity (and perhaps enormity) of the stimuli. Stimuli—for those powers that have them—are

¹⁰ A single response is possible, but I believe that we get better answers by giving two. ¹¹ Cohen and Callender (2009: 3). ¹² ‘Recognizing in science the attempt to produce small sets of basic principles as a result of balancing simplicity and informativeness is the central and powerful insight that motivates MRL’ (Cohen and Callender 2009: 3).

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nothing more than other powers; a stimulated power is a power in a constellation. But how big are constellations? What are their boundaries? Might they be world-size? I discuss these questions in Chapter 6, but no definite answer is offered. Instead I lean on there being some natural answer: constellations are as big as the system of powers has them be. Assuming that they are very large indeed, it is easy enough to say that we need S to get M from P, but actually knowing what constitutes S is something else altogether. Perhaps this can be done, in principle if not in practice. But it is that last proviso that is the troublemaker. This is not what is done in practice; this is not a law like those coming out of the natural sciences. The previous concern that the laws become largely non-navigable owing to multi-tracking and constellation size is not formally intractable, especially if one is motivated by the realist model of laws it generates. But the more complicated things become, the greater the distance between these laws and what passes for laws in scientific practice, and the weaker the motivation to derive a system of laws from the blueprint. There could be miles between principle and practice. Secondly, even if we can bring the powers-based laws in closer correspondence with the laws of scientific practice, incongruence would still result if the former generates fewer laws than the latter. One way this might obtain is if the latter includes a class of laws missing from the former. Here is one way that this could be the case. Bird-style laws are what we might call ‘causal laws’; that is, they are laws that concern causal potentials between a state (or event) and that which it can (or did) produce.¹³ Given how powers operate, instances of Bird-laws result in a cause-andeffect pair in the world. And though it is hard to say what exactly is involved in a powers-based causal law like this, it expresses some sort of diachronic movement from one state of the world to the next. Assuming causal laws are diachronic in this sense, a mismatch could result if scientific practice generates or employs laws that are synchronic, or what we might think of as non-causal laws. So, are there synchronic laws in science? At the heart of Hempel’s discussion of confirmation is an example that seems to fit the bill¹⁴: All Ravens are Black. Putting aside the epistemic worries, consider just the law itself. It relates a kind (Raven) with the having of a specific property type (Black). The law—if it is one—is something like a ‘typifying’ law, a synchronic connection between an object’s being some way and its counting as a member of a natural kind. Maybe not all ravens are black, but laws like this are common in science (both in classificatory schemes and in general). And so we have a putative mismatch. More needs to be said in order to establish that there really is a mismatch (such as: are there fundamental laws like this?), but the early evidence suggests as much. There are also laws that relate properties at a time (such as the ideal gas law), and those that dictate the natures of laws (meta-laws); either would be further grist to the mismatch mill.¹⁵

¹³ Balashov (2003b).

¹⁴ Hempel (1945).

¹⁵ Lange (2007, 2009).

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I lack the space to give this potential mismatch the full attention it deserves, but let me head off one objection that might arise, to the effect that the powers theorist can handle these cases in some other way. That is, perhaps the synchronic laws have diachronic translations (raven states with certain properties give rise to further states with the same properties?), or can be accommodated via the powers ontology in some other way (the meta-laws might be metaphysical laws).¹⁶ The first could help us avoid a mismatch, assuming it could be done. But the latter seems to involve laws that do not reflect the natures of the powers in the same way the Bird-style laws do; they have alternative truthmakers, so to speak. In that case we have two systems of laws (as given by two different applications of the powers ontology), and so we still get a form of hybrid account. If that is the case, then it is a matter of picking one hybrid account over another, and I prefer to leave the synchronic laws on the best-systems side of the fence. Finally, in treating the powers-based generalities as laws, there is a danger that we come to think that the statements that capture the elements of the structure pick out genuine entities. Or even that the structure itself is a genuine entity. The blueprint structure is not real—it is not a thing. It reflects the internal nature of the powers. But taking it as providing a set of laws sounds like the structure is a reified entity. Worse yet, it starts to sound as if the laws do all the work, and not the powers. It is a short path from structure reification to power unemployment. I thus prefer that we not speak of the powers and their exercising in terms of laws, for fear that we take what is the best substitute for laws and turn it into something that it is not. Instead, I suggest the following: embrace—fundamentally speaking—that there are no laws. There are powers, and they form a complicated system that replaces the need for laws, at least as far as the distribution of objects and properties go. There are, as per the mosaic metaphor, internal rules that dictate (from within) the pattern of the tiles, yet the universe is strictly lawless. This satisfies our Mumford-want to have something that governs. But what about our Bird-want to do justice to scientific practice? Start by thinking about the powerfulness of powers, and of the blueprint that is inside each. Now consider all the different histories those powers permit.¹⁷ There are many of them, but only one history is actual. (For illustrative purposes, think about the different mosaics you can generate even though every tile has instructions about what must come next. Which mosaic obtains may well depend on the initial conditions, which themselves could have differed.) We have before us just one of the many histories that could have been. Let us assume that we are largely ignorant of the internal features of blueprint structure (an easy assumption to make). What would it take to discern the blueprint structure, or the causal-potential structure, if you prefer? It seems like the best one can do is as follows: survey the actual history; track the distribution of properties; try to systematize that information; then use the patterns one finds to work backwards in the hope of discovering the internal rules by ¹⁶ We could also resolve the issue some other way entirely, by adding to the metaphysic. For instance, we could adopt a specific theory of natural kinds. However, nothing we add to the metaphysic is going to give us the powers-based laws we seek. ¹⁷ I am speaking of ‘histories’ atemporally, to mean all of existence, wherever or whenever.

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which the patterns were generated. But given all the different ways powers can combine, and all the different ways that the history of the universe could have been, the actual distribution of properties will be only a rough guide to the nature of the powers. By analogy, it is not going to be easy to discern the internal rules of the tiles by looking at the mosaic. If we are very lucky, there are very few power types, constellations will be small, the blueprint would be of a manageable size, and the regularities would be both manageable and reflect the full extent of the blueprint. While this is plausible, and clearly desirable, it is just as plausible that we are not so lucky. Not knowing just how unlucky we are, we could throw our hands up and submit to scepticism, but that response is uncalled for. Even if the actual mosaic is well removed from the luckiest we can get, it still represents our best shot at knowledge, and might provide a satisfying, if incomplete, picture of the blueprint. We take our best stab at what those internal rules might be, based on the information at hand. The most promising way of doing this is to systematize and unify our understanding of the generalities. That is, we should employ the BSA as our best guess at the nature of the powers. That is not to suggest that we should adopt the BSA as our metaphysical account of what the laws are—the metaphysical aspect is given by the lawlessness—but the BSA represents a reasonable way of thinking about what is done in the sciences, and how we can get at the blueprint. And thus the BSB gives us the best of both worlds. Heather Demarest presents a hybrid account of laws which is similar to the BSB, but that promises to bridge the mismatch between the BSA and the powers.¹⁸ According to her account—what she calls the ‘Potency-BSA’—it is the distribution of powers (or ‘potencies’) on which the best-system axioms are based. We have a range of powers in a world, and they are responsible for the actual distribution of properties. The laws are given by the systematization of that distribution. So far, this is more or less identical to my hybrid view. Where it differs is in the range of data points she advocates, and thus the accuracy she can achieve. Rather than restricting the BSA to just the actual distribution of properties, she suggests we systematize any and all possible distributions of the powers, meaning that she can capture generalities that the powers are capable of producing but which did not arise in the actual world: Potency-BSA: The basic laws of nature at w are the axioms of the simplest, most informative, true systematization of all w-potency-distributions, where a w-potency-distribution is a possible distribution of only potencies appearing in w.¹⁹

As we have seen, there is every reason to believe that the generalities present in the actual distribution of powers will be an incomplete and presumably inaccurate guide to the natures of the powers themselves (their blueprints). But the incompleteness— and probably much of the inaccuracy—could be avoided if we had access to not only the actual distribution, but any distribution the powers are capable of generating. For instance, if it just so happens there are two power types that never have instances in a constellation together (or that they only ever happen to appear in the presence of a third, or that different constellation types can produce the same manifestation types,

¹⁸ Demarest (2017).

