Mind as the Mirror of Nature: Fred Dretske on Naturalizing the Mind David Cole 1996 University of Minnesota, Duluth Descartes held that if you use your mental faculties as you should, your mind will form an accurate representation of reality. Fred Dretske holds much the same. But unlike Descartes, Dretske doesn’t appeal to God, nor to reigning in one’s infinite will, to get things right. And unlike Descartes, Dretske works from the outside in. The world creates minds in the world's image. Dretske’s Naturalizing the Mind sets out the case for holding that mental states in general are natural representers of reality. Mental states have functions; for many states the function is to indicate what is going on in the world. Among such indicator states are beliefs. The content of these states is given by what they are supposed to represent. So if a state is supposed to indicate that it’s dark, then “it’s dark” is the content of the state. Thus we can characterize how the organism takes things to be, its subjectivity, by noting first what physical (neural) state it is in, and second what the biological indicator function of that state is. Thus the mind and meaning are naturalized. This account is strongly externalistic. The content of a mental state is determined not by the internal organization of the mind, but by the cause of the connections of the state to external affairs. A token mental state has an occurent cause, something that is causing the organism to be in that state now. But there are also historical causes that make that type of state be the one the organism goes into when its sense organs are stimulated a certain way. For example, the current darkness causes the organism to go into a certain internal state. And evolution brings it about that darkness causes the organism to go into states of that type. Learning can also play the same sort of structuring role as evolution, namely that of recruiting a specific state to be the indicator of some state of affairs. The history of the organism causes it to now respond internally in certain ways to present stimuli. Externalism as an account of linguistic meaning and of the content of belief is not new: it is supported in one form or another by Fodor, Millikan, Kripke, and others. The most interesting development in Naturalizing the Mind is the extension of this externalism to non- propositional and non-conceptual mental content, namely the content of subjective sensory states, or qualia. Dretske holds that if one is an externalist with regard to propositional content, as one should be, one should also be an externalist with regard to sensations and qualia. This strong externalism will be my concern in this paper. This approach is of course quite different from Descartes’ internalism. For Descartes, mental states have intrinsic properties that can be known apart from any knowledge of their connection with any external states of affairs, present or in the past. My thoughts, including mental images, intrinsically represent the world as being one way or another. My sensory states are very much like paintings or photos, on this view: they have intrinsic color and shape properties. The main epistemic question is whether they correctly represent anything, that is, whether there are things out in the world that share the properties of my mental representations: the colors, the shapes, etc. Among contemporary authors, John Searle seems to take a similarly internal line on mental content, or as he calls it, “intrinsic intentionality”. One knows one’s own mind. Other authors, such as Paul Churchland, take the view that mental content is determined by internal relational properties of the possible states of a neural net. In quite different ways, these authors, like Descartes and the Way of Ideas that followed him, stand opposed to the externalism that Dretske represents. The Cartesian/Lockean view that the mind represents the world through resemblance is hopeless, as Berkeley points out at length. It seems impossible to maintain that mental representations represent by sharing properties with their objects of representation. The externalist account has the advantage that the properties of the representing system can be totally unlike the represented. All that is required is that there be a history that makes it the case that there is a normal representational response to a state in the world. So a neural state can represent say a smell, though the two share almost no properties. The externalist view also does away with the seemingly inexplicable gap (Levine 1983) between the physical state of the brain and the subjective state. It does seem hopeless to try to understand how this particular pattern of neural activity could have the subjective feel of say the scent of a rose. What about neuron firings could create qualia? But on Dretske’s account, that is not the problem. The subjective feel is not produced by any present property of neural activity, it is determined by what the neural state is supposed to represent (namely rose scent). That representational content is not created by events inside the head. Since representational properties are the product of causal history, in fact, a history that determines that my neural system goes in that particular pattern of activity in the presence of roses, the gap disappears. At least on paper. The externalist account then has clear theoretical virtues. But I hope it will not come as a surprise that I wish to dwell upon certain counterintuitive aspects of the approach. The