From a Flaw in the Knowledge Argument to a Physicalist Account of Qualia
In this paper, I examine Frank Jackson's famous 'grey Mary' thought experiment, first presented in "Epiphenomenal Qualia" (Jackson 1982) in support of his Knowledge argument against physicalism. I argue that it cannot be claimed as the basis for rejecting physicalism. First, because it is flawed, being so formulated as to predetermine the outcome of the thought experiment in favour of a refutation of physicalism. Second, because, once this is recognised, it becomes clear that there is a perspective on the qualia-physical relationship that will permit physicalism to survive the thought experiment. This perspective, it is suggested, has potential as a good candidate theory for a physicalist account of qualia. The arguments are presented from Section 3 onwards; Section 2 covers the Knowledge argument itself and positions taken for and against it in the literature.
2 Jackson's Knowledge Argument
2.1 The Argument
This is how Jackson first set out his Knowledge argument against physicalism in terms of what is sometimes called the 'grey Mary' thought experiment:
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...
....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.
On the face of it, the case is a persuasive one. The conclusion follows<1> if it is true both:
(1) That Mary (before her release) knows everything physical there is to know about other people. [Premise A]
(2) That Mary (before her release) does not know everything there is to know about other people (because she learns something about them on her release). [Premise B]
If physicalism is true the argument runs, then physical facts are the only facts - but if Mary learns all of the physical facts about colour vision in her black and white room and still learns something new on leaving it, she has acquired a fact that is not a physical fact and physicalism cannot be true.
Whether the conclusion is correct is, of course, another matter, and it is true to say that there is a fair degree of dispute on the point.
2.2 Challenging Premise B
Jackson's argument is usually regarded as presenting a challenge to physicalism that cannot easily be ignored or discounted<2>, but there is much debate over his conclusion. A steady stream of responses for and against it has appeared in the literature since its initial airing in 1982, and the activity shows no sign of ceasing<3>. In the present paper, I shall argue against his conclusion on the grounds that premise A is false. However, since much of the literature to date reflects a continuing debate on challenges to premise B, it is worth considering this first, if only to show that the efficacy of such challenges is still in dispute after many years of discussion
The major positions taken against premise B are these:
2.2.1 Physicalism stands because, contrary to our intuition, Mary learns nothing new on leaving the room
This is a position most often associated with Dennett, (1991), but a similar point is put by Churchland (1985). On Dennett's account, there is no challenge to physicalism. Mary learns nothing new on leaving the room because she is already capable, before leaving it, of identifying the colours she is about to experience by making inferences from observations of the physical states they induce. But is being able to identify a colour by this means the same as knowing what it is like? Others - including Robinson (1993) and Alter (1998) - argue (with some justice) that it is not, and that, therefore, Mary does learn something new and the challenge to physicalism stands.
2.2.2 Physicalism stands because what Mary learns is not a fact, but something else such as know-how or ability.
This position is primarily associated with Nemirov (1980<4>, 1990) and Lewis (1988), but others have supported them or put similar positions<5>. On this account, physicalism is not refuted because Mary does not acquire a new fact on leaving the room, only an ability to imagine, recognise and identify colours like red or green. She is like someone who knows all the facts about bikes and how they work but has never ridden one and learns something new (a new ability or new 'know-how') when she does.
Numerous objections to the ability hypothesis have been raised in the literature (see, for example, Alter 1998, 2001, Chalmers 1996, Conee 1994, Deutsch 1998, Gertler 1999, Loar 1990 and Lycan 1995, 1996), but the primary difficulty seems to be that, as Chalmers points out, it seems likely that Mary acquires more than just an ability when she experiences red for the first time, she also seems to acquire knowledge of what red as experienced is like: 'For all she knew before, the experience of red things might have been like this, or it might have been like that, or it might have been like nothing at all. But now she knows it is like this'. Lycan makes essentially the same point, arguing amongst other things that:
· Knowing what it is like to have an experience is arguably to know that it is like such and such to have that experience - so it is knowing a fact, rather than having an ability.
· Since one can try to describe an experience such as the taste of pineapple to someone, even if we would probably fail, it would appear that knowing what it is like means having some fact to impart.
2.2.3 Physicalism stands because what Mary learns is not a new fact only an old fact in a new guise.
Another much favoured position taken by a range of writers (Horgan 1984, Churchland 1985, Loar 1990, Lycan 1995, Papineau 1993, Tye 1986 are examples, others are referenced in Nida-Rümelin 2002 and Chalmers 1996) is the so-called old fact/new guise argument. This is the view that physicalism is not refuted because what Mary comes to know on leaving the black and white room is not a new fact, just a fact she already new in a new guise. On this account, she is like a person who knows that Mark Twain wrote Tom Sawyer then learns that Samuel Clemens wrote Tome Sawyer, the argument being that physicalism is not refuted because what appears to be a new fact is just an old fact in a new guise.
