The Phenomenal Concept Strategy


Peter Carruthers and Bénédicte Veillet[1]



A powerful reply to a range of familiar anti-physicalist arguments has recently been developed. According to this reply, our possession of phenomenal concepts can explain the facts that the anti-physicalist claims can only be explained by a non-reductive account of phenomenal consciousness. Chalmers (2006) argues that the phenomenal concept strategy is doomed to fail. This paper presents the phenomenal concept strategy, Chalmers’ argument against it, and a defense of the strategy against his argument.


1.         Introduction.

Being in pain feels a certain way. Looking at a red rose, smelling it, feeling the thorns on its stem: these experiences all feel a certain way as well. We will call these feels “phenomenal feels” and we will say that anyone who has such phenomenal feels is phenomenally conscious. Philosophers have presented and defended a range of arguments and thought-experiments designed to show that phenomenal feels cannot be reduced to anything purely physical. There is the famous Mary who is born and kept in a black-and-white room and grows up to become the world’s leading expert on color vision, but is said to learn new facts about color when she experiences colors for the first time (Jackson, 1986). There are zombies and color inverts (Chalmers, 1996): creatures who are physically, functionally, and intentionally identical to us but who lack phenomenal feels altogether; or creatures physically, functionally, and intentionally identical to us who, when we have this experience (a red experience, say) have that experience (a green experience). And then, of course, there is the explanatory gap (Levine, 1983; Chalmers, 1996): it seems that no matter how much information we are given about conscious experience in physical, functional, or intentional terms, that information won’t really explain why our experiences should feel to us the way that they do.

Physicalists in the last decade or so have fleshed out a seemingly powerful reply to these arguments and thought-experiments, by invoking phenomenal concepts. According to physicalist proponents of this strategy (which we will call “the phenomenal concept strategy”, following Stoljar, 2005, and Chalmers, 2006), we possess a special set of concepts for referring to our own experiences. What is said to be distinctive of such concepts is that they are conceptually isolated from any other concepts that we possess, lacking any a priori connections with non-phenomenal concepts of any type (and in particular, lacking such connections with any physical, functional, or intentional concepts). Given that phenomenal concepts are isolated, the physicalist argues, then it won’t be the least bit surprising that we can conceive of zombies and inverts, or that there should be gaps in explanation. This is because no matter how much information one is given in physical, functional, or intentional terms, it will always be possible for us intelligibly to think, “Still, all that might be true, and still this [phenomenal feel] might be absent or different.” There is no need, then, to jump to the anti-physicalist conclusion. All of the arguments referred to above are perfectly compatible with physicalist accounts of phenomenal feelings.

Chalmers (2006) argues that the phenomenal strategy is doomed to fail, however. Either appeals to phenomenal concepts open up a new explanatory gap, one with which the physicalist can’t deal, or phenomenal concepts simply can’t do the work that the physicalist intends them to do. This paper will first spell out the phenomenal concept strategy in more detail. It will then present Chalmers’ sweeping argument against it, before offering our replies.


2.         The Phenomenal Concept Strategy.

Defenders of the phenomenal concept strategy all agree that phenomenal concepts are special in a way that permits a reply to anti-physicalist arguments. But different physicalists have different ways of characterizing what, exactly, is special about phenomenal concepts. We will briefly review some influential accounts.


2.1       Phenomenal Concepts.

According to Loar (1990), Carruthers (2000), and Tye (2000), phenomenal concepts are recognitional concepts of experience. A recognitional concept, unlike a theoretical concept, is applied directly on the basis of perceptual or quasi-perceptual acquaintance with its instances. Consider, for instance, the concept red, which is often construed as a prototypical recognitional concept. It seems plausible that we apply the concept red directly upon perceiving red things. Like the concept red, phenomenal concepts are recognitional concepts. But they are concepts of experience, which means that we apply them directly on the basis of acquaintance with experiences, as when I say that this is my blue-cup experience. But phenomenal concepts aren’t merely recognitional, however. For if they were, then they would be no different from a number of other recognitional concepts like red. They are, to use Carruthers’ terminology, purely recognitional. A concept is purely recognitional if it is both applied directly to instances and if it is conceptually isolated from other concepts. The concept red, in contrast, is connected to concepts like surface; and our judgments of red are modified by our beliefs about normal lighting, normal perceiver conditions, and so forth.

Perry (2001) and O’Dea (2002), in contrast, argue that phenomenal concepts are a form of indexical. They are concepts that pick out brain states under an indexical mode of presentation, in something like the way that the concept I picks out its referent (me) under an indexical mode of presentation. The concept this in, “This is my blue-cup experience”, is such an indexical concept. Indexical concepts are sometimes believed to be isolated from non-indexical concepts. According to some (Perry, 1979), knowing every non-indexical fact about the world won’t be enough for one to deduce what time it is now. Similarly, then, knowing every non-phenomenal fact about the world won’t enable me to deduce any phenomenal facts about it.

Papineau (2002) suggests instead that phenomenal concepts are quotational concepts. They are concepts that somehow contain the states to which they refer. Just as words can be embedded within quotation marks, as in “blue cup”, so Papineau argues that actual phenomenal states (either perceptual states, or images of perceptual states) will be embedded within phenomenal concepts. When I say, “This is a blue cup experience”, the relevant phenomenal concept this in fact has the following sort of form: this: ______, where the blank is filled by an actual phenomenal state. Again it will follow from such an account that one cannot deduce which quotational concepts apply to something just from knowledge of which non-phenomenal concepts apply to it.


2.2       The Strategy.

A number of other accounts of phenomenal concepts have been offered (Nagel, 1974; Sturgeon, 1994; Hill, 1997; Rey 1998; Levine, 2001). But we should now see where all such proposals are leading. Phenomenal concepts, on each of these views, are conceptually isolated. And this conceptual isolation is all that is needed to reply to the anti-physicalist arguments described above. Mary in her black and white room may know all one can know about color and color vision. But that won’t help her to deduce what seeing red feels like. To know what seeing red feels like requires deploying a phenomenal concept. It is just such a concept that she learns upon leaving her room. And why couldn’t she learn that concept before? Wasn’t her extensive knowledge of color vision enough to enable her to learn that phenomenal concept? No. Since it is conceptually isolated, no physical (or functional, or representational) knowledge about color vision would have enabled her to learn the relevant phenomenal concept. So when she leaves her room, she does acquire the capacity to think some new thoughts (these are thoughts involving phenomenal concepts). Hence she also learns some new facts (in the sense of acquiring some new true thoughts). But for all that the argument shows, these new thoughts might just concern the very same physical facts that she already knew, only differently represented (now represented by means of phenomenal concepts).

