This work reexamines Sartre's phenomenology from the perspective of contemporary debates in political theory with particular attention to the reemergence of theories of human nature. For Sartre, any construct that stood between the self and its direct encounter with the world was suspect. Sartre's version of direct realism is a strong refutation of the 'new essentialism' that has emerged in recent years as a back-door invocation of theories of human nature. This book provides an account of the major ideas that inform the new essentialism and that serve to further identify it as other than what it claims to be, a scientific grounding of human behavior. Instead, from the perspective of Sartre's realism it is exposed as an abstract ideology. One aspect of this new essentialism has been its encouragement of ideological claims about human essences, historically and culturally derived attributes of individuals that, it is alleged, define individual human existence itself. Thus human freedom is diminished even while essentialist categories such as male aggression become an overlooked underpinning for political ideology.