The two preceding chapters argued that the concept of human nature is not dead. Whether classical realism or post-classical realism, almost all contemporary realist international-political theory is infused with (hidden) assumptions about human nature. Still, both classicals and post-classicals had to be defended against unsubstantiated criticism. Exposing the human-nature lie of post-classical realism, however, helped to shed light on how it put the philosophy of political realism in an intellectually uncomfortable and defensive position vis-vis its critics. This is unsatisfactory requiring realist international-political theory to deal anew with the human-nature question, a question that post-classicals thought was dealt with more than half a century ago: Does political realism require the concept of human nature? Does political realism require a conception of Man functioning as the philosophical basis of its forays into the international-political?