¹⁹ Demarest (2017: 49).

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and so on), then the laws as given by the BSA will be a less-than-accurate guide to the blueprint structure. But if we allow the BSA to range over not only the actual history, but any history that could have been, then these possibilities will pop up in histories somewhere, and the accuracy of the BSA laws will be markedly improved. In fact, it should give us the entire blueprint structure. This account has everything my hybrid account has (the oomph of the powers, their explanation of generalities, and the coherence with scientific practice), but it also boasts perfect congruence between the BSA laws and the natures of the powers. So, why not go this route? The short answer is that it is impossible. Or more correctly, it requires impossible science, and that violates both scientific practice and consistency. First off, let me briefly register my worry about the use of possible worlds in the analysis and the inherent danger in reasoning in a way best suited to the neoHumean metaphysic, but then quickly move past it (there, I am done). Next, there is a small concern that could arise regarding the origins of the universe. What if the initial state of the universe is fixed, or if there are only a limited number of possible initial conditions? That would mean that certain manifestation types might never arise, and therefore that there are aspects of the blueprints that do not appear in any world, possible or actual. If the initial conditions are fixed this way (assuming there are such things as initial conditions), then the potency-BSA might not be as accurate as we are assuming it would be. This would not be a major setback, but it is the promise of greater accuracy that motivates this account relative to my hybrid account, and so is not to be ignored. But even if the potency-BSA is not quite as accurate as advertised, it would still fare better than my hybrid. The problem with it, as far as I can tell, concerns the possible worlds. Not qua worlds (as per above), but in terms of their content. Consider, once more, the fact that certain power types might never have the opportunity to interact. In that case, the manifestation type they produce might never arise, and so the generalities never crop up, and consequently the BSA laws are less accurate. The potency-BSA promises to fix the mismatch by including possible worlds in which the interaction takes place. But what happens at those worlds? That is, what is the manifestation that obtains? The answer, of course, is whatever is dictated by the blueprints of the relevant powers. Fair enough. But what is that manifestation? The answer is that we have no idea. The only information we have about the blueprints is what we gain from the actual distribution of properties.²⁰ And based on that distribution we not only have no idea what would happen, we may not even be aware that there is a gap in our BSAbased guess at the blueprint. The only information we have—and therefore the only information by which we can dream up the merely possible property distributions of possible worlds—is what we know about the actual world. And that means that it is the BSA (or some other account of our scientific-based best guess) that is dictating the content on which the Potency-BSA would be based. We are, therefore, no closer

²⁰ It is not as if we can compare results with the scientists of the ‘richer’ worlds in which the missing generalities obtain, given that worlds are causally isolated.

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than we were.²¹ Hence, the BSB is as good as one can hope to do as far as accuracy goes, and thus there is no reason to drop it in favour of the potency-BSA.²² Before closing out this section, I offer one additional point in favour of the BSB. Lewis’s BSA is developed around the properties of the fundamental entities. The laws of the BSA are thus restricted to laws that are similarly fundamental. On the present hybrid view, it is the distribution of fundamental powers that constitutes the BSA subvenient base, and hence it, too, is an account of laws at the fundamental level. But not all the laws we find in the sciences are fundamental laws; many (and plenty of the ones we appeal to most often) concern chemicals, biological entities, macrophysical objects, or economic factors. For ease, call these ‘special science’ laws.²³ We have as much reason to want to believe in these special science laws as we do the fundamental ones. They are just as important to our understanding the world, and play at least as large a role in scientific practice and knowledge. Contemporary biology would be unrecognizable without laws of natural selection, but what fundamental entities could possibly play the relevant roles in the law?²⁴ There is nothing at the fundamental level we would recognize as living, but no organism has the powers needed for lawless biological laws. I thus opt for a middle way: the special science laws are laws given by the best system. Actually, they are given by the better best system (BBSA), a BSA expanded so as to include systems of laws relativized to specific fields. Just as much as one can systematize the distribution of properties at the fundamental level and develop after-the-fact laws, one can systematize distributional data regarding the macroscopic kinds and develop laws regarding them. But assuming the fundamental laws are complete (or as near complete as the actual distribution affords), why would we need anything more? Firstly, there is the practical problem of translation, which is compounded by the fact that no one working within the relevant special sciences would attempt to work with entities outside those over which their chosen discipline ranges. But assume we can pole-vault over that massive hurdle; even if we can translate the special science laws into the language of the fundamentals, ‘the resulting law will be too long and disjunctive to make it into the Best System’, and so it will be excluded anyway.²⁵ If we want special science laws, then we need more than fundamental laws to have them. This last requirement poses a much larger problem for the present powers metaphysic. The only properties are powers, and the powers are fundamental. How ²¹ Demarest is optimistic that the mismatch is less than I imagine it to be, and that (actual-world) controlled experiments can fill many of the generality-gaps that nature leaves behind. I nevertheless worry that the best guess we can make regarding the accuracy of our best guess is itself born of our best guess (how else would we identify gaps as such?); hence my pessimism. ²² This should not disguise the fact that I am largely in agreement with Demarest, and that, impossibility aside, her model presents a nice way of representing the relationship between the powers and the BSA laws. One might fruitfully understand the BSA half of her potency-BSA as an alternative characterization of the blueprints, even if possible worlds are a less than ideal construct, and the relevant science cannot be done. ²³ Fodor (1974). ²⁴ Cohen and Callender (2009: 10). Cohen and Callender also discuss entropy and the Past Hypothesis, the latter being a law employed in thermodynamics that relies on the former, non-fundamental notion. ²⁵ Cohen and Callender (2009: 10). See also Fodor (1974).

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then do we have the relevant special science distributions at all? What are they distributions of, if there are no special science properties? And never mind the properties—are there even special science objects? The answer is that yes, there are special science objects, and no, they do not have powers. But they are the subjects of true predications, and those predicates are what appear in the BBSA.

