The knowledge argument and phenomenal concepts (or, Mary’s Room redecorated)

A month or so ago I wrote a post [1] about the knowledge argument against physicalism in which I offered my take on a reply known in the literature as the ‘ability hypothesis’. Roughly put, the ability hypothesis says that while the physically omniscient Mary does have a novel experience when she leaves her monochrome room and sees a rose, her acquisition of this new knowledge-of-what-red-is-like is not an acquisition of a new true belief but of a new ability — the ability to imagine or recall the experience of red.

The analogy to consider is with something like juggling: I could know all the physical facts about juggling and still not know how to juggle, for the simple reason that I spend all my time reading books about the neural peculiarities of legendary jugglers when I could be practicing my 4-ball shower. Naturally, this isn’t a problem for physicalism. Thus if the knowledge argument rests on an equivocation between knowing in the sense of knowing how and in the sense of knowing that — as the ability hypothesis says it does — then it doesn’t stick as an objection to physicalism.

I made a real howler in that piece. I cited David Papineau as having fleshed out a “particularly thorough version” of the ability hypothesis in his paper Phenomenal and Perceptual Concepts, when he does nothing of the sort. The ability hypothesis is in fact usually associated with David Lewis [2], while Papineau’s own reply to the knowledge argument lies several turns in the road beyond it (making it a counter-objection to an objection to a reply to an argument against physicalism — but you all still love the philosophy of mind, right?) In the name of karmic adjustment I shall now try to give Papineau’s argument the airing I denied it last time.

In order to respond to the ability hypothesis one would have to show that with her novel experience Mary acquires not just some new know-how, but also some new ‘know-that’. Consider the following modification of the knowledge argument: rather than being let out of her room to behold a rose, or turning on the colour television, Mary remains in her monochrome environment but while she sleeps some shady character slips a piece of red card into the room via a hatch in the wall. When she wakes and sees it, Mary has a novel experience. But unlike when she sees a rose, or the Australian flag on her television, she does not know which colour concept to associate with it. She knows all about ‘red’ of course — which chemical substances are red, which region of the spectrum it occupies, etc. — but since she has never seen it before, and since a piece of card could be any colour, she doesn’t know that what she’s experiencing is red, as opposed to, say, blue.

Intuition suggests that despite this Mary can still form a concept which references the experience — let us call it Q — with which she can have thoughts such as “that piece of card causes Q”, “I had Q earlier”, etc. If she then discovers or is told that the piece of card is red, it seems that she’s suddenly furnished with all sorts of know-that which she didn’t have (and, more importantly, couldn’t have had) previously. For example, she knows that light in the red region of the colour spectrum elicits Q when it hits her retina. Since ex hypothesi she already possessed all the physical knowledge it cannot have been exhaustive, and the knowledge argument holds tight.

Concepts like Q are called phenomenal concepts. When we start taking phenomenal concepts seriously, the ability hypothesis begins to look thin. The ability to recall an experience is precisely what enables the consistency of reference required for a concept to hook onto it [4], thereby opening the possibility of new know-that. There does not seem to be anything analogous going on in the case of juggling.

This is the juncture at which Papineau’s point becomes relevant, because it inverts the above considerations and uses the notion of a phenomenal concept to flesh out a physicalist response to the knowledge argument. It goes like this. If physicalism is true then the experience referenced by Q simply is some physical or physically instantiated property — call it P. So when Mary learns that light in the red region of the colour spectrum elicits Q when it hits her retina, this is the same as learning that light in the red region elicits P when it hits her retina. But she already knew this, because P is a physical property. So it seems that on a physicalist view Mary has not in fact added anything to her description of the world. What she has done is discovered that P and Q refer to the same thing. Papineau illustrates the point like so [5]:

Suppose a researcher into educational history knows of all the 117 children in Bristol Primary School in 1910—including Archie Leach.  Then she learns, on reading Movie Magazine, that Cary Grant was also at the school in 1910.  In a sense, she has learned something new.  But this doesn’t mean that there was an extra child in the school, in addition to the 117 she already knew about.  In truth, Cary Grant is one and the same person as Archie Leach.  Her new knowledge is only new at the level of concepts.  At the level of reference there is nothing new.  The objective fact which validates her new knowledge that Cary Grant was at that school is no different from the objective fact that validated her old knowledge that Archie Leach was at the school.  (Moreover, if she comes to learn that Cary Grant = Archie Leach, the fact which makes this identity true is similarly none other than the fact she always knew, that Archie Leach = Archie Leach.)

This seems to me to be both nifty and simple. If we accept phenomenal concepts, Mary’s knowledge is not about the world, but about the mappings between two conceptions of the world she’s formed from ‘different angles’. If on the other hand we don’t accept phenomenal concepts, then the ability hypothesis still stands.

Notes:

[1] Mary’s room and the Myth of the Given

[2] David Lewis – What Experience Teaches

[3] Phenomenal concepts are not uncontentious — they seem, for example, to be exactly the sort of thing rendered impossible by Wittgenstein’s private language argument. But hey, there’s hardly any consensus on how successful that is as an argument, so maybe the intuitive plausibility of phenomenal concepts is points against it. (See Papineau’s paper below for more on this.)

[4] David Papineau – Phenomenal Concepts and the Private Language Argument

Mary’s Room and the Myth of the Given

Frank Jackson originally put his knowledge argument against physicalism (aka Mary’s Room) like so [1]:

Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’.… What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false.

