Life, Automata and the Mind-Body Problem

Transcription

1 TEL-AVIV UNIVERSITY LESTER & SALLY ENTIN FACULTY OF HUMANTIES THE SCHOOL OF PHILOSOPHY Life, Automata and the Mind-Body Problem Thesis Submitted for the Degree of Doctor of Philosophy by Vered Glickman Submitted to the Senate of Tel-Aviv University January 2002

2 This work was carried out under the supervision of Prof. Shlomo Biderman, Tel-Aviv University

3 I would like to thank my supervisor, Prof. Shlomo Biderman, for his helpful comments, kind and wise criticism, and continuous encouragement.

4 Contents Introduction 1 ON THE HORNS OF A DILEMMA 7 The First Horn: Against Dualism 8 I. The Argument from the Best Explanation Principle... 8 II. The Argument from the Causal Closure of the Physical World... 9 The Second Horn: Against Reductive Materialism 13 I. The Knowledge Argument II. Kripke s Argument for Dualism III. The Explanatory Gap Argument IV. Arguments against Functionalist Accounts of the Experienced Qualities Failed Attempts to Escape the Dilemma 39 I. Qualities Cleared Away: The Elimination of the Irreducible Properties II. Qualities Cleared Away: The Intentionalization of Sense-Experiences III. Mystifying Consciousness IV. Non-Reductive Naturalism V. Conclusion of Part I TRACING THE ORIGINS OF THE DILEMMA 68 Why was there no Soul-Body Dilemma before Descartes? 69 I. Life, Body and Soul in Ancient Cultures II. Life, Body and Soul in Medieval Philosophy III. Life, Body and Soul in Renaissance Philosophy... 91

5 Body and Mind in Cartesian Philosophy: The Seeds of the Dilemma are Planted 97 I. The Scientific Revolution and its Impact on Descartes Philosophy II. Descartes Arguments for his Theory of the Mind III. The Seeds of the Dilemma are Planted Physicalist Imperialism and Reductionism: The Appearance of the Dilemma123 I. The Rise of Physicalist Imperialism II. From Physicalist Imperialism to Reductionism III. Reductionism and the Irreducibility of the Experienced Qualities IV. Conclusion of Part II OUT OF THE DILEMMA 131 The Demise of Physicalist Imperialism 132 I. Difficulties in Bridging Different Ontological Vocabularies II. Difficulties in Securing the Explanatory Gain of a Nagelian Reduction Pluralism and Autonomy: Alternatives to Physicalist Imperialism 150 I. Non-Reductive Ontology II. Non-Reductive Explanations Out of the Dilemma 159 I. Reduction of the Qualitative Experiences is Not Necessary: One Horn of the Dilemma is Removed II. Qualitative Experiences should not be Metaphysically or Explanatorily Isolated: Another Horn of the Dilemma is Removed Conclusion 179

6 Introduction The causal interaction between body and soul, or mind, presents a major philosophical problem, which is commonly believed to have puzzled philosophers ever since the soul was conceived of as a separate entity that outlives the body. It also seems to be a persisting problem, as none of the so-far attempted solutions is widely accepted. Some even argue that no answer can be given, since the nature of the interaction between body and soul is beyond the reach of the human mind. This mind-body problem a world knot, as Schopenhauer called it still occupies a central place in contemporary philosophical discussion. This conception of the mind-body problem as a long-existing philosophical problem, waiting to be resolved, was, at first, mine as well. I believed that by untangling the conceptual knot that generates this old problem the source of so much controversy over the last two millennia (Searle, 1994, p. 277) one would find a way out of it. All that was needed, I thought, was a careful analysis of the conceptual threads that got tangled in this famous world knot. I no longer hold this view. I now realize that this conceptual knot did not always exist, and that not every philosopher who conceived of the soul as a separate entity had to face the mind-body problem. Only within a specific theoretical context does the problem arise. More precisely, it is only within the theoretical context of Cartesian philosophy that the causal interaction between body and soul becomes inexplicable. Moreover, the theory to be blamed for our inherited philosophical quandary is not, as it is often thought, Descartes theory of mind, but his revolutionary conception of nature and the natural sciences. The integration of this conception into Western thought resulted in the emergence of the mind-body problem. 1

7 But I have also become a skeptic with regard to the possibility of untangling this world knot. I now realize that once we adhere to the Cartesian conception of nature and the natural sciences, the conceptual knot in which we found ourselves trapped cannot be untangled. Instead, we should abandon the whole conceptual framework that generated it, and embrace an alternative, non-cartesian one. My change of view was brought about by the different perspective the historical one from which I learned to see the problem. Although tracing the historical origins of the mind-body problem was not intended at first to be part of my work, it became one of its main topics as the work progressed. I found that the history of the conceptions of body and soul in Western thought not only discloses the conceptual roots of the problem, but may also suggest a way out of it. Even before I embarked on the historical examination of past conceptions of the soul, I had already suspected that only some conceptions would disallow causal interaction between it and the body. What I have further learned from my historical survey was that none of the conceptions of the soul that were held in Western culture before the 17 th century could have raised such a problem. The problem just didn t and couldn t exist in Western thought before the 17 th century, and any attempt to analyze past theories of the soul as addressing the mind-body problem is bound to be anachronistic. As much as Aristotle s theory of the soul, for instance, may inspire contemporary discussions of this subject, it was not contrived, even in part, as an answer to the mind-body problem. The problem is the consequence only of Descartes complete philosophical system. The historical evidence points at yet another, perhaps surprising conclusion. The problem could not have emerged before the 17 th century, not so much because of the different conceptions of the soul that people held at earlier times, but mainly 2

