Abstract
The idea that mentality is multiply realizable has long been considered a major threat to the view that mental properties are identical to properties of physics, chemistry, or neuroscience. While many philosophers of mind happily abandoned the prospect of psychophysical reduction, others have tried to show that considerations of multiple realizability do not pose any fatal threat. This chapter traces highlights of the multiple realizability debate over the past few decades, providing an introduction to its many facets, including precise formulations of different varieties of multiple realizability and what they do and do not entail. This chapter, however, is not purely expository. In the last third of the chapter, starting with Section 1.8, I present and develop what I consider the best reason for thinking that considerations of multiple realizability do in fact provide irresistible evidence that mental properties are not identical to properties of any of the natural sciences. The question of how physicalists (materialists) should cope with this purported fact is the topic of the subsequent chapters.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsNotes
- 1.
The most famous expositions of logical behaviorism include those of Carnap (1932/1933), Hempel (1949), and Ryle (1949). Logical behaviorism differs from the methodological (psychological) behaviorism of John Watson and B.F. Skinner. The latter tells us how to conduct the science of psychology, advising that psychological explanations should not appeal to consciousness, unconscious activity, or any inner psychic causes, and should focus instead on behavioral responses to sensory input. Logical behaviorism, on the other hand, is an account of the meaning of mental terminology, revealed by analysis of our mental concepts. On this view, sentences that employ mentalistic terminology are synonymous with sentences regarding actual and potential behavior.
- 2.
Unlike the super-Spartans Putnam describes, his super-super-Spartans do not exhibit any verbal pain behavior and in general avoid all talk of pain.
- 3.
See Block (1981).
- 4.
Smart (1959) defends the identity theory against some of these.
- 5.
What is questioned here is the identity theory in its traditional from, the type-identity theory of the sort that, e.g., Smart, Place, and more recently, Hill (1991) defended. Multiple realizability is certainly compatible with the token-identity thesis. According to the token thesis, each token of a mental state-type is a token of some physical state-type or other, but not necessarily the same physical state-type on each occasion (and perhaps not even a neural state-type on some occasions).
- 6.
This is quoted by Richardson (1979, pp. 548–549).
- 7.
See, also, Churchland (1979, Sect. 11).
- 8.
See, for example, Searle’s (1992, pp. 112–116) description of some of the many different varieties of reduction.
- 9.
This brand of reduction warrants the title “ontological reduction.” As Clapp indicates, “[i]n the sense in which reduction is relevant to the mind-body problem …, the reduction of one theory T1 to another theory T2 collapses the ontological commitments of T1 to those of T2” (2001, p. 114). Also, as Enc informed us, “one of the objectives of scientific reduction is a reduction in the ontology of things and of properties. And this will not be achieved unless type-type identities are established between the two sciences. And clearly these identities cannot be established unless bridge laws express coextensionalities” (1983, p. 280).
- 10.
Even if one thought, with Bickle, that reductionism “is a claim about how distinct scientific endeavors relate to one another… not explicitly an account of how phenomena relate—objects, entities, properties, processes, states of affairs, and the like—nor an account of the relations that obtain among them” (2010, p. 256), one who cared about the nature of mentality would still have to contend with MRNI.
- 11.
Funkhouser defends a definition equivalent to this. He proposes that a property-type X is multiply realizable relative to science Y iff there are possible instances of X that “exactly resemble one another with regard to their X-ness,” but “their Y-realization bases do not exactly resemble each other with regard to their Y-ness” (2007, p. 476). On this account, mental properties are multiply realizable at the neural level precisely because instances that exactly resemble each other mentally (i.e., are instances of the very same mental property) do not exactly resemble each other neurally (i.e., are instances of different neural properties). What I am calling “mild” multiple realizability is also similar to what Polger (2004, p. 6) labels “weak” multiple realizability.
- 12.
I stress this point in my (1997).
- 13.
This formulation is equivalent to Endicott’s (2005) definition of multiple realizability.
- 14.
Aizawa and Gillett (2009, 2011) offer the following analysis: A property G is multiply realized if and only if (i) under condition S, an individual s has an instance of property G in virtue of the powers contributed by instances of properties/relations F1-Fn to s, or to s’s constituents, but not vice versa; (ii) under condition S* (which may or may not be identical to S), an individual s* (which may or may not be identical to s) has an instance of property G in virtue of the powers contributed by instances of properties/relations F*1-F*m of s* or s*’s constituents, but not vice versa; (iii) F1-Fn ≠ F*1-F*m, and (iv), under conditions S and S*, F1-Fn of s and F*1-F*m of s* are at the same scientific level of properties. Despite its merits, their detailed account does not preclude an F-level property which F1-Fn and F*1-F*m share, and which is nomically necessary and sufficient for the realized property G.
