Those who are familiar with contemporary approaches in philosophy of mind are familiar with Thomas Nagel’s article, “What is it like to be a bat?” In it, he argues that it is quite intuitive to think that bats (and other presumably conscious creatures) have their own unique, subjective experience. While the fact alone is not very interesting, it seems to imply that a reductive or eliminativist account of the mind-body problem conflates two very different sets of facts, namely, “objective” facts about the physical processes of brains and facts about “what it is like” to be a certain kind of conscious organism.
The first major argument delivered in Mind and Cosmos is similar. If we grant that there are facts about what it is like to be different conscious organisms, then it is unclear how and to what extent a reductionist materialism can account for them. If physical, chemical processes are identical to what we mean by consciousness, and the facts corresponding to propositions about physical, chemical processes do not include among them facts about what it is like to be any given organism, then it seems to follow that reductive materialism cannot account for at least one set of facts that constitutes consciousness. This inability is what Nagel calls the “constitutive problem” of consciousness: “We [as conscious organisms] ourselves are large-scale, complex instances of something both objectively physical from outside and subjectively mental from inside” (42).
But the constitutive problem is not the only difficulty facing a reductive materialism, according to Nagel. There is another, namely, the problem of consciousness’ emergence in history. Consciousness is not only profoundly unique and mysterious in its constitution–it is also astonishingly rare in the grand scope of the cosmos. Even if it were possible somehow to describe the material conditions that could have led to the development of conscious life (at this time, it is not), for Nagel this would not eliminate the metaphysical question of “why” it happened in the first place. Given the rather incredible status of consciousness relative to the rest of the cosmos, it seems rational to doubt its absolutely random emergence from fundamental physical processes that are not themselves conscious. It is this aversion to the idea of a random emergence of consciousness in history that leads Nagel to consider two alternative theories, both of which seem to be able to provide a more convincing answer to the “why” question. “For a satisfactory explanation of consciousness as such, a general psychophysical theory of consciousness would have to be woven into the evolutionary story, one which makes intellible . . . why conscious organisms arose in the history of life on earth” (51).
The first of these alternatives is theism, the idea that the material conditions for consciousness were developed for the sake of certain ends that can be meaningfully described in terms of conscious intentionality. On the theistic account, unconscious physical processes are merely the means by which a conscious, intentional mind (God) looks to achieve its ends (59). While this basic theory seems to account for the non-random nature of the emergence of consciousness, it requires positing a clearly supernatural intentionality as the fundamental reality in the cosmos. So, while Nagel is not unsympathetic to conclusions advocated by theists such as Alvin Plantinga, his desire to remain within a naturalistic horizon drives him to consider a different route.
Against the theistic or “intentional” account of why conscious organisms arose, Nagel offers his own “teleological” theory. This teleological account holds that “in addition to the laws governing the behavior of the elements in every circumstance, there are also principles of self-organization or of the development of complexity over time that are not explained by those elemental laws” (59). This preliminary definition is clearly determined by the failure of its foe, reductive materialism, to explain the development of consciousness without resorting to the non-answer (for Nagel) of randomness or chance. As those who are familiar with ancient philosophy will immediately recognize, “This is a throwback to the Aristotelian conception of nature, banished from the scene at the birth of modern science” (66). In response to the recognition of nature’s apparent purposiveness, then, Nagel revives the Aristotelian insistence upon a natural teleology–that is, a natural world that is constituted in part by principles that are directed towards certain ends.
Of course, Nagel realizes that the introduction of teleological principles that are irreducible to physical explanations raises a nightmarishly long list of potential difficulties. Nevertheless, the problems of reductive materialism as a comprehensive ontology warrant such a daring proposition:
One might object that life is hard enough to understand considered purely as a physical phenomenon, and that the mind can wait. But adding the requirement that any theory of life also has to explain the development of consciousness may not make the problem worse. Perhaps, on the contrary, the added features of the natural order needed to account for mind will in the end contribute to the explanation of life as well. The more a theory has to explain, the more powerful it has to be. (69)