[1968. In Encyclopedia of Christianity. Edwin A. Palmer, ed. Wilmington, Delaware: National Foundation for Christian Education.]
EPISTEMOLOGY is the study of how knowledge is possible. The Greek philosophers from Thales (585 B.C.) to Democritus (c. 400 B.C.) were unable to complete their cosmological theories because unsuspected problems of knowledge constantly blocked them. The Sophists (425-375) concluded that knowledge is impossible. Plato and Aristotle opposed this skepticism, and ever since epistemology has been the crucial part of philosophy.
One type of epistemology is Rationalism. Plato had a world of Ideas as objects of knowledge because the world of flux could not be grasped. St. Augustine made extensive use of Plato. Aristotle tried to derived knowledge from sense data. Thomas Aquinas followed him in this. In England John Locked tried his own approach on this basis. But the outcome of British empiricism in Hume reverted to skepticism. Later, Kant, therefore, tried to form a base for knowledge in a certain combination of a priori (rationalistic) forms of the mind and sensory experience. This result in a “knowledge” of appearance, but left “reality,” i.e. things-in-themselves, unknowable. Then Hegel erected a grandiose “System,” too complicated to characterize in a few words.
From the middle of the 19th century philosophy has reacted increasingly against Hegel, either violently empirical as in positivism or violently skeptical and irrational as in existentialism.
GORDON H. CLARK