Pereboom Limits of Introspection

8/12/2019 Pereboom Limits of Introspection

1/16

nternational Phenomenological Society

Bats, Brain Scientists, and the Limitations of IntrospectionAuthor(s): Derk PereboomSource: Philosophy and Phenomenological Research, Vol. 54, No. 2 (Jun., 1994), pp. 315-329Published by: International Phenomenological SocietyStable URL: http://www.jstor.org/stable/2108491.

Accessed: 14/02/2014 20:09

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at.http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms

of scholarship. For more information about JSTOR, please contact [email protected].

.

International Phenomenological Societyis collaborating with JSTOR to digitize, preserve and extend access to

Philosophy and Phenomenological Research.

http://www.jstor.org

This content downloaded from 75.97.192.97 on Fri, 14 Feb 2014 20:09:50 PMAll use subject to JSTOR Terms and Conditions
http://www.jstor.org/action/showPublisher?publisherCode=ipshttp://www.jstor.org/stable/2108491?origin=JSTOR-pdfhttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/stable/2108491?origin=JSTOR-pdfhttp://www.jstor.org/action/showPublisher?publisherCode=ips


2/16

Philosophy and Phenomenological ResearchVol. LIV, No. 2, June1994

Bats,BrainScientists,andtheLimitationsof IntrospectionDERKPEREBOOMUniversity of Vermont

Thomas Nagel and FrankJackson have advancedinfluentialargumentsde-signed to foil any materialistattemptto account for the mental.' These so-called knowledge argumentsassume that if materialism is true, someonewho possesses complete physical knowledge will know every fact aboutmental states there is to know. Thus, because there are facts about mentalstates that will not be known by someone who possesses complete physicalknowledge but has neverenjoyed certainexperiences,it follows thatmateri-alist accounts of the mental areinadequate. n response,defendersof materi-alism have generatedcounterargumentsf several kinds. In my view, no ma-terialist strategyhas so far been successful, but nonetheless, furtherdevel-opment will vindicate one of them.

Early resistance to the knowledge argumentsaimed to show that whatdistinguishesa subjectwho has hadcertainsensoryexperiences from some-one who is physically omniscient but has never had them is not factualknowledge,butmerelyan ability, such as an abilityto imagine,recognize, orremember,2or an ability to apply a concept,3and thathence, there is no factaboutmental states thateludes a materialistaccount.The decisive issue forthis first strategyis whetherhaving an ability of the sort in question never-theless involves possessing factual knowledge about certain phenomenalfeatures of mental states, factualknowledge lacked by the physically omni-

ThomasNagel, "What s it Like to Be a Bat?"The Philosophical Review 83 (1974), pp.435-50; FrankJackson,"EpiphenomenalQualia,"Philosophical Quarterly32 (1980), pp.127-36, "WhatMaryDidn't Know," The Journalof Philosophy83 (1986), pp. 291-95.2 Laurence Nemirow, "Review of Thomas Nagel, Mortal Questions," PhilosophicalReview 89 (1980), pp. 473-77, "Physicalismand the Cognitive Role of Acquaintance,"nMind and Cognition, William G. Lycan, ed. (Oxford: Blackwell, 1990), pp. 490-99;David Lewis, "Postscript o 'MadPain and MartianPain',"Philosophical Papers, vol. 1(New York: Oxford University Press, 1983), "WhatExperienceTeaches," in Mind andCognition, pp. 499-519; Patricia Kitcher, "Phenomenal Qualities," AmericanPhilosophicalQuarterly16 (1979), pp. 123-29.3 Janet Levin, "Could Love Be Like a Heatwave? Physicalism and the SubjectiveCharacterof Experience,"PhilosophicalStudies 49 (1986), pp. 245-61.

