CAUSAL POWERS: A NEO-ARISTOTELIAN METAPHYSIC Jonathan D. Jacobs Submitted to the faculty of the Graduate School in partial fulfillment of the requirements for the degree Doctor of Philosophy in the Department of Philosophy Indiana University December 2007 Accepted by the Graduate Faculty, Indiana University, in partial fulfillment of the requirements of the degree of Doctor of Philosophy. Doctoral Timothy O'Connor, Ph.D. Committee (Principal Advisor) Jordi Cat, Ph.D. David Charles McCarty, Ph.D. December 5, 2007 Frederick F. Schmitt, Ph.D. ii Copyright c 2008 Jonathan D. Jacobs ALL RIGHTS RESERVED iii Dedication To Meaghan, whose power sustains me and whose love empowers me iv Acknowledgements I am grateful for the help of many. My friends and family have supported me in intangible ways during the journey to completion. Special thanks and gratitude are due my wife, Meaghan, and children, Gregory and Emelia. In addition to their patience, love and support, they are a daily source of joy and rejuvenation. Portions of the dissertation were read at Indiana University, the Dispositions and Causes Workshop at the University of Bristol, and Northern Illinois University. The dissertation has benefitted from those conversations. Stephen Crowley was kind enough to read and comment on portions of Chapter 2. Communications with Alexander Bird have both helped my understanding and shaped my views in numerous ways. My committee members, Timothy O'Connor, Jordi Cat, David McCarty and Frederick Schmitt, have taught me much and have provided feedback that has improved the disser- tation immensely. Special thanks are due to David McCarty. In addition to the valuable instruction and support he has given me over the years and on the dissertation, he helped me through the formal aspects of Chapter 6. Indeed, he provided the basic semantics for counterfactuals that I offer there. (Any flaws are, of course, my own making.) Finally, I would like to thank Timothy O'Connor for his instruction and guidance over the years and on the dissertation. He has read many drafts of the dissertation, and his comments and suggestions have been insightful and invaluable. More than that, though, he has been an ideal teacher, mentor and role model. v Abstract Causal powers, say, an electron's power to repel other electrons, are had in virtue of hav- ing properties. Electrons repel other electrons because they are negatively charged. One's views about causal powers are shaped by|and shape|one's views concerning properties, causation, laws of nature and modality. It is no surprise, then, that views about the na- ture of causal powers are generally embedded into larger, more systematic, metaphysical pictures of the world. This dissertation is an exploration of three systematic metaphysics, Neo-Humeanism, Nomicism and Neo-Aristotelianism. I raise problems for the first two and defend the third. A defense of a systematic metaphysics, I take it, involves appealing to pre-theoretical commitments or intuitions, and theoretical issues such as simplicity or explanatory power. While I think that Neo-Aristotelianism is the most intuitive of the available general metaphysical pictures of the world, these kinds of intuitions do not settle the matter. The most widely held of the alternative pictures, Neo-Humeanism, is accepted in great part because of its theoretical power. In contrast, a systematic Neo-Aristotelian metaphysic is, at best, nascent. The way forward for the Neo-Aristotelian, therefore, is a contribution to an ongoing research program, generating Neo-Aristotelian views of modal- ity, causation and laws of nature from the Neo-Aristotelian understanding of causal powers. The central argument of this dissertation is that such views are defensible, and so the Neo-Aristotelian metaphysic ought to be accepted. vi Contents Dedication iv Acknowledgements v Abstract vi 1 Introduction 1 1.1 Causal Powers . 1 1.2 Three Views . 2 1.2.1 Neo-Humeanism . 2 1.2.2 Nomicism . 4 1.2.3 Neo-Aristotelianism . 6 1.3 An Outline . 7 2 Metaphysics and Method 10 2.1 Truthmakers . 10 2.2 In Defense of Metaphysics . 16 2.3 A Methodology . 20 2.3.1 The epistemic base . 21 2.3.2 What counts as best? . 23 vii 3 Natural Properties 25 3.1 Spare and Abundant Conceptions . 25 3.2 Natural Properties and Causation . 27 3.2.1 The Problem with Overdetermination . 27 3.2.2 Boolean Properties are Non-Natural . 32 3.2.3 Structural Properties are Non-Natural . 33 3.2.4 Multiply Realizable Properties are Non-Natural . 33 3.3 Infinite Complexity and Levels of Reality . 35 3.4 Natural Properties and Causal Powers . 38 3.4.1 Functional Specification . 40 4 Neo-Humeanism 43 4.1 Properties . 