two main problems I will discuss are thought experiments centered on the inverted spectrum and swampmen, and some related issues. SWAMPMEN and Function Swampmen first. A swampman is a creature that materializes as a result of random molecular activity of the gases and liquids in a swamp. Abiogenesis. Unlikely, but a real if remote physical possibility. Now among possible swampmen, some are structurally identical to me and some to you. That is, it is theoretically possible that SwampDave come into being, and be absolutely physically identical to me, down to the current momentum of each subatomic particle. But SwampDave does not have my history and since he is not copied from me, he does not benefit from any properties that my history bestows upon me. On the Dretske/millikan historical accounts, those benefits are enormous. It is solely in virtue of my history that any of my mental states have the content that they do (and indeed, any content at all). So SwampDave does not have my beliefs, even though he is physically identical to me -- and even though some form of physicalism is the correct theory of the relation of the mental and the physical. Finally, this difference pervades even qualia: although SwampDave might be in exactly the same brain state as I am when I taste strong hot coffee, he does not have a sensation of heat nor of the smell of coffee. On Dretske’s account, my sensory representation content is determined by my biological history. Namely, I am in certain states which are genetically determined to be produced by the presence of certain chemicals in my environment, because it was adaptive to have such representational capacity. SwampDave has no such qualia conferring pedigree. It could be that this is correct. But my intuitions are strongly otherwise. The question of course is whether the intuitions should be acceded to, or should be dismissed in view of the theoretical advantages of the externalist approach. Dretske of course advocates the latter (he discusses Swampmen at length in chapter 5). One basis for my own intuition, I think, is in fact Cartesian. I reflect that I could be in my present sensory state while there was no world to be represented. Or I reflect, along with Russell, that it is an epistemic possibility that the world came into being five minutes ago with everything in its place -- perhaps we are all SwampMen, and the world swamp is a SwampSwamp. I don’t believe I am this recent, but it seems to be possible that I am; I can’t know with certainty that I am not SwampDave. Dretske’s response to these intuitions might hit at two points. One would be that this is not an epistemic possibility. Afterall, in epistemology there are externalist theories as well, reliabilism, for example. So if my belief that I am not a SwampMan is based upon reliable methods, including my apparent memories of childhood and my reliance upon various public and family records, then I know that I am not a swampman. True belief that results from reliable methods is knowledge -- whether I recognize that or not. The other response to Swampman sympathies might be to hold that if I don’t know whether I am a swampman, then I don’t know whether I am having sensations. Afterall, on Dretske’s view, if I am having sensations, I have a certain history. So if I recognize this historical condition on having sensations, and I know that I have sensations, then I know that I have the requisite history -- a history incompatible with being a SwampMan. But this way of getting from the subjective to the world, a strange Externalist analog to Descartes’ proof of the external world, is not the only way an Externalist can run the argument. Instead of the modus ponens direction, one could as well argue that given the Russell intuition about not knowing the past, then one doesn’t know that one has sensations. And one may not even wrongly think that one has sensations: swampmen don’t think either. Thus on this strong historical view of content, the Cogito is highly problematic. Clear and distinct are quite insufficient -- one needs 20-20 hindsight to know that one is thinking. There is also an other minds problem unique to historical externalist views like Dretske’s. When I meet a stranger and converse with him or her for awhile, I usually think of myself as being able to establish something about the individuals beliefs and mental states. But on the historical account, current behavior is totally inadequate to provide decisive evidence about any mental content. SwampMen will pass any behavioral test with flying colors (well, SwampHarvardMen will). But they have no mental content at all. They speak with the learned, but can’t even think with the vulgar. Finally, an unforunate Cartesian and for me strongly counterintuitive aspect of Dretske’s account is the implication that Swampmen can feel no pain. Thus there appears to be no reason why it would not be perfectly morally permissible to cut them up for the fun of it, or roast them over a flame to watch them squirm. Certainly, they would scream and writhe. And, being physically absolutely identical to you and me, they would beg and plead for us to abandon our pernicious externalism and please have mercy. No matter, on Dretske’s view they are entitled to no more moral status than an insentient machine. They are physically identical to you and me, but lack our illustrious pedigree. And so they, unlike us, are mindless. I do not believe think Dretske’s position denying mental content to Swampmen is internally inconsistent. But