The Knowledge Argument and Two Interpretations of 'Knowing what it's like'* Daniel Stoljar, ANU Introduction The knowledge argument against materialism may be presented in various ways, but in its simplest form, it has two premises. The first premise-K1, as I will call it-is that it is possible for a person to know all the physical facts and not know what it's like to see something red. The second premise-K2, as I will call it-is that if this is possible then materialism is false. Since K1 and K2 together entail that materialism is false, the assessment of the argument turns on the truth or otherwise of the premises. Why believe the premises? The rationale for K1 derives from various imagined cases that seem to illustrate its truth. The best and most famous case is that of Mary, due to Frank Jackson: Mary is confined to a black-and-white room, is educated through black and white books and through lectures relayed on black-and white television. In this way she learns everything there is to know about the physical nature of the world. She knows all the physical facts about us and our environment. . . It seems, however, that Mary does not know all there is to know. For when she is let out of the black-and-white room or given a color television, she will learn what it's like to see something red, say. This is rightly described as learning-she will not say ''ho, hum.'' (Jackson 1986, 291; see also Jackson 1983) Off-hand, there is no contradiction in this story; it apparently describes a possibility, and, moreover, a possibility in which someone knows all the physical facts and yet does not know what it's like to see something red. Hence, on the face of it, K1 is true. The rationale for K2 derives from the idea that materialism-at least in its simplest form1-is the thesis that every fact is a physical fact. Suppose every fact is a physical fact; then if you know every physical fact, you know every fact. Contrariwise, if you know every * I am indebted in what follows to work by Jonathan Schaffer and Jason Stanley, as well as conversations (in some cases from years ago!) with them. More recently, conversations with Ryan Cox, Erick Llamas and Don Nordblom have been extremely helpful. 1 Materialism (aka physicalism) may come in forms much more complex than this, but we can afford to set them aside here. For some discussion of these forms, see Stoljar 2010, 2015. 2 physical fact but do not know every fact, then some fact is not physical. (Compare: if every piece of fruit in the box is an orange, then if you eat every orange in the box you have eaten every piece of fruit. Contrariwise, if you eat every orange but not every piece of fruit, then some piece of fruit is not an orange.) But Mary is apparently someone who knows every physical fact but not know every fact; if so, some facts are not physical and materialism is false. Hence, on the face of it, K2 is true. The knowledge argument is one of those beautiful arguments in philosophy that is simple on the surface but is extremely rich and intricate underneath. In consequence, it is impossible within the confines of a single paper to review and properly discuss the solutions that have been offered to it.2 In what follows, therefore, I am going to focus on just one line of response, a response that starts from various observations about the semantics of the expression 'know what it's like'-I will call it the knowing what it's like response. I should say straightaway that the knowing what it's like response is not my own. In fact, as we will see, I am convinced it is unsuccessful, and that the real problems with the argument lie elsewhere. Nevertheless, the response is extremely interesting and suggestive, and has considerable prima facie plausibility. In addition, so far as I know, it has no defenders in the contemporary literature, though suggestions similar to it certainly do exist, which is a point I will expand on at the end of the discussion. In short, the knowing what it's like response has not been given a fair shake. My aim is to give it that shake. Interrogative v. Free Relative Readings of 'Knowing what it's like' Both premises of the knowledge argument concern the idea of knowing what it's like to see something red, or, more accurately, not knowing what it's like to see something red. But what is it in general it to know what it's like to do or be something? It is this question that lies at the heart of the knowing what it's like response. In Consciousness and Experience, W.G Lycan (1996, pp. 92-3) discusses this issue, and says the following: Indirect-question clauses are closely related to 'that' clauses, both in meaning and grammatically. In particular, instances of 'S knows wh-...' are related to 'S knows that...': 'S knows where X Vs' is true in virtue of S's knowing that X Vs at p, where 'p' 2 For extensive discussion of the argument, as well as information about its background, see Ludlow, Nagasawa and Stoljar 2004. 3 suitably names some place; 'S knows when X Vs' is true in virtue of S's knowing that X Vs at t where 't' suitably names some time; 'S knows who Vs' is true in virtue of Ss knowing that N Vs, where 'N' suitably names some person. ('Suitably' in these formulations hides a multitude of technicalities, but they do not affect the present issue.) He goes on: On this model, 'S knows what it's like to see blue' means roughly 'S knows that it is like Q to see blue, where 'Q' suitably names some inner phenomenal property or condition. Lycan is making three different points here. First, that knowing what it's like is similar to knowing where, knowing who, knowing how, etc.; that is, it is an instance of knowing-wh. Second, that knowledge-wh in general is a kind of propositional knowledge; hence when you know (e.g.) where something is, you know that such and such is the case. Third, that knowing what it's like is a distinctive kind of