BLACK IS OK! A REASSESSMENT OF THE ABILITY HYPOTHESIS PART A: DIRECT ATTACKS

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BLACK IS OK!

A REASSESSMENT OF THE ABILITY HYPOTHESIS PART A: DIRECT ATTACKS

ANDR ´E FUHRMANN AND WILSON P. MENDONC¸ A

1. The problem: The knowledge argument

The AH is an attempt at countering the threat to materialism that derives from a family of closely related arguments. These arguments purport to show that there are certain aspects of experience that go beyond what can be learned by studying the physical nature of the world. Perhaps C.D.

Broad [6, p. 71], and later B.A. Farrell [10] and Herbert Feigl [11, pp.

66-68] were the first to pose the problem; Thomas Nagel [20] rediscovered it, and Frank Jackson [12, 13] formulated it in its most simple and most effective form, theknowledge argument(KA). We only briefly rehearse the scenario here.¹

Mary has accurate and complete knowledge of all physical facts about colour-vision. Indeed we may even assume that Mary has total knowledge of all physical aspects of the world. According to physicalism, that is all there is to know about the world; there are no non-physical facts. However, Mary has acquired this knowledge while being locked-up in a black-and- white laboratory. In her laboratory she has been shown tomatoes but she has never seen the redness of a tomato under natural conditions, i.e. as we typically see tomatoes. So, Mary, in her black-and-white room, does not know what it is like to see the redness of a tomato. This is something she only learns, once released into the world of colours. But if Mary learns something new on being released, namely what it is like to see red tomatoes, then there is a fact that Mary did not know before her release. So, not all facts are physical, contrary to what physicalism claims.

Let Mary1 be Mary prior to her release from the black-and-white room and let Mary2 be Mary after her release into the world of colours. Then we may summarise the argument as follows.

1For a careful exposition of the argument and discussion of some variants see [22].

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(A) Mary1 knows all physical facts.

(B) Mary2 learns something new (what it is like to have the experience of seeing a red tomato under normal conditions).

(C) If Mary2 learns something new, then Mary2 knows a fact that Mary1 did not know.

(D) So (B,C), there are facts that Mary1 did not know.

(E) So (A,D), some facts are not physical facts.

There is no canonical way of formulating the KA. Frequently (B) and (C) are fused into a single premiss:

(BC) Mary2 learns a fact that Mary1 did not know.

In any case the KA should be formulated so as to put the physicalist under sufficient argumentative stress. As Jackson and others have repeatedly observed, this is the sole purpose of the argument.²

“ [...] the polemical strength of the Knowledge Argument is that it is so hard to deny the central claim that one can have all the physical information without having all the information there is to have.” [12, p. 130]

Further, in his “Postscript on Qualia” [14], Jackson writes:

“I now think that the puzzle posed by the knowledge argument is to explain why we have such a strong intuition that Mary learns something about how things are that outruns what can [be] deduced from the physical account of how things are.” (p. 78)

Premiss (A) is part of setting up the case. Of course, a physicalist could suggest that there is some impediment in principle to having total physical knowledge. But the KA does not seem to be the right kind of argument to be turned against (A)—an independent argument against (A) would be needed. With no such argument in sight, physicalists will have to opt for rejecting (BC), i.e. either (B) or (C). Before we consider the option in more detail, let us work the intuition pump a little to see why either option seems to be so unattractive.

Certainly, Mary2 does makesomesort of progress over Mary1. Remem- ber what happened when you first tasted a fruit (or Vegemite) that you had never tried before. You were curious and within a short moment your curiosity was satisfied. But satisfying one’s curiosity is just learning something hitherto unknown. In the same way Mary2 finally satisfies her curiosity as to what it is like to see red. Premiss (B) simply describes the result in a way that should not be controversial. Moreover, once Mary2 has satisfied her curiosity, she knows that seeing red is like such and such. Perhaps she cannot put the “such and such” in any better words than simply using a demonstrative: “Now I know what it is like: It is like this!”. But, if “This is what they say about Vegemite” expresses a fact, then why should “This

2Dennett points out that the argument has no coercive force; he calls it an “intuition pump”. Proponents of the KA can agree with this, adding that the pump is remarkably effective in turning the table against the materialist.

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is what Vegemite tastes like” not equally express a fact? Premiss (C) seems to be as difficult to deny as premiss (B).

Now, the phrase “learns something new” in premiss (B) is a rather casual way of describing the case. In somesense of the phrase, no one wishes to disagree. This explains why the argument has aprima faciestrong appeal.

But it also points to the pivot at which the physicalist can place the lever:

There might be some sense of the phrase that makes (B) true but does not support premiss (C). The two ways of going about the task are well-known in general terms.

First way: Mary2 does not gain access to a new fact in the sense in which

”fact” figures in premiss (A), the assumption that Mary has access to all physical facts. In that assumption ”fact” stands for a set of possibilities.

Mary2 does not learn something in the sense of eliminating possibilities that Mary1 had to leave open. But Mary2 gains access to a new type of experience, and by this she gains mastery of a new type of concept:

the phenomenal concept of redness. The new concept mastery enables her to understand and, hence, learn something that she could not understand and, hence, could not have learned before, namely, e.g., that this is what it is like to see red, where ‘red’ is now understood to be a phenomenal concept. In a morefine-grainedsense ofproposition, Mary2 knows the truth of propositions that employ a concept which was beyond Mary1’s repertoire. Still, Mary1’s concept of redness by measurements and Mary2’s concept of redness by direct visual experience apply to the very same things. So no new facts are learned. On this view then, premiss (C) is false. Mary2 learns new fine-grained propositions, but the new propositions respond to facts already known.