The argument runs:

1. Mary has all the physical knowledge of colour vision there is prior to turning on the television.
2. When Mary turns on the television, she gains some new knowledge of colour vision. (She learns what it is like to see red, say.)
3. Hence, the physical knowledge of colour vision does not exhaust all there is to know about colour vision.
4. Physicalism implies that the physical knowledge of colour vision is all there is to know about colour vision.
5. Hence, physicalism is false.

Objection 1: begs the question

One objection given by Dennett [2] is simply that premise 2 begs the question against physicalism. To say that no amount of physical knowledge of sensations (physiology, word-usage, etc.) can amount to knowing what the sensation is like is just to say that physicalism is false, according to Dennett, and so can hardly be used as the basis of an argument against it.

We can see from this that Dennett signs up to certain aspects of the argument. He seems to accept that were Mary to have a novel experience when she turns the television on, this would be a problem for physicalism. On physicalism, then, Mary should somehow be able to ‘synthesise’ the sensation of red by examining, absorbing, and understanding a whole heap of propositions about colour vision – and nothing else. So even if we accept Dennett’s unfavourable analysis of the logic, the price seems to be admitting that physicalism has implications which border on the magical.

Dennett’s response to this would be that the magic has already been injected into argument by way of the massively unrealistic conditions stipulated in premise 1. And so the wheel keeps turning. For now though, let us forget this line of reasoning. Instead I want to turn to another objection to the knowledge argument, one which I have realised recently is much, much better.

Objection 2: appeals to the myth of the given

The new objection contends that even if Mary were to have a novel experience, this does not entail that she acquires any relevant new knowledge. If this is so, the fact of her having a new experience does not conflict with the physicalist premise that her complete knowledge of the physical facts is exhaustive of the facts in general. The argument misfires completely, and its refutation need not sign physicalists up to any queasy voodoo.

There are many variations on this objection (a thorough one is given by Papineau [3]), but here I want to link the general idea with Wilfrid Sellars’ notion of the ‘myth of the given’ [4]. So from now on let’s assume (a) that Mary knows everything there is to physically know about colour vision (in the broadest possible sense) and (b) that she really does have a novel experience when she turns on the television (contra Dennett).

What does (a) mean? Roughly speaking, to ‘have all the physical knowledge’ is to know all the observable facts about brains, light, colour-word usage, etc., plus all the theoretical facts about how these relate to each other. In other words, (a) stipulates that Mary has a certain amount of propositional knowledge – a body of beliefs satisfying whichever requirements you feel are necessary to earn the title ‘knowledge’. According to (b) she has a novel experience, thus learning something new. But how does having a new experience entail learning a new fact? Perhaps it doesn’t.

OK, but surely she gains some sort of new knowledge? Isn’t that how we’d say it: “Mary now knows what red is like”? Indeed we would, but it’s unclear why this should be relevant. If I say “I know what spinach tastes like”, for example, all I am saying is that I have tasted spinach. Maybe we should add an extra condition that I should be able to recall that taste, in order to fully capture the notion of ‘knowledge-of-what-something-is-like’. Even with this caveat, my transition from not knowing what spinach is like to knowing what it is like does not imply that I know any new facts about spinach. All it implies is that something about me has changed. So there may be new facts about me – I probably even know these new facts – but I don’t know anything new about spinach or spinach flavour [5].

If we call knowledge in the sense of knowing what something is like ‘know-like’, and propositional knowledge ‘know-that’, we can say that when Mary turns on the television and sees red, she gains some new know-like but no new know-that. At a push we might say she does gain some new know-that, but only in the sense that she now knows facts like “I have experienced red”. But this isn’t new knowledge about colour or colour vision, this is new knowledge about her own past – of an event that has occurred only since pressing the television’s on button.

So the question is: why should any of this be a problem for physicalism? The implication of physicalism is that the physical facts determine the mental facts. There is no implication that people who know all the physical facts will have encountered certain sensations, or be able to relive those sensations. In order for Mary’s novel experience to pose a problem, it would have to amount to her epistemic acquisition of some relevant new fact (where relevant means ‘about colour or colour vision’). But to assume that it does is just to conflate sensing with knowing – know-like with know-that – and this is the myth of the given.

It seems to me, then, that the knowledge argument falls straight into Sellars’ trap. In order to conflict with physicalism, premise 2 has to be taken as claiming that Mary not only has a novel experience, but gains some relevant new propositional knowledge. But there is no reason to think this. That she does indeed have a novel experience is a claim that tugs hard at our intuitions, but without some separate account of how the gap between know-like and know-that is to be bridged, the argument is left looking thin.

Edit: the citation I give of David Papineau in this post is highly dubious — Papineau does not support the objection I outlined. Please see this post for correction and elaboration.

Notes:

1. Frank Jackson – Epiphenomenal Qualia
2. Daniel Dennett – Consciousness Explained
3. David Papineau – Phenomenal and Perceptual Concepts
4. Sellars develops this idea in Empiricism and the Philosophy of Mind
5. I suppose it might seem that some know-that has slipped in under the wing of ‘recalling the taste’. But I don’t think it has – to be able to recall a taste is just to be able to relive it in some sense, i.e. to summon it back to consciousness (or some derivative version of it).