Tom Polger

Some people believe that there is an “explanatory gap” between the facts of physics and certain other facts about the world—for example, facts about consciousness. The gap is presented as a challenge to any thoroughgoing naturalism or physicalism. We believe that advocates of the explanatory gap have some reasonable expectations that cannot be merely dismissed. We also believe that naturalistic thinkers have the resources to close the explanatory gap, but that they have not adequately explained how and why these resources work. In this paper we isolate the legitimate explanatory demands in the gap reasoning, as it is defended by Chalmers and Jackson . We then argue that these demands can be met. Our solution involves a novel proposal for understanding the relationship between theories, explanations, and scientific identities

Consciousness and evolution are complex phenomena. It is sometimes thought that if adaptation explanations for some varieties of consciousness, say, conscious visual perception, can be had, then we may be reassured that at least those kinds of consciousness are not epiphenomena. But what if other varieties of consciousness, for example, dreams, are not adaptations? We sort out the connections among evolution, adaptation, and epiphenomenalism in order to show that the consequences for the nature and causal efficacy of consciousness are not as dire as has sometimes been supposed.

Fifty years ago J. J. C. Smart published his pioneering paper, “Sensations and Brain Processes.” It is appropriate to mark the golden anniversary of Smart’s publication by considering how well his article has stood up, and how well the identity theory itself has fared. In this paper I first revisit Smart’s text, reflecting on how it has weathered the years. Then I consider the status of the identity theory in current philosophical thinking, taking into account the objections and replies that Smart discussed as well as some that he did not anticipate. Finally, I offer a brief manifesto for the identity theory, providing a small list of the claims that I believe contemporary identity theorist should accept. As it turns out, these are more or less the ones that Smart defended fifty years ago.

According to the received view in philosophy of mind, mental states or properties are _realized_ by brain states or properties but are not identical to them. This view is often called _realization_ _physicalism_. Carl Gillett has recently defended a detailed formulation of the realization relation. However, Gillett’s formulation cannot be the relation that realization physicalists have in mind. I argue that Gillett’s “dimensioned” view of realization fails to apply to a textbook case of realization. I also argue Gillett counts as realization some cases that should not count if realization physicalism is to be distinguished from its competitors in the usual ways. I conclude that the relation described by Gillett cannot be realization

Recently some philosophers interested in consciousness have begun to turn their attention to the question of what evolutionary advantages, if any, being conscious might confer on an organism. The issue has been pressed in recent dicussions involving David Chalmers, Todd Moody, Owen Flanagan and Thomas Polger, Daniel Dennett, and others. The purpose of this essay is to consider some of the problems that face anyone who wants to give an evolutionary explanation of consciousness. We begin by framing the problem in the context of some current debates. Then we.

Saul Kripke’s modal essentialist argument against materialism remains an obstacle to any prospective Identity Theorist. This paper is an attempt to make room for an Identity Theory without dismissing Kripke’s analytic tools or essentialist intuitions. I propose an explanatory model that can make room for the Identity Theory within the constraints of Kripke’s view; the model is based on ideas from Alan Sidelle’s, “Identity and Identity-like” . My model explains the apparent contingency of some scientific identities by appealing to our epistemic access to the conditions of identity for sensations and brain processes. Pace Kripke, the Identity Theorist can thus explain away the apparent contingency of mind-brain identity claims

Consider what the brain-state theorist has to do to make good his claims. He has to specify a physical–chemical state such that any organism (not just a mammal) is in pain if and only if (a) it possesses a brain of suitable physical–chemical structure; and (b) its brain is in that physical–chemical state. This means that the physical–chemical state in question must be a possible state of a mammalian brain, a reptilian brain, a mollusc’s brain (octopuses are mollusca, and certainly feel pain), etc. At the same time, it must not be a possible (physically possible) state of the brain of any physically possible creature that cannot feel pain. Even if such a state can be found, it must be nomologically certain that it will also be a state of the brain of any extraterrestrial life that may be found that will be capable of feeling pain before we can even entertain the supposition that it may be pain. It is not altogether impossible that such a state will be found... . But this is certainly an ambitious hypothesis. (Putnam 1967/1975, p. 436) The belief that mental states are multiply realized is now nearly universal among philosophers, as is the belief that this fact decisively refutes the identity theory. I argue that the empirical support for multiple realization does not justify the confidence that has been placed in it. In order for multiple realization of mental states to be an objection to the identity theory, the neurological differences among pains, for example, must be such as to guarantee that they are of distinct neurological kinds. But the phenomena traditionally cited do not provide evidence of that sort of variation. In particular, examples of neural plasticity do not provide such evidence.

