Sartre's claim is that there is no human nature, and that this is worse news than it sounds.

If a thing is made for a purpose, what it is comes before that it is: the design of a paper-knife precedes the knife. Sartre's atheism removes the designer, and with it the design. So for a human being existence precedes essence — you turn up first and what you are gets settled afterwards, by what you do, with nothing underwriting it.

The consequence he draws is the part people forget. If nothing settles what you should be, then every choice is yours and none of them can be referred upward. There is no excuse available — not your upbringing, not your character, not the situation. He calls this being condemned to be free, and the word is chosen.

Anguish, abandonment, despair

The three words from the 1946 lecture, each a technical term rather than a mood.

Anguish is what you feel on recognizing that a choice is yours alone and that in choosing you are legislating for everyone — since to choose is to affirm the value of what you chose.

Abandonment is the condition of having no God and therefore no values written anywhere in advance. His example is the student who comes to him during the war torn between joining the Free French and staying with his mother, who has nobody else. No doctrine settles it. Sartre's advice is that he is free, and must invent.

Despair is confining yourself to what is within your control and acting without the guarantee that it will come to anything.

Bad faith — the flight from this freedom into a role or a fact about yourself — is the mechanism that makes all of it bearable, and it has its own page. See bad faith, and Being and Nothingness for the apparatus it sits in.

Freedom and the situation

The standing objection is that radical freedom is obviously false. A person in a prison cell, or starving, or paralyzed, is not free in any sense that matters, and saying otherwise is a philosophy written by a man with options.

Sartre's answer is that freedom is not power. The situation is real and constrains absolutely what you can achieve; what it never determines is the meaning you give it, and there is no situation in which no interpretation is available. The rock is unclimbable only relative to a project of climbing it.

This is defensible and it is also thin, and Sartre came to think so. The Critique of Dialectical Reason (1960) is a long attempt to put the early philosophy inside a Marxist account of how material conditions make people, and it is much less confident that the meaning is always up for grabs. Beauvoir had got there first, in 1947, and more clearly.

The engaged intellectual

He held that a writer is responsible for what their writing does in the world, and that abstention is itself a position. He edited Les Temps modernes, marched, signed, and in 1964 refused the Nobel Prize on the ground that a writer who accepts an institution's honor becomes that institution's instrument.

It is a coherent position, followed further than almost anyone else has followed one.

The objection

The politics is where his admirers stop defending him, and it should be on the page rather than in a footnote elsewhere.

He visited the Soviet Union in 1954 and told Libération that there was total freedom of criticism there, which he knew or should have known was false. He broke with the USSR over Hungary in 1956, which is to his credit, and then spent the 1960s and 70s attaching himself to Maoism and to groups whose programs he had not examined with anything like the rigor he brought to a paragraph of Husserl.

The charge that bites is not that he was wrong about politics — many were. It is that a philosophy whose central claim is that you are wholly responsible for what you do, with no excuses available, was authored by a man who accepted excuses on behalf of régimes when it suited the alignment. Either the standard applies to him or the standard is decorative.

Raymond Aron, who had been his classmate, made this argument at the time and was right about most of it.