10.2 Macro Powers? Like laws of nature, a mature metaphysic will typically have something to say about everyday objects. And though this part of my account is not yet fully baked, I still want to make good on my promise to say something about non-fundamental objects and their dispositions (yes, I said ‘dispositions’, not powers; that was not a mistake). I have also indicated that we might have laws that range over objects beyond the fundamental, and so some discussion of their abilities is in order. Right or wrong, it is my position that such macroscopic (macro) objects as molecules, tables, persons, dinosaurs, and bowling balls exist.²⁶ Belief in middle-sized dry goods (and their smaller and larger kin) should not come as a shock to anyone; these are pretty normal things to believe in, after all. But it might be a bit more surprising to hear that I include them in the powers metaphysic, given that the metaphysic is so heavily skewed in the direction of the microscopic. And I am unlikely to lessen the surprise when I add that the macro entities are not property bearers. That is to say, macro objects do not have powers. But that does not rule out their being able to satisfy predicates. Hence, they can have dispositions truthfully ascribed to them, and so end up being a bit more like we would expect. In this section I want to say something about this pair of commitments, and indicate how they can be squared with the other claims of the book. The simple claim about the existence of macro objects is that they are complex states of affairs, composed of nothing over and above specific arrangements of their parts. Their parts are simple states of affairs. Macro objects, therefore, are identical with arrangements of simple states of affairs (which are themselves just fundamental objects). Constitution—at a time—is identity.²⁷ This will not hold true over time, because we want to maintain the (apparent) truism that macro objects can survive change in the parts that compose them, but that is no barrier to those macro objects having different collections of fundamental entities playing the constituting role at different times in their careers. Macro objects are thus composites, composed of micro objects. But they are not mere collections of simple states of affairs, as that would overlook the need for those constituents to satisfy some configuration or other. Consider a methane molecule: the relevant structure requires that we have four hydrogen atoms centred around a carbon atom, for which the sheer existence of the parts does not suffice. (Those atoms will themselves be a matter of fundamental entities appropriately arranged.) ²⁶ It might be fairer to say that macro objects (in some sense of the word) exist (in some sense of the word), but we will get there soon enough. It might be that minor-league baseball teams and corporations exist, too, but I will leave that question for another day. ²⁷ See Lewis (1986a), Noonan (1993), and Wasserman (2004).

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When the simple states of affairs take on certain arrangements—when they have this or that structure—they constitute this or that macro object. This should sound familiar: causation is a matter of microscopic powers producing manifestations as they form constellations. Some of those constellations (or parts of them) will coincide with the arrangements that satisfy macro objects; which ones will depend on what sorts of macro objects we pick out. That is, those complex states of affairs that count as macro objects will be those that satisfy our various criteria for being an instance of this or that macro-object type. As we have seen, being a methane molecule requires that the micro entities take on a specific structure (or if you prefer, that they take on such structures as hydrogen and carbon atoms, and that those take on further structures). And if left alone, the complex states that follow (the manifestations) will themselves tend to be methane molecules. We thus have a sequence of constellation–manifestation pairs that is at once identical with a persisting methane molecule. It is worth appreciating how the micro-causal picture and the macrocomposing picture coincide. Given the ‘ocean’ of simple states of affairs, we might well wonder why a given constellation (or part thereof) constitutes a macro object, whereas some other constellation (or part thereof) does not. I suggest—albeit cautiously—that it is the temporal stability of constellation types that underlies our picking out various collections over others. Isolatable and (typically) sustainable constellations are those that produce similar manifestations when met with limited interference. That is, they sequentially exhibit static manifestations (§7.2). This is not to suggest that object identity is not present at a time, but it is most apparent when the structures (the complex states of affairs, or large portions thereof) are static over times. We can contrast these static-repeaters with random collections of powers; unlike the former, the latter need not display any cohesion over time. This is what distinguishes genuine macro objects from arbitrary collections of fundamental entities. This is the core of the powers metaphysic account of macro objects, but let me elaborate on this picture by working through a couple of clarifying objections. (It will also serve to shift discussion from the constitution of the macro objects to the matter of their dispositions.) The first worry is that macro objects, as constructions out of powered micro objects, are not something we need in our ontology. They will not be novel: they are complex states of affairs, and so incorporate the simple states of affairs and the relations between them, but they are nothing more than that. Nothing springs into being when certain arrangements obtain that adds to the material tally of the universe. Granted, it might be that at one moment a range of micro objects are not arranged in such a way that they constitute a methane molecule, and then in the next moment they are, but what results is just the first moment of the methane molecule’s existence, and nothing more. A molecule of methane came to be, but its identity with its parts means that, strictly speaking, nothing was added. You cannot have your methane molecule and eat its parts, too. So, given that they are not novel, why introduce them? I argued in §4.1 that we should not admit extrinsic powers into our ontology, largely on the grounds that we should not posit powers that would not have any work to do. Why would the same criteria not apply here? That is, why would we admit macroscopic objects if all

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the work they could do was already being done by the fundamental entities that compose them? The first answer is that there is not, properly speaking, an objection here at all. The novelty principle I appealed to was specific to powers. I claimed that we should not introduce into our ontology any power whose only possible causal roles were those that necessarily duplicated that of another at any time it would act. Applied strictly, this does not extend to macro objects. Hence, there is not really any objection here. However, there is a general principle lurking in the area that warns us against introducing any sort of entity—power or otherwise—if that entity does not have a novel job to do. That nearby principle strikes me as reasonable, and so it here raises a problem. At the very least it invites us to say why it is we should have macro objects if they are ontological coat-tail riders. That brings us to the second answer. What are their roles? I previously cast suspicion on the addition of entities that we supposedly got for free, wherein the cheapness was a matter of some sort of building relation (perhaps supervenience), and the extra entity was not identical to that or those from which it was built. I maintain that this suspicion is well founded, and further that anything we want to add to our ontology needs to earn its keep. But macro objects are exempt from this requirement, because they are not additions to our ontology. They are identical to the simple states of affairs, properly arranged.²⁸ Unlike those would-be entities that are ‘built’ by one-way dependence relations, we get the macro objects for free because they are identical, and thus can be reduced without remainder. (There are no hidden fees of any sort, no secret taxes or tariffs, and no in-app fees.) As ought to be obvious, if Superman is allowed to go beyond the velvet ropes and into the ontology club, you cannot leave Clark Kent out in the cold. Kent’s being identical with Superman means he gets to enter the club for free.²⁹ The second worry concerns what ought to follow about macro objects from the discussion of states of affairs in §1.5. As macro objects are states of affairs, and states of affairs are pseudo-composites of underlying substratum-plus properties, it follows that macro objects have properties. And given what has been argued about properties, macro objects ought to have macro powers. In that case it would seem that a host of objections are in the offing, concerning the existence of those macro powers, whether they are novel, and so on. One of those objections is as follows. There is nothing more to an object over and above those simple states of affairs that compose it. Those simple states of affairs all include powers, and those powers are constantly interacting. More to the point, they do all the work that we might want to credit the macro object with having produced. There is no work for any would-be macro powers to do, and therefore no need to employ them. But as states of affairs, the

²⁸ This reduction is a matter of what is required for them to exist; it does not imply that we could give an adequate explanation of how they could be engineered, as might be required by some other form of reduction. ²⁹ If identity is sufficient for getting an entity past the ontology bouncers, then why were some of the (identity-grounded) token extrinsic powers denied their place? The answer is that identity is sufficient only in some cases. To wit, powers need to be powerful.

