Analytical and Gontinental Philosophy: Methods and Perspectives Papers of the 37th lnternational Wittgenstein SymPosi um' August 10 16, 2014 Kirchberg am Wechsel Volume XXll Editors Sonja Rinofner-Kreidl Harald A. Wiltsche Printed in cooperation with the Department for Science and Research of the Province of Lower Austria Kirchberg am Wechsel, 2014 Austrian Ludwig Wittgenstein Society Distributors Vorstand der 6t-WC Executive Gomittee _ Peter Kampits Christian Kanzian Josef Mitterer Volker Munz Elisabeth Nemeth Alois Pichler Klaus Puhl GUnther Rieck Edmund Runggaldier Friedrich Stadler Paul Weingartner lssN 1022-3398 All Rights Reserved Copyright 2014 by the authors Visuelle Gestaltung: Druck: Eigner Druck, Die Osterreichische Ludwig Wittgenstein Gesellschaft The Austrian Ludwig Wittgenstein Society Markt 63, A-2880 Kirchberg am Wechsel Osterreich / Austria Copyright will remain with the author, rights to use with the society. 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Contact: <joseph.wang@uibk.ac.at> Sascha Windholz A-3040 Neulengbach wtrttW.alws.at On Boyd's Rebuttal of Kripke's Argument for Dualism Klaus Ladstaetter Topeka, KS, USA I ktaus.ladstaetter@washburn.edu Abstract The essay pre-sents Saul Kripke's argument for mind/body-dualism and makes the suppositions explicit on which it rests) My claim, inspiied by Richard Boyd, is thit even if one of Kripke's central suppositions the principle of necessity bf identities using rigid designators is shared by the non-traditional identity theorist, it is still possible for her to rebut Kripke's dualism. Introduction The plan for the essay is first to present Kripke's argument for mindibody-dualism dnd to make the suppositions explicit on which it rests. Second, traditionalidentity theory is distinguished from non-traditional identity theory, if only to set aside further discussion of traditional identity theory. My claim is that even if one of Kripke's centralsuppositions - : the principle of necessity of identities using igid designa- .,,-,'fiirs is accepted by the non-traditionalidentity theorist, it ' ,' is still possible for her io rebut Kripke's dualism. The third's5'ction expounds the non-fraditional identity theorist's possible appeal to an analogy in order to explaiin the relation between mental phenomena (e.9. pain) and physical phenomena (e.9. C-fiber stimulation), while section four reconstructs Kripke's attack on th'is analogy. Refuting Kripke's attack in light of Boyd's proposals in section five, I conclude that non-traditionalidentity theory is viable. ! 1. Kripke's Argument for Mind/BodyDualism Kripke (1980) wants to defend some form of dualism (without defending Cartesian substance dualism though). In order to do so, he uses the Cadesian lntuition, i.e. the intuition that it is possible that the mind exist witho.ut the body and that it is possible that the body exist without the mind. In other words, Kripke deems it possible that there be disembodied minds (or "pure souls") and that there be "disminded" bodies (or "zombies"); either way it is possible that the mind is different from the body, schematically represented by: o ( A + B ) l Due to his conception of names as rigid designators, Kripke is committed to what he calls the principle of necessity of identities using rigid designators (cf. Kripke 1980, e.g. p.146). Henceforth, I shal lcal l this principle (PNIRD): ( A = B ) - + t r ( A = B ) 2 Notice that the logically equivalent contrapositive of this 'principle is: 0 ( A + B ) + ( A # B ) 3 1 As it is common, I use the symbol 'f as abbreviation of the sentential operator "it is possible thaf and ihe symbol 'D' as abbreviation of the phrase 'it is necessary that". Kripke insists that he is concemed with meiaphysical modalities (cf. Kripke 1980, e.g. p.35); his view will not be challenged here. 2 For what follows, the reader should take the letter "A' as a place holder for a name of a mental phenomenon (e.9. pain), and the lefter'B' as a place holder ior a name of a physical phenomenon (e.9. C-fiber stimulation). 3 For the sake of the argument, l'll suppose that (PNIRD) and its equivalent contrapositive are true. I shall thus put aside the obvious objection to lhe contraposiiive that possibility does not imply actuality' Kripke argues that the Cartesian lntuition taken together with the (PNIRD) entails the view that mental phenomena are actLally different from physical phenomena; here's the reconstruction of his argument: ( 1 ) o ( A # B ) Caftesian Intuition (2) (A = B) + tr (A = B) (PNIRD) (3) 0 (A * B) -+ (A # B) from 2, by contraposition ( 4 ) A * B from 1,3, by modus ponens 2. Mind/Body-ldentity Theory ln order to characterize identity theory, it is advisable to disting uish between traditional and non-traditional identity theory. A traditional identity theorisl (whether type or token) rejects the (PNIRD) and thus accepts its negation: -((A = B) -+ ! (A = B)) which is logically equivalent to: ( A = B ) & n ( A = B ; a : The traditional identity theorist thus claims (in the first qonjunct) that, as a matter of fact about the actual world, it is true that pain is identical with C-fiber stimulation, but when sharing the Cadeslan lntuition (in the second conjunct) the theorist adds that this is not necessarily true; it is possibly false because we can imagine a world in which pain exists without there being any C-fiber stimulation (e.9. in "pure souls") and because we can imagine a world in which C-fibgr stimulation exists without