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PHILOSOPHICALPSYCHOLOGY , VOL. 14, NO. 2, 2001

Mental representation and the subjectivity ofconsciousness *

PETE MANDIK

ABSTRACT Many haveurged that the biggest obstacles to a physicalistic understanding of arethe problems raised in connection withthe subjectivity ofconsciousness. These problemsare most acutely expressed in considerationof theknowledge argument against . Idevelopa novelaccount of the subjectivity of consciousness byexplicatingthe ways in whichmental representationsmay be perspectival. Crucial featuresof my accountinvolve analogies between the representationsinvolved in sensoryexperience and theways in whichpictorial representations exhibit perspectivesor points of view. Iarguethat the resultant account of subjectivity provides a basisfor thestrongest response physicalists can give to the knowledge argument.

Introduction Consciousness has beena real pain forphilosophers and cognitive scientists inter- estedin developing materialist theoriesof the . Particularly vexing is the subjectivity ofconsciousness: thesubjective characterof conscious experience. What subjectivity is and whyit posesproblems for physicalists emergesmost vividly in discussions focusing onthework of and Frank Jackson. Nagel (1974) famously asked “whatis it like tobe a bat?”and urged thathumans, notbeing bats, could never know. Mostimportantly in his criticism ofthe limits of physicalism, Nagel argued thatno amount ofknowledge ofthe objective physical factsabout batbrains could yield knowledge ofthe subjective characterof bat experience. Whatis known fromthe objective point of view cannot bridge thegulf toyield whatis known fromthe subjective point of view: knowledge of what it is like . Drawing on similar intuitions, Jackson marshaled thesethemes in an attemptto falsify physicalism by way ofhis nowfamous knowledge argument .The gist ofthe knowledge argument is as follows.Mary has never seen red. She nonethelessknows all thephysical facts. Upon seeing red forthe Ž rsttime, Mary learns something new: what it is like tosee red. Priorto seeing red, Mary knewall thephysical facts; thus

*This paper was the winnerof the 2000William James Prize of the Societyfor and Psychology, awarded for the best paper by agraduate student presentedat the Society’s annualmeeting.

PeteMandik, Departmentof Philosophy, William Paterson University ofNew Jersey, 265Atrium Building, 300Pompton Road, Wayne, NJ07470,USA, email: [email protected]

ISSN 0951-5089/print/ISSN 1465-394X/online/01/020179–24 Ó 2001Taylor &FrancisLtd DOI:10.1080/ 09515080120051553 180 P. MANDIK in learning anewfact upon having ared experience, Mary learns anon-physical fact. Thus thesubjective character of experience is non-physical (Jackson, 1982). Therehave beenmany physicalist responsesto Nagel and Jackson overthe years. Mostare awed and only afewexplicitly address thetopic of subjectivity. In thispaper I develop atheoryof subjectivity and use it in adefenseof physicalism against theknowledge argument. Crucial aspectsof myaccount involve explications ofthe notions of perspective and point ofview .Icultivate an account ofperspective as it arises in pictorial representationsand apply theresultant account ofpictorial perspectiveto mental representations. Icontrastmy account against accounts that analyze perspectivesand pointsof view in termsof indexicals. Keyaspects in my arguments forthe superiority ofthe pictorial theoryof subjectivity overindexical theorieshinge on howthe respective theories are able todeal withthe issues raised in connection withthe knowledge argument. This paperis organized as follows.I begin withfurther discussion ofNagel and Jackson’s original arguments withspecial attention paid tothe role played by the notion ofsubjectivity. Ithenbrie y discuss themain kinds ofphysicalist responses toJackson’ s knowledge argument. Aftercanvassing themain kinds ofphysicalist responsesand their aws, Ilaunch into thearticulation ofmy pictorial theoryof subjectivity. Idiscuss crucial similarities and differencesbetween my pictorial theory and indexical theories,and address several possibleobjections to thepictorial theory.

1.The subjectivity of consciousness andthe knowledge argument against physicalism Nagel’s reections on objectivityand subjectivity have beendeveloped in several places, buthere I focuson his 1974 article “Whatis it like tobe a bat?”Nagel presumesthat bats are conscious, thatthere is something it is like tobe abat. Things thatlack conscious, like rocks,are things forwhich there is nothing it is like tobe. Notonly is Nagel conŽdent thatthere is something it is like tobe a bat, heis conŽdent thatit is radically unlike whatit is like tobe a human. This is plausible. Bats have sensory systemsquite unlike ours; mostnotably theyemploy sonar in their perceptualinteraction withtheir environment. Given thedivergence betweenhu- mans and bats, humans are incapable ofknowing whatit is like tobe a bat. Imagination and extrapolation are oflittle help. Even imagining apping around and hearing ourown voices reected off of the surfaces of objects serves only totell us whatit would belike tobe us under altered circumstances—such imaginings bring us no closerto knowing whatit would belike for bats.Whatwe can knowabout bats are thedeliverances ofobjective physical sciences: factsand propertiesknowable frommultiple pointsof view— objective facts. The factsabout batsbeyond our purview are thesubjective facts: facts known, ifat all, only fromthe point of view of bats. Acrucial pointto note, and onethat I will return toseveral timesin thispaper, is thatNagel intends theseremarks about perspectivesand pointsof view tobe about types and not tokens.Nagel writes: Iam notadverting hereto thealleged privacy ofexperience toits possessor. The pointof view in question is notone accessible only toa single MENTAL REPRESENTATION 181

. Ratherit is a type. Itis oftenpossible to take up apointof view otherthan one’s own, sothe comprehension of such factsis notlimited to one’s owncase. Thereis asense in whichphenomenological factsare perfectlyobjective: one person can knowor say ofanotherwhat the ofthe ’ s experience is. They are subjective, however,in thesense that even thisobjective ascription ofexperience is possibleonly forsomeone sufŽciently similar tothe of ascription tobe able toadopt his point ofview— to understand theascription in theŽ rstperson as well as in the third, soto speak. The moredifferent from oneself the other experiencer is, theless successone can expectwith this enterprise. (1974, pp. 441–442)

Nagel thusurges thatwhat we are cutoff from are factsabout certain properties— universals orrepeatables that are instantiable by multiple . Nagel’s arguments are nottargeting theepistemic problem of knowing theminds ofthose thatare merely numerically distinct fromyou, aproblemthat could arise between you and an otherwiseidentical twin. Nagel is instead concerned topoint out a problemthat arises in trying tocomprehend a quite qualitatively distinct kind of mind. Nagel castshis criticism as pointing outthe limits ofcurrent physicalistic understanding, buthe does not see it as falsifying physicalism. While hehas no doubt that physicalism about subjectivity is true, Nagel says thatwe cannot currently understand how it is true. Jackson, in contrast,cultivates Nagelian themesinto an argument against physicalism: theknowledge argument. Jackson’s knowledge argu- mentinvolves twothought experiments, onemore famous than theother. The famousthought experiment features Mary, thephysically omniscient scientist who only comesto learn whatit is like tosee red late in life. Lessfamous is thethought experiment thatfeatures Fred. WhereMary spends mostof herlife restrictedto the black and whiteroom and thusseeing farfewer colors than theaverage human, Fred is gifted withan unusually sensitive visual systemand thussees more colors than the average human. Whereaverage humans might group asetof ripetomatoes together as all thesame shade ofred, Fredsorts the tomatoes into twogroups thathe calls red1 and red2. Fredassures us thatred1 and red2 are as differentfrom each otheras yellow and blue. He sortsthe same objectsinto thesame groups trial after trial, giving evidence thatthe perceptual categories thathe is tapping into are quite salient and robust.Fred’ s reportsand behavior make us conŽdent thatwhat it is like tobe Fred is differentfrom what it is like tobe a normal human. However, wedo notknow what it is like tobe Fred. Wemay acquire all ofthe physical information about howFred’ s nervous systemworks and whatphysical featuresof objects he is sensitive to,but this is insufŽcient togive us knowledge ofwhat it is like. According toJackson, however,there are otherconditions thatwill sufŽce to give us knowledge ofwhat it is like tobe Fred. Jackson invites us toimagine thathumans have their visual systemssurgically altered toresemble Fred’ s, orupon Fred’s death someone elsereceives a transplant ofFred’ s visual system. Afterthese surgeries, peoplewould cometo learn something new—what it is like tobe Fred. Priorto the surgery, however,the regular humans knewall ofthephysical factsabout Fred. So in coming 182 P. MANDIK tolearn something new, theycome to learn something non-physical. Thus physical- ism is false since notall ofthe facts are physical facts. Like Nagel, Jackson urges thatthese remarks about thesubjective characterof experience targeta pointabout typesof , nottokens. Jackson writes:

When Icomplained thatall thephysical knowledge about Fredwas not enough totell us whathis special colorexperience was like, Iwas not complaining thatwe weren’ t Žnding outwhat it is like to be Fred. I was complaining thatthere is something about his experience, apropertyof it, ofwhich we were left ignorant. And ifand whenwe come to know what thisproperty is westill will notknow what it is like to be Fred, butwe will know more about him. Noamount ofknowledge about Fred, beit physical ornot, amounts toknowledge “fromthe inside” considering Fred. Weare notFred. Thereis thusa wholeset of items of knowledge expressed by formsof words like “thatis I myself whois …”whichFred has and we simply cannot have because weare nothim.

