After having defended the irreducibility of consciousness, Nagel expands his apology on intentionality and knowledge: “What we take ourselves to be doing when we think about what is the case or how we should act is something that cannot be reconciled with reductive naturalism, for reasons distinct from those that entail the irreducibility of consciousness. It is not merely the subjectivity of thought but its capacity to transcend subjectivity and to discover what is objectively the case that presents a problem” (72).
To understand what problem Nagel has in mind here, we need to briefly clarify the meaning of cognition. Nagel defines cognition as the capacity to “transcend the perspective of the immediate life-world given to us by our senses and instincts, and to explore the larger objective reality of nature and value” (71). It is precisely this ability, which consists in remaining in touch with reality, that has to do with normativity, i.e., with the capacity to distinguish appearance from reality, correct from incorrect answers, true from false beliefs (among other normative operations we can list: the avoidance of incoherence, the subsumption of particular cases under general principles, the falsification of general principles on the basis of some particular observations, etc). In virtue of that character, cognition presupposes the use of language, a normatively governed faculty which involves in turn the acquisition of a system of concepts capable of detaching speakers from present experiences.
On the assumption that the attribution of knowledge pertains only to beings that also have consciousness, Nagel states two aspects of the problem we have to deal with in order to grasp a convincing explanation of cognition:
1) the likelihood problem: “is it credible that selection for fitness in the prehistoric past should have fixed capacities that are effective in theoretical pursuits that were unimaginable at the time?”(74)
2) The difficulty of understanding naturalistically the faculty of reason that is the essence of these activities.
As far as the first is concerned, Nagel admits that it might be possible to explain in evolutionary terms how our complex cognitive capacities have sprung from proto-mental dispositions of our living ancestors; however, he underlines again that it might be impossible to set out a completely reductive explanation of it: “Rationality, even more than consciousness, seems necessarily a feature of the functioning of the whole conscious subject, and cannot be conceived of, even speculatively, as composed of countless atoms of miniature rationality” (87). Hence, the second difficulty becomes crucial now. Let me state the overall point Nagel names “Descartes's insight”: we use reason to justify knowledge, and we cannot step back from it, trying to justifying reason itself appealing to some other external source of warrant. Therefore, even a theory of the evolutionary origins of reason has to presuppose reasoned methods for validating cognition, such as inductive reasoning, evidence-based verdicts, modus ponens, and so on. Note that the same evolutionary argument prompted to support the reliability of vision, our most powerful perceptual ability, cannot serve the case of reason and cognitive capacities. In fact, while we can trust vision on the basis that it was fitness enhancing, we cannot assess a line of reasoning in the same way. We cannot say an argument is right or sound as far as it is supported by the evolutionary story of the faculty of reasoning. To properly assess an argument we need logic. And logic resists reduction to fitness-enhancing considerations. In conclusion, once we recognize the autonomy of “the space of reasons”, a clear evolutionary elucidation of cognitive abilities becomes even more mysterious.
|Genetic Science Learning Center (2012, August 6) Foundational Toolkit Genes. Learn.Genetics. Retrieved May 15, 2013, from http://learn.genetics.utah.edu/content/variation/toolkit/|
So we stand in need of both a constitutive explanation of what rationality might consist in, and a historical explanation of how it arose; and both explanations must be consistent with our being, among other things, physical organisms. The understanding of biological organisms and their evolutionary history would have to expand to accommodate this additional explanatory burden, as I have argued it must expand beyond materialism to accommodate the explanation of consciousness”. (86)
But how might it be possible to accomplish this demanding task? According to Nagel, the ultimate possibility after having discarded chance, reductive materialism and intelligent design, is natural teleology, that is, the view which is characterized by “irreducible principles governing temporally extended development” (92). Teleological principles require that laws of physics are not fully deterministic and allow a certain space for values in natural mechanisms. Moreover, teleological principles entail that some processes are more eligible and appropriate than others, in order to grant a special distinction in value between the different possible futures allowed by physical laws: “The existence of teleology requires that successor states in this subset have a significantly higher probability than is entailed by the laws of physics alone – simply because they are on the path toward a certain outcome” (93). This does not mean to deny the effectiveness of physics. On the contrary, we may imagine a universe in which laws of physics and chemistry in their present functioning just prepare the future emergence of certain biological processes endowed with values.
Nagel stresses that natural teleology is no more than a hypothesis as well as chance, causalism and intentional design. Nagel’s conclusions, as I understand it, are quite skeptical on having at hand a complete and convincing explanation of a natural order capable of including consciousness and cognitive abilities. This means that skepticism might back widespread research projects instead of confining our efforts into incommunicable and isolated paradigms destined to reach dead ends.