BATS, BRAIN SCIENTISTS,AND THELIMITATIONSOFINTROSPECTION 315

http://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsp


3/16

scient subjectwho has not had the sensory experiences.One mightargue,forexample, thatif one has the ability to imagine sensingred one must also havefactualknowledgeof whatit is like to sense red,and someone who has com-plete physical knowledge but does not know what it is like to sense red willnot only lack the ability, but the factual knowledge as well. Advocates ofthe first strategy dispute such claims, but to my mind, it is unclear thatNagel and Jacksonhavebeen answered.4

A second strategy, developed by Paul Churchland, Brian Loar, andWilliam Lycan, among others,concedes that the special knowledge that cer-tain sensory experiencesprovide might well be factualknowledge, but it in-sists that all of the facts known by means of these experiences will also beknown by someone who has completephysical knowledgebuthas never hadthe experiences at issue. Complete physical knowledge, all by itself, fails tosupply only modes of presentationof facts, not knowledge of these factsthemselves.' I contend thatthe advocatesof this second strategyhave so farmerely displaced the problem that Nagel and Jackson raise, but that thisstrategycan be enhancedto resolve the controversy n favor of the material-ist. Furthermore, argue that this reinforced mode-of-presentationstrategyexposes a fundamentalmistake in the knowledge arguments:they presup-pose, falsely, that if materialism s true, then complete physical knowledgewill provide cognitive access to everythingabout a subject'smental states asthey are apprehendedn introspection.4 See for example, Levin, "Could Love Be Like a Heatwave?"especially sections IV and

V, and Lewis, "WhatExperienceTeaches," p. 517.5 Paul M. Churchland,"Reduction, Qualia and the Direct Introspection of Brain States,"Journal of Philosophy 82 (1985), pp. 8-28; Brian Loar, "Phenomenal States,"Philosophical Perspectives 4: Action Theory and Philosophy of Mind, ed. JamesTomberlin(Atascadero,California:Ridgeview PublishingCompany, 1990), pp. 81-108,see pp. 85-88 for criticisms of the ability strategy; W. G. Lycan, "What is the'Subjectivity' of the Mental?" Philosophical Perspectives 4, pp. 109-30; Robert VanGulick, "Physicalismandthe Subjectivityof the Mental,"PhilosophicalTopics 13, pp. 51-70, and "Understanding he PhenomenalMind," in Consciousness, Martin Davies andGlyn W. Humphreys, eds. (Oxford: Blackwell, 1993); see also Terence Horgan,"Jacksonon Physical Informationand Qualia,"Philosophical Quarterly 32 (1984), pp.147-52, and Michael Tye, "The Subjective Qualities of Experience," Mind 95 (1986),pp. 1-17. By Van Gulick's classification in "Understandingthe Phenomenal Mind,"Horgan, Churchland,and Tye hold that someone who has complete physical knowledgebut has not had certain experiences lacks no propositional knowledge, while Loar,Lycan, and Van Gulick maintain that she does, and what explains this difference is thatthese last three theorists individuatepropositionsmore finely than do the first three (pp.141-42). All of these philosophers, however, share the view that she does not lackknowledge of any properties, which I characterizeas the view that she lacks no factualknowledge.

6 A third strategy, developedby Daniel Dennettin "QuiningQualia,"Mind and Cognition,Lycan,ed., pp. 519-47, attempts o answerthe anti-materialistby eliminatingthe qualita-tive featuresof experience. For a critiqueof Dennett's view, see William Seager, "TheEliminationof Experience,"Philosophy and PhenomenologicalResearch 53 (1993), pp.345-65.

316 DERK PEREBOOM



4/16


5/16

there s much she does not know abouthumanexperience.She does not know,for example, whatit is like to experience a ripe red tomato, andin particular,she lacks knowledgeof whatit is like to sense red. When she leaves the roomand sees a ripe red tomato, she learns something about.humansensations.Consequently,there is informationabout human sensations that is not phys-ical information, and thus human sensations are not completely physical.'0Schematically,

(i) Mary (while in the room) knows everything physical there is toknow abouthumanbeings.

(ii) Mary (while in the room) does not know everything there is toknow about the natureof humansensations andtheirproperties.