Given the existence of phenomenal concepts, moreover, we should expect zombies and color inverts to be conceivable. Indeed, since such people are supposed to be duplicates of ours, when we describe their physical make-up we deploy all of the same physical (and functional, and representational) concepts that we would apply in describing ourselves. Since phenomenal concepts are conceptually isolated, however, applying all these physical concepts to our duplicates doesn’t entail anything about which phenomenal concepts, if any, will apply to them. Hence I can conceive that my duplicate would lack this experience, and this one, and every other. Alternatively, I can conceive that instead of having this experience, my duplicate would have that one.

Finally, on this view it is no wonder that there is an explanatory gap. To give an explanation of phenomenal feels in physical (or functional, or representational) terms is to deploy only physical, or functional, or representational concepts in the course of the explanation. To think or speak about phenomenal feelings (which is what we hope to explain) is to deploy phenomenal concepts. It is experiences like these that we hope to give an account of. The explanation cannot feel satisfactory, therefore, since the concepts used in the physical explanation don’t entail any applications of the phenomenal concepts in terms of which the explanandum is characterized.

It should now be clear how the phenomenal concept strategy is intended to work. The physicalist will agree with his opponent that there is an explanatory gap, and that zombies and inverts are conceivable. Physicalists deny the next step in the anti-physicalist argument, however. The best explanation for the conceivability of zombies and for the existence of the explanatory gap is not the one the anti-physicalist believes it to be. There is an alternative explanation of these facts, namely that they arise from our possessing and using conceptually isolated phenomenal concepts. Anti-physicalist arguments hence fail to secure their conclusion.

Note that the phenomenal concept strategy takes for granted that the notion of intentional content doesn’t presuppose or implicate phenomenal consciousness. One can only usefully think that some of the puzzling facts about phenomenal consciousness (the conceivability of zombies, the explanatory gap, and so on) are explicable by appeal to the character of our phenomenal concepts, if one also thinks that concepts, and intentional contents more generally, don’t give rise to just the same puzzles. This assumption is by no means uncontroversial, of course. But in our view it is warranted by, among other things, the extensive use that is made of intentional concepts in cognitive science, in ways that make no appeal to phenomenal consciousness. And since Chalmers’ argument doesn’t depend upon challenging this assumption, it can be taken as common ground between us for present purposes.


2.3       Phenomenal Concepts: First versus Third Person Accounts.

It is important to note that there are, according to proponents of the phenomenal concept strategy, two quite different ways in which phenomenal concepts can be thought about and characterized.[2] One is from the first-person perspective of the users of those concepts, or in terms that otherwise presuppose such a perspective. Thus I might say to myself, “A phenomenal concept is a concept like the one that I hereby deploy when thinking about this experience”, for example. Or I might say that a phenomenal concept is a concept that is applied in a recognitional way to phenomenal states, and then go on to characterize the latter first-personally, by thinking that they are states like this, or that, or that.

The other way of characterizing phenomenal concepts is third-personal, and might take any of the forms sketched above. Thus one might say that phenomenal concepts are conceptually isolated recognitional concepts that are deployed in the presence of perceptual states with certain sorts of intentional content, for example. Note that such a description isn’t meant to be a definition, of course. For that would conflict with the claim that phenomenal concepts are conceptually isolated. (Precisely what it means to be conceptually isolated is to possess no conceptual connections to other concepts, including functional and/or intentional concepts like ‘concept’, ‘perceptual state’, and so on.) Rather, such accounts are substantive, empirical, claims about the characteristic functional and intentional roles of the concepts in question. And those who adopt the phenomenal concept strategy argue that if some such claim is true, then the anti-physicalist’s arguments from zombies, from inverts, and from the explanatory gap can all be undermined.

It is imperative that the distinction between first-person and third-person descriptions of phenomenal concepts shouldn’t be conflated with the (alleged) distinction between the wide and narrow intentional contents that such concepts might possess. (This is important, inter alia, because many philosophers deny that narrow contents are even so much as coherent.) Such a confusion might arise quite naturally, because a widely-individuated phenomenal concept (individuated in such a way as to embrace the phenomenal state that is its referent) must be one that a zombie duplicate will lack, just as we will claim that a first-personal description fails to fit any of the zombie’s concepts. And likewise a narrowly-individuated phenomenal concept (individuated in abstraction from the phenomenal state that is its referent) would be one that a zombie duplicate must possess, just as we will claim that a third-personally described phenomenal concept is one that the zombie must have. So in this respect the two distinctions march in parallel.

Our distinction, however, carries no commitments concerning the nature of intentional content or its individuation conditions. Although the third-person description of a phenomenal concept is couched in terms of a (conceptually isolated) form of functional role, it carries no commitment to the truth of any kind of conceptual role semantics, or to the sorts of narrow intentional contents that such a semantics might be thought to warrant. Even a convinced information-semanticist like Fodor (1990) can agree that although phenomenal concepts are individuated in terms of the information that they carry (say), it is still true that they have a conceptually isolated role. And this truth is all that is necessary for the phenomenal concept strategy to succeed. To put the same point slightly differently: we don’t need to claim that my zombie twin and I deploy the same (narrowly individuated) concept in order for our points to go through. It just has to be the case that the zombie deploys a concept that is like mine in the relevant functional-role respects. For it turns out that it is this (conceptually isolated) role that is sufficient to explain the conceivability of zombies, the appearance of an explanatory gap, and so forth.


3.         Chalmers Against the Phenomenal Concept Strategy.

Chalmers (2006) argues that no appeal to phenomenal concepts of any of the sorts sketched above can constitute an adequate defense of physicalism. This is because phenomenal concepts can’t both effectively defuse the anti-physicalist arguments and be physically explicable themselves. Here is the argument as he sees it:

(1) Either we can conceive that Chalmers’ zombie duplicate (call him “Zombie Chalmers”) lacks phenomenal concepts, or we can’t conceive that he lacks such concepts.