knowledge-wh, as distinct from other cases of knowledge-wh as knowing-where is from knowing who. In particular, Lycan says, just as you know where something is just in case you know a fact about a place, so you know what it's like to see red just in case you know a fact about (what Lycan calls) some inner phenomenal property or condition. Are these points correct? As regards his first point, Lycan is clearly right. Knowing what it's like to see red is as much a case of knowledge-wh as, for example, knowing where your car keys are, or knowing who Hillary Clinton is. As regards his third point, Lycan is clearly wrong-or so I think and will assume in what follows, though admittedly the issues here are controversial. For one thing, as Hellie (2004, 359; see also Hellie 2007) notes, it is not clear what his suggestion is; in particular, it is not clear what 'like' means in his analysis. For another thing, as I have argued elsewhere (see Stoljar, forthcoming), 'knowing what it's like to F' is plausibly analyzed in contexts like these as being roughly equivalent to 'knowing how it feels to F,' and this is a sort of knowledge-how, though admittedly not the sort that has attracted the attention of philosophers.3 3 When philosophers talk about knowing-how, they typically restrict attention to cases attributed by sentences in which 'how' is immediately followed by an infinitive verb rather than a finite clause, as in 'Bill knows how to ride a bike'. But many cases of knowledge-how are not like this, e.g., 'Caryl knows how Stalin was to his generals' or 'David knows how John got home'. 4 What about the second point, that knowing-wh is always a case of knowledge-that? Here I think Lycan is right in one way and not right in another. In general, it is plausible that sentences that attribute knowledge-wh are ambiguous. On one reading-which, following Jonathan Schaffer (2010), I will call the interrogative reading-they certainly do attribute propositional knowledge. But on different reading-which, again following Schaffer, I will call the free relative reading-they do not attribute propositional knowledge, or at any rate, there is nothing in the semantics which entails that they do. It is for this reason that Lycan is right in one way but not in another. To illustrate the distinction, consider a standard example of a sentence that attributes knowledge-wh, say, 'Alice knows where the conference is'. On its interrogative reading, this sentence is true just in case Alice knows some fact that answers the embedded question 'where is the conference?'4 Suppose for example that the conference is in Rio and Alice knows this. Then she knows a fact-namely, that the conference is in Rio-and it is in virtue of knowing this that she knows where the conference is. On its free relative reading, however, the sentence is true just in case Alice knows some particular place, namely, the place denoted by the noun phrase (or the free relative- hence the name of the reading) 'where the conference is'. Suppose the conference is in Rio and Alice knows Rio. Then she knows a place-namely, the city of Rio-and it is in virtue of knowing this that she knows where the conference is. The distinction between these interpretations of 'Alice knows where the conference is' is owing to two underlying facts: (a) that in this sentence the complement clause-namely, 'where the conference is'-can be interpreted either as an interrogative or as a noun phrase; and (b) that the verb 'know' permits both sorts of interpretation. But not all verbs are like this. Consider 'Alice wondered where the conference is'. The verb 'wonder' forces the interrogative reading in its complement clause: what Alice wondered is what fact answers the question 'where is the conference?'5 Or consider 'Alice loves where the conference is'. The 4 This is a simplified presentation of the interrogative reading of the sentence, in at least the following ways. First, as we will see later, there is a distinction with the interrogative reading between so-called mention-some and mention-all readings. Second, it may be that on either the mention-some and mention-all readings, the quantifiers contained in the sentence need some sort of contextual restriction. Third, it may be that Alice needs to know this relevant fact not as such but in a certain way, e.g. under the right mode of presentation, or as involving the right concept or mental representation. I will mention some of these complications as they arise in what follows but for the most part I will leave them in the background. For further discussion, see Stanley and Williamson 2001, Stanley 2011, Cath 2009, and Tye, 2010. 5 This point is emphasized in Schaffer 2010. 5 verb 'love' naturally suggests-but does not quite force6-the free relative reading. On that reading, what Alice loves is not a fact but a city, namely, the city where the conference is. If the interrogative/free relative distinction is explained in these ways, we should expect it to apply to all, or at least most,7 cases of knowledge-wh, and to knowing what it's like in particular-and so it does. Consider the positive variant of the sentence that occurs in in the presentation of the knowledge argument offered above: 'Mary knows what it's like to see something red'. On its interrogative reading, the sentence is true just in case Mary knows some fact that answers the question 'what is it like to see something red?' Since that question seems intuitively to ask 'what experience do you have when you see something red' the sentence intuitively means that Mary knows some fact that answers this question. On its free relative reading, by contrast, the sentence is true just in case Mary knows the denotation of the noun phrase 'what it's like to see something red'. Since that expression intuitively denotes a type of experience, on this reading the sentence intuitively means