This broadlyFregean strategyagainst the KA comes in a number of variations, depending on how one specifies the peculiar character of phenomenal concepts.³ What we have said so far should suffice to note a certain tension inherent in the Fregean strategy. On the one hand, the nature of phenomenal concepts must be such as to explain why, by mastering them, we learn something essentially new. On the other hand, in order to unsettle premiss (C), that nature must itself be explained in purely physical terms. Evi- dently, the better the Fregean strategy succeeds on the one task, the more difficult becomes the other task. The notion of a phenomenal concept is thus in danger of turning into an overloaded piece. Whether the tension amounts to an inescapable dilemma (as Chalmers [7, ch. 10]) argues) is subject to a debate which we shall not comment here. Our aim is to explore an alternative to the Fregean strategy.

Second way: Mary2 does not gain access to any new propositional knowledge, neither in the coarse-grained sense of premiss (A) nor in any other sense. There is no proposition P (fine- or coarse-grained) such that it would be true that

(1) Mary1 does not know thatP, while Mary2 knows thatP.

3Stoljar [28] calls it the phenomenal concept strategy, others refer to it as the old facts/new guise-view.

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So what makes (B) true? What does Mary2 learn? How does Mary2 make progress over Mary1? Two answers have been given in the literature:

· Theability hypothesis(AH): Mary2 gains abilities that Mary1 did not have: the abilities to imagine, to recognise, to distinguish, to remember certain experiences.

· Theacquaintance hypothesis: Mary2 becomes acquainted with certain experiences that were denied to Mary1.

In what follows, we shall put aside both Fregean strategies and the acquaintance hypothesis. Instead we shall focus exclusively on the ability hypothesis.

In the hands of a physicalist, the AH serves a certain function.⁴ It is designed to meet the challenge formulated in the quote from Jackson above.

The physicalist must deny the combined premiss (BC). But in doing so, he runs against a strong pre-theoretic inclination to the effect that Mary2 does have knowledge that Mary1 could not have. So the physicalist needs a plausible theory that explains why such an inclination is in error. The AH offers such an error theory. The AH explains in which sense a correct part of the intuition can be preserved—premiss (B)—and how this sense renders another part of that intuition—premiss (C)—false.

It is usually assumed that the AH serves the function of an error theory by entering stage in the garb of a semantic thesis. In this form the AH proposes truth-conditions for locutions like

(2) Mary knows what it is like to have experiencee.

As we shall see in Part B, this is not the only way in which the AH can serve the function for which it was designed. In fact, we shall there argue that as a semantic thesis it enters into a hopeless competition with an alternative account of the truth-conditions of(2). But throughout Part A nothing will hinge on how we interpret the biconditional in the AH. So here the definite description “the AH” will simply refer to the AH as we shall state it in a moment.

2. The semantic ability hypothesis

Here is a statement of the AH, taken from Alter and Howell [5, p. 48]:

”So this is a sort of ’have your cake and eat it too’ view. You grant that Mary learns all physical information through watching the black- and-white lecturesandshe gains knowledge when she leaves the room and sees red. But since the epistemic growth involves gaining abilities instead of information, the case provides no reason to doubt that all information is physical. Neat.”

The AH has a simple and immediately appealing motivation. We are seeking a truth-maker for the statement that

(3) Mary knows what an experience of red is like.

4There is at least one philosopher who endorses the AH independently of the physicalist purpose: D.H. Mellor in [19].

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For the physicalist the threat consists in it being inevitable that the right- hand-side of

(4) (3) iff ...

requires a proposition of the form (5) Mary knows thatP,

where P is a proposition that differentiates between physically indistinct possibilities. But now think of conditions under which we would render(3) true. What would make us attribute to Mary knowledge of what it is like to see red? If(3)is true, then we would expect Mary to have certain abilities:

The ability to conjure up a mental image of a red rather than a yellow rose, the ability to remember what that red rose looked like (as to colour), the ability to sort out red from gray balls on sight and perhaps some more abilities of the kind. And if Mary did not have all, most or some of these abilities we would not attribute to Mary knowledge of what an experience of red it like. So knowing what an experience of red is like, seems to be justa matter of having certain abilities. To give a final touch to the AH we only need to draw up a catalogue of the relevant abilities and determine the right quantifier—some, most, all, or some weighted quantification (e.g. the contextually most salient abilities).

This train of thought yields arguably more than a mere “motive” for adopting for the AH. It can be taken to create a presumption in its favour.

For, if it is only abilities that figure in the assertibility conditions of claims like(3), then unless we have reasons for dissociating assertibility from truth conditions for statements like (3), we should take the conditions for the assertibility of (3) as the conditions for its truth. Note also that this presumption in favour of the AH is independent on what stance one may take on the issue of physicalism.⁵

For present purposes we need neither ponder much on the catalogue of relevant abilities nor on the requisite quantifier (in case that more than one ability should be considered). In assessing most of the arguments below, not much will depend on the catalogue nothing will depend on the best way of quantifying over it. Here is the AH in its simplest form:

AH. X knows what an experience of typeeis like iffX is able to imagine correctly an experience of typee.

There is also a thesis that is sometimes considered to be a mere verbal variation on the AH, theknow-how hypothesis:

KH. X knows what an experience of type e is like iff X knows how to imagine correctly an experience of typee.