When Fredsees the color he alone can see, onething heknowsis theway his experience ofit differsfrom his experience ofseeing red and soon; another is thathe himself is seeing it. Physicalist and freaksalike should acknowledge thatno amount ofinformation ofwhatever kind that others have about Fredamounts toknowledge ofthe second. Mycomplaint though concerned theŽ rstand was thatthe special quality ofhis experience is certainly afactabout it and onewhich Physicalism leaves outbecause no amount ofphysical information told us whatit is. (1982, p.132)

In otherwords, whateverindexical knowledge Fredhas uniquely in virtue of being numerically distinct fromeveryone elseis notthe knowledge thatJackson sees as problematicfor physicalism. Instead, theproblem arises at thelevel oftypes, not tokens. Fredembodies a differenttype of point of view than typical humans. Jackson’s point in thequoted selection might berestatedas follows.One might say thatalthough wecannot knowwhat it is like to be Fred, wecan, aftersurgery, know what it is like tobe Fred. The possibility ofthis latter kind ofknowledge is what Jackson seesas incompatible withphysicalism; theimpossibility ofthe former kind ofknowledge stands regardless ofthe or falsity ofphysicalism. Itwill beuseful toconsider aschematization oftheknowledge argument. Since theversion featuring thethought experiment about Mary is theone most frequently discussed in theliterature, Iwill schematizethe argument in termsof that one.

· Firstpremise: priorto having ared experience, Mary can knowall ofthe physical facts. · Second premise :upon having ared experience forthe Ž rsttime, Mary comesto knowfor the Ž rsttime what it is like tosee red. · Third premise :knowledge ofwhat it is like tosee red is knowledge ofa fact. · Conclusion:since Mary knewall ofthephysical factsprior to seeing red, thenew factshe comes to know upon seeing red is anon-physical fact. MENTAL REPRESENTATION 183

The conclusion oftheknowledge argument constitutesa falsiŽcation ofphysicalism wherephysicalism is construedas thethesis that all factsare physical facts.Physical- istshave beeneager toŽ nd aws in theknowledge argument. Ibriey remarkon someof the most popular kinds ofphysicalist responsesto theknowledge argument. Mostphysicalists responding tothe knowledge argument have granted the argument’s validity while questioning its soundness. The majorkinds ofphysicalist responsesmay begrouped by whichof the premises they question. One premisethat has beensubjected to quite abitof physicalist pressureis thethird premisestating thatknowledge ofwhat it is like is knowledge ofa fact: propositional knowledge or knowing-that. Nemirow(1990) and Lewis(1990) have defended the“ ability hy- pothesis”: thehypothesis that knowledge ofwhat it is like is constitutednot by knowing-that butinstead knowing-how, procedural as opposedto propositional knowledge. The abilities thatMary gains in learning whatit is like tosee red are the abilities toremember seeing red and toimagine seeing red. Intuitively, theseabilities are thesort that could only beacquired byŽrsthaving theexperience ofseeing red, thusexplaining whyprior to seeing red, physically omniscient Mary did notknow whatit was like. The ability hypothesisitself has comeunder attack. The strongest objectionsto the ability hypothesishinge onpointing outthat these abilities are not necessary forknowing whatit is like (Alter, 1998; Tye, 2000). Tye makes thepoint especially forcefullyby pointing outthe degree towhich the speciŽ city ofexperience typically outstripsour abilities toremember or imaginatively relive thoseexperi- ences. Wemay have an experience ofa particular shade ofred, call it “red 35,”but beincapable ofreidentifying precisely thatshade orcalling tomind precisely that shade and notsome other. Nonetheless, at themoment in whichwe are experienc- ing thatshade ofred, weknow, at thatmoment, what it is like. Thus knowing what it is like cannot consistin theabilities mentioned in theability hypothesis. Such criticisms ofthe ability hypothesishighlight theappeal, even tophysical- ists, ofviewing knowledge ofwhatit is like as akind ofpropositional knowledge. In keeping withthis line ofthought is perhapsthe most popular kind ofphysicalist responseto the knowledge argument: themode of presentationresponse. According tothemode of presentationresponse, all ofthe premises of theknowledge argument are true, butthe argument itselfis invalid. The key pointis thateven though there is asense in whichMary gains newpropositional knowledge, it is only in thesense in whichshe comes to represent an old factin anewway— she comes to subsume an old factunder anewmode of presentation. The acquisition ofMary’ s new knowledge is akin tothe transition fromknowing thatMark Twain wrote Huckle- berry Finn withoutknowing thatMark Twain is oneand thesame as Samuel Clemmons toknowing boththat Mark Twain wrote Huckleberry Finn and thatMark Twain is Samuel Clemmons. In learning thatSamuel Clemmons is theauthor of thatbook one comes to representin anewway afactthat one knew already: thefact thatMark Twain wrotethat book. Questions arise, however,of what it is thatMary knewall along, whatthe new modeof presentation is, and whatsubjectivity amounts toon thisview. Foran especially clear answer tothese questions, Iturn toLycan’ s version ofthe mode of presentationresponse. First off, note that Lycan endorsesa representational theory 184 P. MANDIK ofconscious experience. Experiences are representations. When Ihave aconscious experience ofa Žreengine being bright red and six feetaway fromme, the experience itselfis neitherbright red norsix feetaway fromme. The experience itself is astateof mynervous systemthat represents the Ž reengine as being bright red and six feetaway fromme. When Iintrospectmy experience, Iforma second-order representationof theŽ rst-orderrepresentation of theŽ reengine. Otherpeople may formsyntactically similar second-order representations, butthose representations will beabout theirŽ rst-orderstates, notmine. The crucial analogy hereis tothe use ofindexicals in speech.When Isay “my leg hurts”I am referring tomy leg, and only Ican referto my leg by using thatutterance. You may use asyntactically similar construction: you may utterthe words “ my leg hurts,”but in doing so, you would berepresenting your leg, notmine. Analogously, only Ican representmy Žrst-order statesby theintrospective application ofself-referential indexical concepts.Mary is able tothink toherself correctly the thought she would expressby saying “this is whatit is like toexperience red.”Prior to having theexperience, shewas notin a position toemploy correctly the indexical/ demonstrative thought. But thestate of affairs shepicks outwith the demonstrative is oneshe was able topick outby other means priorto having theexperience. This is analogous tohow, prior to visiting my house, you are incapable ofcorrectly thinking toyourself thethought you would expressby saying: “PeteMandik lives here.”Though you cannot referto my home with“ here”until you get here,you can nonethelessrefer to it byothermeans prior toyour arrival, e.g. under thedescription “PeteMandik lives at such-and-such address.”Thus, according toLycan, indexicality is theultimate explication of subjectivity—as Lycan putsit, subjectivity is “pronominal.”Other accounts of subjectivity make similar appeals tothe role of indexicals in thought—see, for instance, Tye (1995) and Rey (1997). But theinsistence thatsubjectivity is indexical is developed at greatestlength by Lycan. One ofthe main virtues ofthe indexical responseis theway thatit connects withcore concepts in standard articulations ofthe notion ofsubjectivity: concepts ofperspective and pointof view. Subjectivity is oftenidentiŽ ed withwhat is known fromthe Ž rst-personpoint of view whereobjectivity is associated withthe third-person pointof view. The relation ofsubjectivity toindexicality is evident whenwe turn tothe role played by notions ofpoint of view in thedescription of writtenlanguage. Prosewritten from the Ž rst-personpoint of view is pepperedwith indexical termsto referto theauthor or alleged author. One famousexample would betheopening line ofMelville’ s Moby Dick:“Call meIshmael.”In contrast,typical instances ofprose written from the third-person point ofview are devoid of indexicals, as in “Herman Melville wrote Moby Dick.” Despitesuch advantages, theindexical responseis deeply awed. One ofthe main problemsis onethat it facessimply in virtue ofbeing aversion ofthe mode of presentationresponse. Recall thatprior to experiencing red, Mary is alleged toknow all ofthephysical facts.This would include, among otherthings, factsabout modes ofpresentation. Mary knowsthat “ MarkTwain” and “Samuel Clemmons”are differentmodes of presentation of the same person, and “Hesperus”and “Phosphorous”are differentmodes of presentation of the same planet. Thus, in MENTAL REPRESENTATION 185 learning something newin experiencing red, Mary cannot belearning anewmode ofpresentation of an old fact. (Similar objectionsare raised by Jackson, 1997, and Alter, 1998). Besides thisblanket objectionto mode of presentation responses, there are objectionsthat apply speciŽcally tothe indexical response.One such problemwith theindexical responseis thatit mistakenly makes numerical differencessufŽ cient for subjectivedifferences. To seewhy this is abad thing, consider thefollowing. Suppose thatwhile Mary doesnot know what it is like tosee red, Cheri, Mary’s color-sighted colleague, doesknow what it is like tosee red. Upon seeing red forthe Žrsttime, notonly doesMary learn whatit is like tosee red, shelearns whatit is like tobe Cheri. IfMary and Cheri werephysical and experiential doppelgangers (though numerically distinct individuals) theycould eachknow what it is like tobe theother person, regardless ofwhether their numerical non-identity entails diver- gence ofthe contents of their indexical thoughts. As Jackson putsa related point:

