 Being and Nothingness (1943) remains the defining treatise of the existentialist “movement”, along with works from de Beauvoir from this period (e.g., The Ethics of Ambiguity). We cannot do justice to the entirety of the book here, but we can indicate the broad outlines of the position. In brief, Sartre provides a series of arguments for the necessary freedom of “human reality” (his gloss on Heidegger’s conception of Dasein), based upon an ontological distinction between what he calls being-for-itself (pour soi) and being-in-itself (en soi), roughly between that which negates and transcends (consciousness) and the "pure plenitude" of objects. That kind of metaphysical position might seem to “beg the question” by assuming what it purports to establish (i.e., radical human freedom). However, Sartre argues that realism and idealism cannot sufficiently account for a wide range of phenomena associated with negation. He also draws on the direct evidence of phenomenological experience (i.e., the experience of anguish). But the argument for his metaphysical picture and human freedom is, on balance, an inference to the best explanation. He contends that his complex metaphysical vision best captures and explains central aspects of human reality.