Laplace's Demon

Laplace (1749-1827) imagined that if we knew the current state of all things in the universe (from large bodies to atoms), and that we also knew the forces acting on them, we could predict events with certainty. This implies a deterministic world and that uncertainty is a consequence of our incomplete knowledge - the concept was termed Laplace's Demon. It affected scientific thinking by attributing differences between predicted and observed results as arising from defects in the theory rather than being due to random effects.