that Mary knows a type of experience, i.e., the one you have when you see something red.8 The Knowing What it's like response Suppose now we agree that 'Mary knows what it's like to see something red' has both an interrogative and a free-relative reading. Then we may formulate the knowing what it's like response to the knowledge argument as having three parts: (a) if this sentence is ambiguous, its negation is likewise ambiguous, and so the knowledge argument itself has two versions; (b) neither version of the argument is persuasive; and (c) the original argument only seemed persuasive because these two versions had not been kept apart. To amplify on (a), suppose that the free-relative reading is uniformly adopted. Then K1 is that it is possible for someone to know all the physical facts, and not know in the free relative sense what it's like to see red. And K2 is that if this is possible then materialism is false. Let's call this version of the knowledge argument, 'KA-1.' Suppose now that the interrogative reading is uniformly adopted. Then K1 is that it is possible for someone to know all the physical facts, and not know in the interrogative sense 6 It does not force it, since one can love a fact: 'I love that the conference is in Rio', Alice might say. Or even, 'I love the fact that the conference is in Rio.' (What's more, one can love that fact even if one does not love Rio.) 7 An exception is cases in which the 'wh'-word is followed by an infinite clause of the sort noted in fn.3 above. 8 As Schaffer 2010 notes, the distinction is a common one in the linguistics literature. 6 what it's like to see red. And K2 is that if this is possible then materialism is false. Let's call this version of the knowledge argument, 'KA-2.' To amplify on (b), KA-1 is unpersuasive because here K2 may easily be denied. On the free relative reading, to know what it's like to see something red is to know a type of experience. Hence to fail to know what it's like is to fail to know a type of experience. But on the face of it, one could fail to know a type of experience and yet not fail to know any particular fact about that type of experience. Perhaps, for example, knowing the experience requires more than knowing some set of facts about the experience; if so, one could know that set of facts and not know the experience. Compare: perhaps knowing Rio requires more than merely knowing a set of facts about Rio; if so, one could fail to know Rio and yet still know that set of facts. The conclusion is that K2 is false on the free relative reading: from the fact that one knows all the physical facts but not what it's like to see something red in the free relative sense, it does not follow that there is any fact one does not know; hence it does not follow that materialism is false. As regards KA-2, this is unpersuasive because here K1 may easily be denied. On the interrogative reading, to know what it's like to see something red is to know some fact that answers the question 'what it's like to see something red?' But, when you focus on it, this requirement is extremely weak. All it demands is that Mary knows some fact-any fact-that answers the relevant question. But surely Mary knows some fact of this sort. She knows for example that to see something red is to detect via vision some distinctive property of the thing in question. She also knows that to see something red is to undergo a process that is rather like seeing a grey thing (something she has done in her room), or at any rate is more like seeing a grey thing than it is like many other things, e.g., playing the piano. The conclusion is that K1 is false on the interrogative reading: someone who knows all the physical facts will know some fact that answers the question 'what it's like to see something red?' Hence, on the interrogative reading, such a person will know what it's like. To amplify on (c), once we have distinguished KA-1 and KA-2, it is natural to say that K1 seemed plausible only because we had in mind the free-relative reading of 'knowing what it's like', and likewise that K2 seemed plausible only because we had in mind the interrogative reading. Once these two interpretations have been distinguished however, the original argument stands revealed as a fallacy of equivocation, and is therefore implausible. Two Cul-de-Sacs 7 How successful is this response to the knowledge argument? As I have said by own view is that it is unsuccessful. In explaining this reaction, however, it is helpful to look first at two possible criticisms that seem to me cul-de-sacs. Cul-de-sac 1 says that the response confuses semantics and metaphysics, or at any rate, semantics and psychology. On this view, the sentence 'Mary knows what it's like to see something red' has a reading on which it is true and attributes non-propositional knowledge, but the fact that makes this sentence on this reading true is a fact about propositional rather than non-propositional knowledge. More generally, this objection says, the analysis of KA-1 presented above is misguided: it focuses on sentences when what we ought to focus on are the psychological facts those sentences report. However, while there is no doubt a distinction between semantics and metaphysics, it is implausible that it may be appealed to in this way. For suppose the sentence 'Mary knows what it's like to see something red' is true. Then we may immediately infer that it is a fact that Mary knows what it's like to see something red. (The underlying rationale for this is that if 'S' is true, we may immediately infer that it is a fact that S.) But in what sense is this latter fact not a fact about non-propositional knowledge? After all, given the analysis we have been operating with, the fact that Mary knows what it's like to see something red just is the fact that Mary knows a type of experience-and that fact is a fact about