[T]heknowledge Mary lacked whichis ofparticular pointfor the knowl- edge argument against physicalism is knowledge aboutthe experiences of others,notabout herown … The troublefor physicalism is that, afterMary seesher Ž rstripe tomato, she will realize howimpoverished herconception ofthe mental life ofothers has been all along. She will realize thatthere was, all thetime she was carrying outher laborious investigations into the neurophysiologies ofothers and into thefunctional rolesof their internal states, something about thesepeople she was quite unaware of.(1995, p. 181)

As such, then, Mary and Cheri would besubjectively identical, in spiteof being indexically distinct. Thus indexicality is inadequate toaccount forsubjectivity. This pointabout whatMary and Cheri knowneeds tobe stated carefully, for thepoint is consistentwith the fact that, forall Mary knows, thereis nothing at all it is like tobeCheri. The point is thatif there is something it is like tobeCheri when Cheri is having experience ofkind X,and ifMary knowswhat it is like tohave experience ofkind X,thenMary knowswhat it is like tobe Cheri. Perhapsan analogy can behelpful here.Questions of what it is like to beX are questions castat thelevel oftypes, nottokens— likewise forquestions of what Xlookslike . You probably knowwhat Da Vinci’s painting, The MonaLisa ,lookslike, even though you probably have notseen theoriginal. Suppose thatI have hanging in my apartmenta painting Idid in high schoolcalled AStudy in Originality , which is a color-by-numbers replica of The MonaLisa .Given thatyou knowwhat The Mona Lisa lookslike, and that AStudy in Originality looks like The MonaLisa ,you thereby know what AStudy in Originality lookslike. And all ofthis is consistentwith the fact thatyou have never beento my apartment, and have notyet seen theparticular painting AStudy in Originality .You may noteven besure thatI have any paintings in myapartment: you may notknow whether Ihave any paintings. Nonetheless, if I have areplica ofthe Mona Lisa,and you knowwhat the Mona Lisa lookslike, then you knowwhat the replica lookslike: you knowwhat it would looklike werethere 186 P. MANDIK one, and you need nothave contactwith that particular instance ofthe type, paintings-that-look-like-the-Mona-Lisa . These aws withthe indexical account ofthe subjectivity ofconsciousness motivatethe pursuit ofan alternative, whichI provide in thefollowing section. Beforecontinuing, Ipreviewthe kind ofresponse to the knowledge argument that will growout of this account ofsubjectivity. FirstI list herewhat I think is right about theknowledge argument. Ithink thatit is right tosay thatMary would learn something newin having ared experience forthe Ž rsttime— prior to having ared experience, Mary could notknow what it is like tosee red. FurtherI think that knowledge ofwhat it is like is akind ofpropositional knowledge. But, in rejecting themode of presentation response, I rejectthe claim thatMary is merely represent- ing an old factin anewway. Whatis wrong withthe knowledge argument, Ishall argue, is theŽ rstpremise— the premise that states that prior to experiencing red Mary is able toknow all ofthe physical facts. Ithink, instead, thatMary is able to knowonly all ofthe objective physical facts.The sortsof facts that she is cutoff from are subjective yetnonetheless wholly physical facts.This sortof response has been suggested by others(Alter, 1998; Deutsch,undated; Flanagan, 1992), butthe credibility ofthe suggestion suffersfrom the meager detail heretoforeprovided about whatthe physical basis ofsubjectivity amounts to.I turn nowto provide such details, beginning witha reexamination ofthe notions ofperspective and pointof view.

2.Mental representation and pictorial perspective The indexical account ofsubjectivity was on theright trackinsofar as it related the notions ofperspective and pointof view torepresentations. But it runs afoul of problemssuch as tying thesubjectivity ofexperience totokens instead oftypes. The indexical theoristanalogizes mental pointsof view tolanguage writtenand spoken in theŽ rst-personpoint of view. Thereis aless literary and moreliteral way of understanding perspectiveand pointof view. This is therather literal sensethat pictorial representationsembody apointof view. Consider twophotographs of the same objecttaken fromtwo different angles. Compare, forexample, twophoto- graphs taken ofa person’s face: theŽ rstmay behead-on, theother may showthe head in proŽle. The camera thatproduced thephotos occupied twodifferent points ofview withrespect to the person’ s head. The representational contentsof the photographsproduced include contentabout thesepoints of view. This is whywe can tell bylooking at thephotographs whether the camera occupied apointof view in frontof or to the side ofthe . Notethat the pictorial senseof “ pointof view” is ratherliteral butnot totally literal. Fewimagistic representationscontain enough information tospecify a particular pointof view. Forexample, atypical map ofChicago presentsa “bird’s eye view”of the city, butabstracts away fromany information thatwould specifya pointof view positioned overthe Sears Toweras opposedto the Hancock Building. This is notto say thatthe map abstractsentirely away frompoint of view: it does contain enough information tospecify that one is viewing thecity fromabove it MENTAL REPRESENTATION 187

FIG.1:(a)and (b)are drawn invanishing-point perspective,thus positioningthe viewerin front of the Žrst and secondhouses, respectively; (c) is drawn inobliqueperspective and thus doesnot specifya point of viewin front of any particularhouse.

