Mind as the Mirror of Nature

8/10/2019 Mind as the Mirror of Nature

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Mind as the Mirror of Nature:Fred Dretske on Naturalizing the Mind

David Cole 1996University of Minnesota, Duluth

Descartes held that if you use your mental faculties as youshould, your mind will form an accurate representation of reality.FredDretske holds much the same. But unlike Descartes, Dretske doesntappealto God, nor to reigning in ones infinite will, to get things right.Andunlike Descartes, Dretske works from the outside in. The worldcreatesminds in the world's image.

Dretskes Naturalizing the Mind sets out the case for holdingthatmental states in general are natural representers of reality. Mentalstates have functions; for many states the function is to indicatewhatis going on in the world. Among such indicator states are beliefs.Thecontent of these states is given by what they are supposed torepresent.So if a state is supposed to indicate that its dark, then its darkis the content of the state. Thus we can characterize how theorganism

takes things to be, its subjectivity, by noting first what physical(neural) state it is in, and second what the biological indicatorfunction of that state is. Thus the mind and meaning are naturalized.

This account is strongly externalistic. The content of amentalstate is determined not by the internal organization of the mind, butbythe cause of the connections of the state to external affairs. Atokenmental state has an occurent cause, something that is causing theorganism to be in that state now. But there are also historical

causesthat make that type of state be the one the organism goes into whenitssense organs are stimulated a certain way. For example, the currentdarkness causes the organism to go into a certain internal state. Andevolution brings it about that darkness causes the organism to go intostates of that type. Learning can also play the same sort ofstructuring role as evolution, namely that of recruiting a specific


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state to be the indicator of some state of affairs. The history oftheorganism causes it to now respond internally in certain ways topresent stimuli.

Externalism as an account of linguistic meaning and of the

content of belief is not new: it is supported in one form or anotherbyFodor, Millikan, Kripke, and others. The most interestingdevelopmentin Naturalizing the Mind is the extension of this externalism to non-propositional and non-conceptual mental content, namely the content ofsubjective sensory states, or qualia. Dretske holds that if one is anexternalist with regard to propositional content, as one should be,oneshould 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 Descartesinternalism. For Descartes, mental states have intrinsic propertiesthat can be known apart from any knowledge of their connection withanyexternal states of affairs, present or in the past. My thoughts,including mental images, intrinsically represent the world as beingoneway or another. My sensory states are very much like paintings orphotos, on this view: they have intrinsic color and shape properties.The main epistemic question is whether they correctly representanything, that is, whether there are things out in the world thatshare

the properties of my mental representations: the colors, the shapes,etc.

Among contemporary authors, John Searle seems to take asimilarlyinternal line on mental content, or as he calls it, intrinsicintentionality. One knows ones own mind. Other authors, such asPaulChurchland, take the view that mental content is determined byinternalrelational properties of the possible states of a neural net. Inquite

different ways, these authors, like Descartes and the Way of Ideasthatfollowed him, stand opposed to the externalism that Dretskerepresents.

The Cartesian/Lockean view that the mind represents the worldthrough resemblance is hopeless, as Berkeley points out at length. Itseems impossible to maintain that mental representations represent by


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sharing properties with their objects of representation. Theexternalist account has the advantage that the properties of therepresenting system can be totally unlike the represented. All thatisrequired is that there be a history that makes it the case that thereis

a normal representational response to a state in the world. So aneuralstate can represent say a smell, though the two share almost noproperties.

The externalist view also does away with the seeminglyinexplicable gap (Levine 1983) between the physical state of the brainand the subjective state. It does seem hopeless to try to understandhow this particular pattern of neural activity could have thesubjectivefeel of say the scent of a rose. What about neuron firings couldcreate

qualia? But on Dretskes account, that is not the problem. Thesubjective feel is not produced by any present property of neuralactivity, it is determined by what the neural state is supposed torepresent (namely rose scent). That representational content is notcreated by events inside the head. Since representational propertiesare the product of causal history, in fact, a history that determinesthat my neural system goes in that particular pattern of activity inthepresence 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 certaincounterintuitive aspects of the approach. The two main problems Iwilldiscuss are thought experiments centered on the inverted spectrum andswampmen, and some related issues.

SWAMPMEN and Function

Swampmen first. A swampman is a creature that materializes as aresultof random molecular activity of the gases and liquids in a swamp.

Abiogenesis. Unlikely, but a real if remote physical possibility.Nowamong possible swampmen, some are structurally identical to me andsometo you. That is, it is theoretically possible that SwampDave comeintobeing, and be absolutely physically identical to me, down to thecurrent


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momentum of each subatomic particle. But SwampDave does not have myhistory and since he is not copied from me, he does not benefit fromanyproperties that my history bestows upon me.