Therefore,(c) There is informationabout human sensations that is not physical,

and thus humansensations are not completely physical.The core intuition underlyingthe knowledge arguments s that if someonewho possesses complete physical knowledge does not thereby know somefact about mental states, then that fact cannot be physical. Given this as-sumption, materialism would seem to be refuted if complete physicalknowledge of a conscious organismdoes not, all by itself, yield knowledgeof what it is like to have (some of) the mental states of thatorganism.Thusone might note that the deeper structureof a knowledge argumentdoes notrequire that it make reference to facts about peculiar creatures or circum-stances. On a proper understandingof this structure, t should be sufficientfor refuting materialismto point out that complete physical knowledge ofone's own nature,all by itself, would not provide knowledge of what it islike to have (some of) the sensations one has, even though one actually

10 In "EpiphenomenalQualia" Jackson focuses his argument against physicalism, and hedefinesphysicalismas the view that"all (correct) nformation s physical information" p.127). Hence, as Torin Alter points out (in correspondence),one might regardthis argu-ment as directed against a thesis about information,and not against a thesis about ontol-ogy, andthus one might consider it to be aimed at dislodging not the view thateverythingis wholly physically realized, but only the claim thatall information s physical informa-tion. But in "WhatMaryDidn't Know"Jackson characterizesphysicalismin ontologicalterms: "Physicalism is not the noncontroversialthesis that the actual world is largelyphysical, but the challenging thesis that it is entirely physical" (p. 291). I conclude thatJackson assumes the informationaland the ontological theses to be logically equivalent,and I interprethis argument accordingly. Furthermore,f one defines physical informa-tion as information about entities that are wholly physically realized,the two theses areindeed logically equivalent.If there is an entity that is not wholly physically realized thenthere will be correspondingnon-physical information,and if there is non-physical infor-mationthere will be a corresponding ntity that is not wholly physically realized.

318 DERK PEREBOOM



6/16


7/16

alone. Accordingly, while in the room Mary would have complete physicalknowledge of the human being even though she lacks introspective knowl-edge of color sensations, because she has knowledge of every intersubjec-tively accessible feature of the humanbeing. Whether color sensations areintersubjectivelyaccessible is in doubt,because it would seem that theirna-ture could not be known directly on the basis of observationsthat someonewith very different kinds of sense organs from ours could make, nor beknown indirectly by inference from such observations.Knowledge of colorsensations, by the very conceptof the physical, would initially appearnot tobe knowledge that is entirely physical.

But accepting this conception of the physical would not result in theknowledge argumentbegging the questionagainst the materialistby havingit simply presuppose that color sensationsare not intersubjectivelyaccessi-ble and therefore not physical. Despite initial appearances, t would still beepistemically possible, at least before we have worked our way throughtheargument, that complete knowledge of color sensations be acquired fromobservations that any being with a reasonably powerful sensory apparatuscould make, or by inference from such observations.If this possibility wereactually realized, Mary's complete knowledge of intersubjectivelyaccessi-ble features of the humanbeing would include all the knowledge of colorsensations that can be gained through ntrospection.Color sensations wouldthen be thoroughly intersubjectivelyaccessible after all.

However, the claim that intersubjectiveaccessibility is part of the con-cept of, or is a necessarycondition for the physical is a legacy of positivistanti-realism. Realists, it would seem, must allow for the possibility thatthere areaspects of the physical thatdefy the intersubjectivemethod thatwehave developed to come to know it. But not all is lost. Realists will affirmthat when something is representedbut is not intersubjectively accessiblewe have good evidence that it is mind-dependent.'3And given that includedin our concept of something physical is that it is mind-independent,whensomething is representedbut is not intersubjectivelyaccessible (in the re-spect we just outlined)we have good evidence thatit is notphysical.

Consequently, althoughwhile in the room Maryhas knowledge of everyintersubjectively accessible feature of the human being, it will not strictlyfollow that she has complete physical knowledge of the humanbeing. ButMary's having all of this knowledge still may provide good evidence thatshe has complete physical knowledge of the humanbeing. This weakerlinkbetween intersubjective accessibility and the physical may well approachwhatNagel has in mind.'4And although, given these conclusions, a success-

13 Derk Pereboom, "Mathematical Expressibility, Perceptual Relativity, and SecondaryQualities,"Studies in History and Philosophy of Science 22 (1991), pp. 63-88.14 Nagel, "What s It LikeTo Be a Bat?" andThe View FromNowhere, pp. 13-17.