- 15.
Shapiro contends that those who support the multiple realizability of mentality face a dilemma. Either the realizing kinds differ in their causally relevant properties or they do not. If they do not, then we do not have a case of genuine multiple realizability. If they do, then there is reason to suspect that they are not realizing the same mental property. For if the realizers “have no or only few causally relevant properties in common, then there are no or just a few laws that are true of both of them” (2000, p. 649), in which case, it is arguable that we have here the realization of genuinely different functional kinds. However, if I am right, one can and should resist at least the first horn of this dilemma.
- 16.
Gillett argues that Shapiro’s reasoning against the multiple realizability of mental properties is ineffective since it presupposes the flat account of realization whereas the non-reductionist’s appeal to multiple realizability is based on the dimensioned view.
- 17.
- 18.
Perhaps this is what Endicott has in mind when he says that “we should not look on the NRS [the ‘narrow reductive strategy’] as a reductive strategy at all, but as a form of eliminativism” (1993, p. 310).
- 19.
Horgan (1993, p. 308) makes this point regarding intentional states.
- 20.
For details about neural plasticity see, for example, Endicott (1993), Buonomano and Merzenich (1998), Stein and Hoffman (2003), Draganski et al. (2006), Wieloch and Nikolich (2006), and Richardson (2009). Although, Polger (2009) argues that neural plasticity does not provide definitive evidence of multiple realizability.
- 21.
In Sect. 4 of their essay, they describe in detail how studying the structure of the brain has greatly contributed to our understanding of visual processing.
- 22.
For additional objections to the reasoning of Bechtel and Mundale (1999) see Aizawa’s (2009). Aizawa argues against two premises in what he calls the “Central Argument” of Bechtel and Mundale. Aizawa objects to the idea that brain taxonomy requires an appeal to psychological function, and he argues against the premise that if psychological functions were multiply realized, then brain taxonomy would have to be carried out independently of psychological function and without comparative evaluation across species. Also see Figdor (2010) for additional critique of Bechtel and Mundale. Here Figdor also provides an informative and detailed description of the cognitive neuroscience research program that attempts to map brain structures to cognitive processes; in particular, Figdor provides a sketch of the phenomenon of degeneracy in cognitive neuroanatomy and explains how the multiple realizability claim is a live empirical hypothesis.
- 23.
The primate’s eye and the octopus eye are homoplasies—similar organs or features in different species not inherited from a common ancestor. So, according to Couch, even with homoplasies there is insufficient evidence for multiple realizability.
- 24.
Besides Polger and Couch, those who emphasize that differences in realizers are arguably always accompanied by differences in the property realized include Shagrir (1998) and Shapiro (2008). Although, see Craver’s (2004) discussion of when the “no dissociable realization” principle (that if there are two distinct realizers, then there are two distinct realized kinds) does and does not apply.
- 25.
Relevant here is the point made by Aizawa and Gillett (2011) that despite differences between individuals in what underlies color vision (e.g., differences in photoreceptors, lens, and the macula), vision scientists still acknowledge the property of normal color vision. Here is a case in which differences in realizers do not lead scientists to deny a common realized property.
- 26.
- 27.
As Melnyk (2008, p. 1294) mentions in a footnote, a “genuine multiple realizability objection would appeal to the metaphysical possibility of, say, pain without the neurophysiological state thought to be identical with pain; such a bare possibility would be enough to contradict the proposed identity claim, given the necessity of identity.”
- 28.
We’re imagining again that P is some non-trivial physical property—unlike, e.g., either a quark or not a quark, indiscriminately had by all items.
- 29.
To be nomically sufficient for the mental property, each disjunct will be what Shoemaker (2007, p. 21) calls a “total” realizer and not merely a “core” realizer. The core realizer of a mental property is what plays the definitive functional role, whereas the total realizer includes not just the core realizer, but whatever relations the core realizer bears to other states of the organism to ensure that it plays the requisite functional role. So each disjunct will be a highly complex physical property.
- 30.
- 31.
- 32.
And this similarity in causal role would seem to require some similarity in physical structure, as Walter indicates (2006, p. 58).
- 33.
Given the necessity of identity, all metaphysically possible realizers will also need to be included.
- 34.
One who is already convinced that mental properties are identical with physical, chemical, or biological properties might rely on the necessity of identity and simply deny the possibility of immaterial realizers. However, this is not a viable response for proponents of the disjunctive strategy, since considerations of multiple realizability have already led them to reject the identity of mental properties with (non-disjunctive) properties of the natural sciences. Without the belief in these non-disjunctive type-identities, there is no good reason for them to reject the physical possibility of immaterial realizers.
- 35.