The following counter-arguments show the difficulty with this position:
(1) Someone who knows that Mark Twain wrote Tom Sawyer then learns that Samuel Clemens wrote Tom Sawyer still learns something new - that Mark Twain and Samuel Clemens are the same person. On this argument, even if experienced red is only brain event X in a new guise, Mary still learns something new when she experiences red - that there is more to be known about seeing red than is known when it is known about in terms of brain event X. Thus it is still the case that she has learned something new.
(2) Second, as Alter 1998 argues, the old fact/new guise argument seems to suggest that the new phenomenal guise (experienced red as opposed to its neurological correlates, for example) is incidental to knowing the fact in question. In the case of qualities such as experienced red, however, knowing the 'phenomenal guise' - the actual experience - appears central to the fact itself. We cannot know experienced red - the fact itself - without knowing the 'phenomenal guise', and since this cannot be known in a black and white room, it cannot be an old fact, it must be a new one. The threat to physicalism stands. An analogy (provided by Alter) would be the suggestion that one could know that the boxer called Ali had once been called Clay without first having acquired the label 'Clay'.
A variation associated with Bigelow and Pargetter (1990) likens Mary to a forgetful historian who has all the objective facts but can still learn that today is July 4th, American Independence day - she has all of the objective facts about colour vision but can still learn that this (experienced red) is red. What is acquired in both cases, it is said, is indexical knowledge and this does not refute physicalism. Again, however, there is a counter argument (Chalmers 1996). No matter how much Mary knew about her indexical relationship to the physical world, she still would not know what red is like.
2.3 Concluding Points; Jackson on Premise B
I will not labour the point on challenges to premise B. The question of their efficacy (or otherwise) has no direct bearing on the arguments presented below. The position developed is that the Knowledge argument fails to refute physicalism because of a problem with premise A, and there is an implication in this that challenges to premise B are unnecessary, but no position is taken, one way or the other, on the question of whether or not such challenges can succeed, and the case made does not depend in any way on the outcome of such challenges. The summary presented above is significant here only insofar as it shows that there is a continuing dispute as to the efficacy of such challenges after many years of discussion - and insofar as this suggests that an approach which takes the focus away from premise B may be worth examining.
One final point is worth making on this front. Jackson himself has latterly suggested (Jackson 1998) that premise B is false. However, as Vinueza n.d. notes, Jackson does not really present a case, only indicates his feeling that there must be one. In any case, if I understand him correctly, he is approaching the problem from the following perspective:
· Physicalism must be true;
· The Knowledge argument is valid, so physicalism must be false unless our intuition is false;
· Therefore, the puzzle is to explain why we are mistaken in our intuition.
If this is so, he may well be willing to concede that the solution to the conundrum of the Knowledge argument proposed in the present paper offers a better alternative, despite the fact that it entails an assumption that Mary does acquire new knowledge. Certainly, his own suggestion as to why our intuition might be mistaken does not convince. This is that Mary's knowledge is not new, but could be arrived at by following a long and complex chain of inference. Our intuition that it is new is an illusion created by the fact that it is acquired in a much more immediate 'all at once' fashion.
3 Challenging Premise A: The Flaw in the Knowledge Argument
3.1 The Flaw in the Knowledge Argument
I believe that Jackson is correct in suspecting that there is a problem with the Knowledge argument, but that the problem lies, not with premise B, but with premise A. The position I take shares common ground, in varying degrees, with positions taken by writers such as:
· Flanagan 1992, who exposes essentially the same problem with premise A identified in the present paper, albeit in a different fashion, and also reaches a similar conclusion as regards Mary's new knowledge - that it can be physical and a way of knowing the physical world without being fully expressible in the language of even a completed science.
· Conee 1994, who argues that Mary's new knowledge is only acquaintance knowledge, not prepositional knowledge, and that there is no case for believing that acquiring such knowledge represents a challenge to physicalism - that acquaintance knowledge may just be knowledge of something physical that Mary already has prepositional knowledge of and that does not encompass any new (prepositional) fact.
· Deutsch 1998, who argues that the Knowledge argument does refute physicalism if we adopt what he calls the language of science conception of physical facts but not if we adopt an ontological conception of the physical facts, and that the first of these is harmless and only tells us that the language of science cannot handle subjective physical facts.
· Sommers 2002, who argues (albeit on different grounds than I do) that we assume too much when we accept premise A.
