This man's most famous work discusses the absence of the waiter Pierre and the effect of "the look.
This philosopher wrote a critical and psychoanalytic biography of Gustave Flaubert entitled The Family Idiot.  In one essay, this thinker wrote that "Man first of all exists, encounters himself, surges up in the world, and defines himself afterwards." This man's most famous work discusses the absence of the waiter Pierre and the effect of "the look." That work explains how a person defines himself through his socially constructed role, a concept this man termed "bad faith." This man explained the philosophy he developed as "a humanism" in another essay. For 10  points, name this French author of Being and Nothingness, perhaps the most influential existentialist thinker.
This philosopher wrote a critical and psychoanalytic biography of Gustave Flaubert entitled The Family Idiot.  
Jean-Paul Sartre