We had reason recently to allude to Frank Jackson’s famous “knowledge argument” against physicalism. You’ll recall that the argument goes like this: Physicalism claims that if you know all the physical facts that there are to know about people, then you know all the facts there are to know about them, period; for human beings are (says the physicalist) entirely physical. But now consider Mary, a master neuroscientist of the future. Mary has lived her entire life in a black and white room, and has never had any experiences of colors. Still, having studied all the relevant neuroscientific literature, she knows everything there is to know about the physics and physiology of color perception. Hence she knows, for example, everything there is to know about what goes on in someone’s brain when he sees a red object, everything there is to know about the surface reflectance properties of red objects, and so forth. Now imagine that she leaves her black and white room and sees a red object herself for the first time. Does she learn something new? Surely she does – she learns what it’s like to see red. But then, physicalism is false. For though Mary knew all the physical facts about human perceptual experience before she left the room, she didn’t know all the facts, since she learned something when she left the room. Hence there are facts about human nature, and in particular facts about conscious experience, that escape the physicalist story – namely facts about “qualia,” the subjective features of a conscious experience in virtue of which there is “something it is like” to have that experience.Jackson first presented this argument is his 1982 paper “Epiphenomenal Qualia,” and repeated it in 1986 in “What Mary Didn’t Know.” (There were several precursors to the argument, such as Thomas Nagel’s “What is it like to be a bat?”, and similar but independently developed ideas, such as Howard Robinson’s deaf scientist example in his 1982 book Matter and Sense.) The argument has generated an enormous literature. Some of it is collected in the Ludlow, Nagasawa, and Stoljar edited volume There’s Something About Mary: Essays on Phenomenal Consciousness and Frank Jackson’s Knowledge Argument. You will find there also some later essays by Jackson in which he expresses second thoughts about the argument; for by the late 1990s he had recanted and embraced physicalism.
Why? For no good reason, in my view; nor in the view of Jackson’s fellow “knowledge argument” proponent Howard Robinson, whose (characteristically excellent) essay “Why Frank Should Not Have Jilted Mary” offers a penetrating critique of Jackson’s current views. (You can read part of Robinson’s article here, though the anthology in which it appeared – Edmond Wright’s The Case for Qualia – is well worth the purchase price.)
As Stoljar and Nagasawa note in their introduction to There’s Something About Mary, “the argument, [the later Jackson] said, contained no obvious fallacy, and yet its conclusion – that physicalism is false – must be mistaken” (p. 23). Again, why? We might distinguish two components of Jackson’s current position. First, there is Jackson’s justification for claiming that something or other must be wrong with the knowledge argument, even if it seems to be perfectly cogent; and second, there is his strategy for explaining away the apparent cogency of the argument by suggesting where a fallacy is most likely to be found in it. The second component involves appeal to a “representationalist” theory of consciousness, and interested readers will find in Robinson’s essay a useful discussion of the problems with Jackson’s application of this theory. (For my money the main problems are two: First, representationalism is, at the end of the day, merely a riff on functionalism, and thus cannot serve to rebut the knowledge argument any more than – by Jackson’s own lights pre-recantation – older versions of functionalism could. Second, the key notion of “representation” itself cannot be accounted for in physicalist terms, so that even a successful representationalist analysis of consciousness could not vindicate physicalism.)
But it is the first component of Jackson’s current position – and some remarks of Robinson’s that are relevant to it – that I want to focus on here. In his 2002 essay “Mind and Illusion” (available in the Ludlow, Nagasawa, and Stoljar volume), Jackson tells us that:
Much of the contemporary debate in the philosophy of mind is concerned with the clash between certain strongly held intuitions and what science tells us about the mind and its relation to the world. What science tells us about the mind points strongly towards some version or other of physicalism. The intuitions, in one way or another, suggest that there is something seriously incomplete about any purely physical story about the mind.
For our purposes, we can be vague about the detail and think broadly of physicalism as the view that the mind is a purely physical part of a purely physical world. Exactly how to delineate the physical will not be crucial: anything of a kind that plays a central role in physics, chemistry, biology, neuroscience, and the like, along with the a priori associated functional and relational properties, count, as far as we are concerned.
