For me, the most startling term I found in my recent reading of Sartre is "optimistic toughness" Here it is in its original context (Sartre: "Existentialism" op,cit., p.34)
"When all is said & done, what we are accused of, at bottom, is not our pessimism, but an optimistic toughness. If people throw up our works of fiction in which we write about people who are soft, weak, cowardly, and sometimes even downright bad, it's not because these people are soft, weak, cowardly, or bad: because if we were to say, as Zola did, that they are that way because of heredity, the workings of environment, society, because of biological or psychological determinism, people would be reassured.They would say 'Well, that's what we're like, no one can do anything about it' " But when the existentialist writes about a coward, he says that this coward is responsible for his cowardice. He's not like that because he has a cowardly heart or lung or brain; he's not like that on account of his physiological make-up; but he's like that because he has made himself a coward by his acts. There's no such thing as a cowardly constitution: there are nervous constitutions, there is poor blood, as the common people say, or strong constitutions But the man whose blood is poor is not a coward on that account, for what makes cowardice is the act of renunciation or yielding. A constitution is not an act; the coward is defined on the basis of the acts he performs. People feel, in a vague sort of way, that this coward we're talking about is guilty of being a coward, and the thought frightens them. What people would like is that a coward or a hero be born that way."
Cowardice? Isn't that the last thing people expect an Existentialist to analyze? They usually expect them to deny all human virtues & ideals, but not stringently analyze vices, declaring cowards responsible for their cowardice. Sartrian Existentialism, profoundly 'conditioned' by the fall of France [1940-], and occupation by Nazi Germany [-1945], is sterner & more judgemental than most Americans dare imagine: it lets nobody off! Still feeling optimistic? Tough?