Pierre-Simon Laplace is often remembered for his atheism and his wholehearted belief in a resolutely deterministic view of the universe. At the same time, the French scientist made major contributions to the development of probability theory.
From determinism to probability --------------------------------
Curiously, the mathematician from Normandy's deterministic conviction appears in the introduction to his Essai philosophique sur les probabilités (Philosophical Essay on Probabilities; see the article "The philosopher of chance"). In the first section of the introduction, entitled "On probability," he writes:
"We must therefore regard the present state of the universe as the effect of its previous state and the cause of the state that will follow. An intelligence that, at a given instant, knew all the forces by which nature is animated and the respective positions of the beings that compose it […] would encompass in a single formula the motions of the greatest bodies and those of the lightest atom: nothing would be uncertain to it."
Quantum mechanics, developed more than a century later, would, as we now know, disprove this overly radical view. But it is worth considering why the staunchly deterministic Laplace took such an interest in probability theory. In 1772, at the age of 22, he first attracted notice with the publication of his Mémoire sur l’analyse des hasards (Memoir on the Analysis of Chance), followed a year later by a second memoir with an equally evocative title: Mémoire sur la probabilité des causes par les évènements (Memoir on the Probability of Causes from Events). Thirty-seven years later, in 1810, he returned to probability theory in earnest with his Mémoire sur les approximations et leur application aux probabilités (Memoir on Approximations and Their Application to Probabilities), followed two years later by his major work, the Théorie analytique des probabilités (Analytical Theory of Probabilities; see the article "Probability and its metaphysics").