Lewis in [15] (though not in the brief first statement of the hypothesis in the 1983 postscript to “Mad pain and Martian pain”) puts the AH sometimes

5For the time being. In part B we shall argue that assertibility and truth-conditions may diverge over(5). This will lead us to a reinterpretation of the AH such that an otherwise forceful objection can be met.

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in terms of know-how and Mellor [19] prefers the KH formulation. For all Mellor says, however, he seems to think of AH and KH as equivalent formulations of a single hypothesis. That may not be quite so, since, in contrast to the AH, the KH is an immediate target for a certain type of attack aired in recent work by Stanley and Williamson [27,25,26].⁶ In this part we shall take AH as the canonical formulation of the hypothesis.

As mentioned above, the AH, as considered in this part, takes the form of a semantic equation. Nemirow [21] is quite explicit about this. He talks of the “ability equation”: “Knowing what it’s like may be identified with knowing how to imagine” [21, p. 493]. He then goes on to turn the equation into “the ability analysis”:

“The expression ‘X knows how to visualize red’ either should replace or can be used to paraphrase ‘X knows what the experience of seeing red is like’. [...] Although the ability analysis palpably parses the meaning of the phrase ‘knowing what it’s like,’ those who generally doubt the meaningfulness of synonymy may view the analysis as a possible linguistic reform that would preserve the explanatory power of the phrase while eliminating the use of a misleading singular term [viz.

‘what it’s like’].” (pp. 494f.)

Lewis [15] is less explicit about the exact formulation of the AH. He is more concerned with showing that Mary1’s new abilities are sufficient to explain the intuition of novelty present in the premiss (BC) (and that the physicalist should better stay clear of Fregean strategies). In other words, Lewis interest in the AH is limited to its value as an error theory. But when it comes to state the thesis in a few words, he too chooses to offer a hypothesis of identity:

The Ability Hypothesis says that knowing what an experience is like justisthe possession of these abilities to remember, imagine and recognise. It isn’t the possession of any kind of information, ordinary or peculiar.

[...] It remains that there are aspects of ability that donot consist simply of possession of information, and that we do call knowledge.

The Ability Hypothesis holds that knowing what an experience is like is that sort of knowledge.” (p. 516)

We have put the AH in terms of ‘imagining correctly’. As remarked above, careful consideration may reveal that this is not the only ability required for knowledge what it is like—though Mellor [19] argues that it is. Although the question of a correct and complete catalogue of abilities should not delay us here, let us note that imagining alone will not do. Mary must imagine red correctly. If Mary imagined a yellow rose each time we ask her to imagine a red one, then Mary would not know what it is like to experience a red rose. (Perhaps we wouldn’t know off-hand that she doesn’t have knowledge

6Stanley and Williamson go on to extend the attack to the AH but that requires an extra move.

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of what it is like to see red. But we would notice when testing her ability to recognise red as opposed to yellow roses by sight.)

3. Objections to the AH

Given our statement of the AH, we can start sorting possible objections to it. First, there are direct attacks on the equivalence claimed. Such attacks typically proceed by offering counterexamples to the one or the other direction of implication. AH, so it is claimed, fails to be truth-preserving in the one or the other direction. But the AH may also fail to preserve other relevant properties. If so, then AH claim to providing an analysis is undermined. We shall consider two such properties: embeddability in complex sentences and arguments, and possibility.

Second, there is a family of objections,indirectattacks, that try to cast doubt on the claim that the AH iseffectiveagainst the KA. Remember that the proponent of the AH typically concedes the novelty premiss that Mary2 gains knowledge of what it is like. The AH tries to analyse that kind of knowledge such that one may gain it without thereby gaining information (in the sense of discarding possibilities). (This is how the AH explains the error in the anti-physicalist interpretation of the novelty premiss.) There are two ways in which this idea may be countered.

One may either argue that the left-hand-side of the AH, i.e.

(6) Mary knows whateis like

(withestanding variably for a suitable kind of experience) entails that there is a proposition P that Mary knows to be the case in virtue of knowing what e is like. Thus, the particular analysis offered by the AH does not even matter. The problematic left-hand-side of the equivalence carriesper sea commitment to genuine propositional knowledge.

Alternatively, the objector may follow the AH from left to right and then argue that

(7) Mary is able to correctly imaginee

only if Mary is in the possession of propositional knowledge characteristic for that ability. Some have taken the “only if” as indicating an inference to the best explanation. Others have argued for a stronger connection, in which case the know-how version KH of the AH may be required as a stepping stone. We shall treat the variants in detail in Part B. F

Finally, we shall briefly treat an objection—also of the second type—

to the effect that there are versions of the KA that bypass the notion of

‘knowledge what it is like’ such that the AH fails to address these versions.

Here is a summary of the menu of possible objections:

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A. Direct attacks on the AH 1. Non-necessity of abilities 2. Non-sufficiency of abilities 3. Wrong analysis (embeddability) 4. Wrong analysis (possibility)

B. Attacks on the AH as used in rejecting the KA 1. Insufficiency on its own to block the argument

a) The left-hand-side (knowing what it is like) implies propositional knowledge.

b) The right-hand-side (having abilities) implies propositional knowledge.