(2) If we can conceive of Zombie Chalmers lacking phenomenal concepts, then a new explanatory gap is formed and phenomenal concepts turn out to be physically inexplicable.

(3) If we can’t conceive of Zombie Chalmers lacking phenomenal concepts, then phenomenal concepts can’t explain the explanatory gap.

(4) It follows that either phenomenal concepts aren’t physically explicable or they don’t explain the explanatory gap.

The argument seems powerful. Premise (1) looks like a necessary truth. Premise (2) looks to be true. For anything that Chalmers has that Zombie Chalmers can be imagined to lack (given that the latter is physically, functionally, and intentionally identical to Chalmers) will be physically inexplicable. Premise (3) also seems true. For if Zombie Chalmers can’t be conceived to lack phenomenal concepts, then that must mean that those concepts are physically or functionally explicable; but we have already agreed that physical and functional facts can’t explain phenomenal consciousness; in which case phenomenal concepts won’t be able to do the work required of them, either. Moreover, the argument as a whole appears valid.

            On further reflection, however, the argument as it stands can be seen to be problematic. For in order for (1) to be a necessary truth, the phrase “phenomenal concepts” will have to be taken univocally. But then when we see that term at work in the two premises that follow, it seems that it must be taken in a different way in each. The usage in Premise (2) seems to require the first-personal understanding of phenomenal concepts distinguished in Section 2.3. (If Zombie Chalmers is conceived to lack phenomenal states, then he must equally be conceived to lack a concept of the sort that I hereby deploy when thinking about this conscious state.) The usage in Premise (3), in contrast, seems to require a third-personal understanding. (Since Zombie Chalmers shares all of Chalmers’ physical, functional, and intentional properties, then the former must also possess conceptually isolated recognitional concepts, say, which he deploys in the presence of his perceptual states.) Hence the argument, as it stands, commits a fallacy of equivocation.

            It would certainly make life easy for physicalists if Chalmers’ argument could be defeated so easily! But in fact it can be reformulated to avoid the difficulty, by framing a version of Premise (1) that no longer purports to be a necessary truth. Thus:

(1*) Phenomenal concepts can either be characterized in a first-person way, or they can be characterized in third-person terms.

(2a) If phenomenal concepts are characterized in first-person terms, then we can conceive of Zombie Chalmers lacking such concepts.

(2b) If we can conceive of Zombie Chalmers lacking phenomenal concepts, then a new explanatory gap is formed and phenomenal concepts turn out to be physically inexplicable.

(3a) If phenomenal concepts are characterized in third-person terms, then we can’t conceive of Zombie Chalmers lacking such concepts.

(3b) If we can’t conceive of Zombie Chalmers lacking phenomenal concepts, then phenomenal concepts can’t explain the explanatory gap.

(4) It follows that neither way of characterizing phenomenal concepts can help with the problem of phenomenal consciousness - either they introduce a new explanatory problem, or they can’t do the explanatory work required.

This argument commits no fallacy that we can see, and all of its premises present at least the appearance of truth. So is the phenomenal concept strategy defeated? We believe not. For we think that there are sufficient grounds for denying the truth of Premise (3b). This will form the focus of the remainder of the paper.[3]


4.         Can Phenomenal Concepts Explain our Epistemic Situation?

Chalmers’ defense of the claim made in Premise (3b) is quite complex, turning crucially on his discussion of what he calls “epistemic situations”. Throughout the discussion of this conditional, however, it should be borne in mind that phenomenal concepts are to be understood in third-person terms, as conceptually isolated concepts being deployed in the presence of certain perceptual states.

Let us recall the original explanatory gap problem, the conceivability of zombies, and the argument from Mary’s new knowledge. And let us, in addition, consider claims like, “I am phenomenally conscious.” These problems (and others like them) and this claim (and others like it) form what Chalmers’ calls our epistemic situation when it comes to phenomenal consciousness. Proponents of the phenomenal concept strategy believe that our possession of phenomenal concepts can explain our epistemic situation. We have already seen how the physicalist will argue that phenomenal concepts explain why there is a gap in explanation, why zombies and inverts are conceivable, and what Mary learns. And when I say, “I am phenomenally conscious”, it may be that I am in fact saying something like: “I have experiences like these”, where these is a phenomenal concept. We are now in a position to schematize Chalmers’ argument for Premise (3b) as follows:

(i) If zombies do indeed possess phenomenal concepts (which must be the case if Zombie Chalmers can’t conceivably lack phenomenal concepts, characterized in the third-person way), but don’t share our epistemic situation, then our having phenomenal concepts can hardly explain our epistemic situation.

(ii) Zombies don’t share our epistemic situation.

(iii) It follows that the possession of phenomenal concepts can’t explain our epistemic situation (given a third-person characterization of phenomenal concepts).

According to the first premise of this argument, if Chalmers and Zombie Chalmers don’t share the same epistemic situation, then phenomenal concepts can’t explain our epistemic situation. Chalmers provides an argument for this claim which parallels, again, the original arguments from zombies and the explanatory gap. The original arguments can be summarized like this: if you can imagine two physical duplicates, one phenomenally conscious and the other not, then phenomenal consciousness can’t be explained in physical terms. Now we can say this: if we can imagine two duplicates both possessing phenomenal concepts, one in our epistemic situation and the other not, then our epistemic situation isn’t explicable in terms of phenomenal concepts. We will grant Chalmers the truth of this premise.

Premise (ii) asserts that Chalmers and his zombie twin don’t share the same epistemic situation. This is more questionable. According to Chalmers (2006, 11), for two duplicates to share the same epistemic situation is for their corresponding beliefs to have the same truth-values and the same epistemic status “as justified or unjustified, and as substantive or insubstantive”. Corresponding beliefs, Chalmers goes on to say, need not have the same contents. Oscar and Twin Oscar, he argues, share the same epistemic situation.[4] Oscar’s belief that water [H2O] is refreshing and Twin Oscar’s corresponding belief that twater [XYZ] is refreshing will both be true, even if the two beliefs don’t have the same content. Chalmers argues that he and his zombie twin, unlike Oscar and Twin Oscar, do not share the same epistemic situation. Chalmers’ belief that he is phenomenally conscious is true, whereas Zombie Chalmers’ belief that he is phenomenally conscious is false. Or think back to Mary, and imagine her possessing a zombie twin. Mary gains new introspectible knowledge when she is finally freed from her room, whereas Twin Mary doesn’t gain all of the same knowledge. So they don’t seem to share the same epistemic situation. Chalmers concludes that our zombie twins cannot share our epistemic situation.

