Einstein: His Life and Universe

by Walter Isaacson

The most influential of these, Einstein later said, was the Scottish empiricist David Hume (1711–1776). In the tradition of Locke and Berkeley, Hume was skeptical about any knowledge other than what could be directly perceived by the senses. Even the apparent laws of causality were suspect to him, mere habits of the mind; a ball hitting another may behave the way that Newton’s laws predict time after time after time, yet that was not, strictly speaking, a reason to believe that it would happen that way the next time. “Hume saw clearly that certain concepts, for example that of causality, cannot be deduced from our perceptions of experience by logical methods,” Einstein noted. A version of this philosophy, sometimes called positivism, denied the validity of any concepts that went beyond descriptions of phenomena that we directly experience.