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macro objects must have them. Either macro objects cannot be states of affairs, or there must be powers that supervene on other powers. Let us start by getting one thing clear: as complex states of affairs, macro objects have properties as a direct consequence of their constituents having properties. So, there is a perfectly good sense in which the macro objects have properties (and therefore powers). I do not deny this. What I am denying is that the macro objects have properties (powers) of their own, properties that are not just the individual powers had by the fundamental entities from which the macro object is composed. Escaping the dilemma requires us to soften the impact of the first horn, thereby allowing us to embrace the seemingly problematic claim that the macro objects are property-less states of affairs. This is prima facie inconsistent to be sure, and only made worse by the fact that it violates my brief account of objects in Chapter 1. But resolution will come about via a revision—or perhaps a provision—to the original claim. The provision is that we should not understand macro objects to be objects in the same sense that the micro objects are. ‘Object’ becomes a bifurcated notion. Micro objects are identical with simple states of affairs; this is the first sense of ‘object’. The second sense is that which applies to the macro objects, all of which are identical with complex states of affairs. Thus, the macro objects are real, and they are what we can safely enough call ‘objects’ in the everyday sense, but they are not objects in the same sense that the fundamental objects are. We can make this sound better if we stop thinking of the fundamental entities as numerous tiny things, but as one giant field. I am open to that possibility, and it would not change my account of powers. But it would make macro ‘objects’ rather different things. They would not be composites of many fundamental entities, but parts of the huge field. Pictured like this, as if the middle-sized objects were like waves in a giant ocean, makes it easier to accept that the middle-sized objects are not quite objects in the same sense as the ocean is an object. It also makes it much easier to come to terms with the claim that they do not have properties, per se. Any properties they would seem to have are properties of the large thing of which they are a part. They do not have any properties of their own. Now flip back to the picture on which the middle-sized objects are composed of simple states of affairs. It should not be much harder to wrestle one’s mind around to the conclusion that, as complexes, the macro objects do not have properties. This suggests a general principle according to which atomic (fundamental) states of affairs are property bearers (that is, the things that strictly have properties), and complex states of affairs are not property bearers. Fundamental states of affairs are a mix of substratum and properties, whereas complex states of affairs are a matter of the fundamental states of affairs standing in relations to other fundamental states of affairs. Recall Joanie’s unrequited love of Chachi. This state of affairs resulted from Joanie’s standing in the loves relation to Chachi, and his not feeling the same about her. We can use this case to help illustrate the point (ignoring the fact that Joanie and Chachi are not simple). We need a complex state of affairs to account for the holding of the non-symmetrical loves relation between them, but the resultant complex state of affairs is not an object. (Not in any standard sense anyway.) Nor is it a property bearer. The only property bearers in the example are Joanie and

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Chachi: the Joanie-loves-Chachi complex is not a thing that itself has properties. This is, of course, a merely illustrative case. Joanie and Chachi are complexes, too, and so not the bearers of properties. The only properties will be those of the simple states of affairs. Those simple states of affairs will stand in various relations, giving rise to complex states of affairs, but without those complexes having properties of their own. This brings us to the real question behind this section: how can we have macro objects without powers? Have we not heard many times about the glass’s fragility and the salt’s solubility? Yes, we have. But these are not powers. Not, at least, in the technical sense of ‘power’ that has been employed throughout this book. They are powers only in the loosest sense of the word. Early on I made a distinction between powers and dispositions, treating the former as the properties at the core of the powers ontology, and the latter as something more like useful talk. Part of that was to help us get past the common-or-garden notion of ‘disposition’ and any confusions it might bring with it. I also said that fragility, solubility, and the like were not powers. What I said was that these were dispositions, and that is what they are. Question: do macroscopic objects have powers? Answer: no, they do not. But they do have dispositions, and dispositions are not identical to powers. Dispositions are among the phenomena to be explained by the powers metaphysic; not by making powers and dispositions identical, but by providing an account of the latter (partly) in terms of the former. I said from the start that glasses are fragile. Most are, and I take that seriously. But their fragility is not a matter of their having a power that goes by that name or any other. Nor is it a matter of their having some ontology-bloating derivative power that is identical to a set of fundamental powers, and therefore a strictly powerless causal coat-tail rider. Glasses are legitimately fragile—we can truly ascribe the predicate ‘is fragile’ to a glass—if, in a given context, the powers of its basic constituents would initiate the relevant process of constellation–manifestation pairs (in this case one that would terminate in the glass’s being broken). But the having of fundamental powers in a given context is all we need for this to be the case. No additional properties of the glass itself are required. Note the parallels here with what the neo-Humean says about fragility. The neoHumean denies that a glass’s being fragile is a matter of its having some power or other. It is true that the glass is fragile, but that truth depends on what sort of categorical properties are had by the entities that compose the glass, along with its being the case that certain laws and counterfactuals obtain (and certain contextual features). The fragility is the phenomenon to be explained; the neo-Humean’s metaphysic accounts for it by providing a story that employs the ontological entities and the metaphysical apparatuses available to her. The powers metaphysician has different entities and different apparatuses, and so provides a different story. But the methodology is the same. It is certainly not the case that one’s commitment to fundamental powers requires one to think that the glass’s fragility is itself a power. We are on the verge of a powers-based analysis of dispositionality. That is what we are really after when we provide a metaphysical story that accounts for some feature of the world. The analysis gives us a carefully articulated account of how the ontology accounts for the relevant feature: in this case what criteria is required for an object to count as having some disposition. That is why the counterfactual analysis has received so much attention in the literature: it is arguably the neo-Humean’s best

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story of how it is objects have dispositions. So, what is the powers theorist’s story of dispositions? The rough-and-ready story I offer is that a macro object has a disposition just in case the object is capable of initiating a process of a certain type. The relevant facts, of course, will be grounded in powers of the fundamental entities that compose the macro object, but the general picture is that of dispositions as process initiators. I will shed a little more light on that story, but I will not go so far as to provide a complete or careful analysis. A macro object is either a constellation unto itself, or part of one. But treat it as if it is just one large constellation. Within that constellation you have a great many micro entities and their powers; those powers are ready to give rise to states of the world, and when exercised, they do. Repeat this a few times, and you can start to track those states. Inevitably you will start to see patterns emerge. If reasonably refined (think BSA), this tracking constitutes a good guide to expected behaviours for macroscopic objects. And experience suggests that we would track the processes (sequences of states—see §6.3) in which those objects participate, connecting early states with late states, until we get to the point where we are quite good at predicting what sort of later states can reasonably be anticipated when the early ones obtain. We can then start to work backwards, recognizing in the early states the potential processes and later states which those early states can give rise to. Furthermore, because the macro objects are nothing more than collections of smaller objects, if we control the other objects in the neighbourhood, we can control—to some extent—the other powers that might enter into the constellation. And thus we can thereby extend our knowledge and predictive ability. The steps in the processes are still short, and the start and end points artificial (in the sense that there were active constellations before what we think of as the initial state, and there will be plenty after), but we can nevertheless isolate indicators, and can have expected outcomes of earlier states. What emerges is a picture of dispositions as process initiators. To have a disposition is for it to be the case that the powers of the constituent entities are poised to bring about one of a range of process types. Those fundamental powers do not have a process as their manifestation; their manifestations are more or less immediate. But we can think of dispositions in a more coarse-grained and imprecise way than we do the powers, as tied to a range of process types and more distal termini. All of this, of course, is relative to context. For any object, however robust, there is probably some constellation that leads to the object’s being broken, but we would not say of all objects that they are fragile. Hence, the disposition ascriptions we make must be sensitive to the sorts of environments in which they find themselves. Some of this is covered when we track constellations: a constellation is itself a part of the context. When we anticipate certain constellations obtaining, we are considering those that are likely based on the powers that are nearby, and ignoring constellations involving powers that are well removed. A fragile glass is thus one that—in the present context—can be part of many constellations that could lead to breaking.³⁰ ³⁰ Comparing the number of constellations that would lead to breaking would provide a basis for grading dispositions as more or less fragile (within a context). See Manley and Wasserman (2007) and Vetter (2015).