Most contemporary philosophers, when given a choice between going with science and going with intuitions, go with science. Although I once dissented from the majority, I have capitulated and now see the interesting issue as being where the arguments from the intuitions against physicalism – the arguments that seem so compelling – go wrong. (p. 421)
This is a remarkable passage – remarkable for the breathtaking rhetorical sleight of hand it embodies. I do not mean to imply that Jackson is being insincere or intentionally manipulative of his readers; I am sure he is not. But – with all due respect to a philosopher whose work I have long admired, and still admire – that is only because he has evidently now “drunk the Kool-Aid” of physicalism so deeply that he is perhaps incapable of seeing how thoroughly tendentious and question-begging is his characterization of the philosophical situation.
Consider the way Jackson frames the issue here – as a debate between “science” and “intuition.” If that really were what the debate is about, how could any rational person fail to understand why Jackson has come to endorse physicalism? Indeed, how, in that case, could any rational person fail to join him in that endorsement? But in fact that is not what the debate is about; certainly Jackson has given us no reason to think it is. Jackson’s younger self certainly didn’t appeal to “intuition.” There is no such appeal in the formulation of the knowledge argument I presented above, and there is no such appeal in Jackson’s presentation in the two articles in which he first put forward the argument. Indeed, in “Epiphenomenal Qualia,” Jackson explicitly says that it is “unfair” to suggest that a qualia-based objection to physicalism must rest on an unargued intuition, explicitly distances himself from the “modal argument” against physicalism precisely because he takes it to rest on a disputable intuition, and explicitly favors the knowledge argument precisely because he there takes it to embody something more firm than an appeal to disputable intuitions!
Consider too that both sides can play the game Jackson is playing in the passage under consideration. The anti-physicalist could say:
We know from the very nature of “the physical” as that tends to be understood in contemporary philosophy that there can in principle be no physicalistic explanation of conscious experience. Arguments like the knowledge argument illustrate this point. And yet many contemporary philosophers have a strongly held intuition that a scientific view of the world requires a commitment to physicalism. Still, other contemporary philosophers, when given a choice between going with solid philosophical arguments and going with disputable intuitions, go with the solid philosophical arguments. Accordingly, they reject physicalism as a misinterpretation of science.
Is this as plausible as Jackson’s way of framing the issue? I maintain that it is far more plausible. And this brings us to the other problem with the passage from Jackson under consideration. Jackson casually assures us that “what science tells us about the mind points strongly towards some version or other of physicalism.” Physicalists say this all the time, of course. But it isn’t true, and Jackson certainly gives us no reason whatsoever to think that it is true. In fact, modern science points solidly away from physicalism, and the reason has precisely to do with the very issue Jackson thinks is “not crucial,” viz. “exactly how to delineate the physical.” For as I have noted in many places – most recently in a post on Chomsky – notions like “matter” and “the physical,” though they have (as Chomsky has rightly emphasized) at best a very elusive positive content in most modern thinking on the mind-body problem, nevertheless have also a very clear negative content. As I stated in the Chomsky post:
Whatever matter turns out to be, there are certain features that modern philosophers, and scientists in their philosophical moments, tend to refuse ever to attribute to it.
For at least some of them, this would seem to include sensory qualities like color, odor, taste, sound, and the like as common sense understands them. For the mechanistic revolution Chomsky alludes to was not merely, and indeed not even essentially, committed to the idea that material causation involves literal contact. It was also and more lastingly committed to some variant or other of a “primary/secondary” quality distinction on which there is nothing in the material world that “resembles” our “ideas” of the sensory qualities mentioned (as Locke would put it). If we want to redefine the “red” of a fire engine in terms of how its surface reflects photons at certain wavelengths, we can say that the fire engine is red. But if by “red” we mean the way red “looks” to us when we perceive it, then nothing like that exists in the fire engine, which is (if we think of color in these commonsense terms) intrinsically “colorless.” And so on for sounds, tastes, and all the rest. Color, odor, taste, sound, and the like – again, as common sense understands them (rather than as redefined for purposes of physics) – are reinterpreted by mechanism as projections of the mind, existing only in consciousness. This is the origin of the “qualia problem,” and the puzzle now becomes how to relate these “qualia” or “phenomenal properties” to the intrinsically colorless, odorless, tasteless particles that make up the brain just as much as they do external material objects.
