Working out of the social and philosophical revolutions from the Enlightenment, contemporary action theory has unwittingly inherited several Cartesian ideas regarding the human mind: that it is unified, rational, and transparent. As a result, we have for too long conceived of action as intimately bound up with reason such that to act at all is to act for a reason, leaving us with theoretical difficulties in accounting for the behavior of non-human animals as well as irrational behavior in human beings.
But rather than propose that such difficulties can be resolved by retreating to a pre-Enlightenment view of human nature, the solution is to make the philosophical turn and embrace the insights that have been secured by Charles Darwin. It is a post-Darwinian evolutionary worldview that can shed some new light on these traditional problems. Two such innovations from the theory of evolution have been evolutionary explanations, which attempt to understand the functions of organisms as having developed in response to environmental pressures, and modular theory, which views organisms as composed of parts with highly specialized functions.
Taking these evolutionary ideas together along with the assumption of biological continuity—that there is a developmental history shared by living organisms—we can begin to conceive of more robust theories of action, mind, and human nature. Contrary to Enlightenment conceptions, reason emerges as just one mental process alongside many, the mind appears anything but Cartesian, and agency begins far earlier along the spectrum of life than we have been supposing