ratherthan belowit. Foranother example ofhow images may embody apointof view withoutspecifying aliteral pointof view, consider drawings in oblique perspec- tive as opposedto drawings in vanishing-point perspective(see Figure 1). Drawings in vanishing-point perspectiverepresent parallel lines thatare not perpendicular totheviewer’ s line ofsight as converging on oneor morepoints (the vanishing-points). Figures 1a and 1b are drawn in vanishing-point perspective.The vanishing-point in Figure 1a is located at thepeak ofthe Ž rsthouse from your left, and in Figure 1b, at thepeak ofthe central house. In oblique perspective,parallel lines notperpendicular tothe viewer’ s line ofsight are parallel in thedrawing, but drawn at non-right angles tothe lines thatare perpendicular tothe viewer’ s line of sight. Figure 1c is drawn employing oblique perspective.Drawings employing oblique perspectiveabstract away fromthe position ofthe viewer more than do picturesemploying vanishing-point perspective.Figure 1a speciŽes a pointof view in frontof the Ž rsthouse and Figure 1b speciŽes a point ofview in frontof the second house. Figure 1c, drawn in oblique perspective,abstracts away fromwhich ofthe three houses the viewer is in frontof, since, unlike in Figures 1aand 1b, the sides ofthe three houses occupy equal portionsof the picture plane. Nonetheless, Figure 1c doesnot abstract away entirely frompoint ofview as is evident fromthe factthat we can seeonly thefront, top, and oneside ofeach house. The pictorial senseof perspective can beunderstood as anotnecessarily implicating aprecisepoint of view. The pictorial notion ofperspective is thusjust thenotion thatpart of therepresentational contentof thepicture includes relations betweenwhat is pictured and theviewer. Such relations would include being in front ofor to the side ofa faceor a house. Otherrelations would include being closerto onepictured objectthan another. Anotherway ofseeing howpictorial perspective abstractsaway fromliteral, geometric,points of view is by considering thenotion of aerial oratmospheric perspective. Pictures employing atmosphericperspective de- pictthings in thefar distance as being fainter, hazier, and bluer than things thatare closerto the viewer. The device ofatmospheric perspective exploits factsabout the behavior oflight in theatmosphere to depictrelations ofdistance betweenthe viewer and whatis pictured, and is afrequently employed device in landscape painting. The sortof relations captured by atmosphericperspective abstract away fromthe precise 188 P. MANDIK location ofthe viewer. Forexample, it would bedifŽ cult toascertain fromatmo- sphericperspective which of the houses in Figure 1a theviewer was in frontof. Pictorial perspectiveis notonly apropertyof photographs, drawings, and paintings. Mental representationsalso exhibit pictorial perspective.In describing picturesas involving pictorial perspectiveI said thatthe representational contentsof thepictures include relations betweenthe things pictured and theviewer. Extending thisaccount ofperspective to mental representationsyields thethesis that some mental representationsinclude in theircontents relations betweenthe representing subjectand thatwhich is represented.Thus such representationsare egocentric (-centered) since theyrepresent relations thatthings bear tothe representer. I turn nowto the case thatthere are such mental representations. The pointthat mental representationsexhibit pictorial perspectivecan be bolsteredby bothphenomenological and empirical scientiŽc considerations. Con- sider Žrstthe phenomenological support.Just as twodifferent photographs of the same housemay befrom two different points of view, somay twodifferent visual experiences befrom two different points of view. Whatit is like tolookat thehouse froma point tothe north of it may bequite differentfrom what it is like tolook at thehouse from a pointto the west of it. Thus theperceptual representations involved in thetwo different experiences exhibit pictorial perspective.We need not actually beperceiving ahousein orderto have mental representationsthat exhibit pictorial perspective.One may instead dream ofseeing ahousefrom one point and thenanother and noticethe differences in pointof view. One may also imagine looking at thehouse from the north and thenthe west and in eachinstance a differencein pointof view is introspectiblein imagination. Thesepoints based on introspectionmay beenhanced by evidence frompsychological studies, towhich I now turn. Muchpsychological researchin thepast several decades has concerned the nature ofmental images and speaks tothe issue ofthe existence ofperspectival representations. Aclassic example is due toR.N. Shepard and his colleagues (see e.g. Shepard &Cooper,1982). Theseresearchers had subjectslook at simul- taneously presentedpairs ofobjects.The second memberof eachpair was eitherthe same as theŽ rstor a mirrorimage. Further,pair memberscould differfrom each otherin theirrotations in depthand in thepicture plane. The researchersfound that thetime it tookfor subjects to make “same ordifferent” judgments increased monotonically withincreases ofrotational displacement betweenpair members. Shepard et al.tookthis reaction timedata as evidence thatsubjects were rotating mental images tosee if theywould matchthe stimulus. The evidence thatShepard et al.collectedalso servesas evidence forthe existence ofpictorially perspectival mental representations. Amental image at any given stage ofa rotationconstitutes aperspectival representationbecause at eachpoint in rotation, theimage represents whatthe object would looklike froma particular pointof view. Sometheorists have postulated thatmechanisms similar tothosepostulated for image rotationmay beat workin visual objectrecognition. Humans recognize visually presentedthree-dimensional objectswith only two-dimensional projections on theretina as aguide. Somehow,we are able torecognize objectsseen from MENTAL REPRESENTATION 189 unfamiliar viewpoints, thatis, based on unfamiliar projectionsonto our retinas. Certain studies ofthe accuracy and reaction timesin visual recognition tasks implicate perspectival representations. Such studies typically examine thereaction timesand accuracy ofrecognition judgments ofobjects seen fromunfamiliar viewpoints. In such studies, average length ofreaction timeand judgment accuracy varies monotonically withthe degree ofrotational deviation (in depthor on the pictureplane) fromfamiliar views ofan object.These correlations are taken as evidence forthe hypothesis that visual objectrecognition is mediated by anormaliza- tion mechanism. The storedrepresentation of an objectis oneor more encoded “views”that encode only two-dimensional information based on previous retinal projections.Recognition offamiliar objectsseen fromunfamiliar viewpoints involves amatchbetween a storedview and theperceptual view via anormalization mechanism whichcompares the views (e.g., Bu¨lthoff& Edelman, 1992; Shepard & Cooper,1982; Ullman, 1989). Forexample, thismight involve mentally rotating an image (Shepard &Cooper,1982). Objectrecognition, as well as imagery, may involve perspectival representations. Perspectival representationsalso surfacein accounts ofnavigation. Justas there is evidence thatan objectmay berecognized betterfrom one point ofview than another, somay adestination bebetter arrived at fromone starting pointthan another. One richbody ofresearchon navigation involves lesion studies ofrats. One kind ofexperiment in ratsconcerns the performance of lesioned ratsin theMorris watermaze. The Morriswater maze is an apparatus Žlled withwater in whichrats can swim. Objectssuch as small platformscan beplaced in thisarena. Milk powder can beadded tothe water to make it opaque, and thelevel ofthe water can be adjusted sothat when a platformis submerged it is notvisible torats swimming in themaze. In Eichenbaum et al.(1990) awatermaze was setup such thatrats had toswimto aplatformvisible during training trials, butoccluded bytheopaque water in thetesting trials. Varied visual stimuli werepositioned around themaze toserve as orientation cues. The experimenterstrained intact and hippocampal-system damaged ratsto swim to theplatform from a given startlocation. During testtrials, boththe intact and damaged ratswere able toswim to the platform if theywere startedfrom the same location as in thelearning trials. However, theperformances ofthe intact and damaged ratsdiverged widely whenthey were started from novel locations in thewater maze. During testtrials, intact ratswere able tonavigate tothe platformfrom novel startlocations, whereasthe hippocampal damaged ratsrequired muchlonger toŽ nd theplatform, and sometimesnever found it during thetest trial. Muchdiscussion ofthese sorts of investigations ofthe neural bases ofrat navigational abilities has concerned theproposal that the hippocampus is alocus of allocentric (“other-centered”) representationsof the spatial locations in themaze and withoutwhich lesioned ratsmust rely on merely egocentric(“ self-centered”) representationsof spatial locations (see e.g. O’Keefe& Nadel, 1978). Evidence of egocentricand allocentric representationsof spatial locations is notconŽ ned to studies ofrats. Forexample, Feigenbaum and Rolls (1991) recordedthe electrical activity ofindividual neurons in thehippocampus of macaque monkeys. In their study, theylooked forneurons thatwere maximally responsive tothe spatial location 190 P. MANDIK ofa visual stimulus. They thenchanged thespatial relation ofthe monkey with respectto thestimulus sothat, although thestimulus had notmoved, it projectedto adifferentpart of the monkey’ s retina. Cases in whichactivity in neurons was still maximally responsive tostimuli in thatlocation regardless ofwhatpart of the retina thestimulus projectedto were regarded as allocentric representationsof that spatial location. In contrast,neural activity maximally responsive toa spatial location deŽned relative tothe site of retinal projectionis regarded as an egocentricrepresen- tation ofthat location. Feigenbaum and Rolls (1991) reportthat the majority (but notall) ofthe cells in thehippocampus that they investigated wereallocentric representationsof spatial location. Wherethe hippocampus has beenwidely impli- cated as thelocus ofallocentric representationsof spatial locations, many kinds of egocentricrepresentations of space (including, forinstance, head-centered and shoulder-centered representations) have beenlocalized in regions ofthe posterior parietal cortex.(See Stein, 1992, and Milner &Goodale, 1995, forgeneral discus- sions ofegocentric representations in parietal cortex.) However, thequestion of where egocentricrepresentations are is notas interesting as thequestion of what egocentricrepresentations are. Iproposeto explore such questions against the backdrop ofnaturalistic theoriesof representational content. HereI will assume an informational psychosemantics, thecrux ofwhich is the view thata brain staterepresents X by virtue ofhaving thefunction ofcarrying information about (being caused by) X.While informational psychosemanticsoffers theseconditions as bothnecessary and sufŽcient forrepresentations, hereI need only toregard themas sufŽcient. ElsewhereI argue against theirnecessity (Mandik, 1999) and offeras an additional setof sufŽ cient conditions that X may represent Y if X has thefunction ofcausing Y.As discussed there,this (procedural instead of informational) account is mostappropriate to accommodating theview, widespread in neuroscience, thatactivations ofareas in motorcortex represent efferent events. Wehave herethen two kinds ofcondition sufŽcient for X torepresent Y: one expressed in termsof X’s causing Y,onein termsof Y’s causing X.Iwill combine thetwo and say thatit is sufŽcient for X torepresent Y that X has thefunction of being causally related to Y (alternately: causally covarying with Y),thuscovering boththe informational (affector)and procedural (effector)cases. Imake no claims onthesesufŽ cient conditions also being necessary. Ihave neitherthe resources nor theneed hereto offer a full-blown account ofrepresentation, an account thatcan supply conditions forall kinds ofmental representations. My main concernhere is withaccounts adequate forrepresentation as it Žgures in sensory experience. Iwill assume withoutfurther argument thatcausal covariational accounts are adequate. The neurobiological paradigms forcausal covariational semantics are feature detectors.A featuredetector consists in oneor moreneurons thatare (i) maximally responsive toa particular typeof stimulus, and (ii) have thefunction ofindicating thepresence of a stimulus ofthat type. Neuroscientistshave hypothesized the existence ofdetectors for stimulus typessuch as high-contrast edges, motion direction, and colors.Some have hypothesized thatthe nervous systemsof frogs contain ydetectors.Lettvin et al.(1959) identiŽed cells in thefrog retina that responded maximally tosmall shapesmoving acrossthe visual Želd. The inference MENTAL REPRESENTATION 191 thatsuch cells have thefunction ofdetecting ies and notjust any small moving thing is based on certain assumptions about thediet and environment offrogs, thus satisfying (ii) as well as (i). Otherexamples offeature detectors include neurons thatare particularly sensitive tothespatial locations ofstimuli. Insomecases theneurons are responsive tolocations relative tothe subject, thus giving rise toperspectival, oregocentric, representationsof spatial locations. In othercases, theneurons are responsive to locations independent ofthe relations betweenthe location and thesubject, thus giving rise tonon-perspectival, orallocentric, representationsof spatial locations. Nowwe are in aposition tosee how the notion ofperspectival representations such as egocentricrepresentations of locations may beaccommodated by acasual covariational psychosemantics. Asubject S has aperspectival representation R of X ifand only ifthe representational contentof R includes relations S bears to X. Cashing outthe notion ofrepresentationin termsof the causal covariational account described above yields thefollowing formulation. Asubject S has aperspectival representation R of X if (but maybe notonly if) R has thefunction ofcausally covarying with X and relations Z1 through Zn that S bears to X.Inthecase ofspatial representations, on whichI will focusfor now, therelations in question will be spatial relations. LaterI will generalize thisdeŽ nition ofperspectival representation tonon-spatial sensory modalities. One class ofspatial perspectival representationsis provided by neurons withretinocentric receptive Ž elds. Such neurons, whetherin cortexor in theretina itself, demonstratepatterns of activity maximally responsive tothe occurrence of a speciŽc kind ofelectromagnetic radiation in acertain spatial location deŽned relative tothe retina. Itis aplausible and widespread assumption thatactivity in neurons withretinocentric receptive Ž elds represent(or “encode”or “codefor” ) luminance incrementsin retina-relative spatial locations. Ifthis assump- tion is correct,then we can seehow such neural representationsconform to the account ofperspectival representations. In thisexample R is acertain kind ofactivity in acertain neuron in S’snervous system, X is aluminance incrementand Z1–Zn include thespatial relations X bears to S (especially spatial relations to S’s retina). Foranother example, consider neural activity thatrepresents goal locations for saccades. Analogous tothe receptive Ž elds ofsensory neurons, motorneurons have whatwe may call “effective”Ž elds. The effectiveŽ eld ofa neuron may bea region in spacethat an organism may moveor reach toward in responseto activity in a particular neuron. Thereare neurons thatcontrol saccades thathave as effective Želds head-relative spatial locations. Ifit is correctto speak ofactivity in such neurons as “representing,”“encoding” or “ coding for”head-relative spatial loca- tions, thenwe have anotherinstance ofperspectival representations. Activity in such motorneurons representsthe movement of the eye towarda location in space deŽned relative tothesubject’ s head. Such neural activations do notsimply causally covary withthe movement of the eyes toa certain location, butthe movement of eyes toa certain location deŽned relative tothe subject, and in thisinstance, relative tothesubject’ s head. And ifthese activations have thefunction ofcausally covarying withthese subject-relative locations thenthey constitute perspectival representations ofspatial locations. 192 P. MANDIK