2. Ineffectiveness to block variants of the KA.

The positions in the above menu may be filled in many ways. In a first perusal of the relevant literature we have counted no less than fifteen fairly distinct objections to the AH—and then gave up counting. Lycan [18, ch. 5]) alone lists ten. Some of these have occurred to different authors independently. Some have been thought to be outright mates. Others are intended to make the AH sufficiently unattractive so as to leave it behind and move on to its competitors. Among the objections considered below are also some that have been put forward only tentatively. The objector gives a possible reply but still believes that the objection weakens the position of the AH. In general objections to the AH are much more prominent in the literature than possible replies to them. This may sum up, on the one hand, to the impression that the AH has a negative balance sheet. On the other hand, a hypothesis dignified by so many objections cannot be that bad. Our aim here is to contribute to a fair assessment of the AH. We shall consider the most important objections one by one. We shall argue that the defendant of the AH can counter most of the objections without much effort, and there certainly is no single mating line against the AH.⁷

The chess metaphor occasionally used above is an apt one in more than one respect. Since the first move in the game (”White”) is the knowledge argument, the AH is a ”black” move and objections to the AH (white moves) branch into a number of variations. As far as these variations can reasonably be followed through, they do not coerce a win for either side. But we can evaluate the positions reached in general terms (“dialectical pawns”). In all directly attacking lines to be considered Black, i.e. the AH under the straightforward semantic interpretations, is ok. But in Part B we shall encounter an objection that forces Black into an unattractive position: Play may go on but the AH looses the initiative (the presumption in its favour) and may get bogged down in a difficult defense. At that point we shall

7Given that among the objections to the AH there is no outright refutation, a careful consideration of these objections is only half of what needs to be done in order to fairly assess the merits of the AH. The other half consists in weighing the AH against its competitors. This task is clearly beyond the scope of this paper and, consequently, we shall have little to say about strategies, physicalist or other, that compete with the AH.

The classic paper is Lewis’s [15]; cf. also Chalmers so-called master argument in [7].

Philip Pettit’s [23] is another notable attempt at pointing out the advantages of the AH over its competitors.

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refocus on the essential function of the hypothesis and start considering what we shall call the pragmatic variation on the AH as the better answer to the KA.

4. Direct attacks A1. Abilities are not necessary.

Objection A1a: Limits of discrimination.

Mary sees a ripe tomato, thereby experiencing a particular shade of red, say red17. So she knows what it is like to see red17. But she is quite unable to perceive any difference between red17 and red16. Consequently she is unable to correctly imagine (or recognise) red17 as opposed to red16. So she knows what it is like to see red17 but—contrary to what AH claims—

does not have the corresponding ability for red17. Here is how Tye [29]

presses the point:

“As she stares at the rose, [Mary] certainly knows what it is like to experience the particular shade of red she is experiencing. If you doubt this, suppose we inform Mary that she is seeing red17. She replies, ’So, this is what it is like to see red17. I had always wondered. Seventeen, you see, is my favorite number; and red the color of my mother’s favorite dress.’ We then say to her, ’No, you don’t know what it is like to see red17. For you won’t remember it accurately, when you take your eyes from the rose; you won’t be able to recognize it when it comes again;

you won’t be able to imagine the experience of seeing red17.’ Should Mary then admit that she doesn’t really know what it is like to see red17 even while she is staring at the rose? She won’t know it later certainly. But it seems intuitively bizarre to deny that she knows it at the time.”

Response: For Mary there is no difference between an experience of red16 and red17. They are exactly alike as to what it is like. Thus on being presented with either red16 or with red17 she has a a single type of red experience. Of course, the colour hue red16 is distinct from the hue red17—

their spectral segments are distinct. But the experience of red16 is just the same as the experience of red17; for Mary it is one and the same type of experience. For that type of experience Mary does have the required imaginative and abilities. So the case presents no counterexample to the AH.

Mary does have knowledge of what seeing red17 is like for her. Given that for Mary red17 is just like red16, it follows that she als also has knowledge of what seeing red16 is like, even though she may never have been exposed to a red16 stimulus. This is as it should be. For it would be bizarre, to saddle Mary with an ability to discriminate in imagination what she cannot discriminate in perception.

That this is the right response is best be seen by considering a structurally identical example. Suppose Mary visits Copacabana beach on a New Year’s eve. Next day the papers report that there were a million people present at the beach. Mary then proudly claims to know what it is like to be

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part of a crowd of a million people. Should we deny her such knowledge, if we learned that there were in fact a million plus three? Of course not.

Although 10⁶ 6= 10⁶+ 3, the experience of being immersed in a crowd of 10⁶ feels just the same as being part of a crowd of 10⁶+ 3. There is no perceivable difference. If one knows what an experience of a stimuluss is like, then one knows what an experience of s⁰ is like, for any stimulus s⁰ that one cannot distinguish in experience froms.

Objection A1b: Limits of discrimination (once more).

Suppose Mary sees red16 and red17 side by side. Now we no longer assume that the difference between red16 and red17 outruns Mary’s capacity to discriminate between them in experience. Side by side she can see the subtle difference between the two colours and she has two distinct experiences: one of red16 and one of red17. Attending to the difference, she can truthfully say: “I know what this (pointing at red16) looks like, and I know what this (pointing at red17) looks like, and the two look differently.” But as soon as (or perhaps a day or two after) the two colour patches are taken from her eyes, she is no longer able to correctly imagine red16 as opposed to red17.

Isn’t this a case where she has knowledge of what red16 looks like without the ability AH postulates?

Response: Knowledge of what experiences are like can be lost. I wish I knew what it was like to pass my day in a cradle. (Did I feel bored?) Once I knew, now I don’t. Why? Nothing comes to my mind when I try to remember. I am quite unable to imagine what it was like.

