A Dissertation Submitted to the Temple University Graduate Board In Partial Fulfillment of the Requirements for the Degree by Examining Committee Members: ii ABSTRACT The Exclusion Argument for physicalism maintains that since every physical effect has a sufficient physical cause, and cases of causal overdetermination (wherein a single effect has more than one sufficient cause) are rare, it follows that if minds cause physical effects as frequently as they seem to, then minds must themselves be physical in nature. I contend that the Exclusion Argument fails to justify the rejection of interactionist dualism (the view that the mind is non-physical but causes physical effects). In support of this contention, I argue that the multiple realizability of mental properties and the phenomenal and intentional features of mental events give us reason to believe that mental properties and their instances are non-physical. I also maintain (a) that depending on how overdetermination is defined, the thesis that causal overdetermination is rare is either dubious or else consistent with interactionist dualism and the claim that every physical effect has a sufficient physical cause, and (b) that the claim that every physical effect has a sufficient physical cause is not clearly supported by current science. The premises of the Exclusion Argument are therefore too weak to justify the view that minds must be physical in order to cause physical effects as frequently as they seem to. iii TABLE OF CONTENTS Page ABSTRACT........................................................................................................................ii LIST OF TABLES..............................................................................................................iv LIST OF FIGURES.............................................................................................................v CHAPTER 1. THE EXCLUSION PROBLEM......................................................................................1 2. HOW NOT TO SOLVE THE EXCLUSION PROBLEM............................................25 3. THE CASE FOR DUALISM AND THE NATURE OF REALIZATION...................57 4. THE MULTIPLE REALIZABILITY OF MENTAL PROPERTIES….....................100 5. THE NOMOLOGICAL IRREDUCIBILITY OF MENTAL PROPERTIES..............149 6. THE IMMATERIALITY OF MENTAL EVENTS....................................................198 7. MENTAL CAUSATION WITHOUT OVERDETERMINATION............................261 8. THE CAUSAL SELF-SUFFICIENCY OF THE PHYSICAL....................................292 9. THE CAUSAL EFFICACY OF THE MIND..............................................................344 BIBLIOGRAPHY............................................................................................................391 iv LIST OF TABLES Table Page 1. Types of realization........................................................................................................95 v LIST OF FIGURES Figure Page 1. Spectral sensitivities of the three types of cone receptors in the human eye...............106 2. Wavelength distributions of two metameric lights......................................................107 3. Example of potential neural circuitry for opponent processing...................................112 4. Chromatic response curves for standard observer.......................................................113 5. Example of simultaneous chromatic contrast..............................................................115 6. Experimental set-up for the double slit experiment.....................................................329 7. Gradual accumulation of particles in the double-slit experiment................................330 8. Diagrammatic representation of the causation of lung cancer.....................................367 9. Diagrammatic representation of the causation of intentional action...........................372 1 CHAPTER 1 THE EXCLUSION PROBLEM It is a belief widely and firmly held that our minds have a causal impact on the world by affecting the motion of our bodies and thence the states of other physical objects in our surrounding environment. When a person gets up from the couch to rummage about in the fridge, it is, we say, their desire for food and belief that there is desirable food in the fridge (which are states of their mind) that cause them to stand up, walk to the kitchen, open the fridge, and have look around. Similarly, when one cuts one’s finger, it is, we say, the resulting sensation of pain (another mental state) that causes one to wince and say “Ow!” One of the most long-standing objections to mind- body dualism is that the assumption that the mind is non-physical makes it very difficult, if not impossible to see how the mind could play any role in the causation of such effects. In contemporary philosophy of mind, this objection has taken on the form of what is now arguably the main argument against any non-epiphenomenalist variety of dualism: the Exclusion Argument for physicalism. Roughly stated, the Exclusion Argument holds that since every physical effect has a sufficient physical cause, and the physical effects of mental events are not typically overdetermined (meaning that they do not normally have more than one sufficient cause), the fact that mental events cause physical effects entails that such events must themselves be physical in nature. Though often treated as a knock- down refutation of all forms of dualism that involve a commitment to the causal efficacy of mental events, I think that the Exclusion Argument fails to provide sufficient evidence 2 to justify belief in the falsity of such a position. The aim of this dissertation will be to substantiate this claim. The present chapter clears the way for the execution of this task by clarifying the central positions to be discussed in what follows and providing a more precise formulation of the Exclusion Argument along with a brief account of some of the historical trends that led to its emergence as one of the primary contemporary arguments against mind-body dualism. The chapter then closes with a short summary of the remaining chapters. 1. A taxonomy of dualisms and definition of physicalism While mind-body dualism comes in many different forms, the Exclusion Argument really only applies to those varieties of dualism that reject epiphenomenalism. This, however, leaves a number of different views open to the Argument that seem to have little in common other than their shared commitment to the idea that the mind is non-physical, the most prominent among these being: Substance Dualism, Neutral Monism, Dual-Aspect Theory, Materialistic Panpsychism, and Emergentism. All five of these positions hold (or are at least consistent with the view) that the mind is causally efficacious. Of these five, only the first (Substance Dualism) holds that mental and physical properties are properties of distinct kinds of substances. The remaining four positions are all substance monistic forms of property dualism. The first two (Neutral Monism and Dual-Aspect Theory) hold that the only substances are neither physical nor mental, while the last two (Materialistic Panpsychism and Emergentism) hold that all 3 substances are physical.1 Partly to simplify matters, and partly because I find it to be the most plausible of the various forms of dualism threatened by the Exclusion Argument, I’ll largely limit my attention in what follows to Emergentism, understood as the conjunction of the following five theses: (a) Mental properties (i.e., properties that things exemplify insofar as they are endowed with intentionality and/or consciousness) and their instances are entirely distinct from, irreducible to, and incapable of being fully explained in terms of physical properties2 and their instances. (b) Instances of mental properties have a causal impact on events in the physical world. (c) There is only one kind of substance in which both mental and physical of properties inhere. (d) All substances are physical substances. (e) Mental properties are exemplified only by aggregates of physical substances that satisfy certain conditions, such as exhibiting a certain complexity of structural and/or functional organization, or standing in certain causal relations to the surrounding environment. 1 In its classical, Spinozistic form, Dual-Aspect Theory is the view that the mental and the physical are two distinct attributes or aspects of a single substance that is intrinsically neither physical nor mental. It is distinguished from Neutral Monism by the fact that the latter allows that a substance may exemplify physical properties without exhibiting any mental properties (or vice versa), whereas according to Dual- Aspect Theory, all finite modes (or substances, if one parts with Spinoza’s belief that substance is one in both kind and number) have both a mental and physical aspect. Dual-Aspect Theory is hence a form of Panpsychism. It is distinguished from Materialistic Panpsychism by the fact that the latter holds that all substances are physical. 2 I.e., those properties that, in Jackson’s (1998, p.8) words, “are those that [(barring panpsychism)] we need to handle the non-sentient, they are broadly akin to those that appear in current physical science, [and] they are those we need to handle the relatively small.” 4 (a)-(e) exemplify a progressive winnowing of the various strains of dualism mentioned above. (a) is a statement of mind-body dualism; as such it is an essential commitment of any dualist view, including epiphenomenalism.