there being any pain (e.9. in "2ombies"). Kripke thinks that traditional identity theory is simply false because it is committed to an incorrect conception gf names as non-rigid designators. I shall share Kripke's supposition of names as rigid designators and of the (PNIRD) throughout this essay; so I shall set aside further discussion o'f traditional identity theory here. The goal of the essay rather is to show that even ff an identity theorist shares Kripke's supposition, it is possible for her to rebut Kripke's dual ism. Non-traditional identity theory (whether type or token) accepts the concepiion of names as rigid designators and the (PNIRD) and is thus committed to the argument: ( 1 ) A = B I dentity Theorist's I ntu ition (2) (A = B) + tr (A = B) (PNIRD) ( 3 ) D (A=B)5 from 1 ,2, by modus ponens 4 This claim is in tum logically equivalent to: (A = B) & 0 (A * B) 175 On Boyd's Rebuttal of Kripke's Argument for Dualism I Klaus Ladstaetter Now, the non-traditional identity theorist cannot attack the validity of Kripke's argument from the Cartesian lntuition and the (PNIRD). So she must, in an effort to establisfr that his argument is unsound, rather attack the Carfesian Intuifion itself (i.e. the negation of the conclusion of her own argument) by showing, for instance, that it is impossible that pain be different from C-fiber stimulation. 3. The Non-Traditionalldentity Theorist's Analogy The non-traditionalidentity theorist (henceforth , the identity theorist) wants to hold: A = B but cannot at the same time hold: o ( A r B ) For the latter claim contradicts the conclusion of her own argument, and the conjunctioh of both claims entails that the identity statement is merely contingent (which would render her a traditional identity theorist). lnstead, the identity theorist must hold: . o ( A # B ) The challenge for her, then, is to say why the above identity statement is only seemingly contingent. The identity thearist must thus explain away its apparent contingency. ln particular, she must explain why it is only apparently possible that pain not be identicalwith C-fiber stimulation, while it is in fact impossible. ,Kripke thinks that the identity theorist cannot meet this challenge. ln his view, she fails to explain away the apparent contingency of the identity statement even if the identity theorisit employs the following analogy and claims: (1A) The situation regarding the statement "pain = Cfiber stimulation" is just like the situation regarding the statement "water = H2O". (2,A) Also the statement: Water = HzO has frequently been deemed merely a contingent trutl'r, but due to Kripke's work it has^turned out to be a necessary truth. (3A) The explanation why this statement has frequently been seen merely as a contingent ruth is that there has been a tendency to mistake it for the statement: . The phenomenon felt as water = HzO6 (4A) Now, this statement is admittedly merely contingently true, i.e. it is true in the actualworld, but: (a) it is possible that the phenomenon felt as water exist without the presence of HzO, i,e. water (e.9. on Twin-Earth); and (b) it is possible that H2O, i.e. water, exist ' without the presence of the phenomenon felt as water (e.9. in a world inhabited by alien creatures who have entirely different sensations produced by H2O). 5 Notice that this claim is logically equivalent to: -0 (A * B) and thus to the negation of the Carfesian lntuition. 6 Altematively The phenomenon that produces the sensation we call 'the sensation of water" = H2O. 176 .: (5A) And the situation is analogous for the statement . "pain = C-fiber'stimulation". 4. Kripke's Attack on the AnalogY Kripke thinks that the identity theorist cannot employ above line of reasoning because, per the analogy, identity theoristwould be committed to claim: (28) Also the statement: Pain = C-fiber stimulation has frequently been deemed merely a contingent truth, but upon reflectiori it has turned out to be a necessary truth. (38) The explanation why this statemeni has frequently been seen merely as a contingent ruth is that there has been a tendency to mistake it for the statement: The phenomenon felt as psifl = C-fiber stimulation' But it is precisely at tfis point where the analogy breaks down for Kripke. For the identity theorist cannot continue to argue: (4B) Now, this statement is admittedly merely contingently true, i.e. it is true in the actualworld, but: (a) it is possible that the phenomenon felt as pain exist without the presence of C-fiber stimulation, i.e. pain (e.9. in "pure souls"); and (b) it is possible that C-fiber stimulation, i.e. pain, exist without the presence of the phenomenon felt as pain (e.9. in "zombies"). The identity theorist's appeal to this analogy is not viable for Kripke, because he thinks that there is no possible world in which the phenomenon felt as pain is different from pain thug rendering the statement: The phenomenon felt as pain = pain a necessary truths, while he also thinks that there is a possible world in which the phenomenon felt as water is different from water thus rendering the statement: Thephenomenon felt as water = water merely a contingent truth (even though "water = HzO" is a necessary truth). Kripke therefore believes that the identity theorist cannot explain aWay the apparent contingency of the statement "pain = C-fiber stimulation" by appeal to the analogy. The identity theorist consequently has to bite the butlet and to accept the Cartesian lntuition: o ( A # B ) But from this premise, together with (PNIRD), it immediately follows that: A # B And so Kripke concludes that some form of dualism is true, while identity theory is false. 