University of Arkansas, Fayetteville ScholarWorks@UARK Theses and Dissertations 8-2012 Defending the Multiple Realization Argument against the Identity Theory David Barrett University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/etd Part of the Philosophy of Mind Commons, and the Philosophy of Science Commons Recommended Citation Barrett, David, "Defending the Multiple Realization Argument against the Identity Theory" (2012). Theses and Dissertations. 459. http://scholarworks.uark.edu/etd/459 This Dissertation is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. DEFENDING THE MULTIPLE REALIZATION ARGUMENT AGAINST THE IDENTITY THEORY DEFENDING THE MULTIPLE REALIZATION ARGUMENT AGAINST THE IDENTITY THEORY A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Philosophy By David Alan Barrett Hendrix College Bachelor of Arts in Philosophy, 2006 University of Arkansas Master of Arts in Philosophy, 2008 August 2012 University of Arkansas Abstract A classic argument in the philosophy of mind is that the identity theory is false because mental state types are multiply realized in brain state types. In this dissertation I provide a detailed elaboration of the argument and a defense of it against a few of its prominent contemporary critics. Finally I offer empirical evidence from inter-species differences in humans and monkeys, and also from a case of extensive neural plasticity, which shows that mental state types are multiply realized in brain state types. This dissertation is approved for recommendation to the Graduate Council. Dissertation Director: __________________________________ Dr. Jack Lyons Dissertation Committee: __________________________________ Dr. Eric Funkhouser __________________________________ Dr. Thomas Senor Dissertation Duplication Release I hereby authorize the University of Arkansas Libraries to duplicate this thesis when needed for research and/or scholarship. Agreed ______________________________ David Alan Barrett Refused _____________________________ David Alan Barrett Acknowledgements I would especially like to thank my director, Jack Lyons, for his help in completing the present work. Without his advice and patience in reading countless drafts and rewrites, the end product would have been much poorer and much longer in coming. I would also like to thank the other members of my dissertation committee, Eric Funkhouser and Thomas Senor. Whatever I get right probably owes very much to their help. Whatever I got wrong is certainly my own doing. Table of Contents Chapter 1: What are the Identity Theory and Multiple Realization? 1 Section 1.1: Explaining Some of the Key Concepts 2 Section 1.2: Functionalism, Identity Theory, and the Multiple Realization Argument 8 Section 1.3: Popular Criticisms of the Multiple Realization Argument 12 Section 1.4: An Outline of the Rest of the Dissertation 24 Chapter 2: What is a Mental State Type? 27 Section 2.1: Why Psychological State Types Instead of Mental State Types? 28 Section 2.2: But What do Psychological State Types Look Like? 35 Section 2.3: The Pros and Cons of Computationalism 38 Section 2.4: An Example of a Psychological Process 45 Chapter 3: What is a Brain State Type? 53 Section 3.1: Old and New Style Cartography 56 Section 3.2: Taking Stock of the Options 63 Section 3.3: Why Brodmann’s Areas are the Best Bet 65 Section 3.4: Why do Neural Areas Provide a Good Guide to Brain State Types? 70 Chapter 4: What Count as Multiple Realizations? A Reply to Shapiro 75 Section 4.1: A Short Explanation of Shapiro’s Attack 75 Section 4.2: Arguing for a Different Account of Distinct Realizations 83 Section 4.3: Criticisms of Shapiro’s View 89 Section 4.4: Constraints on Brains 98 Chapter 5: But Doesn’t Current Neuroscientific Research Presume Identity Theory? A Reply to Bechtel and Mundale 105 Section 5.1: Lower-Level Interventions are not Irrelevant to Psychological Theories 107 Section 5.2: Why this Lack of Irrelevance is Irrelevant 111 Section 5.3: Why Cross-Species Analyses are Important for Psychology, and why this Importance is Irrelevant to Multiple Realization 119 Section 5.4: Bechtel and Mundale on Brain State Types 123 Section 5.5: Criticizing the Idea that Brain State Types are Functionally Individuated 125 Chapter 6: But Don’t Cases of Neural Plasticity Constitute Bad Evidence For Multiple Realization? A Reply to Polger 136 Section 6.1: Begging the Question against the Identity Theorist 136 Section 6.2: Polger on the Nature of the Evidence Required for Multiple Realization 147 Section 6.3: Polger’s Attack on Neural Plasticity 150 Section 6.4: On Polger’s Slipperiness about Neural Taxonomy 162 Chapter 7: The Empirical Evidence for Multiple Realization 166 Section 7.1: An Example of Cross-Species Multiple