Echoes of all of the above views are to be found in what follows, although the the argument is, I think, a new one. In essence, it is that the Knowledge argument as usually formulated is flawed - that, through premise A, it is so constructed as to predetermine the outcome of the thought experiment in favour of a refutation of physicalism.
Briefly put, the position is this. If we know that it is 'just obvious' that there is knowledge that cannot be acquired inside a black and white room, then the simple act of asserting that all physical knowledge can be acquired inside it presupposes, both that the knowledge that cannot be acquired inside the room is non-physical, and that physicalism is false.
If we know there is more knowledge than can be acquired inside a black and white room when constructing our thought experiment, then, by formulating the Knowledge argument so as to assert that all physical knowledge can be acquired inside the room, we effectively define the knowledge that cannot be acquired inside it as non-physical, thereby predetermining the outcome of the thought experiment in favour of a refutation of physicalism (since, if non-physical knowledge exists, physicalism must be false). The appearance of inference is a sham, albeit an unwitting one. If we know that there is knowledge that cannot be acquired inside the room and assert that the knowledge that can be acquired inside it is all of the physical knowledge that exists, then, by implication, we assert that non-physical knowledge exists and presuppose that physicalism is false. More, by taking the set of all knowledge and stating that only a portion of it is all physical knowledge, we assert that the set of all knowledge is subdivided into physical and non-physical knowledge - that physicalism is false.
An illustration may help drive home the point. Imagine a Mary with colour vision in a room full of children's bricks. She collects 99 red bricks and concludes that the statement all bricks in the room are red is true. Then a child tells her he put another brick in a cupboard. He cannot recall its colour and the cupboard is now locked. Mary wants to know if her conclusion still holds. She might argue, as a Knowledge argument supporter might, that since she already has all the red bricks in the room, the remaining brick must be a non-red brick and that the statement all bricks in the room are red is false. If she does, however, she rather obviously skews the argument in favour of a refutation of the statement. To assert that the bricks she has are all the red bricks knowing there is another brick in the cupboard she has not seen, is to define the remaining brick as non-red, ensuring that the statement will be refuted. More, it is to assert that the complete set of bricks is divided into red and non-red bricks and so assume directly that the statement is false.
3.2 All True Statements Versus Physical Knowledge
Of course, the implication in Jackson's argument is that we actually know that Mary can acquire a complete knowledge of the physical in her black and white room - else, as Jackson 1982 points out, the Open University would need colour television to conduct its business. If this is true, we presuppose nothing and the argument holds. But how can it be true? Certainly, there is a good case for holding that Mary in her black and white room can acquire a knowledge of all true statements about the physical, of their significance, and of still and moving pictures of their real world referents (in black and white). We can safely assume, I think:
· That the physicalists outside Mary's room, who do not suffer the limitations that Mary does, can, given sufficient time, ingenuity, and instrumentation, acquire such knowledge of the physical;
· That they can then express this in a set of books and videos illustrated in colour;
· That they can then convert these to black and white but work to ensure that in every case where distinguishing between colours is vital to an understanding of a true statement about the physical, such a distinction is made clear in black and white (and shades of grey) and can be made by someone in a black and white room.
Suppose then that Mary in her black and white room has access to these books and videos, and also to remotely controlled instruments that allow her to repeat key experiments in black and white (and unlimited time). Suppose further that she also has access to interactive instruction from the scientists themselves who do have access to colour information, do understand its relevance to the set of statements, and do understand the limitations placed on Mary and actively strive to overcome them. In these circumstances, there are, I submit, no grounds for holding that she cannot acquire knowledge of all true statements about the physical inside her black and white room. As long as she can distinguish between colours, albeit in black and white, she can learn to understand the contents of the books and videos and also make and understand the observations that support true statements and refute false statements. This being so, there is, I submit, no reason to suppose that she cannot acquire knowledge of all true statements about the physical, of their significance, and of still and moving pictures of their real world referents inside her black and white room<6>. This is sufficient to meet the needs of the Open University in a world before colour TV. It is sufficient to ensure that Mary can pass any exam that might be set on the nature of the physical world. It is even sufficient to ensure that, on leaving her black and white room, she need acquire no new operational knowledge of the physical world despite the limitation she was previously subject to. But is it sufficient to allow us to conclude that she has acquired all physical knowledge inside her black and white room?
The answer, of course, is that it is not. As long as we know that it is 'just obvious' that Mary will learn something new on leaving her room, we cannot safely assume that she has acquired all of the physical knowledge when inside it - any more than our Mary with the bricks can assume that she has all the red bricks in the room when she knows there is another brick of unknown colour in a locked cupboard.