For at least some of them, this would seem to include sensory qualities like color, odor, taste, sound, and the like as common sense understands them. For the mechanistic revolution Chomsky alludes to was not merely, and indeed not even essentially, committed to the idea that material causation involves literal contact. It was also and more lastingly committed to some variant or other of a “primary/secondary” quality distinction on which there is nothing in the material world that “resembles” our “ideas” of the sensory qualities mentioned (as Locke would put it). If we want to redefine the “red” of a fire engine in terms of how its surface reflects photons at certain wavelengths, we can say that the fire engine is red. But if by “red” we mean the way red “looks” to us when we perceive it, then nothing like that exists in the fire engine, which is (if we think of color in these commonsense terms) intrinsically “colorless.” And so on for sounds, tastes, and all the rest. Color, odor, taste, sound, and the like – again, as common sense understands them (rather than as redefined for purposes of physics) – are reinterpreted by mechanism as projections of the mind, existing only in consciousness. This is the origin of the “qualia problem,” and the puzzle now becomes how to relate these “qualia” or “phenomenal properties” to the intrinsically colorless, odorless, tasteless particles that make up the brain just as much as they do external material objects.
Now if one insists on denying these sensory qualities to matter, then it seems clear that we do have a clear enough conception of “body” to generate a mind-body problem. More than that, we have a conception that clearly implies that the mind (in which alone these qualities exist) cannot be something material or bodily – that, at any rate, is the lesson drawn by early modern thinkers like Cudworth and Malebranche, and by contemporary writers like Richard Swinburne, who take the “mechanistic” conception of matter itself to entail dualism.
This lesson, I submit, is precisely what Jackson’s original knowledge argument illustrates. It shows in a new way what early modern philosophers like Descartes, Cudworth, Malebranche, and Locke, and contemporary thinkers like Nagel and Swinburne, already knew and pointed out many times over the centuries – that given the (mechanistic) understanding of “the physical” that all modern philosophers (whether they be Cartesians, idealists, or materialists) tend to take for granted, a “physicalistic” explanation of consciousness is in principle impossible. It is the moderns’ very conception of matter, rather than some “disputable intuition,” that opens the way to dualism. And insofar as modern science has committed itself to this conception of matter, it follows that modern science itself points to dualism and away from physicalism. I hasten to add, though, that this commitment is not really a “scientific” commitment at all, but a purely philosophical one.
And a mistaken one too, from the point of view of Aristotelian-Thomistic philosophers like myself. This brings me to some important remarks from Robinson’s essay. Robinson says:
The dialectical situation in which the knowledge argument is usually taken to be located is the following: it is accepted that physicalism gives an adequate account of non-conscious reality, which constitutes almost 100 percent of the universe, but struggles to accommodate certain features of mental life, namely the “what it’s like” or qualia of certain conscious states. These latter constitute “the hard problem” for physicalism. The fact that they also constitute such a tiny part of the world is presented as a reason for thinking that they cannot plausibly be held to refute a unified physicalist account.
The dialectical situation in which the knowledge argument is usually taken to be located is the following: it is accepted that physicalism gives an adequate account of non-conscious reality, which constitutes almost 100 percent of the universe, but struggles to accommodate certain features of mental life, namely the “what it’s like” or qualia of certain conscious states. These latter constitute “the hard problem” for physicalism. The fact that they also constitute such a tiny part of the world is presented as a reason for thinking that they cannot plausibly be held to refute a unified physicalist account.