We now propose to argue that Premise (ii) is false, however, and that zombies do share our epistemic situation (in one good sense of the notion of “epistemic situation” – we will return to this point in Section 5).

Chalmers compares zombie duplicates to Oscar and Twin Oscar. Oscar, on Earth, is entertaining a thought that he would express with the words, “Water is refreshing.” Our intuition is that Oscar is referring to H2O. When Twin Oscar thinks a thought that he, too, would express with the words, “Water is refreshing”, our intuition is that he is referring to XYZ, and not to H2O. Oscar and Twin Oscar both possess concepts that they deploy under the same circumstances (when they are thirsty), which are associated with certain kinds of perceptual states (seeing a colorless liquid), and so forth. But, according to the externalist, those corresponding concepts will have different contents. The content of Oscar’s concept is tied to H2O, whereas the content of Twin Oscar’s concept is tied to XYZ. Chalmers seems ready to accept the externalist conclusion. He argues that Oscar and Twin Oscar have corresponding beliefs with the same truth-values but different contents. When they say, “This is water”, both are right, although they are talking about different things: Oscar is talking about water (H2O), his twin is talking about twater (XYZ) (Chalmers, 2006, 11). And yet despite this, they share the same epistemic situation.

What prevents us from saying the same thing about Chalmers and his zombie twin? Chalmers and Zombie Chalmers both have concepts that they deploy in similar circumstances in the presence of certain perceptual states, that are conceptually isolated, and so on. An externalist (of the sort that Chalmers seems to be throughout his paper) could very well say that the contents of Chalmers’ phenomenal concepts differ from the contents of his zombie twin’s phenomenal concepts. The content of one of Chalmers’ phenomenal concepts will turn out to involve a phenomenal state, whereas the content of his twin’s corresponding phenomenal concept can’t possibly involve such a state.[5] According to Chalmers it seems plausible that the content of a zombie’s phenomenal concepts would be schmenomenal states. (These would be states that have the same physical, functional, and intentional properties as Chalmers’ states, but that aren’t phenomenally conscious; see 2006, 19.) The physicalist would then argue that Chalmers’ and Zombie Chalmers’ corresponding beliefs have the same truth-values and are justified in similar ways, but they are quite importantly about different things. So Chalmers and Zombie Chalmers can share the same epistemic situation after all, just as do Oscar and his twin.

Chalmers argues that defending this kind of reply, “requires either deflating the phenomenal knowledge of conscious beings, or […] inflating the corresponding knowledge of zombies” (2006, 20). He goes on to argue that either strategy has counterintuitive consequences. No one thinks that Zombie Mary learns just as much as Mary (an implication of the inflationary move). No one thinks that Mary learns just as little as Zombie Mary does (an implication of the deflationary move). When we think of zombies, we aren’t conceiving of creatures possessing something epistemically just as good as consciousness. We are conceiving of deprived creatures with impoverished knowledge of themselves.

But Chalmers is surely confused here. Arguing that zombies’ phenomenal concepts have different contents enables us to say the following about Mary and her zombie twin: they both gain the same amount of knowledge, but (and this is crucial) it is the same amount of knowledge about different things. Mary’s knowledge is knowledge of phenomenal states, Zombie Mary’s knowledge is knowledge of schmenomenal states, just like Oscar’s knowledge is of water (H2O) and his twin’s is knowledge of twater (XYZ). Physicalists needn’t deflate the knowledge gained by Mary or inflate the knowledge gained by Zombie Mary in order for the phenomenal concept strategy to work. All we need to point out is that the objects of their knowledge are very different.

Physicalists can now deal with a variety of third-person claims quite effectively. Consider, for instance, the discussion that Chalmers imagines between a zombie eliminativist and a zombie realist. The eliminativist argues that there is no such thing as phenomenal consciousness and the realist maintains that there is such a thing. Here is what Chalmers says about them:

When such a debate is held in the actual world, the […] materialist and the property dualist agree that the zombie realist is right, and the zombie eliminativist is wrong. But it is plausible that in a zombie scenario, the zombie realist would be wrong, and the zombie eliminativist would be right. (2006, 12.)

But in the zombie scenario, it is just as plausible that the zombies would simply not be talking about phenomenal consciousness. Their debate is about the existence of schmenomenal consciousness. And again, both the realist and his zombie twin may very well be right; their beliefs may very well both be true.

We can say the same type of thing when it comes to the explanatory gap, or the conceivability of zombies. Zombies are thinking about schmenomenal consciousness using their phenomenal concepts, which are conceptually isolated from their other concepts. They will conclude from their reflections that there is a gap in explanation between schmenomenal consciousness and their physical world. They will also conclude that it is conceivable for someone to be physically, functionally, and intentionally identical to them and yet lack this (where the concept this that they deploy picks out a schmenomenal state). And so forth.

This difference-in-content move now allows us to deal with a variety of first-person claims as well. Zombie Mary, after she leaves her room, may well come to believe something that she would express by saying, “This is an experience of blue.” What will make this belief true isn’t her actually having a phenomenal experience of blue, but rather her having a schmenomenal experience – whatever that turns out to be. And so both her beliefs and Mary’s beliefs could plausibly have the same truth-values. Similarly when Chalmers says, “I am phenomenally conscious”, and his zombie twin utters the same string of words, both are in fact saying something different. To assume that they are saying the same thing (that they are both talking about phenomenal consciousness) is to assume that the contents of their states and concepts will be the same. But if there is no reason to assume this about Oscar and Twin Oscar, then there is no reason to assume this about Chalmers and his zombie twin. Zombie Chalmers is really saying that he is schmenomenally conscious, and we have every reason to think that he is right in thinking that, just as Chalmers is right is thinking he (Chalmers) is phenomenally conscious.