3.3 A Continuing Threat to Physicalism from the Grey Mary Thought Experiment
As it stands, the Knowledge argument is flawed and the problem lies with premise A, the assertion that all physical knowledge can be acquired inside Mary's black and white room. The assumption that this is true leads inevitably to the conclusion that Mary's new knowledge is non-physical and that physicalism is false. This conclusion is problematical on two counts:
(1) Given that there is knowledge that can only be acquired outside the black and white room, the assumption that all physical knowledge can be acquired inside it:
· Effectively defines the knowledge that can only be acquired outside the room as non-physical, thereby predetermining the outcome of the thought experiment in favour of a refutation of physicalism
· Subdivides the set of all knowledge into some that is physical and some that is not, thereby assuming in a more direct way that physicalism is false
(2) We can only know for certain that premise A is true by examining Mary's new knowledge and determining directly whether or not it is or, rather (since this is a thought experiment), can be physical knowledge. However, the assumption that premise A is true stops us making this examination by forcing the conclusion that Mary's new knowledge must be non-physical.
Once this flaw is recognised, the apparent threat to physicalism from the Knowledge argument as stated is negated. It is no longer possible to hold that Mary has acquired all physical knowledge in her black and white room and that, therefore, the knowledge she acquires on leaving it is necessarily non-physical knowledge that must refute physicalism. Notice, however, that this does not necessarily negate the threat to physicalism posed by Mary's acquisition of new knowledge on leaving her black and white room - by the thought experiment itself. It is still possible that Mary's new knowledge will refute physicalism. In fact, in this new scenario, it becomes clear that there are additional possibilities to consider in this regard. Mary's new knowledge will refute physicalism if it is non-physical knowledge, or is itself 'made of' something non-physical, or both. What is different in this new situation is that the question is left open. It is no longer necessarily the case that Mary's new knowledge must refute physicalism because it can be nothing but non-physical knowledge. Instead, the question of whether or not physicalism is refuted by the grey Mary thought experiment is decided (as it must be) through an examination of the new knowledge itself. If it can be shown that it is possible, in the situation described in the thought experiment, for Mary's new knowledge to be valid knowledge of the physical that is itself 'made of' something physical, the thought experiment cannot be successfully used as a basis for refuting physicalism. If it can be shown that this is not possible, it can continue to be so used (although not on the basis of Jackson's Knowledge argument).
4 How Physicalism Can Survive the Grey Mary Thought Experiment
In fact, as will now be shown, there is only one set of circumstances in which it is possible for Mary's new knowledge to be physical itself and valid knowledge of the physical given the situation described in the thought experiment - a particular physicalist account of qualia must be true. Specifically, physicalism can survive the thought experiment if and only if it is true of Mary's new knowledge and - by extension - any quale<7>:
(1) That it is really nothing but, or entirely reducible to, some physical event within the organism experiencing it - a physical event experienced as a quale by an inside observer of that human organism, and as an aspect of the flesh, blood and brains view of the organism<8> by an outside observer.
Suppose that, in the first instance, what Mary learns on leaving the black and white room is what experienced yellow is like - that her new knowledge is a yellow quale. Clearly, the new knowledge is a new event in Mary - one that has not occurred before. If this event is not a physical event, it must be a non-physical event and physicalism is refuted. But there is no physical event in humans generally (as opposed to herself individually) that Mary does not already have an outside observer's knowledge of - so if this new event in herself is something physical, it can only be a different perspective on a physical event she already has an outside observer's knowledge of in humans generally. More, it must be true that it is really nothing over and above the physical event in question. If it is not, then it can only be something over and above everything physical in the organism - which is to say something non-physical that will refute physicalism.
(2) That both the inside observer's private experience of it (as a quale) and the outside observer's experience of it (as some aspect of the flesh, blood and brains view of the organism) are limited perspectives on this physical event that 'just is' the quale - that each is the reality as known as distinct from the reality as such.
Suppose that an outside observer experiences the physical event that 'just is' the yellow quale as an electro-chemical reaction occurring between pinky-white fibres in the brain - something very different from the yellow quale experienced by the inside observer, Mary. Call the reaction in the brain a firing b-fibre. If physicalism is to survive the thought experiment, it must be the case (see under point 4(1) above) that the yellow quale is really nothing over and above the firing b-fibre. But how can this be true when the firing b-fibre is so different from the yellow quale - and other qualia such as a dull ache or a loud noise - that it is hard to imagine how the two could possibly be one? There is, I submit, only one possibility. If the two are, in fact, a single reality, it can only be true that each is the reality as known (from a particular limited viewpoint) as distinct from the reality as such. If a yellow quale is really something that has the characteristics we associate with aspects of the flesh, blood and brains view of the human organism, and vice versa, then what we get when we experience a yellow quale or a firing b-fibre must be a limited perspective on a reality rather than the reality in its own right.