it is so revisionary that it’s sources merit scrutiny. Dretske’s strongly historical version of externalism depends upon his acceptance of a particular historical account of biological function (as does Millikan’s). Dretske does not defend that account, but cites Larry Wright and others as the source and developers of the account. In fact, Wright’s account in Teleological Explanations (1976) is not obviously historical. And Fodor has been exploring counterfactuals as the basis of content, rather than history (A theory of Content, 1990). Perhaps one basis for the historical intuition is that someone who takes the historical approach may note that it would be very odd to say that Swampman has a disease, say heart disease. While Swampman possesses an anatomical structure that pumps a red oxygen carrying liquid, there is nothing that that structure is supposed to do. So it can’t fail to do what it is supposed to do, nor can it do it poorly. And “heart” and “blood” are functional biological categories, defined by their function and evolutionary history; there are many forms of heart and types of blood. What all hearts have in common is they exist because hearts pump blood. This is their function. But the pumping thing in Swampman’s chest does not exist because its genetic forebears pumped blood -- it exists solely as the result of a freak accident. So despite appearances, Swampman has no heart and no blood. But you can’t tell this just by looking at him. Same, Dretske concludes, for the mental. Now it seems that it may well be reasonable to resist this inference while granting the initial intuition upon which it is based. It is true that Swampman’s chest pump has no historical purpose, and so it can’t fail to serve that purpose. But it doesn’t follow that it doesn’t function or have a function. There are certain things that the chest pump does that have a decided effect on Swampman’s viability, including his continued existence (and so his reproductive fitness). In particular, his chest pump pumps the red oxygenating liquid around his body. And the continued existence of Swampman’s chest pump structure very much depends upon its pumping, not on its other properties (e.g. the sound it makes). This is much in accord with Wright’s characterization of function (81): The function of X is Z iff: (i) Z is a consequence (result) of X’s being there, (ii) X is there because it does (results in) Z. On a straightforward reading of Wright’s formula, the function of Swampman’s chest pump is to pump the red stuff around -- for all times more than a few seconds after Swampman’s bizarre genesis, the pump is there because it pumps the life (and heart) sustaining blood around. So it’s a heart. It doesn’t share an evolutionary history with our hearts. But there are known independently evolved organs, including eyes in mammals and eyes in cephalopods, such as squids. The same general points may apply to mental states and their functions. As an aside, it seems philosophers such as Dretske and Millikan are too preoccupied with sex. Reproductive success, of course, manifests fitness. But I don’t think it is essential that function emerge over generations. Suppose that reproduction were by budding, and organisms didn’t age but stayed eternally fit if they did not succumb to accidents or predators. Then the first creature with a heart might exist alongside all its surviving budded progeny. Now it seems to me that it would have a heart as much as would its genetically identical progeny. Its heart would serve exactly the same purpose as in its buds -- it would keep it alive in virtue of pumping. The function is manifest in the original, it does not require several generations with only the descendants having hearts. Thus it seems to me that there is a viable alternative naturalistic account of function that is much less historical than is the one Dretske appeals to, and it has the consequence that mentality may not require an evolutionary history of the extent Dretske thinks is required. This requirement of historical structuring causes is at the heart, so to speak, of Dretske’s theory. His denial of mental properties to machines, for example, seems to depend upon these genetic requirements. INVERTED SPECTRUM The other problematic case discussed by Dretske is the inverted spectrum. On the classic account, there could be someone who had different color sensations than do the rest of us. When we all stare at a ripe tomato, and you and I have the sensation of red, he has the sensation we would call “green”. But he has learned to speak with us, and so calls the tomato red (and says of himself that he has a sensation of red). The inverted spectrum possibility is usually supposed to be a theoretical possibility, with implications for the problem of other minds and for Behaviorism. Dretske’s externalism is incompatible with the possibility of an inverted spectrum (which he cites as an advantage, Naturalizing p. 72). To see this, consider the following: let Invert1 be a supposed individual born with an interted spectrum. If my and Invert1’s visual states both have the biological function of representing the color that is common to ripe tomatoes, fresh blood, and very hot iron, then we are ipso facto in the same subjective representing state. The world seems the same to us. The answer to “what is it like to be Invert1” is that it is just the same as being you or me -- there can be no naturally occurring inverted spectra on this externalist account. Consistent however with Dretske’s views