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Furthermore, disposition ascribing was already an imprecise affair, but contextual features amplify the imprecision. We should not expect disposition ascriptions to be any more precise than is our determination of context. The latter are rarely well defined, and so imprecision in disposition ascription will be the norm. Interestingly, as we track processes and ascribe dispositions we find all the traditional problems that plague the neo-Humean’s counterfactual analysis of disposition ascriptions creeping back in. The processes can be thrown off, and they can be prevented and diverted. These are not legitimate problems (in the powers metaphysic), because dispositions are causally inefficacious predications, and thus incapable of producing processes or anything else. But from the macro perspective of disposition tracking, we can find that we cannot always control against: blocks to the causal chains (antidotes); combinations that act in ways other than those anticipated (finks); terminal states arising from states other than those which we had expected (mimics); or extra powers getting into the mix and preventing what we would have expected based on what we took the constellation to be (masking). None of these is a genuine feature of powers-based causation, which is made up of very short, and necessary, steps. But when we assume the coarse-grained dispositional perspective, the imprecision and artificiality brings them back. It should be no surprise that our disposition ascriptions will tend to be understood as being true ceteris paribus.³¹ By understanding dispositions as process initiators, we gain a rough and ready way of allowing for true predication of dispositional predicates without compromising our fundamental ontology of causal powers. Doing so also gives us a basis for thinking that macro objects (which are really pseudo-objects, as they are complex states of affairs) can have pseudo-properties, without getting us into any trouble with redundant or lazy properties. But consider just one final objection. Redundant powers are not something we need, and thus there is no motivation for admitting them into our ontology. But macroscopic objects are harmless non-additions to the world. We get them for free, and that is okay. So, why not say the same about the would-be macroscopic powers? Why not also treat them as innocent? First of all, if macro powers are what get picked out by such names as ‘fragile’ and ‘soluble’, then these powers are not reducible, because many different objects can be fragile or soluble in many different ways. Hence, these macro powers would not be identical with any set of fundamental powers.³² I thus claim these are the names of dispositions—and that they concern context-specific process types and epistemically salient terminal states. We are thus already headed in a different direction. Nevertheless, for the sake of argument, assume that we can correct for this, and thus that the macro powers are highly refined and specific token powers with more or less instant manifestations, just like the fundamental powers are. This replaces the normal motivations for having macro powers, but, in principle, something could still be salvaged.

³¹ This is the same way in which we can avoid talk of total determinism in a system that is deterministic. Tracking dispositions (made true, or better, made true enough) by the patterns of powers had by the fundamental entities will be an indeterministic enterprise (and I hazard gives us all the indeterminism we should ever need), even though the causal system is entirely deterministic. ³² Jackson, Pargetter, and Prior (1982) argue against identity on similar grounds.

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But now ask what those powers could be powers to do? There is nothing these highly refined macro powers could be the powers to do that was not already covered by the micro powers in our ontology. This is not a matter of overdetermination or closure. It is the claim that the powers we admit into our ontology need to be such that they add to the space of powers in the world. It is a test these macro powers fail. They are nothing but specific constellations of fundamental powers. Any contextual features we might cite here in support of the macro powers are nothing more than other fundamental powers arranged thus and so. Consequently, you might get these macro powers for free, but getting something you do not need for free is hardly a gift. These are supposed to be powers, and that is where their innocence is lost. Before ending this section, let us return to the matter of macro laws, and how they get in on the act. How do we have macro laws? The answer is that the patterns we use in developing our disposition ascriptions are the same as those from which the better best-systems laws are derived. Imagine using the best systems—or in the everyday case, a kind of poor man’s best system—to capture frequently observed states, and then using them to track and predict behaviours. On the one hand it gives you dispositions, and on the other you get laws. The more care with which those generalities are tracked, that is, the greater the precision and repetition, and the greater the portion of spacetime they cover, the more refined the claims regarding the best guess at the rules and capacities by which the patterns are governed. I take this to be a virtue of both the account of macro objects and of the better BSB.

10.3 Macro Persistence You might think that the story of macroscopic persistence is just like the one for microscopic persistence (Chapter 8), only substituting larger entities for the fundamental ones. A natural thought to be sure, but a wrong one nonetheless. Not wrong because macroscopic persistence (hereafter ‘MP’) fails to involve immanent causation, but rather because the powers only have an indirect role to play, and the problem of pluck takes on a different form. Let us start with pluck. The problem of pluck is the problem of explaining how objects continue to exist through sameness and change (§8.2). It also concerns the explanation of the existence of the various stages in an object’s career. The pluckiness of fundamental entities is explained by powers-based causation. Constellations give rise to manifestations, and those manifestations are states of affairs; those states of affairs are objects and their powers. With causation comes pluck. But at the macro level things are a little different. We have already accounted for the persistence of the entities that compose the macro objects, so that part of the problem does not need solving. Furthermore, as the macro objects (at a time) are identical with complexes formed out of the fundamental entities (at a time), the fundamental picture has already taken us quite far along in explaining MP. Here is the picture so far: the fundamental entities are engaged in continuous manifestation production, thereby populating the world with numerous fundamental object stages. Many of those fundamental object stages will stand in certain relations to one another, giving rise to complex states of affairs. Some of those complex states of affairs will be identical with the macro objects. Hence, we have plenty of

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macro-object stages (either spread out over time, or arising in sequence). This moves the problem of pluck for macro entities beyond the existential question and on to that of why a macro object at one time should continue to exist at the next moment or moments. For instance, why should this presently existing table in front of me continue to exist? The answer, yet again, comes down to the fundamental entities. Consider the complex state of affairs that is identical with the table at t₁. It is composed of some arrangement of fundamental entities.³³ First things first, that state must be a tableworthy state that answers to the relevant sortal. That is, it needs to satisfy our criteria for tablehood. That is a matter of its having some arrangement that falls within the bandwidth of arrangements we have decided count as tables.³⁴ Those same table-forming fundamental entities either form one large constellation, or are made up of a collection of them. For simplicity, assume it is just the one. That constellation has some state that is its manifestation; it will obtain at t₂. On the assumption that the t₁-state is a complex state of affairs identical with a table, then the expectation is that the t₂-manifestation the t₁-constellation will produce will also be a table. To be clear, the manifestation will be whatever it is going to be. But experience teaches us that tables at a time give rise to table states at later times. The same holds if this is a collection of constellations. They may have individual manifestations, but those will jointly be a table. As we have seen, specific states of the world set things up in a way that favours similarity; static manifestations are often isolatable and sustainable. They are more or less stable over time. If left alone, we would get table state after table state. Hence, what explains the fact that the table tends to stick around (pluck), is that the states of the world that constitute tables are states prone for the production of future table states. This is the nature of immanent causation for macro objects. If it was a caterpillar we were dealing with, we would find that the various states would exhibit minor changes. For some stretch of time, each constellation gives rise to a similar manifestation, but one that is not quite the same, as a matter of growth. The addition of other powers (what we might more easily understand as the addition of food and water), stepwise produce a series of states that are a growing caterpillar. And eventually those states have quite different manifestations to those that preceded them. Once we have this model of MP, it should be easy to see how it can account for change.³⁵ But we might still have doubts about sameness. For instance, if a complex (table) state gives rise to a table state, then the table that results is the same as the first,

³³ Which exactly? It is hard to say. It is possible that there is no precise answer, or that many overlapping complex states of affairs count as tables. But assuming they are all sufficiently close and overlap each other to a high degree, then any or all will do. See Lewis (1993). ³⁴ We assume—correctly, I think—that table states give rise to future (spatially nearby) table states, and that they are similar in quality and location. However, it is possible (for all we know) that this is radically mistaken. We might, after all, be entirely wrong about the what and where of the manifestation of the first state. If so, this would make it awfully hard for us to track objects (and do science). ³⁵ The lack of properties of complex states of affairs means that we can escape the problem of temporary intrinsics. But the nearby problem of temporary intrinsic relations arises, and so we have escaped the frying pan only to land in the fire.