Abriefword needs tobesaid about thecompatibility ofmental imagery and the causal covariational account ofrepresentation. Someresearchers favor an account of imagery wherebyimages representin virtue ofresembling thatwhich is represented (see Kosslyn, 1994). Thereis muchliterature on thisissue, and sufŽce it tosay, few agree thatresemblance is necessary forrepresentation, even in cases wherethe representationsare images. To illustrate thepoint, consider Žnding acreatureinside ofwhich we found something thatlooked like this: Ù Ù Ù .Suppose thatwe wondered whetherthis constituted a representationof something. Itresembles a mountain range. Might it bea representationof amountain range? Italso represents saw-teeth,a rowof evergreen trees,and abandoning visual resemblance, wemay say thatit resemblesa noise witha certain waveform.Which does it represent?Resem- blance, as many have pointed out, underdetermines representation, and even in cases in whichrepresentations do resemblewhat they represent, functional causal covariation may becalled in todo thejob of disambiguation. Forinstance, a photographof Joe equally resemblesJoe and Joe’s identical twin Moe.But thephotograph is aphotographof Joe and notMoe in virtue ofJoe’s position in the causal chain thatled up tothe creation ofthatphotograph. These points about the roleof causal covariation in determining thecontents of imagistic representations are consistentwith a commonanalysis ofmental imagery. According tothisanalysis, imagery is theof ine utilization ofperceptual (and perhapsmotor) processes that are typically used online (see, forexample, Grush, 2001). Since thatis all thereis to imagery, imagery need notresemble what it is an image of.Such aview allows for imagery in non-visual modalities such as olfaction, wherethe possibility ofresem- blance betweenthe representation and therepresented seems obscure. I mention thesepoints not to settle any ongoing controversiesregarding mental imagery, but only toshowthat the existence ofimagistic mental representationis neithernecess- arily norobviously incompatible withaccounts ofrepresentation that make having thefunction ofcausally covarying with X sufŽcient forrepresenting X. Anotheralleged incompatibility ofimagery and causal covariational psychose- mantics can beshown to bemerely apparent. Recall thatpart of theaccount onoffer is thata subject S’srepresentation R of X is perspectival if it has thefunction of carrying information about relations between S and X.Rick Grush (personal communication) objectsthat this kind ofaccount is inadequate forthe perspective embodied in imagery on thegrounds that Taking S tobe the actual real S thenentails thatmy imagining seeing the EiffelTower right nowfrom the north is notperspectival, because it caries no information about therelations between S (theactual mesitting herein the[… ]cafe´)and theEiffel Tower. Grush may becorrect that the event ofimagining doesnot carry information about therelations between S and theEiffel Tower. On aparticular occasion onemay be caused toimagine theEiffel Tower by something otherthan theEiffel Tower, and thusthat particular imagining would notcarry information about theEiffel Tower. However, on theaccount ofimagery sketchedin theprevious paragraph, theevent ofimagining involves astatethat has thefunction ofcarrying information about the MENTAL REPRESENTATION 193 relations between S and theEiffel Tower. Imagining involves running ofine what is run online during :states that are supposedto carry information in the perceptualcase may also bepressed into service forof ine imaginings. Thus the ofine statesemployed in imagining theEiffel Tower owe their representational contentto theinformation theyare supposedto carry in theonline perceptualcase. Icall theanalysis ofperspectiveI offer“ pictorial”in orderto contrast it withthe analysis ofperspective offered by Lycan (1996) and othersin termsof indexicals and theliterary convention ofŽ rst-personpoint ofview. Picturesare theprototypical instances ofrepresentationswith pictorial perspective,but it is importantto empha- size thatthey are notthe only instances. Picturesof a car fromtwo different points ofview may beencoded as bitmaps, whichmay themselvesbe translated into strings ofonesand zerosor sentences describing theoccupants ofevery cell in thebitmap’ s two-dimensional array. One may Žnd it natural tosupposethat such resulting strings ofnumerals and sentencesmay retain therepresentational contentof the pictures fromwhence they came without themselves being pictures. This is notto say, however,that bitmaps have all and only thecontent of the images theyencode. Theremay besome differences in therepresentational contentsof the images and thebitmaps. However, despitepossible differences of representational content,there are also considerable similarities. Ifa bitmapped photographrepresents a car, then thecorresponding numerical string doestoo. After all, thepicture of a car is recoverablefrom the bit string. And if thebitstring retains therepresentational contentof being about acar, thenthere seems no todeny thatthe bitstring also retains therepresentational contentof being about acar as seen froma particular point ofview. Thus, if apictureis perspectival, thenits corresponding bitstrings are perspectival, even though thecorresponding bitstrings are notpictures. Bitstrings are notthe only instances ofrepresentationswith pictorial perspective thatare notpictures. Activations in neurons withretinocentric receptive Ž elds are anotherexample. Such neural activations representthe occurrence of stimuli at spatial locations deŽned relative tothe retina. Itake it as obvious thatthe activation ofa single neuron is nota pictureeven in cases in whichsuch activation may bea spatial representation. BelowI will discuss thepossibility ofperspectival representa- tions oftemperature, thus giving yetanother example ofrepresentations with pictorial perspectivethat are notpictures. Representationswith pictorial perspectiveare notnecessarily pictures. Norare theynecessarily indexical. AboveI mentioned thatI intend thepictorial analysis to contrastwith the indexical analysis, buthave notshown that this is indeed thecase. The reason whyrepresentations with pictorial perspectiveare notnecessarily index- ical has todo withparticularity. Indexicals necessarily involve particularity in away thatnon-indexicals and egocentricrepresentations do not. The representational contentof the utterance “ Iam herenow” picks outa particular individual at a particular location at aparticular . Even whenindexicals and demonstratives are used topick outuniversals, as in saying “thisshade ofred”while holding up achip ofpaint, referenceto the universal (theshade ofred) piggybacks on theparticulars thatsecure the indexical content:the particular paint chipheld by theparticular individual at aparticular time. In contrast,a picturecan exhibit perspectival content 194 P. MANDIK withoutpicking outany particular. Adrawing ofthe 1991 Chevy Cavalier may be used notto representany particular 1991 Chevy Cavalier. Itmay instead beused to representa corresponding universal, say, thegeneral category thatall and only 1991 Chevy Cavaliers belong to.Nonetheless, the picture, in being atwo-dimensional representationof a three-dimensional object,represents the car fromone or another pointof view. Forinstance, thepicture may showthe front of the car butnot the back. Ofcourse, theconventions ofphotography may have an indexical element: a photorepresents me and notmy twin in virtue ofbeing appropriately caused byme, notmy twin. But adrawing ofthe general body style ofthe 1991 Chevy Cavalier need nothave its representational contentdetermined in theway aphotoof a particular 1991 Chevy Cavalier would. But bothwould beperspectival— both would implicate apointof view. Anotherway toput the point is thatwhen pictures are used indexically torepresent a particular object,as in thecase ofa photographof a particular car, theycan implicate a particular pointof view. But picturescan also be putto ause wherebyno particulars are representedand no particular pointsof view are implicated. In thecase ofa drawing ofa general type ofcar, thepoint of view implicated is likewise a type ofpoint ofview. Thus, thereis akind ofperspective— pictorial perspective—that is underdetermined by indexical content.Something may exhibit pictorial perspectivewithout being orcontaining an indexical. Thus completesmy sketchof pictorial perspectiveand its neural underpinnings. All theexamples Iemployed involved spatial