non-propositional knowledge if anything is. Cul-de-sac 2 points out, in relation to a sentence such as 'Alice knows Rio,' that it is hard to see that it can be true unless Alice knows various facts about Rio.9 Likewise, one might argue, it is hard to see that Mary can know what it's like to see something red unless she knows various facts about seeing something red. But doesn't the knowing what it's like response predict that she can? However, the knowing what it's like response predicts nothing of the sort, and this criticism gets things back to front. The situation we have been imagining is not one in which someone knows what it's like to see something red and yet does not know any facts about seeing something red. Rather it is a situation in which someone knows lots of facts about seeing something red, and yet does not know what it's like to see something red. Likewise, in the case of Alice and Rio, the analogous situation is not one in which Alice knows Rio but- bizarrely-does not know any facts about Rio; it is rather one in which Alice knows lots of facts about Rio, and yet does not know Rio. 9 See Crane 2012 and Tye 2012 for further discussion of this sort of view. 8 Two Versions of Mary Even if these two criticisms are no good, there are other more telling lines of thought against the knowing what it's like response. The first of these distinguishes two versions of the Mary story. On the first version, pre-release Mary fails to know what it's like in both of the senses we have isolated. Hence she fails to know what it's like (free relative sense) and fails to know what it's like (interrogative sense). On a natural development of this view, since Mary does not know in the free relative sense, and so does not know the type of experience in question, she fails to understand the experience, fails to possess the concept required to understand it, and so on. Moreover, on this version, there is a natural explanation for why she fails to know what is like to see something red in the interrogative sense: she fails to know in that sense because she does not even understand the fact or facts that answer this question. In other words, she fails to know in the interrogative sense because she fails to know in the free relative sense. On the second version, pre-release Mary fails to know in only one of the senses we have isolated, namely, the interrogative sense. Hence she fails to know what it's like in the interrogative sense but knows that it like in the free relative sense. On a natural development of this view, since Mary knows in the free relative sense, and so knows the type of experience in question, she understand the experience, has the concepts required to understand it, and so on. Moreover, on this version, that she fails to know what it's like in the interrogative sense is not explained by her failing to understand the facts that answer the relevant question; she may understand them well enough. It is rather that she simply does not know these facts. Hence she fails to know in the interrogative sense even though she knows in the free relative sense. What does this distinction have to do with the knowing what it's like response? If we operate with the second version of the story, we may formulate a third version of the knowledge argument, a version different from the two we considered above; let's call it 'KA3.' In this version, K1 says that is possible that someone knows all the physical facts and what it's like to see something red (free relative sense) and yet does not know what it's like to see something red (interrogative sense); and K2 says that if this is possible then materialism is false. And the problem KA-3 presents for the knowing what it's like response is that, while it may be that KA-1 is unpersuasive in just the way the response says, it may nevertheless be 9 that KA-3 is persuasive. If so, we have a version of the knowledge argument that evades the response we have been considering. It might be thought that, while KA-3 evades the knowing what it's like response, it may be dismissed for independent reasons. Take a person who knows all the physical facts and understands the propositions that if true would be answers to a question like 'what is it like to see something red?' Is it really possible that such a person will not know those propositions? However, the response to this is "yes it is possible"-or at any rate so a proponent of the argument may reasonably claim. One consideration in favour of this points out that even if pre-release Mary knows a type of experience, the type you have when you typically see something red, she may still not know that she will have that experience when she comes out of the room. She may reasonably wonder, for example, if she will have a different experience or none at all. From this point of view, the problem is not that she cannot distinguish the possible situation in which will have a particular experience from the situation in which she will have a contrasting one; the problem is rather that she cannot tell, and nor does her impressive physical knowledge enable her to tell, which of these possibilities are actual. It is worth emphasis that the underlying point here-that the knowledge argument can be developed on the basis of the second version of the Mary story-is well-known in the literature on these matters. In some cases-this I think is true of Jackson's original presentation-it is assumed from the start that the second version of the story is in play (see Jackson 1986). In other cases, the two Marys appear as two phases of a single temporal development of Mary (see Nida-Rümelin 1995). In still other cases, a distinction is made between two ways of telling the story of Mary, and hence two versions of the argument (see Stoljar 2005). However the issue is developed, it is a point well established that the knowledge argument may proceed even if (as we would put it here) Mary knows what it like to see something red in the free relative sense. If so, there is no way that KA-3 can be dismissed. It might also be objected that, while KA-3 evades part of the knowing what it's like response, it does not evade the other part. Part of that response focuses on the free-relative reading of 'know what it's like'; and certainly KA-3 avoids that. But another part focuses on the idea that, on the interrogative reading, it appears that Mary does indeed know what it's like to see something red. For, as we have seen, on that reading, if you know a fact that answers the relevant question, you know what it's like, and Mary does plausibly know some fact. And, one might say, this criticism applies just as much to KA-3 as to KA-2. 