Chalmers, to block this line of reply, may now resort to our intuitions about zombies. We have claimed that they will turn out to have something epistemically just as good as phenomenal consciousness, namely schmenomenal consciousness. But doesn’t that feel wrong? When we are conceiving of zombies, aren’t we conceiving of beings with nothing at all that is epistemically like consciousness?

Well, on our view zombies are still zombies in that they are not phenomenally conscious. Their perceptual states don’t have phenomenal feels. In this respect it is all dark inside. Yet they have something playing a certain role in their psychology – a role analogous to the role that phenomenal consciousness plays in ours. They have something epistemically just as good as consciousness, but they don’t have anything that is phenomenally as good. And it seems that this is what matters here. The schmenomenal states they undergo do not feel like anything. Even though their schmenomenal beliefs are true when our corresponding phenomenal beliefs are, their beliefs are, sadly enough, not about the same good stuff as our corresponding beliefs - they are not about the feel of experiences. Zombies are still, it seems, in quite a dreadful situation. So our intuitions about zombies are preserved.


5.         Of Zombies and Zombie Zombies.

We have shown that there are good reasons to resist Chalmers’ claim that zombies fail to share our epistemic situation. If he can’t make this case, then he can’t argue successfully for Premise (3b). And so it isn’t true that if zombies conceivably possess phenomenal concepts, then phenomenal concepts can’t do the work that physicalists want them to do. Or at least, we have been given no reason to believe that this is so. There is, however, a further line of reply open to Chalmers, which we consider in the present section.


5.1       On Epistemic Situations.

We think that Chalmers will object that in conceiving of an “epistemic situation” in such a way that both Chalmers and Zombie Chalmers share the same epistemic situation, the facts crucial to our actual epistemic situation have been omitted. For when I make the judgment that I might express by saying, “This is a blue-cup experience”, I don’t just deploy a conceptually isolated concept in the presence of an intentional state representing the presence of a blue cup. In addition, I deploy such a concept on the basis of my awareness of this type of mental state. And by hypothesis, Zombie Chalmers doesn’t have awareness of any such state. While Chalmers and Zombie Chalmers have much in common - in particular, they make similar judgments in similar circumstances (all of which can be true) and the epistemic liaisons of those judgments (when characterized in third-person terms) are all precisely parallel to one another - there are also crucial differences. For Chalmers’ judgments are grounded in the presence of mental states like these, and those, and this, and that (where the indexicals here express phenomenal concepts), whereas Zombie Chalmers’ judgments are not. This seems like it might be an important - indeed, vital - part of Chalmers’ epistemic situation. In which case the crucial premise in the argument outlined in Section 4 is true: zombies don’t share our epistemic situation.

            Another way of expressing the point just made would be this: Chalmers may deny that the distinction between a property and its mode of presentation finds any application in connection with phenomenal consciousness. Since H2O and XYZ are presented to Oscar and Twin Oscar in the same way, we can say of them that (1) they possess concepts that play similar roles in their mental lives, and (2) they apply those concepts on the basis of the same mode of presentation. Only when these two conditions are met can we say that the twins share the same epistemic situation. Phenomenal properties, in contrast, provide their own modes of presentation: their modes of presentation are essential to them (Kripke, 1972). It follows that a phenomenal property and another distinct (schmenomenal) property cannot be presented to Chalmers and his zombie twin in the same way. So the pair of them possess, at most, (1): concepts that play similar roles in their mental lives. Since they can’t possibly apply those concepts on the basis of the same modes of presentation, they cannot share the same epistemic situation, just as Chalmers maintains. Seen in this light, Chalmers ought to concede that it was a tactical error (or at best misleading) for him to have introduced Oscar and Twin Oscar into the discussion.

Recall, however, the distinction drawn in Section 2.3 between first-person and third-person characterizations of phenomenal concepts – a distinction similar to one Chalmers himself makes between phenomenal and schmenomenal concepts. We claimed there (again roughly as Chalmers himself does) that we could think of phenomenal concepts as applied either in response to phenomenal states (first-person characterization) or in response to perceptual states with certain sorts of intentional content (for example). According to the second horn of Chalmers’ argument that we have been considering since the outset of Section 4, moreover, phenomenal concepts are to be characterized in third-person terms. So both Chalmers and Zombie Chalmers should be said to employ concepts whose applications are prompted by the presence of certain distinctive sorts of intentional / functional state, where those concepts are conceptually isolated from others. In which case, to introduce the feel of the state into our description of the mode of presentation of Chalmers’ concepts is to switch illegitimately to a first-person characterization of those concepts. And if we do restrict ourselves to a third-personal account of the concepts involved, in contrast, then the comparison with Oscar and Twin Oscar is entirely appropriate: in both cases we have pairs of people whose concepts have similar modes of presentation and play the same conceptual roles, but where those concepts happen to pick out different things.

            We have alleged that the response that we made on Chalmers’ behalf would re-introduce (illegitimately) first-personal phenomenal concepts into the defense of Premise (3). Chalmers might reply, however, that this allegation is unfounded. For it isn’t the characterization of phenomenal concepts that is in question, here. What is at issue isn’t what we mean by “phenomenal concept”. Rather, what is in question is the presence, or absence, of the states picked out by such concepts, when those concepts are used by their possessors. It is the presence of this state (the state, not the concept of the state here deployed) that is partly distinctive of Chalmers’ epistemic situation, and which marks its difference from Zombie Chalmers’ epistemic situation.

            But now a problem of a different sort emerges. If Chalmers’ epistemic situation is partly characterized in terms of the presence of this state (a phenomenal state), which we can imagine Zombie Chalmers to lack, then this amounts to saying that it is an important part of Chalmers’ epistemic situation that he has phenomenally conscious mental states, whereas Zombie Chalmers doesn’t. And doesn’t that now beg the question? For this is something that is supposed to be granted on all hands. Defenders of the phenomenal concept strategy, too, allow that we can conceive of someone who is physically, functionally, and intentionally identical to Chalmers (that is, Zombie Chalmers), but who lacks any of the phenomenally conscious mental states that Chalmers enjoys. And we claim to be capable of explaining how such a thing can be conceivable in a way that doesn’t presuppose the existence of anything beyond the physical, the functional, and/or the intentional.