A main reason that ‘physicalism’ came to be considered a more appropriate label is that the physical sciences are not restricted to what qualify as material items.
References
Aizawa, K. 2009. Neuroscience and multiple realization: A reply to Bechtel and Mundale. Synthese 167: 493–510.
Aizawa, K., and C. Gillett. 2009. The (multiple) realization of psychological and other properties in the sciences. Mind and Language 24: 181–208.
Aizawa, K., and C. Gillett. 2011. The autonomy of psychology in the age of neuroscience. In Causality in the sciences, ed. P.M. Illari, F. Russo, and J. Williamson, 202–223. Oxford: Oxford University Press.
Armstrong, D. 1968. A materialist theory of the mind. London: Routledge.
Adams, F. 1979. Properties, functionalism, and the identity theory. Eidos 1: 153–179.
Bechtel, W., and J. Mundale. 1999. Multiple realizability revisited: Linking cognitive and neural states. Philosophy of Science 66: 175–207.
Bickle, J. 1992. Multiple realizability and psychophysical reduction. Behavior and Philosophy 20: 47–58.
Bickle, J. 1998. Psychoneural reduction: The new wave. Cambridge, MA: MIT Press.
Bickle, J. 2003. Philosophy and neuroscience: A ruthlessly reductive account. Dordrecht: Kluwer.
Bickle, J. 2010. Has the last decade of challenges to the multiple realization argument provided aid and comfort to psychoneural reductionists? Synthese 177: 247–260.
Block, N. 1980. Introduction: What is functionalism? In Readings in philosophy of psychology, vol. I, ed. N. Block, 171–184. Cambridge, MA: Harvard University Press.
Block, N. 1981. Psychologism and behaviorism. Philosophical Review 90: 5–43.
Buonomano, D., and M. Merzenich. 1998. Cortical plasticity: From synapses to maps. Annual Review of Neuroscience 21: 149–186.
Carnap, R. 1932/1933. Psychology in physical language. Erkenntnis 3: 107–142.
Churchland, P.M. 1979. Scientific realism and the plasticity of mind. Cambridge: Cambridge University Press.
Churchland, P.M. 1982. Is ‘thinker’ a natural kind? Dialogue 21: 223–238.
Churchland, P.M. 1984. Matter and consciousness. Cambridge, MA: The MIT Press.
Churchland, P.M. 1985. Reduction, qualia, and the direct introspection of brain states. The Journal of Philosophy 82: 8–28.
Clapp, L. 2001. Disjunctive properties: Multiple realizations. The Journal of Philosophy 98: 111–136.
Couch, M. 2004. Discussion: A defense of Bechtel and Mundale. Philosophy of Science 71: 198–204.
Craver, C. 2004. Dissociable realization and kind splitting. Philosophy of Science 71: 960–971.
Draganski, B., C. Gaser, G. Kempermann, H.G. Kuhn, J. Winkler, C. Büchel, and A. May. 2006. Temporal and spatial dynamics of brain structure changes during extensive learning. The Journal of Neuroscience 26: 6314–6317.
Enc, B. 1983. In defense of the identity theory. The Journal of Philosophy 80: 279–298.
Endicott, R. 1989. On physical multiple realization. Pacific Philosophical Quarterly 70: 212–224.
Endicott, R. 1993. Species-specific properties and more narrow reductive strategies. Erkenntnis 38: 303–321.
Endicott, R. 2005. Multiple realizability. In Encyclopedia of philosophy, 2nd ed, ed. D. Borchert, 427–432. Detroit: Thomson Gale/Macmillan Reference.
Figdor, C. 2010. Neuroscience and the multiple realization of cognitive functions. Philosophy of Science 77: 419–456.
Fodor, J. 1974. Special sciences (or: the disunity of science as a working hypothesis). Synthese 28: 97–115.
Francescotti, R. 1997. What multiple realizability does not show. Journal of Mind and Behavior 18: 13–28.
Funkhouser, E. 2007. A liberal conception of multiple realizability. Philosophical Studies 132: 467–494.
Gillett, C. 2003. The metaphysics of realization, multiple realizability, and the special sciences. The Journal of Philosophy 100: 591–603.
Hempel, C. 1949. The logical analysis of psychology. In Readings in philosophical analysis, ed. H. Feigl, and W. Sellars, 373–384. New York: Appleton-Century-Crofts.
Hill, C. 1991. Sensations: A defense of type materialism. Cambridge: Cambridge University Press.
Hooker, C. 1981. Towards a general theory of reduction. Part I: Historical and scientific setting. Part II: Identity in reduction. Part III: Cross-categorial reduction. Dialogue 20:38–59, 201–236, 496–529.
Horgan, T. 1982. Supervenience and microphysics. Pacific Philosophical Quarterly 63: 29–43.