On the Dretske/millikan historical accounts, those benefits

areenormous. It is solely in virtue of my history that any of my mentalstates have the content that they do (and indeed, any content at all).So SwampDave does not have my beliefs, even though he is physicallyidentical to me -- and even though some form of physicalism is thecorrect theory of the relation of the mental and the physical.Finally,this difference pervades even qualia: although SwampDave might be inexactly the same brain state as I am when I taste strong hot coffee,hedoes not have a sensation of heat nor of the smell of coffee. OnDretskes account, my sensory representation content is determined by

mybiological history. Namely, I am in certain states which aregenetically determined to be produced by the presence of certainchemicals in my environment, because it was adaptive to have suchrepresentational capacity. SwampDave has no such qualia conferringpedigree.

It could be that this is correct. But my intuitions arestronglyotherwise. The question of course is whether the intuitions should beacceded to, or should be dismissed in view of the theoreticaladvantages

of the externalist approach. Dretske of course advocates the latter(hediscusses Swampmen at length in chapter 5).

One basis for my own intuition, I think, is in fact Cartesian.Ireflect that I could be in my present sensory state while there was noworld to be represented. Or I reflect, along with Russell, that it isan epistemic possibility that the world came into being five minutesagowith everything in its place -- perhaps we are all SwampMen, and theworld swamp is a SwampSwamp. I dont believe I am this recent, but it

seems to be possible that I am; I cant know with certainty that I amnot SwampDave.

Dretskes response to these intuitions might hit at twopoints.One would be that this is not an epistemic possibility. Afterall, inepistemology there are externalist theories as well, reliabilism, forexample. So if my belief that I am not a SwampMan is based upon


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reliable methods, including my apparent memories of childhood and myreliance upon various public and family records, then I know that I amnot a swampman. True belief that results from reliable methods isknowledge -- whether I recognize that or not.

The other response to Swampman sympathies might be to hold

that ifI dont know whether I am a swampman, then I dont know whether I amhaving sensations. Afterall, on Dretskes view, if I am havingsensations, I have a certain history. So if I recognize thishistoricalcondition on having sensations, and I know that I have sensations,thenI know that I have the requisite history -- a history incompatiblewithbeing a SwampMan. But this way of getting from the subjective to theworld, a strange Externalist analog to Descartes proof of theexternal

world, is not the only way an Externalist can run the argument.Insteadof the modus ponens direction, one could as well argue that given theRussell intuition about not knowing the past, then one doesnt knowthatone has sensations. And one may not even wrongly think that one hassensations: swampmen dont think either. Thus on this stronghistoricalview of content, the Cogito is highly problematic. Clear and distinctare quite insufficient -- one needs 20-20 hindsight to know that oneisthinking.

There is also an other minds problem unique to historicalexternalist views like Dretskes. When I meet a stranger and conversewith him or her for awhile, I usually think of myself as being able toestablish something about the individuals beliefs and mental states.But on the historical account, current behavior is totally inadequatetoprovide decisive evidence about any mental content. SwampMen willpassany behavioral test with flying colors (well, SwampHarvardMen will).But they have no mental content at all. They speak with the learned,but cant even think with the vulgar.

Finally, an unforunate Cartesian and for me stronglycounterintuitive aspect of Dretskes account is the implication thatSwampmen can feel no pain. Thus there appears to be no reason why itwould not be perfectly morally permissible to cut them up for the funofit, or roast them over a flame to watch them squirm. Certainly, theywould scream and writhe. And, being physically absolutely identical


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toyou and me, they would beg and plead for us to abandon our perniciousexternalism and please have mercy. No matter, on Dretskes view theyare entitled to no more moral status than an insentient machine. Theyare physically identical to you and me, but lack our illustriouspedigree. And so they, unlike us, are mindless.

I do not believe think Dretskes position denying mentalcontentto Swampmen is internally inconsistent. But it is so revisionary thatits sources merit scrutiny. Dretskes strongly historical version ofexternalism depends upon his acceptance of a particular historicalaccount of biological function (as does Millikans). Dretske does notdefend that account, but cites Larry Wright and others as the sourceanddevelopers of the account.

In fact, Wrights account in Teleological Explanations (1976)

isnot obviously historical. And Fodor has been exploringcounterfactualsas the basis of content, rather than history (A theory of Content,1990). Perhaps one basis for the historical intuition is that someonewho takes the historical approach may note that it would be very oddtosay that Swampman has a disease, say heart disease. While Swampmanpossesses an anatomical structure that pumps a red oxygen carryingliquid, there is nothing that that structure is supposed to do. So itcant fail to do what it is supposed to do, nor can it do it poorly.And heart and blood are functional biological categories, defined

bytheir function and evolutionary history; there are many forms of heartand types of blood. What all hearts have in common is they existbecause hearts pump blood. This is their function. But the pumpingthing in Swampmans chest does not exist because its genetic forebearspumped blood -- it exists solely as the result of a freak accident.Sodespite appearances, Swampman has no heart and no blood. But youcanttell this just by looking at him. Same, Dretske concludes, for themental.