320 DERKPEREBOOM



8/16

ful knowledge argumentwould not guarantee he falsity of materialism,es-tablishing the unlikelihood of materialism would yet be a significant ac-complishment.15

IIIIn recentarticles, WilliamLycan16and BrianLoar"7 rguethatsomeone whohas complete physical knowledge but has not had certainexperiences doesnot lack knowledge of some fact about the natureof mental states, but ismerely missing some mode of presentationor concept.Humanbeings, Lycanpoints out, have representations f theirown psychological states, andif a subject S hosts such a representation,no one else can use a syntacticallysimilar represen-tation to represent the very first-orderstate-token(of S's own) that is the object of S's ownrepresentation;otherpeople may be able to form syntactically similarrepresentations,but theobject of those representationswill be first-orderstates of their own hosts, not any states ofS's.18

According to Lycan, the differencebetween the bat's andthe scientist's rep-resentationof sonarsensationis akin to the differencebetweenmy use of 'I'and your use of 'you' to representme. Even if you know that I weigh 180pounds,you cannotrepresent his factby 'I weigh 180pounds,' whereasI canrepresent his fact by means of thatsentence.But I do not have knowledge ofsome fact of which you lack knowledge. The only fact to be known here isthatI weigh 180pounds,and we both know it. By analogy,Lycanargues,thescientist and the batknow the same facts about the bat's mental states, onlyby differentkinds of mode of presentation.

In Lycan's view, a bat experiencingecholocation sensations is in a func-tional state of a type distinct from that of the observing scientist, and thiscircumstancegives rise to theirdifferentkinds of mode of presentation."Noone else [thanthis particularbat],human,bat, or bat human,could know thesame facts by being in the samefunctional state."19The unique functionalsituation of the introspectingsubject,Lycan believes, "naturallycreates theillusion of an ontologically special kind of state of affairs." Accordingly,introspective modes of presentationare inferior to their scientific counter-

15 One might note thatalthoughsomething'snot being intersubjectivelyaccessible providesgood evidence that it is not physical, we neverthelesscannot conclude from something'sbeing intersubjectivelyaccessible that it is physical. This is because it seems possible thatthere shouldbe non-physical entities which are intersubjectivelyaccessible. The implica-tion this point has for Jackson's argumentis that if Mary does know everything aboutcolor sensations in virtueof her completeknowledge of intersubjectivelyaccessible enti-ties, we cannotthereby concludethat color sensations arephysical.16 Lycan, "What s the "Subjectivity"of the Mental?"17 Loar,"PhenomenalStates."18 Lycan, p. 120.19 Lycan, p. 124.

BATS, BRAINSCIENTISTS,AND THELIMITATIONSOFINTROSPECTION 321



9/16

parts; "the inner 'feel' that is a representation'sfunctional role has littlerelation to the object that is the representation'sextension."

The central featureof Loar's account is a distinction between "physical-functional concepts" and "phenomenal-recognitional oncepts." These di-verse types of concepts introducedistinct sorts of modes of presentationsofstates.But these distinct sorts of mode of presentationneed not pick out dif-ferent aspects of states. The claim that distinct sorts of mode of presenta-tion must pick out different kinds of mental item would seem to presupposethe discreditedresemblancetheory of representation:"It is as though anti-physicalist intuitions rest on a resemblancetheoryof mentalrepresentation,as though we conclude from the lack of resemblancein our physical-func-tional and phenomenalconceptionsa lack of samenessin the properties heyrefer to."20 n Loar's view, then, the what-it-is-like aspect of an introspec-tive perception s associatedwith a phenomenal-recognitional oncept,a con-cept which facilitatesthe recognitionof a physical property,but does not re-semble that property.