This is probably easier to accept of a quale than it is of the firing b-fibre, which we tend to think of as being, in some sense, more real. In this latter case, however, there is additional supporting evidence. Although I have focused for the sake of simplicity on the idea that Mary's new knowledge is only knowledge of the colour yellow, in reality she would, on leaving her black and white room, begin to experience everything - including the outside observer's flesh, blood and brains view of other humans - in colour. Clearly, therefore, this view is itself a private perspective in the experience of an outside observer and hence, must be something other than the reality of the other human that the outside observer is observing.
Moreover, it should, in any case, be self-evident that the outside observer's physical view is the reality as known as distinct from the reality as such. In this instance, the observer is clearly physically distinct from the reality observed and can only have access to it via his own senses and thoughts which, since he is an outside observer, can only, by definition, be something other than the reality itself - the reality as known as distinct from the reality as such.
Further support for this conclusion comes from a consideration of Leibniz's Law and Kripke's problem for proposed identities.
Leibniz's law is concerned with the conditions under which things can be regarded as identical. It states that if x is y, then any property of x is a property of y. This is a not a problem for a view that holds that what we get when we experience a quale is the reality as known as distinct from the reality as such, but it is otherwise. To claim that something like a yellow quale is identical with something in the brain like a firing b-fibre is to claim that any property of the one is a property of the other. However, if the quale we know 'just is' the reality of the quale, and the same is true of the firing b-fibre, then, on the face of it, each has quite different (and, indeed, incompatible) properties:
· The b-fibre appears solid, fleshy, material, and probably pinky-white, the quale appears yellow and anything but solid, fleshy, and material.
· The b-fibre is publicly observable, the quale is the opposite - a private event known only to the person experiencing it.
· The b-fibre has a definite, locatable, position in space, the quale cannot be so located.
Again, the question is how can two such unalike things be identical?
The answer to this, of course, is provided by the position defended here. In this perspective, what we get when we experience the quale on the one hand and the firing b-fibre on the other is (in each case) the reality as known as distinct from the reality as such. This means that it is entirely consistent with both Leibniz's law and common sense that the two are simply one thing known in two different ways:
· It is not a problem that the yellowness of the quale is not a property of what McGinn (1989) called the 'soggy grey matter' of the brain and its b-fibres and vice versa, because both can be said to be characteristics of this single underlying reality that is the real basis of the identity.
· The fact that public observability is not a property of the quale, and private observability is not a property of the firing b-fibres, and that anything public is, by definition, not private, and vice versa, is not a problem. There is no difficulty because it can be said to be characteristic of the single underlying reality, both that it can be known publicly, and that it can be known privately.
· The fact that every aspect of what the outside observer knows as soggy grey matter has a precise location in physical space and that a quale is impossible to locate in physical space is not a problem. Again, locatability in public space and knowability in terms of private experiences that cannot be so located are both characteristic of the underlying reality in which the identity resides. The reality known by an inside observer as a private experience can be said to be located in public space when known and observed publicly by outside observers. It is simply that, when it is known privately, it is known in a way which makes location in space impossible.
Kripke's Problem for Proposed Identities.
Distinguishing between the reality as known as distinct from the reality as such in this way is also the only way in which an identity position can deal with Kripke's problem for proposed identities. Kripke (1980) notes that Leibniz's Law demands that if A is B then A is necessarily B. There are no circumstances in which this is not true - it is true in all possible worlds. There are examples in the world of identities where this may appear to be false - where it appears we can conceive of possible circumstances in which the identity does not hold. However, if there is true identity, these must arise from a misconception of some kind, and it will be possible to discover and specify the basis of the misconception.
An example is the identity between H2O and water. We can imagine a possible world in which water is not H2O but XYZ - but this, to quote Chalmers (1996) is illusory. In fact, we are imagining something that has the properties of water, but that is not actually water. The identity is not threatened because what we have imagined is not an instance of water not being H2O but only of something like water not being H2O.
Now consider that it is possible to conceive of circumstances in which a quale, such as an experience of pain, can exist without being accompanied by a firing b-fibre, and vice versa - the idea of disembodied pain seems to us to be plausible, as does the idea of a zombie who has the firing b-fibres, but no feelings of pain or anything else. These are examples of a possible world in which a claimed identity between the quale and a firing b-fibre appears not to hold. By Kripke's argument, unless it can be shown that they are based on misconceptions, they threaten the claimed identity.