Now it seems that it may well be reasonable to resist thisinference while granting the initial intuition upon which it is based.It is true that Swampmans chest pump has no historical purpose, andsoit cant fail to serve that purpose. But it doesnt follow that itdoesnt function or have a function. There are certain things thatthechest pump does that have a decided effect on Swampmans viability,


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including his continued existence (and so his reproductive fitness).Inparticular, his chest pump pumps the red oxygenating liquid around hisbody. And the continued existence of Swampmans chest pump structurevery much depends upon its pumping, not on its other properties (e.g.the sound it makes). This is much in accord with Wrights

characterization of function (81):

The function of X is Z iff:(i) Z is a consequence (result) of Xs being there,(ii) X is there because it does (results in) Z.

On a straightforward reading of Wrights formula, the function ofSwampmans chest pump is to pump the red stuff around -- for all timesmore than a few seconds after Swampmans bizarre genesis, the pump isthere because it pumps the life (and heart) sustaining blood around.Soits a heart. It doesnt share an evolutionary history with our

hearts.But there are known independently evolved organs, including eyes inmammals and eyes in cephalopods, such as squids.

The same general points may apply to mental states and theirfunctions.

As an aside, it seems philosophers such as Dretske andMillikanare too preoccupied with sex. Reproductive success, of course,manifests fitness. But I dont think it is essential that functionemerge over generations. Suppose that reproduction were by budding,

andorganisms didnt age but stayed eternally fit if they did not succumbtoaccidents or predators. Then the first creature with a heart mightexist alongside all its surviving budded progeny. Now it seems to methat it would have a heart as much as would its genetically identicalprogeny. Its heart would serve exactly the same purpose as in its buds-- it would keep it alive in virtue of pumping. The function ismanifest in the original, it does not require several generations withonly the descendants having hearts. Thus it seems to me that there isaviable alternative naturalistic account of function that is much less

historical than is the one Dretske appeals to, and it has theconsequence that mentality may not require an evolutionary history ofthe extent Dretske thinks is required. This requirement of historicalstructuring causes is at the heart, so to speak, of Dretskes theory.His denial of mental properties to machines, for example, seems todepend upon these genetic requirements.

INVERTED SPECTRUM


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The other problematic case discussed by Dretske is theinvertedspectrum. On the classic account, there could be someone who haddifferent color sensations than do the rest of us. When we all stareat

a ripe tomato, and you and I have the sensation of red, he has thesensation 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 asensationof red). The inverted spectrum possibility is usually supposed to beatheoretical possibility, with implications for the problem of otherminds and for Behaviorism.

Dretskes externalism is incompatible with the possibility ofaninverted spectrum (which he cites as an advantage, Naturalizing p.

72).To see this, consider the following: let Invert1 be a supposedindividual born with an interted spectrum. If my and Invert1s visualstates both have the biological function of representing the colorthatis common to ripe tomatoes, fresh blood, and very hot iron, then weareipso facto in the same subjective representing state. The world seemsthe same to us. The answer to what is it like to be Invert1 is thatit is just the same as being you or me -- there can be no naturallyoccurring inverted spectra on this externalist account.

Consistent however with Dretskes views there could be otheracquired cases of inverted spectrum which he does not consider. Thesemight be produced by microsurgery, say by reconnecting neurons at theback of the eye to different cone cells. Suppose Invert2 is thevictimof such surgery. Then Invert2 will indeed have the sensation of greenina perceptual situation in which I would have the sensation of red.Andof course will show it by behaving oddly after the operation. But onDretskes view that is just because Invert2 will be in the state thathas the historical function of representing what we all call green.

Hisgreen indicators have been switched so they come on in the presence ofred. He is subjectively different from me, and indeed misrepresentscolor, but only because the internal indicators are switched around,notbecause of any intrinsic qualitative character they have.

I think this is a powerful view. But let us consider a


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crucialgedanken experiment. Suppose in normal humans the red detecting coneson the retina are connected to type A neurons and the green detectingcenters connect to type B neurons. Then the firing of A neuronsindicates the presence of red objects and the firing of B neurons isan

indicator of the presence of green objects. Suppose also that A and Bneurons are physically distinct, say As are striated and Bs not.

Suppose also that poor Biff is a mutant born with the A and Bneurons reversed, his B neurons connected to red detectors, etc. Ofcourse, as in the standard inverted spectrum case, Biff learns tospeakas does a normal, and so is not behaviorally different. But one dayina routine PETscan the mutation is detected. And then surgicallycorrected by reversing the connections of the A and B type neurons tothe retina. Now on Dretskes account, Biff will have perfectly normal

subjective responses to color stimuli. His A type now indicate red,hisB type green, just as in the rest of us.

