Evolutionary Ethics

Empirical Approaches

Contemporary empirical research into the evolutionary roots of our moral minds was energized by an approach to the mind inaugurated in earnest in the 1970s: evolutionary psychology (EP). The underlying premise of EP is that, like other observable phenotypic traits (e.g., the structure of the heart or skin pigmentation), some/many/all of our current mental traits were biological solutions to adaptive problems routinely confronted by our hominid ancestors. The mental traits of most interest to E P, of course, are those that issue in behavior. So, to take some of the more notorious traits, it has been maintained that the reason why males typically prefer nubile females while females prefer males of means and status is that these preferences tended, over time, to increase individual reproductive fitness.

From this vantage, it was reasonable to speculate that there must be evolutionary reasons why humans tend to deploy moral concepts. One reason that has figured in several contemporary accounts is that thinking morally was an effective means of ensuring social cohesion. Anthropologists maintain that individual survival depended critically on social cohesion. Beginning with one's immediate family, the spheres of interdependence spread outward to relatives, neighbors, and other members of the group. Cooperating with these individuals was essential for things such as child rearing, protection, food gathering, hunting, and so on. But while cooperation is a more prudential strategy than “going it alone,” unswerving cooperation has its limitations. Occasions will inevitably arise in which one can gain more by exploiting the cooperation of others than by doing one's fair share (as powerfully demonstrated by Prisoner's Dilemma—style games). This strategy of occasional exploitation, however, is unstable under the assumption that most individuals interact regularly over time. For it is thought that regular interactions would inevitably expose cheaters. And over the long run, cheaters who were exposed suffered more than cooperators, who always refrained from exploiting others. It is here that some believe moral thinking earned its spot. An individual who believed that cheating others was prohibited—was immoral—and who felt the corresponding motivation to abide by that belief enjoyed the long-term benefits of appearing trustworthy. In rough outline, this is the evolutionary account.

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