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in the sense of ‘same’ we apply to persisting entities. But what if that table state had come about by some other—that is, non-causal—means? What if unbeknownst to us the new table state was not the product of the previous table state, but the result of an angry god who vaporized the early stage and replaced it with a qualitatively indistinguishable second?³⁶ Fortunately, this is not a possibility we need worry about. It simply cannot be that a state of the world that is about to give rise to a table (because it is a complex state identical with a table) could fail to do this. That is the necessity of powers-based causation at work. That is not to suggest that a god could not intervene, but the intervention would work with the table (it would be causally complicit), and so the replacement scenario could not arise without it still being the case that the one table stage is causally involved in the production of its successor. (The non-causal case is exactly the sort of imagined problem that the neo-Humean account of possibility fuels, and thus one the powers theorist can avoid.) Sameness, then, is a matter of the relevant complex states of affairs giving rise to similarly sortal-appropriate complex states of affairs.

10.4 Prix Fixe Metaphysics We have seen the main theses of the neo-Humean metaphysic and how they inform one another. We have also had a chance to consider the powers ontology, and one metaphysic that can be built with it. At this stage you might find yourself attracted to some parts of the latter, but not interested in the package as a whole. Unfortunately, as I have said from the start, there is no à la carte option when it comes to the debate between the neo-Humean and the powers theorist: this metaphysical menu is prix fixe only. As was the case with the vacuums with which the book opens, the parts that go with one rarely work with the other. You do, of course, have a limited range of options when it comes to some of the courses—the metaphysic presented in these pages is not the only way to have a powers metaphysic, for instance—but the main elements are not options found on both the powers and the neo-Humean menus. Given the extent to which the powers metaphysic turns the neo-Humean metaphysic on its head, this lack of à la carte options was apparent from the outset. NeoHumean par excellence David Lewis recognized early on that this was the case. But rather than leaving the job of putting the flesh on the bones of this claim as an exercise to the reader, we now have the tools to briefly present how the central theses of each metaphysic hang together but fail to mix well with those of the other.³⁷ When you try to borrow a small portion of a metaphysic, a great deal more of it comes along for the ride. Case in point, if you find yourself fond of neo-Humeanism in general, but taken with the power theorist’s account of causation, you might think you could borrow just that part. But powers-based causation does not work without its being the case that some (or all) of the fundamental properties are powers. They are the basis of the causal account, after all. On the present account, the blueprint ³⁶ See Shoemaker (1979) and Armstrong (1980a). ³⁷ Note that I am not claiming that any of these theses entails any other. In some instances that is clearly the case, but their supporting and conspiring are typically more a matter of good pairing than of logical entailment.

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structure is part of the identity of the power types. They would not be the power that they are without the ways in which they stand to other powers as constellation and manifestation. And they would not be ready to work with one another—they would not ‘fit’—if this was not written into their natures. Therefore, via the adoption of powers, you thereby adopt a fundamental and irreducible modality. You have also instituted in the world a series of necessary connections between distinct essences. It follows that your attempt to pick of the powers menu à la carte-style has failed: you have bought a whole powers meal, complete with a drink and supersize fries. And the problems do not end there. Consider what the adoption of these theses means for the neo-Humean theses you had wanted to keep. Gone is Hume’s Dictum, because you have fundamental properties that bear necessary relations to one another. You might assert it in other cases, but if the principle is not a general principle—a metaphysical rule that dictates what can and cannot be—then it is of little use. And that means that recombinations are in trouble, too. That is not to claim that they are impossible, but the set of things you can recombine has been severely limited, as are the sorts of collages you can construct from those parts. This handcuffs the account of possibility. And do not forget that you have imported whatever possibilities the powers themselves ground, which helps in one sense, but is really a different kettle of fish.³⁸ What about pure categoricalism? That, too, has gone out of the window, because some or all of your properties are powers. I would think that all of them were, if you wanted the powers-based account of causation, but you could have a dualism of idle categorical properties (in the vein of the options discussed in §5.2). In any case, this is no longer an array of quiddities you are dealing with. And laws of nature? You can still have the best-systems account of laws, built (as was suggested above) on the array of states that actually obtain. But you also have either lawlessness or strong laws, which are contrary to the spirit in which Humean Supervenience is offered. You could, of course, try to keep more of each, but that combination is about as appetizing as a cold pasta salad made with shrimps, peas, black olives, cabbage, and corn. Long story short, the neo-Humean metaphysic and its powers competitor are fullmeal deals. You have your choice—and maybe even the choice of something else entirely—but whatever it is you choose, you must take it as a package deal.³⁹ There is no leaving bits out, and no selecting of parts from elsewhere.

10.5 Final Remarks Our sojourn through the present powers metaphysic is complete, but there are still a few final loose ends that need tying up. I am sure you are dying to know the answers to the following questions. (1) Do Joanie and Chachi work things out? (2) Does Angus fully recover from the snake bite? And most important of all, (3) Do you ever ³⁸ I did not present that part of the metaphysic. Interested readers should seek out Williams and Borghini (2008), Contessa (2010), Jacobs (2010), Pruss (2011), and Vetter (2015). For some of the potential troubles with the view, see: Vance (2014), Wang (2015), and Yates (2015). ³⁹ We have discussed the neo-Humean metaphysic and a powers-based rival. But I have no reason to think that these are the only two out there.

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escape from the dystopian railway? Unfortunately, Chachi’s heart belongs to another, and so there is no helping the sad state of affairs that is Joanie’s unrequited love for him. Angus is doing just fine. He learned a great deal from his brush with death, and now he and Malcolm give guided tours on the deadly creatures of the outback. As for the railway, yes, you escape, but I cannot tell you how. (An Internet rumour claims that you escaped by riding out on the back of an ineffable quality to the land of richness and being, but the reality is something much, much darker.) Oh, and as for the matter of the vacuum sale, you will be glad to hear that Homeowner decided to purchase the new vacuum, much to Salesperson’s delight. Perhaps you are now interested in doing the same?