This is a potential problem for a claim that any given quale is identical with some aspect of the flesh, blood and brains view of the human organism. The kind of argument detailed above for H2O and XYZ does not work for pain and firing b-fibres. Pain 'just is' pain, and firing b-fibres 'just are' firing b-fibres. We cannot plausibly argue for the existence of something that feels like pain but is not or something that appears to be a firing b-fibre but is not. If the examples of zombies without feelings and disembodied pain are to be shown to be misconceptions, it must be on some other basis.
As will be evident, however, the problem disappears if we accept the perspective outlined in this section (4(2)). From this position, what we know as pain and what we know as the corresponding b-fibre are different perspectives on one underlying reality. Zombies and disembodied pain appear reasonable to us, but this is based on a misconception. They appear reasonable because they are usually only observed in isolation from each other - one of the perspectives is accessible only to an inside observer of the human organism, the other is accessible only to an outside observer, and (except in very unusual circumstances) the two are unlikely to ever be accessible to one observer simultaneously. Despite this, they are, in this view, one reality. Zombies and disembodied pain seem reasonable possibilities but they are not - pain is always accompanied by the corresponding firing b-fibre and vice versa. We can observe the one occurring without the other if our perspective is limited. However, in reality, they do not exist separately - they are different views of one underlying reality.
If, however, we do not distinguish between what we know as pain and an underlying reality, and what we know as b-fibres and an underlying reality, this explanation is not available. This means that it cannot be the case that a quale is really nothing but some aspect of the flesh, blood and brains perspective on the human organism and, hence, that physicalism cannot survive the grey Mary thought experiment.
(3) That the knowledge content of the inside observer's perspective on the physical event that 'just is' the quale:
· Cannot be expressed verbally without loss
Clearly, if the knowledge content of Mary's new knowledge can be expressed verbally without loss, then it can be expressed as a statement. But Mary has already acquired all true physical statements in her black and white room. If she learns something new that can be expressed as a statement, the knowledge must be non-physical and physicalism is refuted. Only if the knowledge content of her yellow quale is experiential knowledge that cannot be expressed verbally without loss - an entirely reasonable circumstance given what we know about qualia - can physicalism survive her acquisition of new knowledge.
· Is irreducible to the knowledge content of the set of true physical statements that comprise a complete propositional knowledge of the event
Equally clearly, if Mary's new knowledge cannot be expressed verbally without loss, as must be the case if physicalism is to survive, it is obviously irreducible to the set of true physical statements that comprise a complete propositional knowledge of the event (and must be so if physicalism is to survive).
· Is nevertheless additional physical knowledge that is in some sense valid.
Finally, either Mary's new knowledge is non-physical knowledge and physicalism fails, or it is physical knowledge and physicalism stands. If it is truly physical knowledge, and is irreducible to the set of true physical statements, then it is clearly physical knowledge that is additional to this set of true statements. If it cannot be expressed verbally without loss, then it cannot be held to be true (or false) in the normal sense, but if it is (as it must be in the scenario described in the thought experiment) truly physical knowledge then, it must, in some sense, be valid physical knowledge - specifically, knowledge that is a true reflection of what the occurrence of the physical event in question is like for an inside observer of the human organism.
(4) That the set of true physical statements that comprise a complete verbally expressible knowledge of the (physical) event that 'just is' the quale is sufficiently comprehensive in terms of knowledge content:
· To permit the re-creation of the event, including its experiential aspect
If physicalism is true, a quale 'just is' the physical event known to an outside observer as something like a firing b-fibre. The outside observer's experience of the event as a firing b-fibre is the reality as known as distinct from the reality as such, but it is the reality as such that is studied by scientists<9>, and it is this study that gives rise to our propositional knowledge of the event. Normally, if we have acquired a complete propositional knowledge of a physical reality then, practical difficulties aside, it is safe to say that we have sufficient knowledge to recreate the event, together with all of its characteristics, and there is no reason to suppose that the same would not be true of the physical event that 'just is' a quale. If the quale 'just is' a particular firing b-fibre, then making that b-fibre fire will give rise, in the organism itself, to the experience associated with the quale - and, practical difficulties aside, we should have no difficulty in making the b-fibre fire if we have a complete propositional knowledge of it. If it turns out that we do, then there must be some doubt as to whether the quale 'just is' the firing b-fibre (or whatever physical event we like to substitute for it) - and, hence, some doubt as to whether physicalism holds.
