Many philosophers accept the conceivability of zombies: creatures that lack consciousness but are physically and functionally identical to conscious human beings. Many also believe that the conceivability of zombies supports their metaphysical possibility. And most agree that if zombies are metaphysically possible, then physicalism is false. So, the claim that zombies are conceivable may have considerable significance. 1.

: Phenomenal knowledge usually comes from experience. But it need not. For example, one could know what it’s like to see red without seeing red—indeed, without having any color experiences. Daniel Dennett (2007) and Pete Mandik (forthcoming) argue that this and related considerations undermine the knowledge argument against physicalism. If they are right, then this is not only a problem for anti‐physicalists. Their argument threatens to undermine any version of phenomenal realism— the view that there are phenomenal properties, or qualia, (...) that are not conceptually reducible to physical or functional properties. I will argue that this threat is illusory. Explaining why will clarify what is and is not at issue in discussions of the knowledge argument and phenomenal realism. This will strengthen the case for physically and functionally irreducible qualia. 2 Phenomenal knowledge usually comes from experience. For example, I know what it’s like to see red because I have done so. Does knowing what it’s like to have an experience with phenomenal character X require having an experience with X? No. A famous counterexample is Hume’s missing shade of blue, in which one can extrapolate from phenomenally similar experiences (A Treatise of Human Nature, Bk. I, Pt. I, Sec. I).1 One might think that a weaker version of the no‐phenomenal‐knowledge‐without‐experience thesis remains tenable, e.g., that knowing what it’s like to see in color requires having or having had color experiences. But this thesis also seems doubtful. Peter Unger (1966) devised plausible counterexamples over four decades ago, and since then others (e.g., Lewis 1988, Alter 1998, Stoljar 2005) have done the same. One could have phenomenal knowledge of color experiences without having such experiences. Indeed, one could have such knowledge without having experiences that are remotely like color experiences. What is the significance of this observation for contemporary debates about consciousness and physicalism? Daniel Dennett (2007) and Pete Mandik (forthcoming) suggest that it undermines the knowledge argument against physicalism.2 That is because they take the claim that someone who has never seen in color could not know what it’s like to see in color to be the basis of the knowledge argument’s main epistemic premise: the premise that (roughly put) 3 no amount of physical knowledge is sufficient for phenomenal knowledge of color experiences. If they are right, then this is not only a problem for anti‐ physicalists. Many physicalists (e.g., Loar 1990/97, Papineau 2002, 2007) accept the knowledge argument’s epistemic premise. Dennett’s and Mandik’s arguments threaten all versions of what David Chalmers (2003) calls phenomenal realism, the view that there are phenomenal properties, or qualia, that are not conceptually reducible to physical or functional properties.3 I will argue that this threat is illusory. Explaining why will clarify what is and is not at issue in discussions of the knowledge argument and phenomenal realism. The net result will be to strengthen the case for physically inexplicable qualia. (shrink)

The so-called subjectivity of conscious experience is central to much recent work in the philosophy of mind. Subjectivity is the alleged property of consciousness whereby one can know what it is like to have certain conscious states only if one has undergone such states oneself. I review neurophilosophical work on consciousness and concepts pertinent to this claim and argue that subjectivity eliminativism is at least as well supported, if not more supported, than subjectivity reductionism.

Defenders of the Knowledge Argument contend that physicalism is false because knowing all the physical truths is not sufficient to know all the truths about the world. In particular, proponents of the Knowledge Argument claim that physicalism is false because the truths about the character of conscious experience are not knowable from the complete set of physical truths. This dissertation is a defense of the Knowledge Argument. Chapter one characterizes what physicalism is and provides support for the claim that if (...) knowing all the physical truths is not sufficient to know all the truths about the world, then physicalism is false. In chapter two, I defend the claim that knowing all the physical truths is not sufficient for knowing all the truths about the world. In addition to mounting a prima facie case for the knowledge intuition, I present and defend an epistemology grounded in direct acquaintance to provide a more substantive argument to accept it. Chapters three through five address the physicalist objections to the Knowledge Argument. The first set of objections advocates that knowing all the physical truths is, in fact, sufficient for knowing all the truths about the world. The next set of objections admits that there is some sense in which knowing all the physical truths is not sufficient for knowing all the truths about the world. However, these objections maintain that the kind of knowledge that is absent from the complete set of physical truths is know-how or knowledge by acquaintance, and not factual or propositional knowledge. The final set of objections maintain that the kind of propositional knowledge that is left out of the complete set of physical truths is compatible with physicalism. My response to these objections is part of advancing my prima facie case for the Knowledge Argument. The final chapter addresses a structural question that pertains to the Knowledge Argument. Some philosophers have maintained that the structure of the Knowledge Argument invites a kind of self-refutation of any systematic account of reality. The concern is that the Knowledge Argument proves too much, and that the dualist who uses the argument to refute physicalism risks the argument defeating his own position. I will argue that the Knowledge Argument does not refute dualism. (shrink)