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Blaise Pascal and the wager
1623–1662; Pensées published 1670· Philosopher· Reality, mind & God
Well documentedSolid records, texts or physical evidence.
French mathematician and Catholic thinker who argued that betting on God is the rational choice when reason cannot settle the question.
See it on the Philosophy map →The idea
Idea: if God exists and you believe, you gain infinitely; if not, you lose little, so wager on God. Reasoning: reason cannot prove or disprove God, yet you must choose, and the expected payoff favors belief. A prodigy, he built an early calculating machine, founded probability theory with Fermat in 1654, and tested air pressure. A mystical night that year renewed and deepened his faith. Main objection: which God? Many religions promise rewards and punishments.
Why it matters
The wager is an early piece of decision theory, weighing odds against payoffs, and his line 'the heart has its reasons, which reason does not know' challenged Descartes' faith in reason.
Think of it like
Like buying cheap insurance against an unlikely but catastrophic loss: small premium, enormous payout if it happens.
Legacy and sources
The Pensées are notes found after his death in 1662 and published in 1670. His 'Memorial' of the 1654 night was found sewn into his coat.
Still debated
The Pensées were unfinished fragments; their intended order, and whether the wager was meant to convert or only to unsettle, are debated.
Connections (2)
▸Blaise Pascal and the wager answered with a bet, not a proof, Does God exist?Well documented
The connection
Pascal said reason cannot prove or disprove God, so treat the question as a bet. If you believe and God exists, you gain infinitely; if God does not exist, you lose little. Disbelief risks infinite loss, so a prudent person wagers on God.
When and how
Paris, c. 1657–1662; his notes were published after his death as the Pensées (1670).
How we know
The wager passage survives in his own manuscript notes, now kept at the Bibliothèque nationale de France.
Debates and open questions
Critics ask which God to bet on (the many-gods objection) and whether belief adopted for gain can be genuine.
▸Blaise Pascal and the wager rejected the "God of the philosophers" of René DescartesMostly agreed
The connection
Pascal respected Descartes' science but rejected his rational route to God. For Pascal, God is known by the heart and faith, not proofs: his Memorial praises the 'God of Abraham, God of Isaac, God of Jacob, not of the philosophers and scholars', and the Pensées call Descartes 'useless and uncertain'.
When and how
Pascal met Descartes in Paris in September 1647; the Memorial is dated 23 November 1654; the Pensées were published in 1670.
How sure are we?
The Pensées criticize Descartes by name; the famous complaint that Descartes needed God only for a 'flick' to start the world was recorded by Pascal's circle.
Debates and open questions
Descartes later claimed he suggested Pascal's 1648 air-pressure experiment on the Puy de Dôme; who deserves the credit, and how much rivalry colored Pascal's view, is disputed.