John Searle on Naturalizing ContentThe Rediscovery of the Mind (Cambridge University Press: 1992), p. 50-1.
So far no attempt at naturalizing content has produced an explanation (analysis, reduction) of intentional content that is even remotely plausible. A symptom that something is radically wrong with the project is that intentional notions are inherently normative. They set standards of truth, rationality, consistency, etc., and there is no way that these standards can be intrinsic to a system consisting entirely of brute, blind, nonintentional causal relations. There is no mean component to billiard ball causation. Darwinian biological attempts at naturalizing content try to avoid this problem by appealing to what they suppose is the inherently teleological, normative character of biological evolution. But this is a very deep mistake. There is nothing normative or teleological about Darwinian evolution. Indeed, Darwin’s major contribution was precisely to remove purpose, and teleology from evolution, and substitute for it purely natural forms.