A common view is that the truth of multiple realization—e.g., about psychological states—entails the truth of functionalism. This is supposed to follow because what is multiply realized is eo ipso realized. I argue that view is mistaken by demonstrating how it misrepresents arguments from multiple realization. In particular, it undermines the empirical component of the arguments, and renders the multiplicity of the realization irrelevant. I suggest an alternative reading of multiple realizability arguments, particularly in philosophy of psychology. And I explain the proper way to understand the relation between realization and multiple realization

A widely accepted theory holds that emotional experiences occur mainly in a part of the human brain called the amygdala. A different theory asserts that color sensation is located in a small subpart of the visual cortex called V4. If these theories are correct, or even approximately correct, then they are remarkable advances toward a scientific explanation of human conscious experience. Yet even understanding the claims of such theories—much less evaluating them—raises some puzzles. Conscious experience does not present itself as a brain process. Indeed experience seems entirely unlike neural activity. For example, to some people it seems that an exact physical duplicate of you could have different sensations than you do, or could have no sensations at all. If so, then how is it even possible that sensations could turn out to be brain processes?

Forthcoming in Philosophy of Science. Despite some recent advances, multiple realization remains a largely misunderstood thesis. Consider the dispute between Lawrence Shapiro and Carl Gillett over the application of Shapiro’s recipe for deciding when we have genuine cases of multiple realization. I argue that Gillett follows many philosophers in mistakenly supposing that multiple realization is absolute and transitive. Both of these are problematic. They are tempting only when we extract the question of multiple realization from the explanatory context in which it is invoked. Anchoring multiple realizability in its theoretical context provides grounds for arbitrating disagreements. Doing so, I argue, favors the view advanced by Shapiro.

G. E. Moore argues that goodness is an intrinsic non-natural property that supervenes irreducibly on the intrinsic natural properties of its bearers. Accordingly, it is often supposed that “Moorean” supervenience is incompatible with physicalism, a naturalistic thesis. In this paper I argue that Moorean supervenience is not in itself incompatible with physicalism, Moore’s ethical non-naturalism notwithstanding. Understanding why will help us to better appreciate the full range of resources available to physicalists.

Suppose that consciousness is a natural feature of biological organisms, and that it is a capacity or property or process that resides in a single organ. In that case there is a straightforward question about the consciousness organ, namely: How did the consciousness organ come to be formed and why is its presence maintained in those organisms that have it? Of course answering this question might be rather difficult, particularly if the consciousness organ is made of soft tissue that leaves at best indirect fossil records, or if it has been fixed in the populations for such a long time that there are few available examples of organisms that lack the consciousness organ on which to conduct comparative experiments. No doubt there are other confounding practical obstacles as well. But these are just the complications that face biologists and natural historians on a regular basis, and they do not reflect any special problems about the study of consciousness. This is just to say that if consciousness is a natural feature of biological organisms then its origins and history can be studied in the same manner as other features of the biological world. It’s a hard business, but biologists are pretty good at it

My topic is the confluence of two recently active philosophical research programs. One research program concerns the metaphysics of realization. The other research program concerns scientific explanation in terms of mechanisms. In this paper I introduce a distinction between descriptive and explanatory approaches to realization. I then use this distinction to argue that a well-known account of realization, due to Carl Gillett, is incompatible with a well-known account of mechanistic explanation, due to Peter Machamer, Lindley Darden, and Carl Craver (MDC, Philos Sci 57: 1-25, 2000). This is surprising, not least of which because Gillett has cited MDC's work as evidence that his account of realization is the right way to think about realization in the sciences

David Chalmers burst onto the philosophical scene in the mid-1990s with his work on consciousness, which awakened slumbering zombie arguments against physicalism and transformed the explanatory gap into the hard problem of consciousness. The distinction between hard and easy problems of consciousness became a central dogma of the movement. Chalmers’ influence in philosophy and consciousness studies is unquestionable. But enthusiasts of Chalmers’ work on consciousness may be excused for not fully appreciating his own justification for drawing the hard/easy distinction, or even exactly which distinction he is drawing. Consequently, it is not clear that the ‘Chalmers’ hard problem’ that has been widely influential is Chalmers’ ‘hard problem’ of consciousness. Chalmers’ ‘hard problem’ rests on, among other things: a methodological view about how philosophy—metaphysics, especially—ought to be conducted; a view about the requirements for explanation and reduction in philosophy and in the sciences; and a theory of the semantics of concepts.1 Although Chalmers writes that the present book is not intended as a foundation for his