Let us first consider a quibble one might raise against the mode-of-pre-sentation strategy (the ingredientsof an answer to this quibble are touchedon by both Lycan and Loar). It seems plausible thatphenomenalmodes ofpresentationare states or aspects of states with content sufficient to accountfor our representingsensations as having certain characteristicswhich aredifferent from those that physical-functional modes of presentation rep-resent sensations as having.In particular,phenomenalmodes of presentationrepresentsensations as havinga phenomenalcharacterwhich is not intersub-jectively accessible in the way that complete physical realization wouldstrongly suggest, while physical-functional modes of presentation do notrepresentsensations as havingsuch a character.This fact is perhapsobscuredby the analogy with indexicals. When I representthe fact thatI weigh 180pounds by 'I weigh 180 pounds' and you representthis fact by 'You weigh180 pounds' these distinct types of representationdo not representme ashaving different characteristics.Let us thereforeprovide the anti-materialistwith the strongestpossible case, andsupposethatphenomenalmodes of pre-sentationrepresentsome mentalstates as having a characterwhich is not in-tersubjectivelyaccessible.

There is a convincing response to this quibble. Supposing that phenome-nal modes of presentationdo representmental states as having a characterwhich is not intersubjectivelyaccessible in the way that complete physicalrealization would strongly suggest, these mental states still might not ac-tually be as they appearto introspection. We might draw an analogy be-tween our introspectiveawarenessof mentalstates and our sensations of ex-ternalobjects.Because oursensoryawarenessof externalobjects is mediated20 Loar, p. 90.

322 DERK PEREBOOM



10/16

by representations ausedby those objects, the possibility arises thatthere isa discrepancybetween the way externalobjects appearto the senses and theway they really are. Familiarly,many agree that the secondary qualities ofexternal objects-their colors, tastes, and sounds-are not as they appear nsensation. When I visually perceive the leaves of the maple -tree,my sensa-tion of red fails to representsome quality of the leaves as it really is. Onemight analyze this disparitybetween appearanceand reality along Lockeanlines, by suggesting that in the case of secondary quality representation,their content fails to resemble the representedquality.21

Similarly, it is plausible that our introspective awareness is also medi-ated by representations caused by the mental states they represent.Consequently, the possibility also arises that mental states are not as theyappear to introspection, as Kant argues.22For example, according to theLycan/Loaraccount,one aspectof my introspectiveawarenessof a sensationof red is a phenomenalmode of presentation-what it is like to sense red.Given that my introspective awareness is mediated by representations,mysensation of red might not actuallybe just as this mode of presentationrep-resents it. This sensationmight really be intersubjectivelyaccessible in theway that complete physical realization would strongly suggest, even if tointrospectionit appearsto have a character hat is not intersubjectivelyac-cessible in this way.

Thus even if phenomenalmodes of presentation, uch as what it is like tosense red, representsensations as having a character hat is not intersubjec-tively accessible, a modified reply to the knowledge arguments alongLycan/Loar lines is effective. For since mental states might well not be asthey appearto introspection, sensations might yet be thoroughly intersub-jectively accessible and wholly physically realized. This possible disparitybetween appearanceandrealitymight also be analyzedin the Lockeanman-ner. Perhaps it is plausible to say that the content of an introspectiverepre-sentationmight fail to resemble the mental state it represents.

IVThe Lycan/Loaraccount,however, suffers from a more significantproblem.In Loar's view, beforeMary'semergencefrom the room, she has knowledgeof the real nature of the mental state sensing red in virtue of her completephysical knowledge. When she emerges from the room and sees a ripe redtomato, by introspective awareness of her sensation of red she acquires aphenomenal mode of presentationof sensing red for the first time. Mary21 John Locke, Essay Concerning Human Understanding, Peter Nidditch, ed. (Oxford:Oxford University Press, 1975), II, viii; cf. Pereboom, "MathematicalExpressibility,PerceptualRelativity,and Secondary Qualities."22 Immanuel Kant, Critiqueof Pure Reason, trans.Norman Kemp-Smith(New York: St.Martin'sPress, 1965), B152-9.