8 because of their different conception of the body. Before Descartes, the bodily world the world of bodies without souls was not conceived of as a causally complete world. Not everything about bodies, especially living bodies, could be explained in bodily terms alone. Therefore, on earlier conceptions of nature, the bodily world was not closed to the causal influence of non-bodily entities. Causal interaction between body and soul became unaccountable only when both body and soul were defined as self-sufficient beings. Such a definition was indeed part of Descartes metaphysics, a definition which was a result of his new conception of nature and the natural sciences. Descartes new philosophy of science is therefore responsible for the gap that was opened between body and soul. It is therefore also responsible for the difficulties modern philosophers face when attempting to naturalize mental phenomena. Not only does it involve the closure of the natural world to causal interaction with anything that is not part of this world, it also prevents mental phenomena from being readmitted into this world. The constraints that this philosophy of science puts on what may count as a natural phenomenon ensure the failure of mental phenomena to qualify. Philosophers who embrace Cartesianism thus face a dilemma: they can neither account for the evident interaction between bodily and mental phenomena when the latter are conceived as immaterial, nor solve this problem by naturalizing mental phenomena. This dilemma of the relation between mental and bodily phenomena is better known as the mind-body problem. And Cartesian philosophy is its conceptual birthplace. The dilemma of the soul-body relation is, thus, unavoidable once we accept Descartes philosophical principles. And since the roots of the dilemma are found in Descartes conception of nature and the natural sciences, this particular conception 3

9 should be questioned, if we desire to escape the dilemma. It does not suffice contrary to the view of many philosophers to criticize the Cartesian conception of mind. More of our Cartesian heritage should be rejected, if the soul-body dilemma is to be avoided. The Cartesian view of nature and science should be replaced by an alternative one that does not encounter similar difficulties. These are the general conclusions I have drawn from my historical examination of past conceptions of soul and body in Western thought. In my work I present and discuss the historical evidence and the theoretical arguments that have brought me to these conclusions. The work is divided as follows. The dilemma of the soul-body relation is presented in Part I. Here I introduce and discuss the arguments that engender the two horns of the dilemma. First I present the arguments for the necessity of a reduction of mental phenomena to bodily ones, of which the most powerful one is the Argument from the Causal Closure of the Physical World. Following that is a critical presentation of the main arguments put forward in recent years against the possibility of a psycho-physical reduction. These arguments center mainly on the possibility of reducing conscious experiences to brain states. The qualitative aspects of these experiences is claimed to be irreducible. The Problem of Consciousness, as it has come to be called, constitutes the second horn of the soul-body dilemma. Many have attempted to confront the dilemma. In chapter III of Part I, I examine these various attempts. Some deny the existence of irreducible qualities, either by eliminating them from our ontology, or by proving them to be intentional, and thus reducible, phenomena. Others accept the conclusion of the anti-reductionist arguments. Of the latter, those who accept materialism either maintain that mental 4

10 phenomena are in some sense essentially mysterious, or defend some version of nonreductive naturalism. All these attempts, I argue, fail to escape the dilemma. In Part II I trace the conceptual origins of the dilemma. This part includes a short historical review of past conceptions of body and soul in Western thought up to the 17 th century. This historical review aims to show why the dilemma of the soulbody relation could not have emerged before Descartes. Chapters II and III of this part complete the historical analysis by tracing the conceptual roots of both horns of the soul-body dilemma in Descartes new philosophy, particularly in his conception of nature and the natural sciences. Since the soul-body dilemma is inescapable once the Cartesian conception of nature and the natural sciences are accepted, one may want to replace them with alternative ones. This possibility is discussed in Part III. In my search for theories that incorporate such alternative conceptions I found that the Cartesian philosophy of science, in particular its notion of a unified science, is indeed challenged by some scientists and philosophers of science. Contemporary philosophers of mind ignore the fact that in addition to the failure of the psycho-physical reduction, there are reasons for believing that reduction cannot be achieved in other fields of natural science as well. It follows that Descartes vision of a unified science must be rejected, together with the metaphysics that underlies it. In the work of these philosophers of science we find not only powerful arguments against Descartes theory of nature and the natural sciences, but also a defense of alternative theories. The alternative theories suggest a pluralist metaphysics of nature, and a conception of the different-order sciences as autonomous sciences, linked, nonetheless, by various explanatory relations. Drawing on these arguments I propose my solution to the dilemma of the soul-body relation. 5

11 Both horns of the dilemma, I argue, are avoided if these alternative, non-cartesian, theories are adopted. 6