Similarly, one day Peter sat on that seat, the other day on that other seat in the bus. When he sat on the one, it felt differently from when he sat on the other. In both cases he knew what it felt like and the two cases did not feel the same way. But as time passes, he only remembers the bus ride. The distinct experiences of riding the bus on the one, respectively on the other seat have fused into a single blurry image. Does Peter still know what it is like to ride the bus on that particular seat? No. Once Peter knew, now he doesn’t. What remains is knowledge of what it is like to ride on that bus, seated somewhere.

Same with Mary: As she sees the two patches side by side, she has distinct experiences. As time goes by (a few seconds, a day, or two), the once distinct experiences collapse into the image of a single, less specific experience. At that point she has lost her knowledge of what seeing red16 is like as opposed to what seeing red17 is like. What remains is knowledge of seeing red16-or- red17 is like. For that knowledge May does have the imaginative abilities required by the AH.

If knowledge of what it is like can be lost, then such knowledge must carry a temporal index. Perhaps we should make that index implicit in the statement of the AH:

X knows at timetwhat eis like iffX is able to correctly imagineeatt.

The right-hand-side of this equation must be understood rightly. In most cases, the attribution of an ability had at timetrequires that the ability be present during some sufficiently large time interval, including and extending

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beyondt. Typically abilities are not instantaneous. There is, for example, no such thing as the ability to ride a bicycle for a second. Attributions of abilities, including imaginative or recognitional abilities, are in this sense vague: they come in degrees. If the AH is true, then this vagueness transfers to knowledge of what it is like. But as we have just seen, it is independently plausible that knowledge of what it is like can be gained and lost in degrees.

The AH offers a ready explanation of this observation. What started as an objection to the AH ended as an argument in its favour.

Objection A1c: Pathological failures of imagination.

According to the AH, if someone knows what it is like to taste A¸ca´ı, then he has the ability to correctly imagine that taste. Consider John, drinking a glass of A¸ca´ı. He senses all the nuances of the taste of A¸ca´ı. His sense of taste works perfectly. This seems to suffice to ascribe to John knowledge of what A¸ca´ı tastes like. As he sips his A¸ca´ı, Mary says: ”Now he knows what A¸ca´ı tastes like.” Yet, suppose that John has a deficiency: Without A¸ca´ı on his tongue he is unable toimagine what it tastes like. He cannot conjure up the taste image. So the ability to imagine cannot be necessary for knowledge of what it is like. The example is easily adapted to apply to any other ability that the ability theorist may deem to be necessary for knowing what it is like.

Response: This is an extreme version of the continued objection above, a pathologically accelerated loss of memory. John looses almost immediately his knowledge of what A¸ca´ı tastes like. What is true is that John has undergone the experience of tasting A¸ca´ı, as I have undergone the experience of lying in a cradle. But he no longer knows what that experience is like, just as I no longer know what it is like to lie in a cradle. It took me perhaps some years to loose my knowledge—that’s natural. It took John a few seconds to loose his knowledge—that’s pathological.

Reply (White): So abilities to discriminate or to imagine can be lost (or gained) gradually. They come in degrees. But knowledge does not come in degrees. Either you know it or you don’t.

Response: That may be true for knowledge-that. We take the lesson and note that it does not hold for knowledge of what it is like. You can more or less know what it is like to have a certain experience. If you take a whole spoon of it, you know better what A¸ca´ı tastes like than if you are granted only the prong of a fork. That much is independently plausible. It is a virtue of the AH that it readily explains why knowledge of what it is like comes in degrees. If knowledge-that is Boolean, then so much the worse for the prospects of parsing knowledge of what it is like as some kind of knowledge-that.

A2. Abilities are not sufficient.

Objection A2a: Unexercised abilities.

Consider Martha who has an ability to imagine colour shades she has so far not experienced. She has seen, for example, red16 and red18 and, asked to imagine red17, she comes up with a correct image of red17 (distinct from

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red16 and red18, we may suppose now) before her inner eye. So Martha has the ability to correctly imagine red17. But suppose she is never asked to exercise that ability. Then she does not know what an experience of red17 is like. So the ability to correctly imagine an experience is not sufficient for knowing what that experience is like.

First (tentative) response(as in [8]): Amend the AH so as to include the ability to correctlyrememberwhat the experience in question is like. Since Martha never had an experience of red17 she is unable to remember such an experience. So the amended AH predicts correctly that Martha does not know what an experience of red17 is like.

Reply (White): The response lets the amended AH too easily off the hook. Consider Maria, the chess prodigy. Maria is able to remember any position on the board; i.e., for any position, if that position is shown to her, she is able to reconstruct it at some later time. The conditional does not imply that Maria has seen the position that she is able to reconstruct.

Being able to remember a position does not imply that one has encountered that position on the board—though simply remembering a position does.

Likewise, being able to remember an experience does not imply that one has had that experience—though simply remembering an experience does.

Remembering is factive; being able to remember is not. To remember an experience you must have had it; to be able to remember an experience you must only be able to have had it. That latter ability Martha does have.

Yet, so the objection goes, she does not know what having the experience is like. So if the imaginative abilities are not sufficient for knowing what it is like, then adding the ability to correctly remember the relevant experience will make no difference in that respect.⁸ Black needs to respond differently.

Second (tentative) response: We try to make good the fault of the first response. Amend the AH so as include the condition that the subject must not only be able to imagine an experience of the kind but that he must have hadthe experience.