46 4.1.1 Categoricalism and Quidditism . 47 4.2 Possible Worlds . 49 4.2.1 Lewisian Worlds . 50 4.2.2 Ersatz Worlds . 51 4.3 Modality . 54 4.3.1 Comparative Similarity . 56 4.3.2 Counterfactuals . 58 4.4 Causation . 61 4.5 Laws . 62 4.6 Causal Powers . 64 4.7 Objections . 66 4.7.1 Properties, Powers and Counterfactuals . 67 4.7.2 Singularism versus Generalism, and Locality . 75 4.7.3 Causal Supervenience . 77 viii 4.7.4 Nomic Supervenience . 80 4.7.5 Pre-emption . 83 4.7.6 The Big, Bad Bug: Chance . 90 4.7.7 Context Sensitivity and Subjectivity . 105 4.7.8 Modality and Changing the Subject . 106 4.8 Conclusion . 109 5 Nomicism 110 5.1 Contingent Nomicism . 111 5.1.1 Properties . 111 5.1.2 Laws . 115 5.1.3 Causation . 117 5.1.4 Modality . 117 5.1.5 Causal Powers . 118 5.1.6 Objections . 119 5.2 Necessary Nomicism . 125 5.3 Conclusion . 127 6 Neo-Aristotelianism 128 6.1 Properties . 130 6.1.1 Natures . 131 6.1.2 Quiddities . 133 6.1.3 The Pure Powers View . 135 6.1.4 The Physical Intentionality View . 147 6.1.5 The Powerful Qualities View . 150 6.1.6 The Truthmaker View . 153 6.1.7 Relations . 163 6.2 Modality . 165 ix 6.2.1 Neo-Aristotelianism With Possible Worlds? . 165 6.2.2 Neo-Aristotelianism Without Possible Worlds . 167 6.2.3 A Powers Semantics for Counterfactuals . 169 6.2.4 Modal Facts are Counterfactual Facts . 177 6.2.5 The Plenitude of Possibility . 179 6.2.6 The Illusion of Contingency . 181 6.3 Causation . 183 6.4 Laws . 186 6.5 Conclusion . 190 x 1 Introduction 1.1 Causal Powers The things around us in this world are powerful. They|and you and I, too|have the ability to bring things about, to make things occur. They have this ability because they have capacities, tendencies, dispositions, causal powers. For present purposes, I will treat each of these as roughly equivalent to a causal power, and a brief description of causal powers will suffice. First, the having of a causal power is not inexplicable. Objects have causal powers in virtue of having certain properties. Electrons have the causal powers to repel other electrons and attract positively charged particles. They have these powers in virtue of being negatively charged. Second, the exercise of a causal power involves causation. When an electron manifests or exercises its power to repel another electron, it (or some event of which it is a constituent) is at least part of the causal story for why the other electron was repelled. Third, when objects exercise their causal powers, they do so in a law-like manner|or at least that's how things seem to be in the actual world. They do not act in a haphazard way, but rather in a way that exhibits patterns or regularities and is subject to generalizations. 1 1. Introduction 2 (These generalizations may be of a ceterus paribus sort, but they are generalizations nev- ertheless.) Among those generalizations is that causal powers are associated with typical triggering conditions and manifestations. A negatively charged particle is typically trig- gered by being situated near another charged particle, and, if it is near a negatively charged particle, it will typically manifest its negative charge by repelling the other particle. Fourth, the having of a causal power is not merely a fact about actuality. It has modal implications|implications dealing with possibility and necessity. To say that an electron is negatively charged is not merely to say something about what the electron is actually like; it is to say something about what the electron might, would, and must do. In fact, it seems that an object can have a causal power that it never actually manifests. An electron need never repel another electron in order to have the power to do so. Its charge, in this way, is importantly related to counterfactual conditionals. If it were situated near a negatively charged particle, then it would repel it with such-and-such force. 1.2 Three Views The topic of causal powers, therefore, sits at the center of a nexus of fundamental issues in metaphysics. One's views about causal powers are shaped by|and shape|one's views concerning properties, causation, laws of nature and modality. It is no surprise, then, that views about the nature of causal powers are generally embedded into larger, more systematic, metaphysical pictures of the world. 1.2.1 Neo-Humeanism According to the neo-Humean metaphysic, defended most prominently by David Lewis,1 the world is simply a vast collection of particular, local matters of fact|it's just one damn thing after another. Necessary connections between distinct existences are, on this view, 1See Lewis (1986a, 1994), for example. 1. Introduction 3 anathema. \[A]nything can coexist with anything else.