Chapter 9 From Language and Problems of Knowledge Noam Chomsky

It is interesting to observe the fate of the Cartesian version of the mind-body problem and the problem of the existence of other minds. The mind-body problem can be posed sensibly only insofar as we have a definite conception of body.

Another line of development was the "general and philosophical grammar" (in our terms, scientific grammar) of the seventeenth, eighteenth, and early nineteenth centuries, which was much influenced by Cartesian conceptions, particularly in the early period. These inquiries into universal grammar sought to lay bare the general principles of language. These were regarded as not essentially different from the general princi­ples of thought, so that language is "a mirror of mind," in the conventional phrase. For various reasons—some good, some not—these inquiries were disparaged and aban­doned for a century, to be resurrected, again independently, a generation ago, though in quite different terms and without recourse to any dualist assumptions.

It is also interesting to see how the Cartesian conception of body and mind entered sodal thought, most strikingly in the libertarian ideas of Jean-Jacques Rousseau, which were based on strictly Cartesian conceptions of body and mind.

The Cartesian conception of a second substance was generally abandoned in later years, but it is important to recognize that it was not the theory of mind that was refuted (one might argue that it was hardly clear enough to be confirmed or refuted). Rather, the Cartesian concept of body was refuted by seventeenth-century physics, particularly in the work of Isaac Newton, which laid the foundations for modem sci­ence. Newton demonstrated that the motions of the heavenly bodies could not be explained by the principles of Descartes's contact mechanics, so that the Cartesian concept of body must be abandoned. In the Newtonian framework there is a "force" that one body exerts on another, without contact between them, a kind of "action at a distance." Whatever this force may be, it does not fall within the Cartesian framework of contact mechanics. Newton himself found this conclusion unsatisfying. He some­times referred to gravitational force as "occult" and suggested that his theory gave only a mathematical description of events in the physical world, not a true "philosophical" (in more modem terminology, "scientific") explanation of these events. Until the late nineteenth century it was still widely held that a true explanation must be framed somehow in mechanical or quasi-mechanical terms. Others, notably the chemist and philosopher Joseph Priestley, argued that bodies themselves possess capacities that go beyond the limits of contact mechanics, specifically the property of attracting other bodies, but perhaps far more.

What is the concept of body that finally emerged? The answer is that there is no clear and definite concept of body. If the best theory of the material world that we can construct includes a variety of forces, particles that have no mass, and other entities that would have been offensive to the "scientific common sense" of the Cartesians, then so be it: We conclude that these are properties of the physical world, the world of body. The conclusions are tentative, as befits empirical hypotheses, but are not subject to criticism because they transcend some a priori conception of body. There is no longer any definite conception of body. Rather, the material world is whatever we discover it to be, with whatever properties it must be assumed to have for the purposes of explana­tory theory. Any intelligible theory that offers genuine explanations and that can be assimilated to the core notions of physics becomes part of the theory of the material world, part of our account of body. If we have such a theory in some domain, we seek to assimilate it to the core notions of physics, perhaps modifying these notions as we carry out this enterprise. In the study of human psychology, if we develop a theory of some cognitive faculty (the language faculty, for example) and find that this faculty has certain properties, we seek to discover the mechanisms of the brain that exhibit these properties and to account for them in the terms of the physical sciences—keeping open the possibility that the concepts of the physical sciences might have to be modified, just as the concepts of Cartesian contact mechanics had to be modified to account for the motion of the heavenly bodies, and as has happened repeatedly in the evolution of the natural sciences since Newton's day.

In short, there is no definite concept of body. Rather, there is a material world, the properties of which are to be discovered, with no a priori demarcation of what will count as "body." The mind-body problem can therefore not even be formulated.

turn out that these fundamental sciences must be modified or extended to provide foundations for the abstract theories of complex systems, such as the human mind.

Our task, then, is to discover genuine explanatory theories and to use these dis­coveries to facilitate inquiry into physical mechanisms with the properties outlined in these theories. Wherever this inquiry leads, it will be within the domain of 'body." Or more accurately, we simply abandon the whole conception of body as possibly distinct from something else and use the methods of rational inquiry to Ieam as much as we can about the world—what we call the material world, whatever exotic properties it turns out to have.

The mind-body problem remains the subject of much controversy, debate, and spec­ulation, and in this regard the problem is still very much alive. But the discussion seems to me incoherent in fundamental respects. Unlike the Cartesians, we have no definite concept of body. It is therefore quite unclear how we can even ask whether some phenomena lie beyond the range of the study of body, falling within the separate study of mind.

Recall the logic of Descartes's argument for the existence of a second substance, res cogitans. Having defined "body" in terms of contact mechanics, he argued that certain phenomena lie beyond its domain, so that some new principle was required; given his metaphysics, a second substance must be postulated. The logic is essentially sound; it is, in fact, much like Newton's, when he demonstrated the inadequacy of Cartesian contact mechanics for the explanation of the motion of the heavenly bodies so that a new principle, the principle of gravitational attraction, had to be postulated. The crudal difference between the Cartesian and the Newtonian enterprises was that the latter offered a genuine explanatory theory of the behavior of bodies, whereas the Cartesian theory offered no satisfactory account of properties such as the creative aspect of language use that lie beyond mechanical explanation in Descartes's view. Therefore Newton's conceptions came to be the "scientific common sense" of later generations of scientists, while Descartes's fell by the wayside.