As a philosopher of knowledge, or epistemologist, John Locke (1632–1704) sidestepped the metaphysical problems raised by René Descartes (1596–1650) and offered a theory of the mind and its capabilities that grounded modern ideas of education, psychology, and philosophy of science.

Locke’s political views about democratic government and individual rights were foundational not only for the modern British parliamentary system, but also for the basic principles of the U.S. Constitution. His idea of natural law persists in practical political theories to this day.