BATS, BRAIN SCIENTISTS,AND THELIMITATIONSOF INTROSPECTION 323



11/16

does not therebycome to know a fact aboutsensing red she did not previ-ously know. Suppose that all of this is true. But let us now focus our atten-tion not on sensing red, and on whatMary can know aboutit, but ratheronthe state that she is in when she introspectsher state sensing red. If materi-alism is true, exhaustive factual knowledge of this further state, a statewhich featuresthe typical humanphenomenalmode of presentationof sens-ing red-what it is like to sense red-will be hadby someone who has com-plete physical knowledge but has never enjoyed a sensationof red. But, theanti-materialist hould object, it will not be. Just by having complete physi-cal knowledge one will not know, for example, that

(1) The mental state that features the typical human phenomenalmode of presentationof sensing red has this property.

where 'this' refersto whatit is like to sense red.This objectioncapturesall of the originalforce of Nagel's and Jackson's

arguments.In Lycan's and Loar's analyses, the what-it-is-like aspect is as-signed to a mode of presentationof the sensation,and not to the sensationit-self. According to Nagel's initial contention, it is precisely this aspect thatresists a materialistaccount. If the what-it-is-like aspect is assigned awayfrom the sensationto a mode of presentation, hen the crucialissue becomeswhethera state that featuresthis mode of presentationhas a materialistac-count. Thus, partof the force of our objection is that the problemfor mate-rialism that its opponents have raised has not been addressed,but merelydisplaced.

But given the way we managed the quibble raised earlier against themode-of-presentationstrategy, we are now in a position to deal with thismore significantproblem.We have saic thatjust as the secondaryquality,redness, might not be as it appears n sensation,so sensing red might not beas it appearsto introspection.In particular,a state featuringthe phenomenalmode of presentationwhat it is like to sense red might not representsensingred as it really is. But we can now ascend a level. Not implausibly,our in-trospectiveaccess to mentalstates featuringphenomenalmodes of presenta-tion is also mediated by representations caused by these states.Consequently,the possibility arises that mental states featuring such modesof presentationare not as they appear.Hence, the mental state featuringthemode of presentationwhat it is like to sense red might be intersubjectivelyaccessible in the way that complete physical realization would stronglysuggest, even if to introspection t appears o have a character hatis not in-tersubjectivelyaccessible in this way, and it might in fact be wholly physi-cally realized.

Moreover,one can make the same point for any further terationof intro-spective perceptionsof states featuring phenomenalmodes of presentation.324 DERK PEREBOOM



12/16

Any mental state, no matterhow high it is in the hierarchyof introspectionsof introspections, might be thoroughly intersubjectively accessible andwholly physically realized, despite the way we represent t in introspection.Jackson's argumentthus fails to show that Mary does not have exhaustivefactual knowledge of the real nature of mental states that featurephenome-nal modes of presentationof color sensations, and furthermore,no versionof the knowledge argumentcan demonstrate hatsomeone who is physicallyomniscient might yet lack factualknowledge of the real natureof any men-tal state.23

Perhapsthereis something odd about the claim that there might be a dis-tinction between appearanceand reality even for our apprehensionof phe-nomenal modes of presentation. n ConsciousnessExplainedDaniel Dennettdisputes this type of claim, which he attributes o a view he calls the imageof the Cartesian Theater:The CartesianTheater may be a comforting image because it preservesthe reality/appearancedistinction at the heart of humansubjectivity, but as well as being scientifically unmotivated,this is metaphysically dubious, because it creates the bizarrecategory of the objectively sub-jective-the way things actually,objectively seem to you even if they don't seem to seem thatway to you (Smullyan (1981)) Some thinkers have their faces set so hard against"verificationism" nd "operationalism"'hatthey want to deny it even in the one arena where itmakes manifest good sense: the realm of subjectivity.24But it is not odd to say that there is a difference between the real natureofhow somethingseems to you and how it seems to seem to you. For this to beso there need only be a difference between the real natureof a mentalstate ofsomething's seeming a certainway to you and how that state appearsto youin introspection.However a mental state seems to you in introspection,thatstate might not have the characteristicsit appears to have, and in fact itmight be intersubjectivelyaccessible in the way thatcomplete physical real-ization would strongly suggest, even though it appears to have a characterthat is not intersubjectivelyaccessible in this way.

