存在と無
The Ethics of Ambiguity () is Simone de Beauvoir's second major non-fiction work. It was prompted by a lecture she gave in 1945, after which she claimed that it was impossible to base an ethical system on her partner Jean-Paul Sartre's major philosophical work "Being and Nothingness" (). The following year, over a six-month period, she took on the challenge, publishing the resulting text first as installments in "Les Temps modernes" and then, in November 1947, as a book.