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Index abilities 49, 63, 69–70, 86, 96–7 ‘alien’ properties 25–6 Anjum, R.L. 6, 140, 170–2, 204–5 anomalous monism 115 antecedent strengthening test 140–2 antidotes 10, 140, 231–2 argument by display 8 Aristotle 12 and Hume 12 and immanent causation 166 and realism 94–5 Armstrong, D.M. 35, 107–8, 116–18, 160–1, 180, 189–93, 217–18 and laws of nature 7–8, 35 and states of affairs 16–17 arrangements 31–2, 49–50, 64–5, 109, 120, 127–9, 219, 226–7, 233–4 ball-and-stick models 90–1 bare particulars 15–16 Bauer, W. 76–7 best scientific theories 30–1 best systems analysis (BSA) account 217, 220, 222–5, 230–1 best systems blueprint (BSB) account 219–20, 222–5, 233 beyond bal 126 Bird, A. 51–2, 83, 85, 93, 95, 131, 218–22 Blackburn, S. 99–100 blueprints 85, 93–5, 104, 112, 138, 220, 223–5 Broad, C.D. 185–6, 191–3 bundle theory 15, 27–8 Casati, R. 152–4 categoricalism 29, 41, 51 causal relevance 104, 107–9, 146–7 of absences 108, 146–7 See also dualism causally isolated 7, 145–6, 224 causation 35–41, 120–3, 147–53, 161–3, 165–72, 188–9 absence 108, 122–3, 146–7 and change (see also static manifestations) 233 conditional analysis of 161–2 folk concept of 120, 146 immanent (see also Aristotle) 150, 164–9, 188–92, 194, 214–16, 234 local 145–6, 151 mutual 86–7, 124, 163–4

and necessary connection 27 as reciprocal 86–7, 124 simultaneous 150–2, 169–72 stochastic 138, 164 transeunt 165–9, 189–90, 192–3 transitivity of 121–3, 146–8 ceteris paribus clause 133–4, 218, 231–2 Chakravartty, A. 206–7 change 95, 97–8, 111–12, 150–7, 162–3, 170–1, 174–5, 177–8, 183, 185–6, 210 See also persistence character 98–103, 109–19. See also quality composition 27–8, 113, 176, 187–8 conceivability 23–4, 117–18 constellation-manifestation pairs 92–3, 136, 142–3, 148, 169, 171–2, 186–8, 211–12, 214, 226, 230 constellations 49–51, 74–5, 127–8, 137–8, 141–8, 163–5, 171–2, 188–91, 211–12, 230–2 context-sensitivity 206, 209 contributions 84 counterfactuals 11, 31, 37–9, 54–5, 60, 63, 82, 92–3, 115, 219–20, 230. See also antecedent strengthening test; simple conditional analysis creation ex nihilo 213–14 Demarest, H. 223, 225 Dennett, D. 196–7 dependence 16, 37–9, 228 Descartes, R. 198 directedness 29–30, 57, 64–5, 71, 99–100, 166 disposition ascriptions 10–11, 52–3, 55–6, 70, 74–6, 81–2, 140, 231–3. See also predicates dispositional concepts 54. See also fragility dispositions 10–11, 46–9, 53–4, 75–6, 196–7, 205–7, 225–6, 229–32 sui generis 10–11 dominoes 132, 142–3, 211, 214 Dretske, F. 217–18. See also laws of nature dualism 56–7, 68–9, 96–7, 102–4, 107–12, 114, 119 a-type 103–4, 106–10 b-type 103–4, 109–11, 114 c-type 103–4, 110–13, 119 Duhem-Quine thesis 22. See also theory-laden DV objection 196–201, 203–5

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

effects 36, 50–1, 59, 63, 65–6, 69–70, 84, 107–8, 157, 159, 170, 197–8 eleatic principle 71 Ellis, B. 6, 63–4, 103–4, 162–3, 202 empiricism 3 endurantism 20, 175–7, 179, 183, 209–10, 213 entailment 60–1, 235 of subjective conditionals from powers 60–3 essences 27, 29, 41–2, 57–61, 63, 67, 94–5, 103–5, 109–10 eternalism 20, 175–6, 180–1 events 26, 36–9, 41, 129–32, 134–6, 151–3, 210–11, 218–19 explanation 156–7, 178–80, 182, 195–8, 200, 202–9 causal 187, 196–200, 202–9 upper and lower level 152, 198, 207 See also laws of nature fragility 29–32, 47–8, 52, 54–6, 61–3, 76, 129–30, 135, 229–30 fundamental objects 12–13, 215–16, 225–6, 229 fundamental ontology 6–9, 11, 96–7, 102, 201, 232 fundamental properties 14, 30–1, 50–1, 56–7, 68–9, 90, 96–7, 101–3, 110, 113, 201, 235–6 grounds 44, 99, 152, 158, 161–4, 169, 185, 208, 218, 227, 232 gunk 195, 215–16 Handfield, T. 131–2 Harré, R. 78–9 Hawley, K. 166–7, 175–6, 184–6, 190–3 Heil, J. 67–8, 84–5, 115–17, 119, 170–1 Heller, M. 185–6, 215 Hempel, K. 221 holism 52–3, 85, 89, 94–5 blueprint 89, 94–5 power 52–3, 85–6, 89–90, 93–5 and structure 85–6 Hume, D. 3–4, 11–12, 21–8, 30–7, 41–5, 63–6, 234–6. See also Hume’s Dictum; necessary connection; neo-Humean metaphysic; recombinatorialism Hume causes 64 Hume laws 64 Humean Supervenience 23, 32–3, 236 Hume’s Dictum 26–7, 36–7, 117–18, 185–6, 235–6 identity 52–3, 82, 94, 97–8, 100–1, 106–7, 115–18, 174, 176–7, 193, 228–9 diachronic 174, 178 identity theory 114–15 imaginability 39, 43. See also conceivability

indiscernibility of identicals 174 interference 140, 227 interruptibility 134, 136, 142–3, 211–12 intrinsicality 54, 67, 86 intuitions 6–7, 37, 54, 122, 136, 140, 145–6, 150–1, 153, 174, 182–3, 219. See also scientific image; manifest image Jackson, F. 13, 63–4, 120–2, 232 Jacobs, J. 115, 119, 236 jigsaw puzzle analogy 87–8 Johnson, W.E. 166–9 Kant, I. 102, 170–1 Kuhn, T. 9, 40 laws of nature 32–5, 42–3, 51, 95, 105–6, 137–8, 197, 217–20 best systems analysis (BSA) account 217, 220, 222–5, 230–1 best systems blueprint (BSB) account 219–20, 222–5, 233 Dretske-Tooley-Armstrong account 192–3, 217 as generalizations 33–4, 218–20 hybrid account of 109–10, 219–20, 222–5 non-causal 109–10, 221 as relations 160 and supervenience 218 Lotze, H. 166–9 Lowe, E.J. 80–3, 152, 157–8, 178–9, 200–1, 204, 206–7 Mackie, J.L. 197–8 manifest image 6 manifestations 84–7, 96–7, 129–37, 142–3, 154–7, 159–60, 165, 187–8 blocked 133–4 mutual 86–7, 124, 126–7, 163–4 ontology of 50, 113, 210–11 static 88, 149–50, 154–7, 159, 161, 171, 189, 227, 234 triggers 124, 140 Martin, C.B. 9–12, 99, 114–17, 163–6, 170–1 masks 140 McKitrick, J. 68, 133–4, 204–5 Mellor, D.H. 60–2 metaphysic, the powers 3–6, 9, 12–14, 35, 45, 111–12, 117–18, 120, 183, 185–6, 217, 234–5 micro-reductionism 18–20 Mill, J.S. 33–4, 124–5, 217–18 Mill-Ramsey-Lewis account 220–1. See also laws of nature mimics 231–2 mixed monism 56–9, 68–9, 94, 96–7, 102–4, 109–10, 112–15, 119