Realization 172 7.1.1: The Case Study: What the Researchers Were Looking for and What They Found 173 7.1.2: Evaluating the Case Study’s Evidence for Multiple Realization 178 7.1.3: Conclusion 185 Section 7.2: An Example of Multiple Realization from Neural Plasticity 186 7.2.1: A Case Study of the Serial Lesion Effect 188 7.2.2: Evaluating the Case Study’s Evidence for Multiple Realization 190 7.2.3: The GRP More Generally 195 7.2.4: Conclusion 197 Section 7.3: The Famous Cross-Wired Ferrets Case 199 7.3.1: The Experiment on the Ferrets: Why the Researchers Rewired and What They Found 199 7.3.2: Evaluating the Evidence the Ferrets Provide for Multiple Realization: What Shapiro and Polger have to Say and My Response 202 7.3.3: Conclusion 209 Bibliography 212 Chapter One: What are the Identity Theory and Multiple Realization? Undoubtedly a classic argument—perhaps the classic argument—in the history of the philosophy of mind is to show that identity theory is false because mental states are multiply realized. Beginning chiefly with papers by Place (1956) and Smart (1960), the dualistic outlook on the old mind-body problem was replaced by a thoroughgoing physicalism. In particular these writers argued, mainly via Ockham’s Razor, for the view that mental state types and brain state types are identical. Of course, as so often happens in philosophy, there was some general agreement (at least in terms of commitment to physicalism) combined with much criticism. In this case, there was a general agreement about accepting physicalism, but the kind of physicalism to adopt became the main issue. Putnam (1967) and Fodor (1968) and (1974) represent the initial and starkest criticism of the early advocacy of identity theory, arguing that classic line about mental states kinds being multiply realized in various brain state kinds. The influence of this Putnam/Fodor criticism was enough to make what came to be called nonreductive physicalism the received theory of mind. And, from what I can tell, nothing much has changed in recent years. That is not to say that no contemporary criticism exists of the view—or especially of the multiple realization argument used to get there. Indeed most of the writers who shun nonreductive physicalism have also published explicit rejections of the Putnam/Fodor argument. Examples of such writers include Bechtel and McCauley (1999), Bechtel and Mundale (1999), Boyd (1999), Kim (1992) and (2005), Millikan (1999), Polger (2002) and (2004), Richardson (1979), Sober (1999) and Shapiro (2000) and (2004). Somewhat surprisingly, amidst what clearly constitutes a substantial and recent backlash to the received view, very few writers have bothered to deal with various criticisms leveled by 1 the writers listed above. The purpose of my dissertation is thus roughly to provide such a response. I do not plan to respond individually to every argument or view contained in the above works, which would just take too long. Rather I would like to spend most of what follows developing this classic multiple realization argument against identity theory to some detail, hoping that such a development and a defense of the way in which I do develop the argument will form a compelling response to the general trends present in these works. Where I think battles against the individual arguments or views are worthwhile, instructional, or just plainly necessary (with respect to the line I want to take), I will save the back third or so of the dissertation to wage them. But there will be plenty of time and space for the dialectic from Smart to Shapiro. I will cover a good deal of it eventually. First we should do some preliminary work explaining more precisely what the early identity theorists were up to, the arguments from which they drew support for their view, and then finally the details of the Putnam/Fodor argument which came to dominate the discussion. Only after this orientating work will the development of the argument against identity theory and the defense of it I try to provide from more modern criticism be fully comprehensible. It is to that work I turn first. Section 1.1: Explaining Some of the Key Concepts As is customary, it is best to start by getting clear on some of the key issues and terms. The obvious starting place is to be clear about what is meant by ‘multiple realization.’ One attempt at explaining it is: a kind, or property, or type, is generally said to be multiply realized if there are many different ways for that kind (property, type) to be. And, of course, a kind is 2 multiply realizable if it is possible (pick your modality) for it to be multiply realized. There will be much opportunity to discuss the notions of ‘kinds’, ‘properties’, and ‘types’ as we go along.