As Arnhart acknowledges, the major intellectual challenge of the 20th century is to justify moral judgments rationally and to provide moral authority for political action when individuals meet as moral strangers who do not share common moral assumptions. This is the task of a secular morality that aspires to transcend particular religious or ideological commitments. The arguments for nihilism suggest that such a task cannot be successfully completed. There are three ways one might attempt to escape the threat of nihilism. First, one might endeavor to show that the Aristotelian project to read human moral goals and the lineaments of proper political structure from the characteristics of human biology can be successful, despite the skepticism of authors who have articulated the naturalistic fallacy: from what is the case, one cannot conclude what ought to be the case. A neo-Aristotelian approach would need to derive from the biological nature of humans a proper code for human conduct and morally justified guidelines for human political action. Second, one might attempt to discover, as Kant had hoped, content in the very nature of reason. Here the “nature” at stake is not an external biological nature, but the characteristics of reason or reasoning itself. A contemporary example of the Kantian undertaking is found in Rawls' Theory of Justice (1971). The Aristotelian and Kantian traditions provide two quite different senses of “natural,” from which Western thinkers have attempted (in different ways) to establish the content of natural law and to justify moral and political rules.