 modality 11, 57, 63, 105–6, 235. See also possibility models, causal ball-and-stick 90–1 pegboard 106–10, 113–16 Molière, J.B. 195–7, 203, 206, 208 Molnar, G. 5–6, 67–8, 103–4, 116–17, 133–4, 202 monism 46, 56–9, 68–9, 96–7, 99, 101–3, 109–10, 112–15, 119 See also categoricalism, powers monism mosaic 23, 33–5, 39, 58, 64, 95, 173–4, 180, 185, 217, 222–3 Mumford, S. 95, 115, 170–2, 196–7, 204–6, 210, 217–20 natural kind 221 naturalism 94–5, 163–4 necessary connection 26–7, 29, 32–3, 106–7, 109–10, 112, 117, 235 Newton, I. 160–1, 166, 198 non-power properties 46, 51, 103. See also categoricalism non-redundancy requirement 70 objects 15–17, 34, 78–9, 167–8, 173–4, 176–9, 183–4, 189, 225–31 Occam’s razor 18. See also parsimony ontological reduction 8, 10–11 oomph 3–4, 27, 32–8, 40, 120, 122–3, 138–9, 223–4 ordinary language 47–8. See also disposition ascriptions overdetermination 38, 41, 70, 232 parsimony 69–70, 156 partial consideration 116 patterns 33–7, 39, 42, 64, 85–6, 180, 217, 222–3, 230–3 perdurantism 175–7, 179, 183, 209–11, 213 persistence 12–13, 173–83, 187–93, 195, 208–10, 233 macroscopic 181, 233 problems of 173–4, 176–80, 189 See also tracing problem physical theory 13–14, 216 Platonism 94–5 pluck 173–4, 177–83, 187–93, 209, 233–4 pluriverse 7–8, 44 possibility 22–5, 27–9, 35, 42–5, 79, 95, 117–18, 215–16, 234 possible worlds 28–9, 39, 44–5, 137, 224–5. See also Lewis, D. potency-BSA 224–5 power terms 13, 201, 207–8 powers 47–52, 68–70, 74–6, 104–5, 125–9, 161–5, 196–8, 200–1, 204–5, 207–9, 231–2 and ability 49, 63, 69–70, 86, 96–7 and addition 18, 58, 68, 73, 75, 234



baseless 51 collective 72–3, 76, 120, 162 directed 57, 64–5, 71, 99–100, 166 emergent 68, 71, 77–8 eternalism and 180 macroscopic 31, 181, 204–5, 217, 225–7, 229–30, 232–3 manifestations of 51–2, 84, 93–4, 105–6 monism 56, 58–9, 96–9, 101–2, 106, 108–10 multi-track 49, 52, 79–80, 83–4, 92, 126, 165, 190–1, 219 ontology of 6, 10, 12, 35, 50, 112–13, 200–1, 210–11, 232 as process initiators 137, 230–2 as properties 50, 200–1 protective 75–6, 83–4 reverse engineering 81, 89, 197, 200 salience of 208, 232 unilateral 51, 164–5, 189–91, 195 pragmatic approach 145, 206–7 predicates 10–11, 31–2, 62, 186, 208–9, 225–6, 232. See also disposition ascriptions primitives 14, 156–7 Prior, E. 47–8, 61, 232 problem of temporary intrinsics 174–5, 234 processes 16, 129–37, 142–3, 163–4, 171–2, 210–11, 230–2 as continuous 210–11 as events 135–6 interruptibility of 134, 136, 142–3, 211–12 production 86–7, 99, 122–4, 126, 149–50, 159, 161–3, 233–4 propensities 47, 162–3. See also Ellis, B. properties 15–19, 29–35, 41–2, 59–61, 63–5, 67, 94–5, 104–5, 109–15 categorical 13, 29–31, 41–2, 56–63, 66, 69, 100–1, 197 inert 3, 13, 22–3, 30, 35, 119, 202 intrinsic vs. extrinsic 67–9, 77–8, 85–6, 150, 174–7, 184, 192–3, 210 minimalism about 18–19 relational 86–7, 89, 150 second-class 13, 30–1, 197, 199, 208 sparsism about 18–19, 68, 204 upper- and lower-level 77–8, 152, 198, 200–1 as ways 15, 68–9, 102, 109 property instantiation 63–6, 94–5, 98, 111, 128–9, 158, 160–1, 163, 174–7, 184–6, 188, 210 qualitative similarity 18, 94 quality 46, 98–9, 101–2, 114–15, 118, 234, 236 quiddity 41–2, 58–9, 100, 102 Quine, W.V.O. 22, 152–3, 206–7. See also theory-laden, Duhem-Quine thesis Ramsey, F.P. 33–4, 217–18 realism 3, 6–7, 16, 50–1, 94–5, 153





recombinatorialism 117–18 redundancy 18, 70, 169. See also non-redundancy principle regress of pure powers 97–8 regularity 36, 218. See also patterns relations 39, 160, 235–6 causal 36–9, 41, 85, 90–1, 95, 180, 191–2, 234 internal 39, 219 laws of nature, as 160 potentiality 51–2, 99–100 reverse engineering powers 81, 89, 197, 200 Russell, B. 185–6, 191–4 Ryle, G. 40, 49, 79 salience 72 causal 124–5, 205, 207–8 of powers 208, 232 Salmon, W. 196–8 scepticism 3, 124, 158–9, 183, 193–4, 202, 212, 222–3 Schaffer, J. 160–1 Schrenk, M. 140–2, 144 Shoemaker, S. 62, 98, 183–4, 191–3, 215, 235 Sider, T. 17, 166–7, 173, 177–8, 187–8, 191–2, 214–15 simple conditional analysis 9–10, 161. See also antecedent strengthening test, causation sparsism 18–19, 68 stage theory 166–7, 175–6, 183, 209–11 states of affairs 16–17, 49, 51–2, 90–2, 109, 129–30, 135–6, 189, 226–9, 233–4 complex 90–1, 112, 226–9, 232–4

stimulation 123–5, 140–2, 149–50, 161–2, 164–5, 171 structure 85–6, 90–5, 98, 105–7, 109–10, 113–14, 156, 222–3. See also blueprints substances 15–16, 46, 101–2, 135–6, 163–4, 183. See also bare particulars supervenience 23, 32–3, 218, 228, 236 Swoyer, C. 191–3 systematic metaphysics 4–6, 8, 69, 215 temporal parts 173, 175–7, 179–80, 183, 185–7, 191–3, 209–13 theory of everything 10–12 Thomson, J.J. 213–14 Tooley, M. 217–18. See also laws of nature tracing problem 175–9, 182, 189, 193 triggers 124. See also stimulation trope theory 15 truthmakers 31–2, 55, 115, 222 Tugby, M. 16, 85, 94 two brothers 130–1 type and token identity 109, 157–8, 160–1, 190–1, 228–9, 232 ultra-grounding 78–9 Unger, P. 117–18, 191–2, 196 universals 7–8, 15–16, 94, 160–1 upper level 101–2 Varzi, A. 152–4, 217 worm theory 175–6