Reply (White): Now we have fallen into the trap of making the condition too strong. Does one really need to have had an experience of kind e so as to be said to know what that experience is like? If so, this would make attempts at triangulating experiences futile. Perhaps I have never seen a traffic light with all three colours lit simultaneously. But I know what it is like to see the red, the yellow, and the green light in succession, i.e.

separately. Nothing easier than to fuse these three pieces of knowledge of what it is like. The result is knowledge of what seeing a traffic light with that particular defect is like. No need to see the defect in action.⁹

8Unless the the added condition collaborates with the imaginative abilities so as to secure the required sufficiency. But this is speculation without serious backup.

9Lewis [15] and Mellor [19] mention further examples of the kind. A composer may know what the performance of a score is like without ever having the opportunity to hear it performed. “Similarly with imaginative poems, novels, plays and films which find ways of telling us in words or pictures what it’s like to have experiences and emotions that in reality we may never have.” [19, p. 5f].

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Third (tentative) response: In response to this reply the AH-theorist could weaken the second response to requiring that the subject must have had an imagining of the experience (rather than the experience itself). Since this would be equivalent to requiring that the ability to imagine must be exer- cised, there could be no counterexamples to AH that draw on unexercised abilities.

Reply: That cannot be right either. Like the second response it requires more than is necessary for knowing what it is like, as can be seen by spinning further (into the direction of the case of Martha) the traffic light example:

Peter has never seen the traffic light defect mentioned above. He knows what it is like to see the light signalling red, then yellow, and then green.

Ifasked to imagine what the defect would look like, he would quickly come up with a correct image of a situation of the kind. But, as in the case of Martha, no one ever asks. Is it fair to deny Peter knowledge of what an experience of the defect is like, simply because no occasion arises to actually imagine such a situation?¹⁰

Fourth (settled) response: On reflection, the case of Martha is far from being a counterexample to the AH; it may even work in its favour. What is at issue here is the possibility of triangulating knowledge of what it is like.

The ability to imaginatively triangulate an experience is a sufficient basis for ascribing knowledge of what the experience is like. This is what Black should say. Black thus simply denies that Martha does not know what an experience of red17 is like—just as Peter knows what seeing the defective traffic light is like.¹¹ The two cases are structurally exactly parallel. What is a fair comment in the case of Peter must be a fair comment in the case of Martha. Black applies in his response the following principle of closure under triangulation:

TC. IfX knows what canddare like, and

X can work out whateis like, if he knows what canddis like, thenX knows what eis like.

White, pushing the case of Martha to a conclusion against the AH, must deny triangulative closure.

First, TC is independently plausible. It is a natural companion to a weak deductive closure principle governing propositional knowledge. Suppose—

for the sake of the argument—that propositional knowledge is not closed

10Here is another example. Martha knows what it is like to see Netanjahu on the UN stage. Martha also knows what it is like to see Ahmedehijad on the UN stage. (Suppose that Martha has actually seen each of them speaking to the UN. She has also occasionally shaken hands with other people. If the objection from unexercised abilities is cogent, then—unless she has actually entertained such an unlikely encounter—Martha does not know what it is like to see Netanjahu and Ahmedehijad shaking hands on the UN stage.

But, surely, she does know that.

11Or should we rather say “what itwouldbe like”? We could—but if we did, it would make no difference. “X knows whatewould be like” is elliptical and needs complemen- tation by a subjunctive conditionC: “Xknows whatewould be like, ifCwere the case”.

The relevant condition here is thatX undergoes (“has”) the experience e, so that the completed phrase is “X knows whatewould be like, if he hade”. But this is just to say that the phenomenal character of experienceeholds no surprise forX, i.e. thatX knows what (the phenomenal character of)eislike.

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under logical consequencetout court. The effort required to perform a given deduction may just outrun a subject’s computational resources. In that case the subject may not acknowledge a consequence of his stock of knowledge without acting thereby irrationally. In natural agents rationally is bounded by nature. But as far the consequences what a subject explicitly knows are within easy reach, these consequences are known. For, what a subject knows is what he can reasonably expected to work out from his explicit knowledge.

This is the sense in which pupils know the answers to questions before they have actually been posed. Analogously, this is the sense in which Martha knows what red17 is like before anyone asks her to imagine that colour.

Second, TC need not be construed as any stronger than a matching closure principle that White must employ so as to set up his counterexample.

This is the closure ofabilitiesunder triangulation:

AC. IfX has the c-abilities and thed-abilities, and

X can work out the e-abilities, if she has thec- and thed-abilities, thenX has the e-abilities.

White needs to recognise and apply AC for some sense of “can work out”, that is, for some degree of computational capacity. But how can White then deny the parallel principle TC for the same degree of computational capacity? Clearly, TC and AC go hand-in-hand and any theory that tries to separate the two ends up in the defensive. In this line Black gains the initiative: Not only does Black acknowledge the parallel between TC and AC; it also explains it in a straightforward manner.

Objection A2b: Dormant abilities.

Mary1 does not know what an experience of red is like. This is the novelty premiss (B) of the KA and for the present purpose we may assume it to be true. (Remember that the AH offers a way of denying the second premiss, (C), of the KA. It would be unfortunate, if the AH also had to deny premiss (B).) Mary2 is not much different from Mary1. Mary2 is only given an opportunity that was denied to Mary1: seeing, and consequently imagining colours in natural light. How could Mary2 perform this little feat if Mary1 did not already have the ability—unexercisable though in her black and white room—to see and, consequently, to imagine visual experience. But if Mary1 dose have the ability, then, by the AH, she knows what it is like to see red, contrary to the novelty premiss.