Except of course that after his operation his verbal behaviorisdecidedly defective. When he first opens his eyes, suppose Biff isshown a ripe tomato: he will say it is bright green. He willassociateit with grass, trees, and the taste of unripe fruit. If you ask himhowthe tomato looks, he will say it looks green.

Now as I understand Dretskes account, since Biff is in theinternal neural state that has the biologically determined function ofindicating red, namely the firing of A neurons, the tomato looks redtoBiff, despite what he says. But this I think does excessive violencetowhat we mean by subjectivity. Indeed, we can imagine being Biff. Itwill not do to have someone driven by an externalist theory tellingyouthat your sensations are completely other than as you take them to be.Perhaps ones judgments about ones sensations are not incorrigible,

butit is pernicious to say they can be completely and consistentlymistaken.

[What would Dretske say about how things appeared to Biffbeforethe operation? I think he would say that when he Biff is in what isin


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normals the red detecting state, things appear red to him. Of course,Biff is in that state when he is shown something green, which hecorrectly reports as being green. So on this view, how things appeartoone can only be determined on the basis of a neurophysiologicalinvestigation, and indeed, comparison of ones neurophysiology with

thatof the statistically normal population.]

CONCLUSION

The moral I draw is that a purely externalist and historicalapproach to sensory subjectivity, qualia, is inadequate. Currentinternal organization is relevant to how things seem, and morerelevantthan history. The fact that a certain internal state evolved withcertain indicator functions does not mean it will have that indicatorfunction for a particular organism when its connections with sensors

andhigher reactive and interpretative subsystems is altered. Howsomethingseems to an organism is very much bound up with what the organism doeswith its representations. Changing this functional role changes howthings seem to the system. If you surgically modify me so the state Igo into when a ripe tomato is shown to me is a state that makes meassociate its color with the appearance of healthy lawns, unripefruit,one side of a dollar bill, and to say to myself and others, Boy isthatgreen, then it seems green to me. The evolutionary history of that

state cannot trump the role the state now has in my mental life, suchthat one familiar with the history could override all my own judgmentsabout the state. By parity of reasoning, a being that has states thatplay a similar functional role to my visual representing states willhave similar subjective states, no matter how different (or totallydeficient, as in the case of SwampDave) the beings history is.SwampDave has the same subjective states as I have in virtue of hispresent neurophysiological organization. And we can know he hassubjective states by observing him and his structure, and withoutknowing his history.

I believe that to a lesser extent conceptual and propositional

states depend for their content on internal organization (I brieflyarguethis for belief and concepts in Cole 1996). Here I have tried toprovidesome of reasons for thinking that Dretskes historical and externalistaccount of sensory subjectivity is inadequate, and the emphasis on thebiological past as the decisive determinant of mental content dependsupon a needlessly historical understanding of biological function.


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Bibliography

Churchland, Paul 1995 The Engine of Reason, the Seat of the SoulCambridge, MA: MIT Press

Cole, David 1990 "Functionalism and Inverted Spectra" Synthese 82,pp.207-222.

1994 "Thought and Qualia" Minds and Machines 4, pp. 283-302

1995 "The Causal Powers of CPU's" in Eric Dietrich (ed.)ThinkingComputers and Virtual Persons, pp. 139-156.

1996 Review of Jerry Fodor and Ernest LePore, Holism: AShoppers

Guide in Minds and Machines forthcoming Fall 1996

Descartes 1642 Meditations on First Philosophy

Dretske, Fred 1988 Explaining Behavior Cambridge: MIT Press

1995 Naturalizing the Mind Cambridge: MIT PressFodor, Jerry 1981 "The Mind-Body Problem" Scientific American 244,pp.114-125.

Fodor, Jerry 1990 A Theory of Content and Other Essays Cambridge: MITPress

Levine, Joseph 1983 "Materialism and Qualia: The Explanatory Gap"Pacific Philosophical Quarterly 64, pp. 354-361

Locke, John 1690 An Essay Concerning Human Understanding

Lycan, William 1987 Consciousness Cambridge: MIT Press

1990 "What is the `Subjectivity' of the mental?"Philosophical

Perspectives

Millikan, Ruth 1984 Language, Thought and Other Biological CategoriesCambridge: MIT PressRorty, Richard 1979 Philosophy and the Mirror of Nature Princeton,NJ:Princeton University Press


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Searle, John 1983 Intentionality: An Essay in the Philosophy of MindCambridge, UK: Cambridge University Press

1992 The Rediscovery of the Mind Cambridge: MIT Press

Shoemaker, Sydney 1975 Functionalism and Qualia Philosophical Studies27: 291-315

Wright, Larry 1976 Teleological Explanation Berkeley: University ofCalifornia Press

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Mind as the Mirror of Nature