10 I think this point is a good one. What it shows is that the point about the two Marys blocks only part of the knowing what it's like response. To see how to block the other part, we need to consider another criticism of the response. It is to that other criticism that I now turn. Mention-all v. Mention-some We have distinguished between the interrogative and the free relative readings of 'knowing what is like'. But we should also distinguish, within the interrogative reading, two rather different possibilities. On the first, 'Alice knows where the conference is' is true just in case she knows some fact that answers the question 'where is the conference?' On the second, 'Alice knows where the conference is' is true just in case she knows all facts that answer the relevant question. In the linguistics and philosophy of language literature, the first of these readings is often called a 'mention-some' reading, while the second is called a 'mention-all' reading.10 On the face of it there are sentences fitting both paradigms. To borrow and slightly adapt some examples discussed by Jason Stanley (see Stanley 2011, 115-22), in 'Hannah knows where to buy an Italian newspaper in New York' one is inclined to think that it is true just in case Hannah knows some answer to the embedded question. If she knew only that that you can get an Italian newspaper at that place on Second Avenue, for example, that would be sufficient for her to have the knowledge in question. By contrast in, 'John knows which Beatles albums are good ones,' one is inclined to think it is true just in case John knows every answer to the relevant question. If he knew only that Revolver is a good album, for example, that would not be sufficient to have the knowledge in question; rather he must know, of each good Beatles album, that it is a good one. How does the mention-all/mention-some distinction bear on the response we have been examining? So far, we have uncritically adopted a mention-some reading of 'knowing what is like'. For we have assumed that 'Mary knows what it's like to see something red' is true just in case she knows some fact that answers the embedded question. Moreover, this assumption played an essential role in the criticism of KA-2 described above and, by extension, of KA-3 as well. For that criticism pointed out that pre-release Mary knows some fact that answers the question 'what it's like to see something red?' and then drew the 10 For a philosophically accessible discussion of this distinction, see Stanley 2011. As Stanley makes clear, examples of the sort discussed in the text are in turn taken from the linguistics literature. 11 conclusion that Mary knows what it's like to see something red, contrary to the first premise of KA-2. Clearly that inference is reasonable only if the mention-some reading is in play. But suppose instead that the mention-all reading is in play. In that case, 'Mary knows what it's like to see something red' is true just in case she knows every fact that answers the relevant question. Now we cannot infer from the premise that Mary knows some fact to the conclusion that she knows what it's like to see something red. Indeed, once the mention-all reading is in play, if even one answer eludes her, she will fail to know what it's like. The upshot is that the knowing what it's like response is unconvincing if 'knowing what it's like' has a mention-all reading. One might respond that 'Mary does not know what it's like to see something red' does not have a mention-all reading, or at least not a legitimate one. But the problem with this is that the mention-some/mention-all issue is a hugely contested empirical matter in linguistics and philosophy of language. As such, it would be very ill advised in one's philosophy of mind to insist on the mention-some reading. Alternatively, one might point out that, if insisting on a mention-some reading is ill advised, insisting on a mention-all reading is likewise ill advised, and for the same reason. But doesn't the criticism of the knowing what it is like response we have just made precisely depend on us doing so? However, while there is certainly some truth in this objection, I think we may formulate our criticism of the knowing what it's like response without taking a stand on any tendentious empirical issue. In particular, in view of the material just introduced, we may formulate a fourth and final version of the knowledge argument-let us call it 'KA-4'. On this version, K1 is that it is possible for someone to know all the physical facts and know in the free relative sense what it's like to see something red, and yet not know some fact which answers the question 'what is it like to see something red?'; and K2 is that it if this is possible then materialism is false. The problem that this version of the argument presents for the knowing what it's like response is that nothing in that response says it is unpersuasive. The material about the free-relative reading remains sidelined in the case KA-4 just as it did for KA-3. And the material about the interrogative reading has no effect on KA-4 since this argument operates not with 'Mary does not know what it is like to see something red', but with the distinct but closely related, 'Mary does not know a fact that answers the question 'what is it like to see something red?'' As we have seen, if the mention-all reading is in play, then the second of these entails the first. But even if that reading is not in play, the second by itself causes a problem for materialism, as KA-4 illustrates. 