Asserting that this strategy cannot work because phenomenal states themselves are part of what is distinctive of Chalmers’ epistemic situation, and pointing out that the strategy can’t explain them, is to insist that the phenomenal concept strategy should explain phenomenal consciousness. But that was never at issue. The phenomenal concept strategy is a strategy for explaining the conceivability of zombies, the explanatory gap, and so forth, not for explaining phenomenal consciousness per se. To put the point somewhat differently, the phrase “our epistemic situation” is supposed to be a handy label for the various phenomena that the phenomenal concept strategy is intended to explain (the conceivability of zombies etc.). But since that strategy was never intended as a reductive explanation of phenomenal consciousness as such, “our epistemic situation” should not be understood in such a way as to encompass phenomenal feelings.[6]

            The true dialectical situation is as follows, we believe. Insofar as they argue legitimately, Chalmers and other anti-physicalists are asserting that the best explanation of the conceivability of zombies, the conceivability of experiential inversions, the explanatory gap, and so on is that our experiences possess distinctive properties (call them “qualia”) that cannot be reductively explained in physical, functional, or intentional terms. Chalmers might concede that we do possess phenomenal concepts, characterized in something like the way that the proponent of the phenomenal concept strategy characterizes them (conceptual isolation and so forth). But he denies that an appeal to these concepts alone can explain what needs to be explained (the possibility of zombies, the explanatory gap, and so forth). His opponent, in contrast, asserts that we don’t need to appeal to any special properties of phenomenally conscious experience to do the work: the entire explanatory burden can be taken up by appeal to the phenomenal concepts in terms of which we think about those experiences.


5.2       Zombie-Zombie Chalmers.

In order to move this debate forwards, we need to introduce a further character into the story: Zombie-Zombie Chalmers. Recall that Zombie Chalmers has been allowed to possess phenomenal concepts, characterized in a third-person way. For example, he has concepts that are applied purely recognitionally on the basis of his perceptual and imagistic states, and which are conceptually isolated from all of his other concepts (whether physical, functional, or intentional). Possessing such concepts, Zombie Chalmers will be able to conceive of a zombie version of himself (Zombie-Zombie Chalmers). If on a given occasion he uses the word “this” to express one of his phenomenal concepts, then he will be able to entertain thoughts that he might articulate by saying, “There might exist someone who is physically, functionally, and intentionally identical with myself, but who nevertheless lacks anything resembling this type of state.” Since his phenomenal concept is conceptually isolated, there will be no hidden contradiction in this thought that he would be capable of detecting a priori.

            Likewise if Zombie Chalmers uses the word “this” to express a phenomenal concept that applies to one of his percepts of color. (For these purposes, Zombie Chalmers’ perceptions of color need to be characterized purely functionally and intentionally, of course. They are perceptual states with a fine-grained intentional content representing properties of surfaces that impact the latter’s reflection of light, perhaps.) Then he, too, will fall subject to the Mary thought-experiment. He will be inclined to think, “Mary brought up in her black and white room couldn’t know what it is like to undergo this type of perceptual state, no matter how much she knows about the physical, functional, and intentional properties of color vision.” And he will be inclined to think this precisely because the concept that he expresses by “this” is a conceptually isolated one.

            By the same token, Zombie Chalmers will think that there is an explanatory gap between all physical, functional, and intentional facts, on the one hand, and his own mental states (characterized using phenomenal concepts), on the other. Because those concepts are conceptually isolated ones, he will be able to think, “No matter how much you tell me about the physical, functional, and intentional facts involved in perception, it will still be possible that all of what you tell me should be true, while states of this sort are absent or inverted.” So he, too, will be inclined to think that there is something mysterious about his perceptual (and imagistic, and emotional) states, which puts them outside the reach of physicalist explanation.

            It is plain that it is Zombie Chalmers’ possession of phenomenal concepts that explains why he should find the existence of Zombie-Zombie Chalmers conceivable. And likewise it is his possession of such concepts that explains the conceivability to him of perceptual inversions, that explains why he thinks Mary would learn something new, and that explains why he would think that there is an explanatory gap between the character of his own mental states and all physical, functional, and intentional facts. Plainly, since Zombie Chalmers is being conceived to lack any phenomenally conscious states, it cannot be the presence of such states in him that explains the conceivability of Zombie-Zombie Chalmers, and the rest.

            Zombie Chalmers, when presented with the phenomenal concept strategy for explaining the conceivability of Zombie-Zombie Chalmers and so forth, might even be inclined to insist that this strategy can’t explain what is distinctive of his own epistemic situation. He will allow that Zombie-Zombie Chalmers would make parallel judgments to himself, of course, and would act in exactly similar ways, and on similar grounds. But he will be inclined to insist that something crucial is left out by the phenomenal concept strategy. What is left out is that he (Zombie Chalmers) bases his judgments on the presence of states like this, and this, and that, whereas, by hypothesis, Zombie-Zombie Chalmers is being conceived to lack such states.

            Now we can bring it all back home. For in connection with everything that Chalmers thinks, and for every possibility that Chalmers can conceive, and for every argument that Chalmers can offer, Zombie Chalmers can offer a parallel one. Of course, from our perspective, conceiving all of this along with Chalmers, we are conceiving that they are thinking about different things: Chalmers is thinking about phenomenal states, whereas Zombie Chalmers is thinking about schmenomenal states. But this difference plays no role in explaining what each is capable of thinking. On the contrary, it is their mutual possession of phenomenal concepts (characterized in the third-person way) that does that. Since it can’t be the fact that Zombie Chalmers possesses phenomenal states that explains his capacity to conceive of Zombie-Zombie Chalmers and the rest (for by hypothesis, he possesses no such states), we shouldn’t allow that Chalmers’ possession of phenomenal states plays any role in explaining how he can conceive of Zombie Chalmers, either.

            This “zombie-zombie argument”, as one might call it, seems to us to decisively shift the burden of proof in this area onto the anti-physicalist.[7] Since an appeal to phenomenal concepts (characterized in a third-person way as conceptually isolated and so on) can explain everything that Zombie Chalmers is inclined to think and say (and in particular, since it can explain the conceivability to Zombie Chalmers of Zombie-Zombie Chalmers), and since everything that Zombie Chalmers is inclined to think and say, Chalmers is also inclined to think and say and vice versa (controlling for what will seem from Chalmers’ perspective to be differences of content), the most reasonable conclusion to draw is that it is Chalmers’ possession of phenomenal concepts, too, that explains the conceivability of zombies, the explanatory gap, and so forth.