· To account for it having, both this experiential characteristic and, indeed, any experiential characteristic at all
We should also, in these circumstances, be able to account both, for the physical event that 'just is' the quale having this particular experiential characteristic, and for it having any experiential characteristic at all. Once it is recognised that the yellow experience is as much a characteristic of the physical event that underlies the firing b-fibre as its pinky-white colour or fleshy feel, it becomes evident that we can account for it having both this particular experiential characteristic, and for it having any experiential characteristic at all. We should be able to do this in the same way that we do it for all other observed characteristics of things in the physical world - by specifying what physical things have the characteristics, how they differ from other physical things that do not, and how those differences account for the differences in observed characteristics. If physicalism is true, then some physical things 'just are' qualia - they exhibit experiential characteristics and they do so because they differ in discoverable ways from physical things that are not qualia. Equally, different physical things that exhibit these characteristics differ in the kinds of experiential characteristics they display - and they do so because they differ in discoverable ways from each other. Again, if this is not true there must be some doubt as to whether the quale 'just is' some physical event and, hence, whether physicalism is true.
(5) That a comprehensive physical knowledge of the quale must nevertheless include the irreducible knowledge content of the experiential aspect itself if it is to be considered complete
It is, of course, possible to express our explanation of experiential qualities in wholly verbal terms, and this will normally be enough for most human purposes – most of us know what is meant by phrases like 'yellow experience' and 'sweet taste'. However, if experiential knowledge is valid knowledge of the physical that cannot be expressed verbally without loss and is additional to the set of all true physical statements (as - see 4(3) it must be if physicalism is true), then a purely verbal account of qualia cannot, of itself, be considered complete. If it is to be regarded as comprehensive, our physical knowledge of the quale must be explicitely recognised as including the non-verbal ‘what its like’ experience associated with the quale and, more, must actually encompass, not just a verbal reference to that non-verbal experience, but the actual non-verbal experience itself. An alien race with entirely different sensory systems might in time come to understand our verbal account of experience and experiential differences, but they would never have a complete knowledge of the physical events that 'just are' qualia, because they would lack knowledge of what it is like to experience them.
The above analysis does not show that physicalism is true, nor even that the grey Mary thought experiment fails to refute it. What it shows is that the question of whether or not the grey Mary thought experiment refutes physicalism can only be resolved by further examination of the perspective on the qualia-physical relationship drawn out as a result of the analysis. If the perspective is false - if the position set out under 4 (1) to 4(5) above is not an accurate description of the actual nature of qualia - the thought experiment will refute physicalism, there being no other position that will permit it to survive the thought experiment. If the perspective is true - if it is an accurate description of the actual nature of qualia - the thought experiment will fail to refute physicalism, a significant outcome in circumstances where qualia are probably the only question mark remaining against the physicalist viewpoint.
5 The Hard Problem of Consciousness
Another significant point in favour of the position outlined is this. The perspective described in 4(4) and 4(5) above permits us to give an account of experience in terms of what Chalmers (1995) calls the physical as we presently understand it, to do so without losing the unique experiential aspect of qualia, and - since the experiential is included as knowledge that cannot be expressed as a statement and cannot be true or false in the normal sense, but only as valid, non-propositional, knowledge of the physical - to do so without in any way undermining our view of the physical as we presently understand it.
The key to this is the recognition that a quale and some aspect of the flesh, blood and brains view of the human organism can be one physical reality provided we recognise that what we get when we perceive this reality from either of these perspectives is the reality as known as distinct from the reality as such. Without this distinction then, as is clear from 4(2) above, we are left with a position where qualia are (or appear to be) irreducible to the physical as we presently understand it and cannot be dealt with in terms of it. If we give a complete account of the human organism in terms of the physical as we presently understand it without making this distinction, it fails to deal with experience on two counts. On the one hand, since experience is irreducible to the physical in this perspective, we cannot reasonably hold that the physical account deals with experience. On the other, a purely physical account (in this perspective) leaves experience itself out of the account. If we then wish to deal with experience in terms of a physical viewpoint, we are led inevitably to a position akin to that expounded by Chalmers (1995) where experience itself must be taken as a fundamental property of the world alongside mass, charge, and space-time (we must, in effect, 'add' experience to our view of what we regard as physical).