12 Overall Assessment I am now in a position to formulate my overall assessment of the knowing what it's like response to the knowledge argument. According to this response, reflections on the semantics 'knowing what it's like' reveals two versions of the knowledge argument, neither of which is persuasive. An attractive feature of this response is that the observations it is founded on are plausible. However-and here is the problem with the response-when we think through these observations, it emerges that there are many further versions of the knowledge argument than the two the response operates with. Moreover, at least one of these versions is such that nothing in the knowing what it's like response undermines it. It is for this reason that this response is ineffective against the knowledge argument. How should one proceed from this point? One option would be to go on to explain what response is effective against the knowledge argument. In other work, I have argued that what it is wrong with the argument is the assumption that Mary knows all the physical facts (see, e.g., Stoljar 2006). Rather than trying to defend that proposal here, however, I want instead to return to the point mentioned at the outset, namely, that the knowing what it's like response has not been defended in the literature. To illustrate this claim, I will finish the paper by briefly comparing the proposal we have been considering with two related but different proposals, the first of which is due to David Lewis, the second to Michael Tye. Lewis's View The basic shape of Lewis's (1988) response to the knowledge argument is well known.11 He starts with a distinction inherited from Gilbert Ryle between propositional knowledge and knowledge how, i.e. knowledge reported by sentences of the form 'S knows how to F' (see Ryle 1949). He goes on to suggest that Mary is best described as gaining a sort of knowledge-how when she comes out of her room, the reason being that she gains some abilities to imagine, recollect and think about experiences that she did not have before and that these abilities are best thought of a sort of knowledge how. Finally, he says, the version of the argument that invokes knowledge-how is implausible, and the reason-to put it in our terms-is that K2 is false: the mere fact that one can know all the physical facts and lack an ability or lack some know how does not in any way threaten materialism since it does not entail that you fail to know any fact. 11 As Lewis makes clear, his account follows that suggested in Nemirow 1980. 13 Lewis's response closely resembles the knowing what it's like response; in particular, both responses involve the suggestion that there two kinds of knowledge and the argument illegitimately conflates them. What distinguishes them however is that Lewis's view relies on the distinction between knowing how and knowing that, while the knowing what it is like response does not rely on that distinction. There is much to say about Lewis's view but here I will focus on one very influential line of attack against it, a line suggested in the passage from Lycan quoted above (cf. Lycan 1986), and developed in detail by Stanley and Williamson (see Stanley and Williamson 2001; see also Stanley 2010, Cath 2009). According to this criticism, there is no distinction between knowing-how and knowing that of the sort Ryle assumed: knowledge-how is itself a sort of propositional knowledge. To know how to ride a bike, for example, is to know, of some way to ride a bike, that one can ride a bike that way. Hence, Lewis's response, which relies on the Rylean distinction, is a failure. In the light our discussion of the knowing what it's like response, however, it is possible to defend Lewis against this criticism, or at any rate to imagine a slightly altered version of what he said that evades it. What Lewis should have said, one might say, is that, in gaining the abilities that she does, Mary is best described, not as knowing how to do something, but as knowing what it's like in the free relative sense. If so, Lewis's basic position may be recast in a non-Rylean, rather than a Rylean, mould.12 How far does this recasting of Lewis's view do violence to his underlying intentions? There is no doubt that Lewis did formulate his view in terms of knowing how, and so to drop that element is clearly to depart from what he said. But there are reasons also for thinking he would be content with this departure.13 For example, at one point Lewis describes his view about what happens when Mary comes out of her room in the following way: Materialists have said many things about what happens in such a case. I myself, following Nemirow, call it a case of know-how; Mary gains new imaginative abilities. Others have said that Mary gains new relations of acquaintance, or new means of mental representation; or that the change in her is just that she has now 12 One response one might make on Lewis's behalf here is that sentences attributing knowledge-how, like similar sentences, has two readings, a propositional reading and a non-propositional reading. But the problem with this again is that knowledge-wh in which the wh is followed by an infinite verb seems to be an exception. 13 For further reasons to think that Lewis would not disagree with our formulation, see Stoljar 2015. 