Eliminative materialism and the propositional attitudes

Staying within an objectual interpretation of the quantifiers, perhaps the simplest way to make systematic sense of expressions like ' x believes that P ' and closed sentences formed therefrom is just to construe whatever occurs in :he nested positior. held by 'p', 'g', etc. as there having the function of a singular term. Accordingly, the standard connectives, as they occur between terms in that nested position, must be construed as there functioning as operators that form cornpound singular terms from other singular terms, and not as sentence operators. The compound singular terms so formed denote the appropriate compound propositions. S~lbstitutional quantification will of course underwrite a different interpretation, and there are other approaches as well. Especially appealing is the prosentential approach of Dorothy Grover, Joseph Camp, and Nuel Belnap, "A Prosentential 'Theory of Truth," Philosophical Studies, s x v ~ r , 2 (February 1975): 73-125. But the resolution of these issues is not \ ital to the present discussion. 72 THE JOURNAL OF PHILOSOPHY Finally, the realization that folk psychology is a theory puts a new light on the mind-body problem. The issue becomes a matter of how the ontology of one theory (folk psychology) is, or is not, going to be related to the ontology of another theory (completed neuroscience) ; and the major philosophical positions on the mindbody problem emerge as so many different anticipations of what future research will reveal about the intertheoretic status and integrity of folk psychology. The identity theorist optimistically expects that folk psychology will be smoothly reduced by'completed neuroscience, and its ontology preserved by dint of transtheoretic identities. The dualist expects that it will prove irreducible to completed neuroscience, by dint of being a nonredundant description of an autonomous, nonphysical domain of natural phenomena. The functionalist also expects that it will prove irreducible, but on the quite different grounds that the internal economy characterized by folk psychology is not, in the last analysis, a law-governed economy of natural states, but an abstract organization of functional states, an organization instantiable in a variety of quite different material substrates. I t is therefore irreducible to the principles peculiar to any of them. Finally, the eliminative materialist is also pessimistic about the prospects for reduction, but his reason is that folk psychology is a radically inadequate account of our internal activities, too confused and too defective to win survival through intertheoretic reduction. On his view it will simply be displaced by a better theory of those activities. Which of these fates is the real destiny of folk psychology, we shall attempt to divine presently. For now, the point to keep in mind is that we shall be exploring the fate of a theory, a systematic, corrigible, speculative theory. Given that folk psychology is an empirical theory, i t is a t least an abstract possibility that its principles are radically false and that its ontology is an illusion. With the exception of eliminative materialism, however, none of the major positions takes this possibility seriously. None of them doubts the basic integrity or truth of folk psychology (hereafter, "FP"), and all of them anticipate a future in which its laws and categories are conserved. This conservatism is not without some foundation. After all, F P does enjoy a substantial amount of explanatory and predictive E:LIMINATIVE MATERIALlSM 73 success. And what better grounds than this for confidence in the integrity of its categories ? LThat better grounds indeed? Even so, the presumption in FP's favor is spurious, born of innocence and tunnel vision. A more searching examination reveals a different picture. First, we must reckon not only with FP's successes, but with its explanatory failures, and with their extent and seriousness. Second, we must consider the long-term history of FP, its growth, fertility, and current promise of future development. And third, we must consider what sorts of theories are likely to be true of the etiology of our behavior, given what else we have learned about ourselves in recent history. That is, we must evaluate F P with regard to its coherence and continuity with fertile and well-established theories in adjacent and overlapping domains-with evolutionary theory, biology, and neuroscience, for example-because active coherence with the rest of what we presume to know is perhaps the final measure of any hypothesis. A serious inventory of this sort reveals a very troubled situation, one which would evoke open skepticism in the case of any theory less familiar and dear to us. Let me sketch some relevant detail. When one centers one's attention not on what F P can explain, but on what it cannot explain or fails even to address, one discovers that there is a very great deal. As examples of central and important