5.3       Replies to Objections.

Chalmers will surely reply as follows: the zombie-zombie argument presupposes that when Zombie Chalmers claims, “I am phenomenally conscious”, he says something true, and yet (Chalmers will insist) it much more plausible that this claim is false. Surely, in the zombie world, there is no phenomenal consciousness, and so Zombie Chalmers’ claim, in that world, that he is phenomenally conscious must be false.[8]

This can’t possibly be a good reply to the argument of the present paper, however. Certainly it can’t be if it assumes that Zombie Chalmers’ concept phenomenal consciousness refers to phenomenal consciousness. For as we have shown in Section 4, Zombie’s Chalmers’ phenomenal concepts plausibly refer to his perceptual states (characterized purely functionally and intentionally). Actually, it isn’t in the least plausible that a zombie’s phenomenal concepts (characterized third-personally) should be referring to the zombie’s (non-existent) phenomenal states (which would make what he says wrong). This would be like saying that Twin Oscar’s twater concept actually refers to H2O, in which case he is wrong every time he says, “This water tastes good.” But clearly that is just absurd. No theory of concepts does (or should) yield such a counterintuitive claim. Zombie Chalmers is correct when he says that he is conscious, because he isn’t saying that he has phenomenal states as we understand them. He is correct because he means that he has schmenomenal states, and he has them.

As we have argued, all of Zombie Chalmers’ beliefs turn out to have the same truth-values as Chalmers’ corresponding ones. As a realist about phenomenal consciousness, Chalmers here on Earth will say, “There are phenomenal states”, and he will be right. His zombie twin will utter the same words but will mean that there are schmenomenal (i.e. physical, functional, and/or intentional) states, and he, too, will be right. Likewise if someone here on Earth denies that there are phenomenal states and turns out to be wrong, his zombie twin will likewise turn out to be wrong in the zombie world, since he will be denying, there, that there are schmenomenal (e.g. functional and/or intentional) states.

In fact, it seems that such pairs of corresponding beliefs will turn out not to have the same truth value only if dualism is true. If dualism is true and Chalmers says, “Phenomenal states aren’t physical”, then he will be right; but his zombie twin uttering the same words will mean that schmenomenal (e.g. functional and/or intentional) states aren’t physical, and he will be wrong; for by hypothesis his schmenomenal states are physical. Since Chalmers’ overall goal is to argue for dualism and against physicalism, he begs the question when he assumes that his zombie twin’s corresponding beliefs don’t have the same truth-values as his own.[9]

Chalmers is very likely to adopt a rather different tactic, however: he will argue that the zombie’s phenomenal statements are false, not because they refer to phenomenal states that he doesn’t have, but because they fail to refer altogether. The right analogy isn’t between Earth and Twin Earth but rather between Earth and Dry Earth. Dry Oscar’s claims about water (e.g., that it is refreshing) are false because he is subject to some sort of grand illusion: there is no such thing as water in his environment. If this is the right analogy then we would have to grant Chalmers that the epistemic situation of zombies isn’t, as a matter of fact, the same as ours. But we have two responses to make to this argument. One is to deny that this is the right analogy. The other is to say that even if it is, we can still run a version of the zombie-zombie argument. Let us elaborate.

How could Zombie Chalmers’ phenomenal concepts fail to refer? For these are concepts that, in their third-person characterization, are applied in a recognitional way in the presence of content-bearing mental states of a distinctive sort (perceptual and imagistic states). How could these concepts fail to refer to the very states that prompt their application? One option would be to claim that there is something else built into their content. For example, as Chalmers once suggested (1996, p. 204), they might include the commitment that they should not refer to any physical or functional property. But this would be inconsistent with the claim that phenomenal concepts are conceptually isolated. Concepts that are so isolated must lack any commitments of this sort.

Another option would be to claim that the presence of phenomenal consciousness is a constitutive aspect of the content of a phenomenal concept. In which case Zombie Chalmers’ “thoughts” involving phenomenal concepts will be either false or truth-valueless because employing a contentless concept. (Chalmers develops such a position at length in his 2003.) But this option is entirely question-begging in the present context. Chalmers (2003) develops his account of the content of phenomenal concepts within the framework of his own anti-physicalist position, assuming that there are irreducible qualia and such like. But that position is supposed to be established on the basis of arguments from the conceivability of zombies and so forth, and hence cannot be taken for granted in the evaluation of those arguments. Moreover the horn of Chalmers’ dilemma that we have been addressing for most of this paper (Sections 4 and onwards) presupposes a third-person characterization of phenomenal concepts. And given such a characterization, there is no reason whatever to think that the thoughts of Zombie Chalmers, employing such a concept, should be empty.

Even if we allow that Zombie Chalmers’ phenomenal concepts might fail to refer, however, we can still run a version of the zombie-zombie argument. For we surely need to explain the inferences that the zombie makes, and the reasons why he thinks (granted, mistakenly) that he can conceive of a zombie version of himself. The fact that the zombie’s beliefs are false (because containing an empty term) doesn’t mean we are under no obligation to explain his reasoning and his behavior. We can explain why it is that little John wants to be nice by appealing, in part, to his (false) belief that Santa will only give him presents if he is nice. Although his concept santa fails to refer, it still plays a role in his reasoning and behavior. What, then, explains the zombie’s reasoning and behavior? Clearly, the presence of phenomenal feels can’t explain that reasoning. Just as in the case in which we assume that the zombie’s phenomenal concepts refer to physical states, so in the case in which his concepts are empty, his reasoning can’t be explained by an appeal to phenomenal states. The only thing that can truly explain the relevant bits of reasoning is the fact that Zombie Chalmers has a concept (in the original case, referring to a physical property, now being allowed to be empty) which is conceptually isolated from all physical, functional, and intentional concepts.