14 seen colour. These suggestions need not be taken as rival alternatives. (1994; 2934) Lewis does not mention the knowing what it's like response here, but it is natural to suppose that his attitude to it would be similar to the one he adopts in the case of the suggestions he does consider, viz., that it does not need to be seen as a rival to his own. If so, he would be free to adopt it and so drop the Rylean element that gets him into trouble. Of course, that Lewis's view can be recast as the knowing what it's like response does not mean it is successful. As we have seen, the problem with that response is that the KA can be reformulated to avoid it. The same would be true of Lewis's view on the suggested reformulation. Still, our discussion at least shows that Lewis's proposal can be understood so that it withstands perhaps the most prominent objection to his account. Tye's View Turning to Michael Tye's view,14 he begins by drawing a distinction between knowing what it's like, one the one hand, and knowing the phenomenal character of the experience, on the other. The former, Tye thinks, is a case of propositional knowledge; in particular it involves knowing that something red is like this, where the demonstrative 'this' picks out (in the relevant context) a particular property of the state of seeing something red. The latter, Tye says, is a case of non-propositional knowledge ("object knowledge", he calls it); in particular it involves being aware of, or being conscious of, some thing or property. How does Tye use these ideas to respond to the knowledge argument? One might have expected him to draw a distinction between propositional knowledge and object knowledge, and argue that K2 is false if object knowledge is in play, while K1 is false if propositional knowledge is in play. 15 However, Tye does not quite do this. He certainly thinks the K2 is false if object knowledge is in play, but he argues in addition that it is false even if propositional knowledge is in play. The reason is that, according to Tye, one should draw a further distinction between two ways to conceiving of propositional knowledge, and related to this, two ways of conceiving of knowing the answer to a question. On the first, 14 I will concentrate in the text on the position presented in Tye 2010. But see also Tye 2009 and 2012. 15 This would be to interpret Tye as advancing a so-called 'acquaintance hypothesis' similar to that developed in (e.g.) Conee 2004 (see also part IV of Ludlow, Nagasawa and Stoljar 2004). Of course, the proposal I have been interested in in this paper is closely related with the acquaintance hypothesis as well, but I won't try to pursue that further connection here. 15 which we may call the modal conception, to know or learn something requires "the addition of a piece of knowledge that shrinks the set of worlds consistent with what we know (2010, 307)." On the second, which we may call the non-modal conception, to know or learn something does not require this, but merely involves "coming to think new thoughts" (2010, 307). The importance of this distinction for Tye is that, if we operate with the non-modal conception, we may allow that Mary knows what it is like in the interrogative sense and at the same time deny K2. Tye's response to the knowledge argument appeals to a distinction between propositional and non-propositional knowledge, and in that sense resembles the response we have been looking at. But his approach is also distinct from it in two main ways: (i) he relies on the distinction between knowing what it is like and knowing the phenomenal character an experience, whereas the response we have been considering does not; and (ii) he relies on the further idea that learning what it is like is in certain cases not learning a new fact. Clearly there is much to say here, but I will limit myself to two observations, one about (i), the other about (ii). As regards (i), Tye motivates the distinction between knowing what it's like and knowing phenomenal character in the following way. First, he suggests (2010, 300) that the following sentences are consistent:16 (2a) Paul knows Ann. (2b) Ann is who Sebastian loves. (2c) Paul does not know who Sebastian loves. He then argues that the reason these are consistent is that one cannot substitute co-referring expressions within the scope of 'know'. Hence, even if Ann is who Sebastian loves, it does not follow that Paul knows who Sebastian loves from the fact that he knows Ann. Finally, Tye says, the same thing applies in the 'what it's like' case. Even if the phenomenal character of an experience is what it is like to have it, it does not follow that someone knows the phenomenal character from the fact that they know what it is like. In the light of our earlier discussion, however, it should be clear that this line of thought does not capture what is going on in examples like (2a-c). As we have seen, (2c) is ambiguous. On its interrogative reading, at least on the mention-some reading, it means that 16 I have maintained Tye's numbering. 16 Paul does not know a fact that answers the question 'who does Sebastian love?' On that reading, it is certainly consistent with (2a-b). On its free relative reading, however, it means that Paul does not know the person who is denoted by the noun phrase 'who Sebastian loves'. On that reading, it is inconsistent with (2a-b). So it is not in general true that (2a-c) are consistent; rather, they are consistent on one reading and inconsistent on another. Moreover, the reason that (2a-c) are consistent (on the relevant reading) does not have to do with failure of substitution; it rather has to do with the fact that Paul can know Ann and fail to know an answer to the question 'who does Sebastian love?' even though Ann is in fact who Sebastian loves. Of course, it is possible to understand Tye's view so that it does not reply on this particular account of (2a-c). In particular, it is possible to say, not that there