Moreover, if Mary1 does have the ability in question and does not exercise it, then the case of Mary does not seem relevantly different from the case of Martha, discussed in the previous objection. Only, in the case of Mary1, ascribing knowledge of what it is like, is not an option. So in the case of Martha it cannot be an option either, thus vitiating the final response to A2a.

Response: Mary1 has visual abilities, including the ability to experience and distinguish colours by sight in natural light. But, in contrast to Mary2, Mary1 does not have the ability to imagine what an experience of colour in natural light is like. AH predicts therefore correctly that Mary1 does not

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know what an experience of red is like. In general, it is not surprising that one may have the ability to undergo experiences without, at the same time, having the ability to imagine what such an experience is like. That is to say, the inference

from

X is able to have an experience of typee infer

X is able to imagine an experience of typee

is not truth-preserving. Most people have the ability to undergo the experience of tasting A¸ca´ı. But being in a state that enables a subject at timetto have the experience is not in general a state that enables the same subject at t to imagine correctly that experience. Since Mary1 does not have the imaginative ability, she is in this respect relevantly different from Martha.

So the two cases are distinct and thus do not force a single response.

Objection A2c: Mary distracted.

Suppose that Mary takes a stroll. Along the street there are parked cars of different colours she has never seen before.¹² But Mary does not pay attention. So she does not know what they look like. But Mary could attend to these colours, if she wanted to. So Mary has the ability, unexercised though, to imagine what seeing these colours is like. The ability is present but knowledge of what it is like is absent.¹³

Response: As in White’s previous move, there is the same non-sequitur here. One may have the ability to attentively perceive a colour without thereby being able to imagine that colour. In the case at hand, Mary has the former ability without having the latter. As Mary strolls along the row of parked cars she is able to attend to the colour of that van: she could direct her attention to the van, if she wanted to. But Mary is distracted. So the colours of the parked cars escape her attention. Given the assumptions of the case, Mary is thus unable to imagine the colour of that van. According to AH, Mary does not know what the colour in question looks like.

Objection A2d: Frankenmary.

In her laboratory Mary1 creates a molecule-for-molecule clone of what Mary2 would be like. Let us call this clone ”Frankenmary” (following [5, p. 66]). Frankenmary is a materialised anticipation of Mary2. Since the anticipated Mary2 has undergone the experience of seeing a red tomato, Frankenmary must be able to imagine that experience just as well as Mary2.

This must be true, in particular, given physicalist assumptions about the material basis of imaginative abilities. But does Frankenmary really know what it is like to see red?

12Let us also rule out by assumption that Mary is able to triangulate in imagination the colours of the parked cars.

13Tye [29] takes A1a to be a winning move against Black. He then proposes a version of the AH to which that objection does not apply. To that new version of the AH he then raises the objection above. We here adapt this new objection and examine whether it can be made effective against the original AH.

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Response: The crucial test is whether Frankenmary learns anything new, as Mary does, once released from capture and presented with a tomato in natural light. Will Frankenmary enjoy an epiphany on seeing red? Or, equivalently, on being shown a blue tomato will Frankenmary fail to notice that this is not what tomatoes look like? That will only be the case, if she was unable to imagine that experience prior to her release. But, by assumption, Frankenmaryisable to imagine experiences of red in the black- and-white room. So there can be no epiphany on seeing a red tomato and there must be a big surprise on seeing a blue one. Why? Because Frankenmary knows what it is like to see a red tomato.

A3. AH is a wrong analysis.

The attacks on the AH considered so far proceeded by claiming that the proposed equivalence may fail in the one or the other direction. The AH, so it was alleged, does not guarantee the preservation of truth. But there are other relevant properties, besides truth, that should not vary independently between the left- and the right-hand-sides of an analytic equivalence claim.

If AH has instances such that the two sides flanking the equivalence end up distinct under such a property, then AH fails as an analysis of what knowledge of an experience is like. We shall consider two such properties:

embeddability and possible truth.

Objection A3a: Embeddability.

According to Brian Loar [16], the two sides of the AH differ over the property of being embeddable in complex sentences and inferences.

“One can have knowledge not only of the form ‘pains feel like such and such’ but also of the form ‘if pains feel like such and such, then Q’.

Perhaps you could get away with saying that the former expresses (not a genuine judgment but) the mere possession of recognitional know- how. There seems however to be no comparable way of accounting for the embedded occurrence of ‘feels like such and such’ in the latter; it seems to introduce a predicate with a distinctive content.” (p. 86) Response(as in [29]): The AH never offered an analysis of “pain feels like such and such”. Rather, the analysis applies to locutions of the type “the subject knows what pain feels like”. It isknowledgeof what pain feels like which, according to the AH, is a matter of abilities—not the fact that pain feels like such and such.

As Tye [29] has noted, the phrase “feels like such and such” is not without problems. To bypass these problems (as in [29]), let us take a demonstrative instance: “Pain feels like this”. Now, pain is plausibly just the experience of pain; Lewis, for instance, subscribes to this equation. If so, then “Pain feels like this” means just the same as “This is pain”. For a Lewisian, this proposition expresses a demonstrative identification of a functional state that happens to be a brain state. There is nothing in the AH that would make it evenprima facielook odd to embed such a proposition in a conditional, like “If this is pain, then I prefer to be without it”.

Reply (White) (cf. Crane [9, p. 96]): True, AH does not immediately []

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analyse “Pain feels like such and such” in terms of abilities. But Mary2 can use a conditional like

(8) If red looks like this, then I prefer green to reason to the conclusion

(9) I prefer green.