I think that this constitutes a radical misunderstanding of the dialectical situation. What the argument really brings out is that only experience of the appropriate kind can reveal the qualitative, as opposed to purely formal and structural, features of the world. The kind of thing that Mary did not know, generalized from color vision to all the other sensible qualities, is essential to any contentful conception of the world, and physicalism without it would lack any empirical content. (p. 240)
There are two themes here that I want briefly to develop. The first is the entirely illusory character of the widespread assumption that “everything else has been given a physicalistic explanation,” so that the mind cannot plausibly be regarded as immune to such explanation. In fact, the reason it seems that “everything else has been given a physicalistic explanation” is precisely the reason that the mind cannot be “explained” in the same way. For “everything else” has been “explained” in a physicalistic manner precisely by carving off the aspects of mind-independent reality that do not fit the physicalistic model and relocating them in the mind, treating them as mere projections. Again, color, odor, sound, taste, heat, cold, and the like, as common sense understands them, were “explained” only by denying that these qualities really exist in the external physical world at all in the first place. Instead, color, odor, sound, and the rest were for purposes of physics redefined in physicalistically “respectable” terms – color in terms of surface reflectance, sound in terms of compression waves, and so on. Color, sound, etc. as common sense understands them were then reinterpreted as existing only in our conscious experience of the material world, rather than in the material world itself. In short, they are not truly “explained” at all, but just swept under the rug of the mind. (As I have argued before, the problem intentionality poses for physicalism has a similar origin.)
The early moderns generally recognized that this entails a kind of dualism – that it is simply incoherent to suppose that one can get rid of the sensory qualities so reinterpreted by further relocation and redefinition, any more than one can get rid of literal dirt that one has swept under a rug by further application of the “sweep it under the rug” strategy. Contemporary writers like Thomas Nagel see this too – see that it is precisely the physicalist’s own understanding of what “reductive explanation” involves that precludes in principle a “reductive explanation” of conscious experience itself. But contemporary physicalists, forgetful of the history of their discipline, cluelessly draw precisely the opposite conclusion: “Come on, we’ve gotten rid of all the other dirt in the room by sweeping it under the rug; so why wouldn’t we be able to deal with the dirt under the rug in the same way?”
The second theme from Robinson I want to call attention to is his suggestion that “only experience of the appropriate kind can reveal the qualitative, as opposed to purely formal and structural, features of the world.” What he is getting at is this. When the natural world is denuded of the qualitative features common sense takes it to have – color, odor, taste, sound, and the like, as we experience them in everyday life – what we are left with is an entirely abstract structure, the sort of thing physics expresses in the language of mathematics. But it is simply incoherent to regard the mind-independent world as nothing but an abstract structure; there must be something which has the structure. Moreover, to deny the existence of the qualitative features themselves – as some eliminative materialists have suggested doing as a way of “solving,” by brute force, the problem qualia pose for physicalism – would in effect be to cut off the scientific redefinition of nature from any empirical support at all. We would be denying, in the name of science, the very existence of the conscious experience from which scientific inquiry proceeds (a paradox that was not lost on the ancient Greek atomist Democritus, as I noted in an earlier post).
Bertrand Russell, E. A. Burtt, and other early twentieth-century thinkers were well aware of these problems. Russell’s solution was to suggest that the sensory qualities which the moderns had redefined as mere projections of the mind have to be put back into the natural world after all. Accordingly, something like what philosophers now call “qualia” were, for Russell, the intrinsic features of the external physical world – that which “fleshes out” or makes concrete the otherwise abstract structure described by physics. Contemporary philosophers like Michael Lockwood, David Chalmers, and Galen Strawson have followed Russell’s lead, and Robinson’s position seems to bear a family resemblance to theirs. The trouble is that, given the “mental” character modern philosophers tend to attribute to the sensory qualities, this Russellian approach seems to lead to a kind of idealism or panpsychism, on which the natural world is mental through and through (though Russell and Lockwood, at least, try to resist this consequence). This is, I think, a less mad view than physicalism is, but it is mad all the same.
From an Aristotelian-Thomistic point of view, the mistake was opting for a mechanistic-cum-quantitative conception of nature in the first place, and philosophers of mind have been on the wrong track ever since Descartes, Hobbes, and Co. The value of the knowledge argument is that it shows, as Robinson puts it, that “classical physicalism is broken-backed from the start” (p. 243). But Cartesian dualism, property dualism, idealism, panpsychism, etc. are at best only less bad than physicalism. The correct remedy is a full-blown return to Aristotelian-Thomistic hylemorphism, on which alone the quantitative picture of the world presented to us by modern science can properly be understood – as an important part of the correct story about the natural world, but never the whole story.