But furthermore, he anti-materialistmight arguethat one must have di-rect apprehensionof one's representations-apprehension that is not medi-ated by additional representations which can give rise to an appear-ance/reality distinction-for otherwise a vicious infinite regress would begenerated.If I did not have such direct apprehensionof my representations,23 The mode-of-presentation strategy also provides an effective response to a knowledge

argumentdirected solely against reductionist materialism,for despite the way mentalstates appear o introspection, hey might still be intersubjectivelyaccessible and fully de-scribedby an ideal physics or an ideal neurophysiology,at least for all a knowledge ar-gumentcan show.

24 Daniel Dennett,ConsciousnessExplained(Boston: Little, Brown,andCompany, 1991), p.132. The work by R. M. Smullyan Dennett cites is "An Epistemological Nightmare," nThe Mind's I: Fantasies and Reflections on Self and Soul, D. R. Hofstadter and DanielDennett, eds. (New York:Basic Books, 1981), pp. 415-27.

BATS, BRAINSCIENTISTS,AND THE LIMITATIONSOF INTROSPECTION 325



13/16

my apprehension of the redness of the tomato would be mediated by a(sensory) representation,but so would my apprehensionof this representa-tion of redness, and so would my apprehensionof the representationof thisrepresentationof redness,ad infinitum.So if one apprehendeda representa-tion, one would have to have an infinite series of representations f represen-tations, which is absurd.The best way to stop the regress is to admit appre-hension of one's representations hat is not mediated by any additionalrep-resentations.Thus when I perceive a tomato, one shouldsuppose thatmy in-trospective apprehensionof my sensation of its redness is direct in this way,and consequently, that this sensation is just as it appearsin introspection.The materialistmust accountfor the natureof this sensation, and if it is notcognitively accessible as it is apprehendedn introspectionby someone whohas complete physical knowledge but lacks certainexperiences, then an as-pect of the mentallacks a materialistaccount.

But there is no vicious regress here. One must make a distinctionbetweenhaving a representationof somethingandapprehending hat representation.One can have a representationwithoutin turnapprehending hatrepresenta-tion, andmoreover,having a representation an be causally efficacious evenwhen thatrepresentations not apprehended.Consideran exampleconceivedby David Armstrong.25 uppose thatyou have been driving a car for a longtime, and you are on "automaticpilot." In this situation, you are aware ofthe road-otherwise yourcarwould be in the ditch. But you are not aware ofyourawarenessof theroad.Perhaps,undermoreusualdrivingcircumstances,you would be awareof yourawareness,butnow you are not. You mightnowchoose to "snapout of it," and to become awareof your awareness, but thiswould be a separate mental act, which you might or might not perform.Hence, yourhavinga representation f the road is distinctfrom,and does notentail, your apprehending hatrepresentation.And thus no regress is gener-ated by the supposition that one lacks direct, unmediatedapprehensionofone s representations, ince having a representationdoes not entail that onealso apprehends hatrepresentation.

A furtherobjection to my view is fueled by the intuition that one couldnot have a sensation with a first-personphenomenalmode of presentationofa differenttype from the one it actuallyhas.26One's sensationof red, intro-spectively presented n the way sensations of red typically are, could not bepresented from the first-personpoint of view in the way that a sensation ofblue typically is. If a sensationappeared o the first-personpoint of view as asensation of blue typically does, then it could not be a sensation of red; itwould have to be a sensationof blue. But since by this intuition a sensation25 David Armstrong, "The Nature of Mental States," in Readings in the Philosophy of

Psychology, vol. 1, Ned Block, ed. (Cambridge: HarvardUniversity Press, 1980), pp.191-99.26 TorinAlter makes this objection (in correspondence).

326 DERK PEREBOOM



14/16

and a first-personmode of presentation annot be separated, t would seem tosupport the claim that sensations are identical with first-personmodes ofpresentation.It would follow, in turn, that there is no distinction betweenthe real natureof a sensation and how it is presentedfrom the introspectivepoint of view, and thatthereis no possibility thatfirst-person.modes of pre-sentationof sensationsfail to representsensations as they really are.

