Émilie du Châtelet

Key ideas

Two first principles

All knowledge rests on two principles, the principle of contradiction and the principle of sufficient reason, which says that nothing is without a reason why it is so and not otherwise. Some truths of metaphysics can be demonstrated as rigorously as those of geometry.

Takes up Gottfried Wilhelm Leibniz’s principle of sufficient reason

Metaphysics beneath physics

Newton’s physics describes the world mathematically but needs a foundation. Du Châtelet supplied one modelled on Leibniz and Wolff, beginning with God, the sufficient reason for a world of contingent things, who chose this world for its interconnection and order.

Simple beings, not atoms

Atoms are defined as extended yet indivisible, but whatever is extended can be divided, so atoms are impossible. The ultimate constituents of bodies must be unextended simple beings, which must exist if the composite, extended things we experience exist.

Takes up Gottfried Wilhelm Leibniz’s Monads

In defence of hypotheses

Against the fashion of the Royal Society and the Académie, and of Voltaire, du Châtelet held that good hypotheses are the work of the greatest scientists, Copernicus, Kepler, Descartes and Newton among them, and that banning them would harm science.

Attraction within limits

Newton’s attraction explains gravity better than Descartes’ vortices, and also the tides and the motions of the moon. But some of Newton’s followers stretched it too far, making it explain cohesion, elasticity and electricity, as though attraction were a property of matter itself.