Now, this piece of reasoning it available to Mary only after her release. So either the antecedent or the conditional must be new to her. The conditional is truth-valued. And since the conditional is truth-valued, only if its antecedent is, the antecedent must be truth-valued too. So whatever is new to Mary is a proposition, not an ability.

Response: As above, “Red looks like this” expresses the demonstrative identification of an instance of a functional state (a red experience). The truth of this identity is in principle available to Mary1. The conditional expresses a preference among mental states, which, we may assume, has not changed as Mary1 passes to Mary2. The material realisation of that preference relation is also not hidden in principle from Mary1. So the above piece of reasoning is already available to Mary1. What possibly creates the illusion of novelty is the kind of demonstrative identification that requires Mary to actually undergo the experience. But the illusion is immediately dispelled, if we suppose that Mary1 inspects (“cerebroscopically”) the mental state of Martha, having a red experience outside the black and white room. Then Mary1 may reason in the same way, only replacing “this”

(pointing at her own mental state) by “that” (pointing at Martha’s mental state).

Next, we turn to possible truth. To illustrate, consider the following schema for an explication of knowledge:

KR. X knows that P if and only if R(X, P),

whereR(X, P) indicates thatX stands in a certain relation toP. Instances of KR may be counterexampled by pointing out that for someX andP the one side may be true while the other is not. But we may also refute KR by observing independent variation between the two side not with respect to truth but with respect to possibility. Thus, either (a) observing (for some P) that it is possible to know thatP but that it is not possible to stand in relationR toP, or (b) observing that one may stand in relation RtoP but cannot know thatP suffices for the purpose of refuting KR. (Put very simply, (a) is the way optimistic epistemologists proceed against sceptical demands on knowledge, while (b) is the blueprint for attacking optimistic theories of knowledge.)

The AH fits an obvious variant of schema KR. (X knows whate is like just in caseX stands in a certain ability relation to the experiencee.) So, in principle, the AH may be a target for objections of type (a) and (b).

To the best of our knowledge, only type (b) has found an instance. The argument has been tentatively suggested by a proponent of the AH, D.H.

Mellor (in [19]). In nucethe objection runs thus: There are clearly instances []

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of a subject knowing what a certain experience is like. So the left-hand-side of the AH expresses a possibility. But no subject can have the imaginative ability that the AH requires. So the AH must by wrong.

Objection A3b: Vicious regress.

The AH requires for knowledge what an experience is like, that the subject is able to correctly imagine that experience. Imaging an experience is itself an experience, a secondary one, we may say. Now what does the ability to pick out a correct secondary experience require? Must the subject not know what a correct secondary experience of a given primary one is like?

But this is just another case of knowing what an experience is like. Accord- ing to the AH it requires that the subject be able to imagine correctly a secondary experience, i.e. to have a correct tertiary experience. And so on;

“an obviously vicious regress” [19, p. 12]. So the AH requires something impossible. We must either conclude that we never know what experiences are like or that the AH is inconsistent with the assumption that there is such knowledge.

Response: The ability to imagine correctly an experience does not require that the subject knows that the imagining is correct. In this sense, the experience of imagining an experience is not one of which we know what it is like. An analogy helps to see the simple point: The ability to recognise red things does not require the subject to have recognitional abilities with respect to experiences of red things. It only requires that one sees things as red when the things seen are red. Similarly, the ability to correctly imagine an experience of red things, does not require the subject to be able to recognise imaginings of experiences of red things, let alone imaginings of such imaginings. The purported regress is a bogus one.

5. Conclusion

We have argued that none of the direct attacks on the AH succeeds. In each case the AH-theorist has a way of meeting the challenge without having to retreat from the original position. Moreover, the responses draw on observations which are independently plausible. In some cases the AH even offers a simple explanation of these observations, thus strengthening the case for the AH. To recapitulate:

· Knowing what an experience is like cannot be finer grained than the experience itself (A1a).

· Knowledge of what it is like can fade away (A1b and A1c).

· One can have knowledge of what it is like by triangulation even if the triangulation is actually not carried out (A2a).

· One must carefully distinguish between the ability to undergo an experience and the ability to imagine that experience. The former does not entail the latter (A2b and A2c).

· Mary1’s resources ought not to be underestimated. There is a sense in which Mary1 already knows what seeing red is like. When asked what it is like, she may e.g. point to a cerebroscopic image: “This is what it is like” (A3a).

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· The ability to imagine an experience correctly does not require that one knows what the experience of a correct image is like (A3b).

All of the theses above can be argued for on grounds that are independent of the AH. Most of the theses are uncontroversial and should be respected by any account of knowing what an experience is like. At this stage Black certainly is ok.

Acknowledgements

The idea for this paper originated at the Rio Conference on Phenomenal Concepts in January 2013. Presentations and discussions there gave the impression that the ability hypothesis had been taken off the menu of attractive physicalist responses to the knowledge argument. We were concerned that this impression may give rise to the folklore that the AHisno longer available; that it had been refuted or, at least, that its weaknesses are so many that the physicalist should better look elsewhere. A fair assessment of the state of the game was called for. We wish to thank the participants in the above mentioned conference, our graduate students in Rio de Janeiro and Frankfurt, and various audiences who commented on parts and versions of the paper.

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AF

Institut f¨ur Philosophie

Goethe-Universit¨at Frankfurt am Main fuhrmann@em.uni-frankfurt.de

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WM

Departamento de Filosofia, IFCS Universidade Federal do Rio de Janeiro mendonca@ifcs.ufrj.br

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