It continued to be an article of faith among most physicists that the laws of strict cause-and-effect allow us to predict, in principle, the course of all events above the atomic level.
The great French physicist Pierre Simon de Laplace articulated this belief in a famous statement: "An intelligence which, at a certain instant, knew all the forces of nature and also the situations [positions and velocities] of the entities in it, and which furthermore was capable of analyzing all these data, could encompass in the same formula the motions of the largest bodies in the universe and those of the lightest atom; to it [this intelligence] nothing would be uncertain, and the future would be as clear to it as the past."