In March of 1980, Le Nouvel Observateur published the final interviews between the philosopher Jean-Paul Sartre, then blind and debilitated, and his young assistant, Benny Levy. Readers immediately denounced the interviews as distorted and fraudulent for portraying a Sartre who had abandoned his leftist convictions, rejected his most intimate friends, and cast aside his fundamental beliefs in favor of a messianic Judaism. Sartre's supporters argued that it was his orthodox interlocutor, Levy, who had twisted the words of the ailing philosopher.

Yet, shortly before his death, Sartre...