representations. One obstacleto claiming thatpictorial perspectiveis an appropriateway ofthinking ofthe subjec- tivity ofconscious experience will depend on extending theaccount tonon-spatial cases. While weexperience spatial locations and relations, wealso experience non-spatial featuresof the world, including colors,odors, and temperatures[1]. In orderto show that the account ofperspective I favor can beextended tonon-spatial cases, Inext discuss howexperiences oftemperature may involve perspectival representationsof temperature. Inadetailed examination ofthermoperception (drawing on thework of Hensel, 1982), Akins (2001) Žnds grounds forquestioning whetherthermoreceptors allow thebrain torepresent features of the objective world (in thiscase, temperatures). Akins argues thatin orderfor thermoperception to be in thebusiness ofrepresenting temperature,three conditions mustobtain. First, theremust be constant correlation betweenreceptor activity and temperaturestimuli. Second, theactivity ofthe receptorsmust preserve relevant structureof the stimuli (e.g. greater and lesser activity in thereceptor must re ect greater and lessertemperature). Third, the sensory systemmust be servile in thesense thatit doesnot embroider upon the information extracted fromthe environment. Akins argues thatthermoperception fails all threecriteria. While Akins’critique provides an obstacleto viewing thermoreceptorsas representing objectiveproperties, Akins’ analysis leaves entirely openthe possibility thatthese receptors serve to represent temperature in an egocentricway. Thus, on theaccount Ifavor, thecontents of thedeliverance ofthese sensory systemsare less like reporting thatthe water is 5degrees Celsius and morelike reporting thatthe wateris toocold forme. Iagree withAkins thatthermoperception is whatAkins MENTAL REPRESENTATION 195 calls a“narcissistic”system. Idepart fromAkins in thatI view thermoperceptionas representing narcissistic propertieswhereas Akins holds thatthermoreception does notrepresent at all. Ifocuson twoaspects of Akins’ discussion ofthermoreceptors (cold receptors and warmthreceptors) that lend tothinking ofthehuman thermoperceptivesystem as producing perspectival representationsof temperature.The Žrstconcerns the fact thatthermoreceptors are notdistributed acrossthe skin in auniform concentration, and thatdifferent concentrations of thermoreceptorsgive rise todifferent sensations given aparticular skin temperature.The ratio ofcold towarmreceptors varies across differentparts of the body. One result ofthisis thatdifferent parts of thebody may have varying degrees ofcomfort for water at agiven temperature.Water that feels comfortablytepid onthehands may feelshockingly cold whendumped overthe top ofthe head. The second aspectof thermoreceptorsthat lend themto a perspectival view is thatthey have dynamic responsefunctions. Athermoreceptor’s responseto agiven temperatureat agiven timeis in parta function ofwhat its responseat a previous instant was. This is evident in awell-known example ofthe context sensitivity oftemperature perception. Prior to submerging your hands in abucket tepid water,hold onehand in abucketof ice and theother hand in hotwater. The waterin thebucket will feelhot to the previously chilled hand and muchcooler to thepreviously heated hand. Boththe differing concentrations ofreceptors and thedynamic responsefunc- tions give rise toa many-to-one mapping oftemperature sensations and tempera- tures. Asample ofwater of a given temperaturewill give rise tomany different sensations depending on theconcentrations of receptors and thelevel oftheir previous activity. Thesemany-to-one mappings are arguably and plausibly partand parcel ofthe proper functioning ofthermoreceptors. A given temperaturemay be morehazardous totissue in onepart of the body than another, and thus, amore sensitive alarm systemmay beaccomplished by varying receptorconcentrations. Dynamic responsesmay beadaptive since arapid change oftemperature can be damaging totissue even ifit occursin arange oftemperaturesthat would otherwise beharmless. Akins sums up theseaspects of thermoreceptors by describing themas “narcissistic”: theyare less concerned withhow things are independently ofthe organism and moreconcerned withhow things relate tothe organism, thusechoing thehuman narcissist’s favoritequestion: “So whatdoes this have todo withme?” She takesthe narcissism ofthermoperception to count against theclaim that thermorecptivesensory systemsrepresent at all. Ifavor thealternative interpretation thatthermoperception represents temperature, albeit in aperspectival way. A given temperaturesensation doesnot just represent a temperatureof aregion on or near theskin butrepresents temperatures as being ofvarying degrees ofhazard orharmlessness tothe subject’ s tissues. The outputof a thermoreceptorin responseto a given temperaturedoes not represent a given temperatureper se but instead whetherthe given temperatureis, forexample, toohot, too cold, orjust right. The propertyof being toohot cannot bedeŽ ned independently ofanswering thequestion “toohot for whom?” and thesubject relativity ofsuch apropertyis 196 P. MANDIK whatmakes it narcissistic. Thermoreceptorsinclude in therepresentational contents oftheir outputs relations thatthe temperatures bear tothe representing subject, muchin theway thatretinocentric representations of spatial locations represent locations deŽned relative tothe subject. Arguably, perspectival representationmay befound in examples beyond spatial and thermalperception. Our detectionof chemicals in olfactoryand gustatory senses may notbe in thejob of simply representing thepresence of a certain chemical but also representing thechemical as noxious orpoisonous ornutritious. But theseare propertiesthat can only bedeŽ ned in relation tothe organism: oneman’ s meatis anotherman’ s poisonand all that. Thus any systemthat has thefunction ofcausally covarying withsuch propertiesthereby produces perspectival representationsof chemical concentrations: representationsof chemical-involving narcissistic proper- ties. Akins’objects to the proposal that thermoreception represents narcissistic propertieson thegrounds thatthe proposal depends on accepting thedetection thesis: theclaim that“ each and every sensory system functions to detect properties ” (Akins, 2001, p. 383, emphasis in original). Akins thengives tworeasons for doubting thedetection thesis: theŽ rstis thatthe thesis is overly strong given the relatively small amount ofevidence regarding sensory function collectedto date. The second is thatin at least onecase— the case ofproprioception— interpreting sensory activity as having thefunction ofdetecting is unhelpful and unenlightening. Iproposeto grant Akins thefalsity ofthe detection thesis, since such a concessionleaves unscathed theproposal I favor. Forconvenience Iwill call the proposal“ thenarcissistic representationproposal” — theproposal that thermoper- ceptionrepresents narcissistic properties.Akins misconstruesthe logic ofthe situ- ation in asserting thatthe narcissistic representationproposal depends on the detectionthesis. Contra Akins, thedetection thesis is nota necessary condition on thetruth of the narcissistic representationproposal. The narcissistic representation proposalplausibly has as anecessary condition thetruth of the thesis that at least one sensory systemfunctions todetectproperties. But it is notat all obvious howit could have as anecessary condition theclaim that“ each and every ”sensory system functions todetect properties. And formy immediate purpose,the purpose of establishing theplausibility ofnon-spatial representationsthat nonetheless have pictorial perspective,the detection thesis may bedisregarded as irrelevant [2]. Ihave proposedthat some mental representationsexhibit pictorial perspective. Weneed totiethis into consciousness. Dostates of consciousness possessthis kind ofperspective? Regarding whetherconscious statesexhibit thiskind ofperspective, theanswer seemsa resounding “yes.”The thermoperceptionexamples are all examples ofconscious sensations thatvary independently ofactual temperature: whatenters into sensation includes relations ofthe temperature to states of the subject.Water of a given temperaturemay feelcolder on thehead than on the hands. Likewise, theremarks about thephenomenology ofvisual experience lead naturally toŽnding pictorial perspectivein conscious representation. Myperceptof seeing ahousediffers depending on whereI am standing. Itdepends on my literal pointof view. MENTAL REPRESENTATION 197

