A 17th-century mathematician treated belief in God as a bet.
Blaise Pascal argued that reason can't settle whether God exists, yet we can't avoid choosing how to live. So weigh the stakes: a finite cost against a possible infinite reward. His wager is often called the first formal use of decision theory. Critics have been poking holes in it ever since.
Blaise Pascal, who died in 1662, was a French mathematician, physicist and religious thinker. The wager appears in his Pensées ('Thoughts'), a collection of notes published after his death. It is striking less for its conclusion than for its method: it turns a question of faith into something like a gamble with payoffs, and is often described as the first formal application of decision theory.
Pascal's starting point is that reason cannot decide the question; it is like a coin toss. But you cannot sit it out. 'You must wager,' he wrote; simply by living, you are already committed to acting as though God exists or as though God does not. Then compare outcomes. If you live as a believer and God does not exist, you lose only finite things, some pleasures perhaps. If God does exist, the gain is infinite. When one side of a bet offers an infinite payoff, even a small chance of winning outweighs any finite stake.
Pascal did not present this as a proof that God exists. It is a practical argument about what it is reasonable to do under uncertainty. He also admitted that some people cannot bring themselves to believe, and suggested they work on themselves by acting as believers do.
Criticism came fast. Voltaire called the wager indecent and childish, observing that having an interest in believing something is no evidence that it is true. Denis Diderot noted that an imam could reason exactly the same way: once you count the many religions making exclusive promises, the neat two-way bet dissolves, a problem known as the argument from inconsistent revelations. Others question whether belief adopted for its payoff is genuine belief at all. Whatever you make of its conclusion, the wager's structure, weighing probabilities against the size of outcomes, lives on in how we reason about rare but extreme risks.
Source: Wikipedia — Pascal's wager · Text summarised from Wikipedia (CC BY-SA 4.0)