There are several replies to this objection that preserve the distinctionmy view requiresbetween sensations andtheirfirst-personmodes of presen-tation. The first is that althoughwe may naturallybelieve that a sensationcould not have a first-personmode of presentationof a different type fromthe one it actually has, this belief is mistaken. Analogously, we might havethe naturalbelief that somethingcould not be gold unless it were presentedin the familiarsensory way, but we know thatthis belief is in error.A sec-ond response is thatcausal laws are such thatany token of a particular ypeof sensation can directly cause first-personmodes of presentationonly ofone particulartype. Consequently, we can account for the intuition that asensation could not have a first-personmode of presentationof a differenttype while maintainingthat sensations and their first-personmodes of pre-sentation are distinct n the way my view demands.

One might resist the first response because of the strengthof the intu-ition at issue, and the second because one holds that even if the causal lawswere different, a sensation still could not have a first-personmode of pre-sentationof a differenttype from the one it actuallyhas. I am not convincedby these rejoinders,but a thirdresponse,which I favor,accommodates hem.Since our access to sensationsis typically by our first-personmodes of pre-sentation, and since these modes of presentationplay an importantrole inthe causal relations sensationshave, types of sensations are individuatedbysuch first-personmodes of presentation.Accordingly, sensations of red are,by definition,whateversensations arepresented n such-and-sucha first-per-son mode, where this mode is that familiarway sensations of red appeartointrospection.Thus, by the very definition of a sensation-type, it would belogically and not merely causally impossible for it to have a first-personmode of presentationof a different type from the one it actuallyhas. Yet onthis conceptionthe distinctionrequired or my view between sensations andtheir first-personmodes of presentation can be preserved. This conceptioncan sustain first-personmodes of presentation of sensations that might notrepresent hose sensations as they really are.

According to our challenge to the Lycan/Loarversion of the mode-of-presentationstrategy, Marycannot know that

(1) The mental state that features the typical human phenomenalmode of presentationof sensing redhas this property.

BATS, BRAIN SCIENTISTS,AND THELIMITATIONSOF INTROSPECTION 327



15/16

where 'this' demonstrateswhat it is like to sense red.Now we can see thatithas not been shown that Mary will not know this fact. The demonstratedproperty is indeed represented ntrospectively in a way in which someonewho has complete physical knowledge but has never had a sensation of reddoes not have access to it, but this does not show that such a knower does nothave access to its real nature.And furthermore, he same type of point ap-plies to any further terationof introspective perceptions. Hence, the mode-of-presentationstrategycan survive the challenge we raised for Lycan's andLoar' developmentof this approach.

VLet us return o the accessibility principle,the truthof which is presupposedby the various versions of the knowledge argument:

(A) If materialism s true, then one will have cognitive access to ev-erythingabouta subject's mental states, as they are apprehendedin introspection, solely in virtue of having complete physicalknowledge.

The considerations ust advanced enable us to see that we have insufficientreason to embrace this principle. Mental states, including states featuringphenomenal modes of presentation,might well not be as they appearto in-trospection. Consequently, there is insufficient reason to suppose that formaterialism to be true, physical omniscience must provide cognitive accessto mental states as they appearto introspection.The core intuitionunderly-ing the knowledge argumentsis that if someone who possesses completephysical knowledge does not thereby know some fact about mental states,then that fact cannotbe physical.But if whatthis physically omniscient sub-ject will fail to grasp is a mental state as it is apprehendedby means of amode of presentationthat might well not represent the state as it really is,then we cannot conclude that some aspect of the real natureof that state es-capes the materialist's net.

We can, however, formulatea moreplausible accessibility principle:(B) If materialism s true, then one will have cognitive access to ev-

erythingabout the real natureof a subject's mental states solelyin virtue of having complete physical knowledge.

Nevertheless, the argumentsof Jackson and Nagel fail to show that Maryand the chiropterologistwill not have complete knowledge of the real na-ture of theirrespective subjects' mental states. Mary does not have cognitiveaccess to everythingaboutthese states as they are apprehendedn introspec-tion, but again, one cannot therefore presume that she lacks knowledge of

328 DERKPEREBOOM



16/16

Documents

Pereboom Limits of Introspection