mental phenomena that remain largely or wholly mysterious within the framework of FP, consider the nature and dynamics of mental illness, the faculty of creative imagination, or the ground of intelligence differences between individuals. Consider our utter ignorance of the nature and psychological functions of sleep, that curious state in which a third of one's life is spent. Reflect on the common ability to catch an outfield fly ball on the run, or hit a moving car with a snowball. Consider the internal construction of a 3-D visual image from subtle differences in the 2-D array of stimulations in our respective retinas. Consider the rich variety of perceptual illusions, visual and otherwise. Or consider the miracle of memory, with its lightning capacity for relevant retrieval. On these and many other mental phenomena, F P sheds negligible light. One particularly outstanding mystery is the nature of the learning process itself, especially where i t involves large-scale conceptual change, and especially as it appears in its pre-linguistic or entirely nonlinguistic form (as in infants and animals), which is by far the most common form in nature. F P is faced with special 7 1 THE JOURNAL OF PHILOSOPHY difficulties here, since its conception of learning as the manipulation and storage of propositional attitudes founders on the fact that how to formulate, manipulate, and store a rich fabric of propositional attitudes is itself something that is learned, and is only one among many acquired cognitive skills. F P would thus appear constitutionally incapable of even addressing this most basic of mysteries4 Failures on such a large scale do not (yet) show that F P is a false theory, but they do move that prospect well into the range of real possibility, and they do show decisively that F P is at best a highly superficial theory, a partial and unpenetrating gloss on a deeper and more complex reality. Having reached this opinion, we may be forgiven for exploring the possibility that F P provides a positively misleading sketch of our internal kinematics and dynamics, one whose success is owed more to selective application and forced interpretation on our part than to genuine theoretical insight on FP's part. A look a t the history of F P does little to allay such fears, once raised. The story is one of retreat, infertility, and decadence. The presumed domain of F P used to be much larger than it is now. In primitive cultures, the behavior of most of the elements of nature were understood in intentional terms. The wind could know anger, the moon jealousy, the river generosity, the sea fury, and so forth. These were not metaphors. Sacrifices were made and auguries undertaken to placate or divine the changing passions of the gods. Despite its sterility, this animistic approach to nature has dominated our history, and it is only in the last two or three thousand years that we have restricted FP's literal application to the domain of the higher animals. Even in this preferred domain, however, both the content and the success of F P have not advanced sensibly in two or three thousand years. The F P of the Greeks is essentially the F P we use today, and we are negligibly better a t explaining human behavior in its terms than was Sophocles. This is a very long period of stagnation and infertility for any theory to display, especially when faced with such an enormous backlog of anomalies and A possible response here is t o insist that the cognitive activity of animals and infants is linguaformal in its elements, structures, and processing right from birth. J. A. Fodor, in The Language of Thought (New York: Crowell 1975), has erected a positive theory of thought on the assumption that the innate forms of cognitive activity have precisely the for111 here denied. For a critique of Fodor's view, see Patricia Churchland, "Fodor on Language Learning," . Yynthese, X X X ~ I I I ,1 (hlay 1978): 149-159. ELIMINATIVE MATERIALISM 75 mysteries in its own explanatory domain. Perfect theories, perhaps, have no need to evolve. But F P is profoundly imperfect. Its failure to develop its resources and extend its range of success is therefore darkly curious, and one must query the integrity of its basic categories. To use Imre Lakatos' terms, F P is a stagnant or degenerating research program, and has been for millennia. Explanatory success to date is of course not the only dimension in which a theory can display virtue or promise. A troubled or stagnant theory may merit patience and solicitude on other grounds; for example, on grounds that it is the only theory or theoretical approach that fits well with other theories about adjacent subject matters, or the only one that promises to reduce to or be explained by some established background theory whose domain encompasses the domain of the theory a t issue. In sum, it may rate credence because it holds promise of theoretical integration. How does F P rate in this dimension ? I t is just here, perhaps, that F P fares poore