Tom Polger

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

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

In the early years of the 1990s, a number of philosophers and cognitive scientists became enthused about the idea that mental states are spatially and temporally distributed in the brain, and that this has significant consequences for philosophy of mind. Daniel Dennett (1991), for example, appealed to the spatial and temporal distribution of cognitive processes in the brain in order to argue that there is no unified place where or time when consciousness occurs in the brain. Dennett used this interim conclusion as a premise in a series of arguments designed to undermine what he calls the “Cartesian Theater” view of consciousness, according to which there is an independent and fact of the matter about when and where conscious mental states occur. Most famously, Dennett argues that anyone who believes there are such facts of the matter must choose between “Orwellian” and “Stalinesque” theories of the timing of consciousness, in order to accommodate certain data about the spatial distribution of the timing of consciousness-related brain events. But, he claims, that distinction is a distinction without a difference: The choice between “Orwellian” and “Stalinesque” views is either nonsense, or at the very least one that we could never be justified in making. And this, Dennett takes it, is a reductio ad absurdum of any theory of consciousness that says there is a fact of the matter about when and where is occurs

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

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?

Karen Bennett has recently articulated and defended a “compatibilist” solution to the causal exclusion problem. Bennett’s solution works by rejecting the exclusion principle on the grounds that even though physical realizers are distinct from the mental states or properties that they realize, they necessarily co-occur such that they fail to satisfy standard accounts of causal over-determination. This is the case, Bennett argues, because the causal background conditions for core realizers being sufficient causes of their effects are identical to the “surround” conditions with which the core realizers are metaphysically sufficient the states or properties that they realize. Here we demonstrate that the background conditions for the causal sufficiency of core realizers for their effects are not identical to the core realizer’s surrounds, nor do backgrounds necessitate such surround conditions. If compatibilist solutions to exclusion can be defended, a different argument will be needed

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.

Drew Khlentozos’ Naturalistic Realism and the Antirealist Challenge is a meticulous introduction and roadmap to the core arguments of the contemporary realism/antirealism debate. It has several features that I especially admire. The book is carefully argued and for the most part clearly written. Rare among recent writers in Anglo-American philosophy, Khlentzos is a charitable reader of his opponents and earnestly endeavors to present their views as clearly and generously as possible. This generosity and thoroughness are also the book’s main fault, as it is long (weighing in 408 pages) and sometimes plodding. In a few cases Khlentzos’ charity is overly generous. This seems to me to be the case, for example, with some of his contortions on behalf of Dummett, not least of which being a lengthy chapter on how intuitionism drives Dummett’s antirealism that probably should have been an appendix. But these are drawbacks that we can all live with—especially for the purpose of graduate teaching, for which this monograph is well suited. Naturalistic Realism and the Antirealist Challenge begins (Section I) by setting out the realist/anti-realist debate. Khlentzos argues that the kinds of metaphysical realists who have been quickest to shrug off semantic arguments against realism are particularly susceptible to those arguments. Specifically, naturalistic realists—among whom Khlentzos counts himself—cannot dismiss critiques like those from Dummett and Putnam merely by observing that realism is a metaphysical rather than semantic or epistemic doctrine. The trouble is, “If the world is as resolutely mind-independent as the realist makes out, then there is a problem about how we get to know about it in the first place” (4). Khlentzos calls this the representation problem, saying.

The enduring metaphysical question about minds and mental phenomena concerns their nature. At least since Descartes this question—the mind-body problem—has been understood in terms of the viability or necessity of mind-body dualism, the thesis that minds and bodies are essentially distinct kinds of substance. Assuming that the nonmental (‘body’) portions of the world are constituted of physical stuff, the remaining question is: Are minds or mental phenomena essentially distinct non-physical substances, or phenomena that essentially involve such distinct kinds of substances? By the middle of the Twentieth Century there was broad philosophical and scientific consensus that the answer to this classical question about minds is negative: Minds and mental phenomena are not essentially distinct substances, nor are they phenomena that essentially involve distinct kinds of substances. There are at least two broad trends and one specific argument that lead to this conclusion. One trend is the decreasing influence of specifically theological arguments and commitments in philosophical argumentation, so that religious belief in immortal souls was no longer given much weight in the ontology of mind. The second trend, perhaps related to the first, is the increased demand that metaphysical theories bear explanatory fruits, so that the postulation of an immaterial and essentially mental substance appears to be a abdication from explanatory duties rather than a useful proposal. The argument, known to Descartes from the very beginning, is that there has never been an adequate account of 1 how two essentially distinct and incompatible substances could causally interact.1 Descartes’ solution was inadequate and brute, and his followers struggled with the problem—leading to Leibniz’s parallelism and Malebranche’s occasionalism, among other views. The problem of mental causation, then, is the central difficulty that underines substance dualism.2 The negative answer on the question of substance dualism, however, only increases the pressure for some monistic account of the nature of minds..