Justin Horn

After falling out of favor for much of the twentieth century, moral realism—the view that there exist objective moral standards that hold independently of anyone's attitudes toward them—has made an impressive comeback among philosophers, and now has many sophisticated defenders. This dissertation provides a detailed examination of the challenge to moral realism raised by the emerging field of evolutionary psychology. A mounting body of evidence suggests that the content of our moral judgments has been significantly shaped by natural selection. The project argues that this evidence poses an insurmountable skeptical challenge for those who would hold that morality is a domain of robustly objective truth. This skeptical challenge can be avoided by contemporary anti-realist views of ethics.