7 Alternatively: The phenomenon that produces the sensation we call "the sensation of pain" = C-fiber stimulation. 8 Notice that for Kripke, then, there is a definite description that is a rigid designator. the the On Boyd's Rebuttal of Kripke's Argument for Dualism I Klaus Ladstaetter 5. The ldentity Theorist's Rebuttal Boyd (1980, cf. p.83ff.) attempts to refute Kripke's attack on the analogy by arguing from the identiU fheor'sf's point of view as follows: (1C) The situation regarding the statement "pain = Cfiber stimulation" is exactly like the situation regarding the statement "water = HzO". (2C) The statement: Water = HzO I is due to Kripke's work indeed a necessary truth. (3C) But the explanation why this statement has fre- "quently been seen merely as a contingent ruth is rather that there has been a tendency to mistake it for the statement: Water = the phenomenon identified as HzO by standard tests available in the actual world s (4C) Now, this statement is admittedly merely contingently true, i.e. it is true in the actualworld, but: (a) it is possible that water exist without the presence of standard tests available in the actualworld to identify the phenomenon as H2O; and (b) it is possible that standard tests available in the actualworld to identify the phenomenon as H2O exist without the presence of water. (5C) And this situation is precisely analogous for the statement "pain = C-fiber stimulation". For, per Boyd, the analogy expands as follows: (2D) True, the statement: Pain = C-fiber-stim ulation. is a necessary truth. (3D) However, the explanation why this statement has frequently been seen merely as a contingent ruth is that there has been a tendency to mistake it for the statement: Pain = the phenomenon identified as Cfiber stimulation bv standard tests available in the actual wqrld. lo (4D) Now, this statement"is admittedly merely contingently true, i.e. it is true in the actualworld, but: (a) it is possible that pain exist without the presence of standard tests available in the actual world to identify the phenomenon as C-fiber stimulation; and (b) it is possible that standard tests available in the actualworld to identify the phenomenon as G-fiber stimulation exist without the presence of pain. The identity theorist's appeal to this analogy is viable for Boyd, because he thinks that there is a possible world in which the phenomenon identified as C-fiber-stimulation by standard tests available in the actual world is different from pain and because he also thinks that there is a possible 9 Alternatively: Water = the liquid that _ (where a description of standard tests to identify water in the actual wodd goes into the blank). '10 Alternatively: Pain = the phenomenon that (where a description of standard tests to identify C-fiber stimulation in the actual world goes inio the blank). world in which the phenomenon identified as H2O by stan-'dard tests available in the actual world is different from water. Boyd thus thinks that both the statement: Pain = the phenomenon identified as C-fiber-stimulation by standard tests available in the actualworld and the statement: Water = ihe phenomenon identified as HzO by standard tests available in the actualworld are merely contingent and not necessa.ry truths (even though "water = HzO" and "pain = C*fiber stimulation" are both necessary truths) Conclusion ' I agree with Boyd that the identity theori$t can explain awa! the merely apparent contingency of the statement I "p?ifl = C-fiber stimulation". \l/hile Kripke focuses on the . left-hand sides of the identity statements "water = HzO"' and "pain = G-fiber.stimulation" and replaces them with mentalistic definite descriptions of the form "the phenomenon felt as _" in order to establish the alleged disanalogy, Boyd focuses on the right-hand sides of the identity ,statements and replaces thgm with physicalistic definite descriptions of the form "the phenomenon identified as _ by standard tests available in the actual world" in order to establish the analogy. And Boyd is right. Water is not identical with the phe-. nomenon felt as water; rather it is identical with the phenomenon identified as HzO by standard tests available in the actual world. Likewise, pain is not identical with the phenomenon felt as pain; rather it is identicalwith the phenomenon identified as C-fiber stimulation by standard tests available in the actualworld. Hence, the identity theorist can hold that the case of pain being identical with C-fiber stirnulation is just like other cases of identity, e.g. that of water being identical with )zO, or that of heat being identical with mean molecular n _ r e I energy, etc. The theorist can thus reject the Cartesian /nI Kr n&ft6 tuition and accept its negation: 0 ( A t B ) in which cgge_ftn{ she does-not have. to accept Kripk6's H L9 conclusion that some form of dualism is true. lnstead, the identity theorist can maintain that materialism (preferably some form of non-reductive token materialism) is true, and she can at the-same time commit herself to the (PNIRG). Literature Boyd, Richard N. 1980 "Materialism without Reductionism: \Mrat Physicalisin Does Not Entail", in: Ned Block (ed.), Readings in Phi- ' losophy of Psychology, Vol. 1, Cambridge: Harvard UP, 67-106. Kripke, Saul A. 1980 Naming and Necessrdz, Cambridge: Harvard UP. 1 7