This completesmy sketchof the pictorial account ofhow mental representa- tions may beperspectival. Iturn nowto address theproblems about perspectiveand subjectivity raised by theknowledge argument.

3.Pictorial perspective and the knowledge argument Onthealternate responseto theknowledge argument thatI favor, theŽ rstpremise ofthe argument is false: it is false thatthe subject could knowall thephysical facts withouthaving an experience ofred. Ifavor theview thatthere are bothobjective and subjective physical facts.What a subjectcan learn only by having an experience ofred is asubjective, yetnonetheless wholly physical fact. The account ofpictorial perspectivedescribed above renders intelligible thecompatibility ofphysicalism and subjectivity. Itallows us tosee how a physicalistic frameworkcan tolerate,Ž rst, physical propertiesthat depend fortheir existence on representationsand, second, physical propertiesthat can berepresented only by therepresentations that they depend on. Thus, such physical factsare subjective in theclassical sensesof being, Žrst, mind-dependent, and, second, knowable only by arestrictedmode of access. Thesenotions may bebrie y characterized byreferenceto imagistic representations. The subjectdependence involved may besketched as follows.What an image of X representsis theway X would looklike fromsome particular location. Whatthe image representsdepends forits existence on theprocess of its representationin the sense thatprecisely whatis representedcannot becharacterized independently of specifying thepoint of view ofthe representing subject.For example, partof what is representedis whatthe object looks like fromone location as opposedto another. Consider apictorial representation, such as aphotographof a complexobject like theStatue ofLiberty. Given thepoint of view fromwhich the photograph was taken, only afractionof the surface of thestatue is explicitly representedin thephotograph. Certain regions seen fromone angle would beobscured from another angle. Consider theset of regions thatare captured by thephotograph: the set of all and only theregions explicitly representedin thephotograph. What is it thatuniŽ es thoseregions as aset?What is commonto all and only thoseregions? The point of view occupied byaviewer—agenerator ofpictorial representations—is theunifying essenceof those particular regions. Itis in thissense, then, thatthe things thatare representeddepend onbeing represented.Of course, thereis asense in whichthey would exist even ifno onewere to represent them. But in specifying theset comprisedof all and only thespatial regions captured in theimage, onedoes not carve nature at thejoints, butinstead carves nature into agerrymandered collection ofitems that would beof no interestapart fromtheir involvement in aparticular representation. That muchof neural representationis concerned withsuch gerry- mandered propertiesshould notcome as an enormoussurprise. Forinstance, it makes sense thatan animal’s chemoreceptorswould beless interestedin carving nature into theperiodic table ofelements and moreinterested in carving nature into thenutrients and thepoisons— categories thatmake no sense apart fromthe needs ofa particular typeof organism. The restrictedepistemic access involved may besketched in termsof imagistic 198 P. MANDIK representationsas follows.What is representedby an image can only berepresented, withoutaddition ordeletion, by an image. Even astring anumerals coding abitmap foran image doesnot have all and only therepresentational contentof the image. The numeral string constitutes,in part, arecipefor constructing an image, and in doing soit has contentthat the image itselflacks. Thereare propertiesrepresented in sensory experience thatmay only berepresented in sensory experience. Part of whatis representedin olfaction, say, may beconveyed in someother mode of representationlike spokenlanguage— “your perfumesmells like vanilla and roses.” But thesuggestion that all and only whatis representedin olfactoryexperience can only berepresented in olfactoryexperience is an entirely physical possibility, ifnot aphysical actuality. That experience is perspectival in thissense allows us to conceive ofphysical factsthat may beknowable only by arestrictedmode of access, thatis, physical factsthat may only berepresented by speciŽc sensory experiences. Onmyview, restrictedepistemic access to somefact is restrictedrepresentabil- ity. Something thatcan beknown in only arestrictednumber ofways is something thatcan berepresented in only arestrictednumber ofways. Conversely, something thatis knowable in amultiple ways can berepresented in multiple ways. The causal covariational psychosemanticssketched above helpsto spell outthis notion of restrictedepistemic access. Ifthereis aproperty P thatwe can representwith some representation R,thenthere must be at least onekind ofcausal interaction that P entersinto, namely, onethat relates P to R withoutwhich, R could notrepresent P. If property P is knowable frommultiple kinds ofpoint of view, thenthere are multiple kinds ofrepresentations— R1 through Rn thatmay represent P and thus multiple kinds ofcausal interactions that P may enterinto. Suppose instead that property P entersinto only arestrictednumber ofcausal interactions. This is indeed aphysical possibility. Nothing in physicalism rules it out. Such aproperty,in virtue ofentering into only afewkinds ofcausal interactions is thusrepresentable, ifat all, in only afewnumber ofways. What might examples ofsuch propertiesand interactions be? Consider theold tornJell-O box trick. Dennett(1997, p. 637) describesan old spy trickof tearing apieceof paper, orin thecase ofthe Rosenbergs, aJell-O box, tocreate an un-forgeable identiŽer. The matching halves are soinformationally complexthat the only way ofidentifying oneis by identifying theother. As Dennettputs it,