Saying that psychological states are functional states, the functionalist claims more than that psychological states have functions. Rather, functionalism is the theory that psychological states are defined and constituted by their functions. On this view, what it is to be a psychological state of a certain sort just is and consists entirely of having a certain function. Anything that has that function in a suitable system would therefore be that psychological state. If storing information for later use is the essential function of memory, then anything that has that function counts as a memory. Similarly, one might say that anything that traps or kills mice counts as a mouse trap

To what degree must the brains and bodies of creatures with minds have to be similar to the brains and bodies of human beings? Since the late 1960’s, most philosophers and cognitive scientists have supposed that there a relatively few constraints on what sorts of brains and bodies can realize minds. It is widely believed that minds are multiply realizable. Of course there were always dissenters, and in recent years their grumbling has grown harder to dismiss. In The Mind Incarnate , Lawrence Shapiro provides the first book-length study of the multiple realizability thesis. Such an examination is long overdue, and Shapiro’s treatment is sure to set the standard for the budding debate

Multiple realizability has recently attractedrenewed attention, for example Bickle, 1998;Bechtel and Mundale, 1999; Bechtel and McCauley,1999; Heil, 1999; and Sober, 1999. Many of thesewriters revisit the topic of multiplerealizability in order to show that someversion of a mind-brain identity theory isviable. Although there is much of value inthese recent explorations, they do not addressthe underlying intuitions that have vexedphilosophers of mind since Hilary Putnamintroduced the concern (1967). I argue that thestandard way of construing multiplerealizability is a much stronger claim thanthat of Putnam's intuition alone. I distinguishfour interpretations of the multiplerealizability intuition. Some commonformulations of multiple realizability arealmost certainly true, while others are not atall plausible. I argue that the plausible formsof multiple realizability do not impugn theprospects for a mind-brain Identity Theory.

In this article I reply to the challenge set forth by Dennett in his critique of Flanagan and Polger (1995). Through careful textual analysis, I show that Dennett is presenting us with a dilemma and that this dilemma is the keystone of Dennett’s argument in his Consciousness Explained. I argue that one horn of the dilemma does not have the consequence that Dennett claims; Specifically, I argue that theories that allow for the possibility of non-conscious functional duplicates of conscious beings (so called zombies) do not thereby entail epiphenomenalism about consciousness. I demonstrate how Dennett’s argument falls prey to a common mistake in reasoning about the functions of things, and recommend a correction.

Michael Tye has recently been a vocal defender of color realism or, as I shall call it, color objectivism. Objectivism about color is the view that color properties are identical to intrinsic physical properties of the surfaces of objects. Subjectivism about color is the denial of color objectivism. Objectivists argue that color claims must be taken at face value. In this paper I forego the usual bickering about whether there are surface reflectance properties that can be identified with colors as the objectivist theory requires. Supposing that some such properties could be found, I argue that if objectivism about color were correct it would have the unsavory consequence that we are rarely if ever right—perhaps never right—about the particular colors of particular things. So objectivism does not bear out common attribution of colors to the surfaces of things, after all.

It is commonly held that there are two obstacles to precisely formulating the doctrine of physicalism: Hempel’s Problem, and Hume’s Problem.² Hempel’s Problem is that if physicalism is to be formulated in terms of physics—or in terms of any science, for the problem is fully general if it is a problem at all—whether to use the current or future science. If physicalism is formulated in terms of current physics, then it is most likely false because current physics is at least very likely to be false and is perhaps known to be incomplete or inconsistent. If physicalism is formulated in terms of future physics, then (the worry goes) physicalism will prove to be trivial, vacuous, or simply of indeterminate content. Horgan offers no direct guidance on Hempel’s Problem, though he seems to adopt a future-physics view.³

On the one hand, it is obvious that a person’s conscious experiences are unified with one another in a way that they are not unified with anyone else’s experiences. My experiences are mine, and yours are not. On the other hand, it is equally plain that a person’s experiences are not monolithic. Generally, I can distinguish various aspects of my experiences, and I can attend to some rather than others. Conscious experience is unified, and it is not. Is there a unification thesis that is substantial, interesting and plausible? Tim Bayne sets out to defend an affirmative answer in his The Unity of Consciousness.