What emerges, then, is that the zombie-zombie argument can still work even if we allow that Chalmers and Zombie Chalmers don’t share the same epistemic situation (because all of the latter’s beliefs involving phenomenal concepts are false by virtue of failing to refer). Since it is the conceptual isolation of Zombie Chalmers’ (empty) phenomenal concepts that explains the conceivability to him of Zombie-Zombie Chalmers and so forth, parity of reasoning suggests that in Chalmers’ case, too, it is the conceptual isolation of his phenomenal concepts and not the presence of phenomenal consciousness itself which explains the various problematic thought experiments. We want to emphasize, however, that we are actually very unwilling to allow that the corresponding beliefs of Chalmers and Zombie Chalmers should differ in truth value. We think that it is much more plausible that Zombie Chalmers’ phenomenal concepts should refer successfully to his schmenomenal states.


6.         Conclusion.

It is worth noting in closing that there is both a weaker and a stronger conclusion that might be drawn from our defense of the phenomenal concept strategy. The weaker conclusion is that the arguments from zombies, from the explanatory gap, and so forth, to the mysterious and/or non-physical nature of phenomenal consciousness is decisively blocked. For everyone can agree that our phenomenal concepts fit some or other variant of the third-person descriptions canvassed in Section 2. Everyone can agree that it is possible for us to form concepts of experience that are purely recognitional, or that “quote” percepts or images, or whatever. What they will disagree about is whether our phenomenal concepts are exhausted by such factors. Anti-physicalists will insist that something has been left out, namely that those concepts pick out non-relational, non-intentional properties of experience like these. So if the zombie and explanatory gap thought experiments can be fully explained in terms of our possession of phenomenal concepts, then there is no longer any argument from those thought experiments to the existence of qualia, the mysteriousness of consciousness, property dualism, and so forth. Such claims might still be correct, but the arguments for them have collapsed.

The stronger conclusion that might be drawn from our discussion is this. Once we see that all the puzzling factors can be explained in terms of our deployment of phenomenal concepts; and perhaps especially once we see in those terms that even the conceived-of zombies will be able to conceive of zombie versions of themselves, then the most plausible conclusion to draw overall is that there is nothing more to our phenomenal concepts than is described in the third-person description. (Remember, however, that the third-person description is not supposed to be any sort of analysis or partial definition of our phenomenal concepts.) So the most reasonable conclusion is that a phenomenal state just is a perceptual state with a certain distinctive sort of intentional content (non-conceptual, perhaps) that occurs in such a way as to ground the application of phenomenal concepts. Hence we can conclude that phenomenal consciousness can be fully reductively explained (somehow – of course there are a number of mutually inconsistent competing accounts, here)[10] in physical, functional, and/or intentional terms.

We have provided a number of reasons for thinking that Chalmers’ argument against the phenomenal concept strategy is unsuccessful. On the contrary, that strategy still stands as providing a powerful response to a wide range of anti-physicalist thought-experiments, enabling us to draw the anti-physicalist sting from the latter.







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[1] The ordering of the authors’ names is alphabetical. We would like to thank David Chalmers, Rocco Gennaro, Georges Rey, and an anonymous referee for this journal for their helpful comments on earlier drafts of this paper.

[2] These two ways correspond roughly to the distinction that Chalmers (2006) draws between phenomenal concepts and what he calls quasi-phenomenal or (mostly) schmenomenal concepts. (The latter are the sorts of concepts that a zombie might employ in the presence of its own perceptual states.)

[3] For present purposes we propose to concede the truth of Premises (2a) and (2b). We would actually want to argue against (2b) that there is no new explanatory gap formed; but this isn’t really relevant to our main goal: defending the phenomenal concept strategy.

[4] For those unfamiliar with the famous Twin Earth thought-experiment (Putnam, 1975), Twin Oscar is a microphysical duplicate of Earthling Oscar who lives on Twin Earth, a planet just like Earth except that the identical-looking stuff in the lakes, rivers, and so on, isn’t H2O but XYZ. The latter is a substance that can only be distinguished from H2O by means of sophisticated laboratory tests. (Of course Twin Oscar cannot be a complete duplicate of Oscar, since his body contains XYZ whereas Oscar’s contains H2O. But by hypothesis this is supposed to make not the smallest difference to their cellular, neurological, or cognitive processes.)

[5] This isn’t to say that phenomenal concepts are characterized in terms of those phenomenal states, as they are on a first-person interpretation. Again, throughout this section of the paper phenomenal concepts are characterized as conceptually isolated concepts deployed in the right sorts of circumstances. But (and this is our point) there is no reason to think that our phenomenal concepts have the same content as our zombie twins’ corresponding concepts.

[6] It is important to note, too, that a physicalist who deploys the phenomenal concept strategy is not here arguing for physicalism. Stoljar (2005) goes wrong on just this point. For he claims that the physicalist’s reply to conceivability arguments comes in two stages, the first of which is that the conceptual isolation of phenomenal concepts/truths entails that the conditional, (1) If P, then P*, is a posteriori necessary (where P is a summary of all physical truths, and P* is a summary of all phenomenal truths). But physicalists who adopt the phenomenal concept strategy aren’t attempting to show the truth of this entailment. Making the case that (1) is a necessary truth would, it is true, be making the case for physicalism. But the phenomenal concept strategy is only intended to be defensive. The physicalist is only arguing that the conceivability arguments don’t show that physicalism is false, despite what their proponents claim: there is another explanation for why we can conceive of these things, an explanation that appeals to phenomenal concepts. So Stoljar misses the fact that the phenomenal concept strategy is essentially a defensive strategy. It is a strategy that physicalists employ to show that the key anti-physicalist arguments fail. It isn’t meant to make a positive case for the truth of physicalism, or for the necessary a posteriori truth of (1).

[7] Remember, though, that the argument isn’t supposed to be an argument in support of physicalism. It is rather a defensive argument intended to undermine a set of arguments against physicalism (the arguments from zombies, explanatory gaps, and so forth).

[8] Chalmers (2006) makes a very similar reply to an argument by Balog (1999) that parallels ours (but deployed in the service of a different conclusion: Balog is interested in denying that there is a link between conceivability and possibility).

[9] Our own argument, in contrast, isn’t question-begging. For as we pointed out in Section 5.1, the phenomenal concept strategy is only intended as a defense of physicalism against anti-physicalist arguments, not as an independent argument in support of physicalism, nor as a purported reductive explanation of phenomenal consciousness itself.

[10] One of the issues outstanding will concern the selection of the best third-person description of the nature and role of phenomenal concepts. About this matter we have said nothing.