Pierre-Simon Laplace
1749 – 1827 · Normandy; Paris
A mathematician and astronomer who gave determinism its most famous image: an intellect that could know the whole future from the present.
Key ideas
In the introduction to his Philosophical Essay on Probabilities, Laplace described an intellect that knew every force in nature and the position of every particle at one moment. For such a mind, nothing would be uncertain; the future, like the past, would be present to its eyes. Later writers called it Laplace's demon, and it remains the standard picture of determinism.
Ironically, the point of the passage was to explain why we need probability: we are not such an intellect, and probability measures our ignorance. Laplace did foundational work on probability theory, including methods of reasoning from evidence that anticipate modern Bayesianism.
Life, briefly
Laplace was born in Normandy to a modest family and made his name in Paris as a young mathematician. His five-volume Celestial Mechanics showed that the solar system is stable under Newtonian gravity. He held office under Napoleon, briefly as minister of the interior, and later under the restored monarchy. A well-known story has Napoleon asking why his book did not mention God, and Laplace replying that he had no need of that hypothesis; the story may be embellished.
Major works
- Celestial Mechanics (1799–1825)
- Analytic Theory of Probabilities (1812)
- A Philosophical Essay on Probabilities (1814)
Appears in
Further reading
- WikipediaPierre-Simon Laplace