Sartre is the philosopher most people picture when they hear the word "existentialist." Black turtleneck, cigarette, cafe, cross-eyed stare, Paris, Simone de Beauvoir somewhere in the next chair over. He's the brand. And he earned that brand by writing some of the most uncompromising philosophy of the 20th century, in dense French prose, in a Paris cafe, while running a complicated polyamorous relationship and chain-smoking himself toward an early grave.
He was born in Paris in 1905. His father, a naval officer, died when Jean-Paul was 15 months old. He was raised by his mother and his grandfather, Charles Schweitzer — a brilliant, domineering, terrifying scholar who shaped young Sartre's intellect through sheer pressure. Sartre was a small, awkward, cross-eyed kid who became aware early that the world wasn't going to find him beautiful. He retreated into books. By his teens he was already writing.
He went to the École Normale Supérieure, the elite Paris school that produces basically every French intellectual you've ever heard of. There, in 1929, while preparing for the brutal final philosophy exams, he met a fellow student named Simone de Beauvoir. They came in first and second on the exams, with Sartre edging her out by a hair (the examiners later said it was probably the wrong call). They became inseparable. They never got married. They had what they called a "pact" — they were each other's primary partner, but each was free to have other relationships, on the condition that they told each other everything. The pact lasted 51 years until Sartre's death.
Sartre spent the 1930s teaching philosophy in provincial French high schools, hating it. He went to Berlin in 1933 to study Husserl's phenomenology. That trip changed his philosophical career. He came back determined to write a philosophy of consciousness that was more rigorous than anything French philosophy had produced.
When World War II broke out he was drafted, captured by the Germans, held in a POW camp for nine months, eventually escaped, and made his way back to Paris. He spent the rest of the war writing — he wrote his masterpiece Being and Nothingness in occupied Paris. The book came out in 1943, weighing in at over 700 pages, and almost no one read it for years because it was almost unreadable. It became a foundational text of 20th-century philosophy anyway.
Here's the central argument of his philosophy, in plain language. He distinguishes between two modes of being. Being-in-itself is what objects have — a chair is a chair, fully equal to itself, with no possibility of being otherwise. Being-for-itself is what consciousness has — and consciousness, he says, is fundamentally a kind of nothing, a gap, an absence. Consciousness is always about something, never an object in itself. It's the perpetual ability to step back from any state and consider it.
From this technical setup he draws a radical conclusion: humans, because they are this constant gap of consciousness rather than fixed objects, are not anything in advance. There's no human nature. There's no essence you have to live up to. Existence comes first; you exist; only then, through your actual choices, do you become something. Existence precedes essence.
Man is condemned to be free.
That's the most famous line, and it's a strange one. Condemned to be free. Why is freedom a condemnation? Because it's overwhelming. You can't get rid of it. Even when you try not to choose, the not-choosing is itself a choice. You can't blame your nature, because there is no nature. You can't blame God, because for Sartre God doesn't exist. You can't blame your circumstances, because the way you respond to your circumstances is also a choice. The buck stops with you, every time, forever.
Most people, he says, can't handle this. So they engage in what he calls bad faith — the lie we tell ourselves that we have to be a certain way, that our role determines us, that we have no choice. The waiter who plays at being a waiter so completely he loses sight of the fact that he's a person choosing to be a waiter. The husband who insists he had to stay because that's what husbands do. The student who says they had to take the safe job. All of it, Sartre says, is bad faith — a denial of the freedom we can't actually escape.
His example I always come back to: imagine you're in a cafe, and a man asks you to dance. You hate this. You want to refuse. But you don't want a confrontation. So your hand sits in his hand, and you talk about something abstract while he holds it, and you act as if your hand is just a thing happening to you, separate from your will. That's bad faith — pretending you're a passive object in a situation where you're actually a free agent making a choice.
Hell is — other people.
From his play No Exit, and almost universally misunderstood. He didn't mean other people are awful. He meant that other people see us. They turn us into objects in their consciousness in a way we can't control. We are constantly being defined by their gaze, and we can't escape it. The other is hell because we're never fully free as long as anyone else is looking.
He kept moving leftward politically through the 50s and 60s. He aligned with the French Communist Party, then broke with them. He supported Algerian independence at huge personal risk — his apartment was bombed twice by anti-independence terrorists. He was offered the Nobel Prize for Literature in 1964 and refused it, saying writers shouldn't accept honors that turn them into institutions. He marched in the May 1968 student uprisings in Paris, in his 60s, with cigarette in hand.
His health got worse and worse. The amphetamines he'd been taking for decades to write through the night had wrecked him. By his 70s he was nearly blind and could barely walk. He kept giving interviews and talks anyway. He died in 1980 at 74 of pulmonary edema. Fifty thousand people followed his casket through the streets of Paris. He's buried alongside Beauvoir in Montparnasse Cemetery, in the same grave.
The reason Sartre still matters to me is that the central diagnosis he gave is the diagnosis of modern life. We are free in a way no previous generation has been free. And we don't know what to do with it. We chase the easy answer — let our jobs define us, let social media tell us who to be, let algorithms make our choices. He'd say: that's bad faith. The freedom is still there. You're still the one choosing, even when you choose to pretend you're not.
If you're feeling lost af and the lostness has the specific shape of nobody's coming to tell me what to do with my life — Sartre would say: yeah. That's the situation. Nobody's coming. You're it. The good news is that this is also where dignity is. The choice is yours, and that's terrifying, and it's also the only real game in town.