is a distinction between knowing what it's like and knowing the phenomenal character of the experience, but rather that there are two sorts of things one has in mind by 'knowing what it's like': one just is knowing the phenomenal character, and one is knowing an answer to a question. Understood this way, (i) above would be replaced with the knowing what it's like response. Moreover, since, as we have seen, this is unsuccessful, all the weight of Tye's response to the knowledge argument rests on (ii), namely, the idea that there are distinct conceptions of propositional knowledge, the modal and the non-modal conceptions, and that in consequence K2 can be denied. Turning then to (ii), the modal/non-modal distinction, and the response to the knowledge argument founded on it, is a familiar one in the literature, and is not something I can assess here.17 It is worth noting, however, that the material about 'knowing what it is like' we have been looking at does not affect its plausibility in any way. Tye is, I think, correct to say that if materialism is true, then it can't be that Mary comes to learn what it is like on the modal conception-at any rate she cannot if she knows all the physical facts. And if this is correct, it is useful to view many different responses to the knowledge argument as different attempts to undermine the impression-for it is a natural impression-that Mary does indeed learn what it is like in this sense. One way in which one might try to do this is to draw a distinction between propositional and non-propositional knowledge. That is what Lewis tries to do, for example, and that is what the knowing what it is like response tries to do as well. And as we have seen it is unlikely that anything along these lines will succeed. But if I understand Tye correctly, while he does draw a distinction along these lines, it is not this 17 For extensive discussion of this sort of view see the papers on the 'old-fact-new mode' approaches to the knowledge argument in Ludlow, Nagasawa and Stoljar 2004. 17 element of his view that is crucial to his response to the knowledge argument. Rather what is crucial is the distinction between the modal and the non-modal conceptions of propositional knowledge. In that sense, Tye's response is ultimately different from the knowing what it's like response. Conclusion In this paper I have considered a response to the knowledge argument that is founded on the idea that 'knowing what it's like' is ambiguous between an interrogative reading and a freerelative reading. I have argued that this response is unsuccessful on the ground that the knowledge argument can be formulated to avoid it. I have also distinguished the response from two related proposals in the literature, one by David Lewis, the other by Michael Tye. References Cath, Y. 2009. 'The Ability Hypothesis and the New Knowledge How' Nous 43:1 (2009) 137–156. Conee, E. 2004 'Phenomenal Knowledge', Australasian Journal of Philosophy, 72: 136-50. Reprinted in There's something about Mary, ed. Peter Ludlow, Yujin Nagasawa, and Daniel Stoljar, MIT Press, Cambridge MA, pp.197-215 Crane, T. 2012 'Tye on Acquaintance and the Problem of Consciousness', Philosophy and Phenomenological Research Volume 84, Issue 1, pages 190–198, January 2012 Hellie, Benj. 2004 'Inexpressible Truths and the Allure of the Knowledge Argument'. In There's something about Mary, ed. Peter Ludlow, Yujin Nagasawa, and Daniel Stoljar, MIT Press, Cambridge MA, pp. 333-64. Hellie, Benj. 2007 "'There is something it like' and the Structure of Consciousness", Philosophical Review, Vol. 116, No.3, pp.441-463. Jackson, F. 1983. 'Epiphenomenal Qualia' Philosophical Quarterly 32:127-136 Jackson, F. 1986. 'What Mary Doesn't Know', Journal of Philosophy 83:291-5 Lewis, D. 1988. 'What Experience Teaches', Proceedings of the Russellian Society, 13: 2957, repr. in N. Block et alia eds., The Nature of Consciousness: Philosophical Debates (Cambridge, MA: MIT Press, 1997), 579-596. References are to the reprinted version. Lewis, D. 1994. 'Reduction of Mind', in S. Guttenplan ed., A Companion to the Philosophy of Mind (Oxford: Blackwell,1994), 412-31. Lewis, D. 1995. 'Should a Materialist Believe in Qualia?' Australasian Journal of Philosophy, 73: 140-144, repr. in his Papers in Metaphysics and Epistemology 18 (Cambridge: Cambridge University Press, 1999), 325-31. All references are to the reprinted version. Lycan, William G. 1986 Consciousness and Experience MIT Press, Cambridge MA Ludlow, P, Nagasawa, Y and Stoljar, D. (eds) 2004 There's something about Mary: Essays on Phenomenal consciousness and Jackson's Knowledge Argument, MIT Press, Cambridge MA. Nemirow, L. 1980 'Review of Nagel's Mortal Questions,' Philosophical Review, 89, pp. 475-476 Schaffer, J, 2010. 'Knowing the Answer Redux' Philosophy and Phenomenological Research, vol. 78, no. 2, pp. 477-500. Stanley, J and Williamson T, 2001. 'Knowing How' Journal of Philosophy 98:411-444 Stanley, J. 2011. Know How (Oxford: Oxford University Press) Stoljar, D. 2005. 'Physicalism and Phenomenal Concepts' Mind and Language 20 (5) 469494 Stoljar, D. 2006. Ignorance and Imagination (New York: Oxford University Press) Stoljar, D. 2010. Physicalism (London: Routledge) Stoljar, D. 2015 'Lewis on Experience and Materialism', in Jonathan Schaffer and Barry Loewer (eds.), A Companion to David Lewis, (Wiley Blackwell), pp. 519-532 Stoljar, D. Forthcoming The semantics of 'what it's like' and the nature of consciousness, Mind, forthcoming. Tye, M. 2009 Consciousness Revisited: Materialism without Phenomenal Concepts, MIT Press Tye, M. 2010 'Knowing What it's like," in Knowing How: Essays on Knowledge, Mind, and Action, ed. John Bengson and Mark Moffett, Oxford University Press, 2010 Tye, M 2012 'Précis of Consciousness Revisited', Philosophy and Phenomenological Research Volume 84, Issue 1, pages 187–189, January