[t]he only readily available way ofsaying whatproperty M is [theproperty thatmakes onepiece of the Jell-O box amatchfor the other] is justto point to our M detectorand say that M is theshape property detected by this thing here.(p. 637)

As Iwould statethe case, theonly detection supporting causal interactions thatone pieceof the Jell-O box entersinto are causal interactions involving theother piece ofthe box. In thepsychosemantics glossed above, theparadigm examples of representationare sensory detection, and theexample ofthe Jell-O box helpsus appreciate thepossibility thatmany oftheproperties represented in sensory mecha- nisms are propertiesthat enter into only afew detection supporting causal interactions, MENTAL REPRESENTATION 199 namely, interactions withthe senses. And someonewithout those sensory mecha- nisms could notrepresent those physical properties. What, then, did thecolor-blind Mary notknow? Therewas aphysical property thatshe was incapable ofrepresenting until sheŽ rsthad herred experience, because thisphysical propertyenters into detectionsupporting causal interactions only with themechanisms ofhuman colorvision. Note,however, that it is knowledge about a property,notknowledge restrictedto theparticularity ofher own case. Thus, unlike theindexical account criticized above, thepresent account doesnot mistakenly tie subjectivity totokens but to types. Whatmore can besaid about theproperty that Mary comesto have knowledge of?By deŽnition, notmuch. Such aproperty,if representable only bycertain sensory experiences, by deŽnition could notbe represented by linguistic representations. Besides telling you “it’s that property”— whichis obviously uninformative—nothing morecan besaid since thissubjective property, this subjective fact, doesnot enter into therich number ofkinds ofdetection supporting causal interactions that objectiveproperties and factsenter into. The possibility sketchedabove is oneno physicalist should have qualms about admitting. Physicalism provides no toexpect that all physical propertiesbe objectivein theabove senses. Physicalism doesnot rule outthe possibility ofa propertythat is instantiated in causal remotenessfrom most other properties and is thusrepresented, if at all, only in arestrictednumber ofways. Nonetheless, familiarity withthe sorts of considerations invoked in Nagel and Jackson’s thought experimentsmay incline us tocontrary intuitions. Students ofthese thought exper- iments are accustomedto imagining (or at least pretending toimagine) thata suitably informedhuman mind could bewrapped around theentirety ofthe objectivephysical factsabout somedomain. Forinstance, it is oftsupposed that all the physicalfacts about batscould beknown, orat least represented,from the objectivepoint of view withouthaving batty experiences. But it is precisely thiskind ofsupposition thatI call into question. Muchof theproblem, I want tosuggest, has todo withambiguities in ourword “represent.”There is onesense, Iwill grant, thatwe can representall ofthe physical propertiesfrom the objective point ofview, and anothersense in whichwe cannot. And it is thislatter sense thatis crucial, Isuggest, in therepresentations supporting knowledge of what it is like .Consider thelinguistic representation“ All ofthe people in France are less than 3meterstall” and thefact that my friend, Jacques Blanc, is in France and is less than 3meterstall. Doesthe linguistic representationin question representthe fact in question, thespeciŽ c factabout Jacques Blanc? Itake it as obvious thatthere is asense in whichit doesand asense in whichit doesnot. The sensein whichit doesis thesense in whichit says something trueof Jacques Blanc. The sensein whichit doesnot is thesense in whichit is notspeciŽ cally about Jacques—it doesnot single outJacques fromthe other inhabitants ofFrance. Sensory experience is analogously speciŽc and sois theaccompanying knowledge of whatit is like tohave speciŽc kinds ofexperiences. One whomerely knowswhat it is like tosee colors may notknow what is like tosee some speciŽ c color.One who has seen only shades ofblue and yellow doesnot thereby know what it is like tosee 200 P. MANDIK red, justas thenormal humans did notknow what it was like toseeFred’ s red1 and red2 in Jackson’s thoughtexperiment. The propertiesdelivered in sensory experi- enceare quite speciŽc. But theways thatwe representphysical propertiesin thought experimentsasserting thepossibility ofphysical omniscience fromthe objective pointof view are devoid oftherequisite speciŽcity. Weimagine abunch ofelectrons hereand abunch ofprotonsthere, a bunch ofneurons hereand abunch ofganglia there.Physical theoryprovides us withthe means ofthe relatively unspeciŽc linguistic representation“ everything is made ofelectrons,protons, etc.” But physical theorydoes not provide us themeans ofidentifying onehalf ofthe Jell-O box withoutrecourse to the other half. Norshould weexpect it to.Further, and more importantly, thisgives us no ground forconcluding thatJell-O box halves are non-physical. Likewisephysical theorydoes not provide us withthe means of representing all and only theproperties represented in batexperience. And we should neitherexpect it tonor conclude fromthis failure thatthere is something non-physical thatwe are therebycut off from.

4.Conclusion The pictorial account ofperspectival mental representationallows us tosee how subjectivity may bephysical in away thatsquelches the threat of the knowledge argument. Ihave notedseveral differencesbetween the present account ofsubjec- tivity and previous accounts. Forinstance, Ihave emphasized theway in which subjectivity comesin at thelevel oftypes, nottokens. Icloseby noting afurther differencenot yet made explicit. Accountsof subjectivity like thoseprovided by Lycan (1996) and Tye (1995, 2000) portraysubjectivity as entering thepicture with theintrospective application ofconcepts. On theiraccount, whatmakes knowledge ofwhat it is like perspectival is the way thething is known, notthe thing that is known. On such views then, if therewere no creaturescapable ofapplying second- orderrepresentations to their Ž rst-orderexperiences, therewould beno subjectivity. On theview Iadvocate, subjectivity entersthe picture with the Ž rst-orderstates. This is neitherthe time nor the place toattack higher-order theoriesof conscious- ness like Rosenthal’s (1986), but if thereis something it is like tobe a creaturethat has Žrst-orderexperiential representationseven ifthat creature has no second-order representations, then thereis something it is like tobe the creature whether the creatureknows it ornot. Theremay besomething it is like tobe abatwhether bats themselvesknow it ornot. Regardless ofwhether bats know it ornot, we do not knowwhat it is like tobe a bat. Why not? Because factsof what it is like are subjective physical facts,facts that depend on experiences, even though theymay notdepend on higher-order representationsof those experiences.

Acknowledgements Forespecially detailed and useful commentson oral presentationsof thismaterial I thank Robertvan Gulick and MarkMcCulloch. Iam also thankful forcomments on previous versions ofthismaterial fromBill Bechtel, PeterMachammer, Rick Grush, MENTAL REPRESENTATION 201

Tad Zawidzki, Jonathan Waskan, EricSteinhart, Chase Wrenn, Andy Clark, William Lycan, JessePrinz, RobertGordon, MuratAydede, Wade Savage, David Rosenthal, Brian Keeley, Chris Eliasmith, JohnBickle and ChristopherGauker. For useful feedbackI thank also audiences ofpresented versions ofthis material at meetings ofthe Society forPhilosophy and Psychology, theEastern Division ofthe American Philosophical Association, theNew Jersey Regional Philosophical Associ- ation, theMcDonnell Projectfor Philosophy and theNeurosciences, the Philosophy Departmentof Washington University in St. Louis, thePhilosophy Department of William PatersonUniversity ofNewJersey, and theTheoretical Cognition Group at theUniversity ofPittsburgh.

Notes [1]For further discussionof spatial experienceand its connectionto the topics of objectivityand subjectivity,see Mandik (1998, 1999). [2]For additional discussion of Akins’account of thermoperception,see Bickle and Mandik(1999).

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