The position outlined above does not require this and is therefore a better solution to what Chalmers calls the hard problem of consciousness (although, in this account, it is just another of the 'easy' problems of consciousness). Some physical things 'just are' qualia - they exhibit experiential characteristics and they do so because they differ in discoverable ways from physical things that are not qualia. Equally, different physical things that exhibit these characteristics differ in the kinds of experiential characteristics they display - and they do so because they differ in discoverable ways from each other. A complete verbally expressible account of the physical events and their inter-relationships will account, both for the experience itself, and the differences between types of experience. Of itself, such an account will also 'miss out' experience. However, in this perspective it is an easy matter to include it as additional knowledge that cannot be expressed verbally, is neither true nor false but valid physical knowledge nonetheless, and that simply makes our knowledge of experience comprehensive by encompassing what it is like in our total physical account. It is not necessary, as it is in Chalmers' perspective, to regard it as an additional fundamental feature of the world alongside mass, charge, and space-time.
6 Conclusion: A Candidate Theory for a Physicalist Account of Qualia
Whether or not the perspective outlined is an accurate description of the true nature of qualia is a matter for further discussion and debate. I submit, however, that it does have a potential as a candidate theory for a physicalist account of qualia:
(1) Dealing with Jackson's Thought Experiment
It is not simply one position that will permit physicalism to survive the grey Mary thought experiment, it is the only position that will permit it to do so - physicalism fails if any of the requirements described above are not met. This, in itself, makes it of interest as a candidate theory for a physicalist account of qualia. Not only does the position outlined negate the force of a thought experiment that many regard as a serious challenge to physicalism, it is the only position that can do so - the challenge against physicalism succeeds if the position is not an accurate description of the actual situation.
(2) Dealing with Leibniz's Law.
It shows how the idea that qualia can be identical with some aspect of the physical as we presently understand it can be consistent with Leibniz's law.
(3) Dealing with Kripke's Problem for Proposed Identities.
It shows how an identity position can deal with Kripke's Problem for Proposed Identities.
(4) Dealing with Chalmers' Hard Problem.
It offers a solution to Chalmers' hard problem without the need to take experience itself as a fundamental property of the world alongside mass, charge, and space-time (Chalmers 1995).
(5) A Plausible Account.
It is a plausible account of the qualia-physical relationship - it is quite possible and reasonable to imagine that it may be true.
These various points are not conclusive. The position outlined may have flaws not drawn out here, or may, in the event, turn out to be a view that can be shown empirically to be incorrect. I submit, however, that the position does have clear points in its favour and is worthy of further consideration as a reasonable candidate theory for a physicalist account of qualia (or, at least, the basis for one<10>).
<1>. As Thomas 1998 notes, there appears to be a general acceptance in the literature that the argument itself is sound, a point I will not dispute since it is not necessary to my case
<2>. See, for example, Graham and Horgan 2000 - self-confessed physicalists who argue that the strength of its challenge to physicalism cannot be ignored
<3>. For further information on this literature see Nida-Rümelin 2002
<4>. Its first statement predates the Knowledge argument as such, and was a response to Nagel's 'What is it Like to be a Bat?' (Nagel, 1994). This is an influential paper to which Jackson (1982) acknowledges a debt, but is not considered further in the present paper.
<5>. See, e.g. Churchland (1985), who goes further and argues the new knowledge need not be an ability to refute Jackson's argument so long as it is a different type of knowledge of exactly the same thing, and Mellor 1993.
<6>. Thomas 1998 has argued that Jackson's argument fails because it is incoherent - that Mary could not acquire a complete knowledge of the physical inside the black and white room because it is impossible to do so without access to colour information. This may or may not be true, but even if it is true, it need not affect Mary in the circumstances described. On the one hand, Mary is only claimed to have acquired knowledge of true statements, not experiential colour knowledge. On the other, she does have indirect knowledge of colour - because the scientists have this knowledge and make every effort to pass it on to her where it is relevant to her acquisition of true statements.
<7>. In the thought experiment described here, Mary's new knowledge comprises only all colour qualia - a blue quale, a green quale, a red quale, and so on. However, as Jackson himself notes in his initial paper on the Knowledge argument (Jackson , 1982), "... the same style of Knowledge argument could be developed for taste, hearing, the bodily sensations...". In short, Mary's new knowledge in this example can be taken as representative of any quale.
<8>. I avoid calling this perspective physical deliberately here. If physicalism is true, both perspectives are 'physical views' of the organism.
<9>. When we conduct scientific experiments and record the results, we make our observations via our senses or our senses as extended by instrumentation – through ‘the reality as known’. However, it is the reality itself that we put in the experimental circumstances, and it is the reality itself that reacts to those circumstances and that provides the data for our observations and the basis for our propositional knowledge.
<10>. Note that the repeated references to firing b-fibres in the account are illustrative only. There is no suggestion that a firing b-fibre (whatever that may be) is the type of physical event that a quale is identical with, only that it is possible to derive a position in which it is possible for a quale to be identical with some (as yet undiscovered) physical event.
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