there could be other acquired cases of inverted spectrum which he does not consider. These might be produced by microsurgery, say by reconnecting neurons at the back of the eye to different cone cells. Suppose Invert2 is the victim of such surgery. Then Invert2 will indeed have the sensation of green in a perceptual situation in which I would have the sensation of red. And of course will show it by behaving oddly after the operation. But on Dretske’s view that is just because Invert2 will be in the state that has the historical function of representing what we all call green. His green indicators have been switched so they come on in the presence of red. He is subjectively different from me, and indeed misrepresents color, but only because the internal indicators are switched around, not because of any intrinsic qualitative character they have. I think this is a powerful view. But let us consider a crucial gedanken experiment. Suppose in normal humans the red detecting cones on the retina are connected to type A neurons and the green detecting centers connect to type B neurons. Then the firing of A neurons indicates the presence of red objects and the firing of B neurons is an indicator of the presence of green objects. Suppose also that A and B neurons are physically distinct, say A’s are striated and B’s not. Suppose also that poor Biff is a mutant born with the A and B neurons reversed, his B neurons connected to red detectors, etc. Of course, as in the standard inverted spectrum case, Biff learns to speak as does a normal, and so is not behaviorally different. But one day in a routine PETscan the mutation is detected. And then surgically corrected by reversing the connections of the A and B type neurons to the retina. Now on Dretske’s account, Biff will have perfectly normal subjective responses to color stimuli. His A type now indicate red, his B type green, just as in the rest of us. Except of course that after his operation his verbal behavior is decidedly defective. When he first opens his eyes, suppose Biff is shown a ripe tomato: he will say it is bright green. He will associate it with grass, trees, and the taste of unripe fruit. If you ask him how the tomato looks, he will say it looks green. Now as I understand Dretske’s account, since Biff is in the internal neural state that has the biologically determined function of indicating red, namely the firing of A neurons, the tomato looks red to Biff, despite what he says. But this I think does excessive violence to what we mean by subjectivity. Indeed, we can imagine being Biff. It will not do to have someone driven by an externalist theory telling you that your sensations are completely other than as you take them to be. Perhaps one’s judgments about one’s sensations are not incorrigible, but it is pernicious to say they can be completely and consistently mistaken. [What would Dretske say about how things appeared to Biff before the operation? I think he would say that when he Biff is in what is in normals the red detecting state, things appear red to him. Of course, Biff is in that state when he is shown something green, which he correctly reports as being green. So on this view, how things appear to one can only be determined on the basis of a neurophysiological investigation, and indeed, comparison of one’s neurophysiology with that of the statistically normal population.] CONCLUSION The moral I draw is that a purely externalist and historical approach to sensory subjectivity, qualia, is inadequate. Current internal organization is relevant to how things seem, and more relevant than history. The fact that a certain internal state evolved with certain indicator functions does not mean it will have that indicator function for a particular organism when its connections with sensors and higher reactive and interpretative subsystems is altered. How something seems to an organism is very much bound up with what the organism does with its representations. Changing this functional role changes how things seem to the system. If you surgically modify me so the state I go into when a ripe tomato is shown to me is a state that makes me associate its color with the appearance of healthy lawns, unripe fruit, one side of a dollar bill, and to say to myself and others, “Boy is that green,” then it seems green to me. The evolutionary history of that state cannot trump the role the state now has in my mental life, such that one familiar with the history could override all my own judgments about the state. By parity of reasoning, a being that has states that play a similar functional role to my visual representing states will have similar subjective states, no matter how different (or totally deficient, as in the case of SwampDave) the being’s history is. SwampDave has the same subjective states as I have in virtue of his present neurophysiological organization. And we can know he has subjective states by observing him and his structure, and without knowing his history. I believe that to a lesser extent conceptual and propositional states depend for their content on internal organization (I briefly argue this for belief and concepts in Cole 1996). Here I have tried to provide some of reasons for thinking that Dretske’s historical and externalist account of sensory subjectivity is inadequate, and the emphasis on the biological past as the decisive determinant of mental content depends upon a needlessly historical understanding of biological function. 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