Horgan, T. 1993. Nonreductive materialism and the explanatory autonomy of psychology. In Naturalism: A critical appraisal, ed. S.J. Wagner, and R. Warner, 295–320. South Bend, IN: University of Notre Dame Press.
Kim, J. 1972. Phenomenal properties, psychophysical laws, and the identity theory. Monist 56: 177–192.
Kim, J. 1989. The myth of nonreductive materialism. Proceedings and Addresses of the American Philosophical Association 63: 31–47.
Kim, S. 2002. Testing multiple realizability: A discussion of Bechtel and Mundale. Philosophy of Science 69: 606–610.
Lewis, D. 1966. An argument for the identity theory. The Journal of Philosophy 63: 17–25.
Lewis, D. 1969. Review of Art, mind, and religion. The Journal of Philosophy 66: 22–27.
Lewis, D. 1980. Mad pain and Martian pain. In Readings in philosophy of psychology, vol. I, ed. N. Block, 216–222. Cambridge, Mass: Harvard University Press.
Lewis, D. 1983. New work for a theory of universals. Australasian Journal of Philosophy 61: 343–377.
Melnyk, A. 2008. Can physicalism be non-reductive? Philosophy Compass 3: 1281–1296.
Nagel, E. 1961. The structure of science: Problems in the logic of scientific explanation. New York: Harcourt, Brace, and World.
Pereboom, D., and H. Kornblith. 1991. The metaphysics of irreducibility. Philosophical Studies 63: 125–145.
Place, U.T. 1956. Is consciousness a brain process? British Journal of Psychology 47: 44–50.
Polger, T. 2004. Natural minds. Cambridge, Mass.: MIT Press.
Polger, T. 2007. Realization and the metaphysics of mind. Australasian Journal of Philosophy 85: 233–259.
Polger, T. 2008. Two confusions concerning multiple realization. Philosophy of Science 75: 537–547.
Polger, T. 2009. Evaluating the evidence for multiple realization. Synthese 167: 457–472.
Polger, T., and L. Shapiro. 2008. Understanding the dimensions of realization. The Journal of Philosophy 105: 213–222.
Putnam, H. 1965. Brains and behavior. In Analytical philosophy: Second series, ed. R. Butler, 1–19. Oxford: Blackwell.
Putnam, H. 1967. Psychological predicates. In Art, mind, and religion, ed. W.H. Capitan, and D.D. Merrill, 37–48. Pittsburgh: University of Pittsburgh Press.
Richardson, R. 1979. Functionalism and reductionism. Philosophy of Science 46: 533–558.
Richardson, R. 1982. How not to reduce a functional psychology. Philosophy of science 49: 125–137.
Richardson, R. 2008. Autonomy and multiple realization. Philosophy of Science 75: 526–536.
Richardson, R. 2009. Multiple realization and methodological pluralism. Synthese 167: 473–492.
Ryle, G. 1949. The concept of mind. London: Hutchinson.
Seager, W. 1991. Disjunctive laws and supervenience. Analysis 51: 93–98.
Searle, J. 1992. The rediscovery of the mind. Cambridge, Mass.: MIT Press.
Shagrir, O. 1998. Multiple realization, computation and the taxonomy of psychological states. Synthese 114: 445–461.
Shapiro, L. 2000. Multiple realizations. The Journal of Philosophy 97: 635–654.
Shapiro, L. 2008. How to test for multiple realization. Philosophy of Science 75: 514–525.
Shoemaker, S. 2007. Physical Realization. New York: Oxford University Press.
Smart, J.J.C. 1959. Sensations and brain processes. The Philosophical Review 68: 141–156.
Stein, D., and S. Hoffman. 2003. Concepts of CNS plasticity in the context of brain damage and repair. The Journal of Head Trauma Rehabilitation 18: 317–341.
Walter, S. 2006. Multiple realizability and reduction: A defense of the disjunctive move. Metaphysica 7: 43–65.
Wieloch, T., and K. Nikolich. 2006. Mechanisms of neural plasticity following brain injury. Current Opinion in Neurobiology 16: 258–264.
Zangwill, N. 1995. Supervenience, reduction, and infinite disjunction. Philosophia 24: 321–330.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Copyright information
© 2014 The Author(s)
About this chapter
Cite this chapter
Francescotti, R. (2014). Multiple Realizability. In: Physicalism and the Mind. SpringerBriefs in Philosophy. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-9451-0_1
Download citation
DOI: https://doi.org/10.1007/978-94-017-9451-0_1
Published:
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-017-9450-3
Online ISBN: 978-94-017-9451-0
eBook Packages: Humanities, Social Sciences and LawPhilosophy and Religion (R0)