Philosophy for 345 years has been little more than epistemology. "Episteme" in Greek means knowledge, and our derived word in English means the study of how we know. Since 1637 when Descartes wrote Discourse on Method
, which founded modern philosophy, few philosophers have strayed into knowledge itself. The attempts at speculative philosophy have since died out. Philosophers have largely limited themselves to how
we can know, not what
we can know. Indeed, many have proscribed fields of knowledge as impossible to deal with.
What Pandora's box did Descartes open which could not be closed again? The philosophers might be the last to admit it, but Ernst Gellner's The Devil in Modern Philosophy
(1974) traces the problem to the hypothetical demon of Descartes' Meditations
(1641). Descartes pondered whether a demon could have tricked him into believing everything which common sense makes each of us believe.
With his "clear and distinct" ideas founded upon his classic "I think, therefore I am," Descartes believed that he answered the problem of tricks by a demon. His solution was a deduced God of truth and goodness. Ever so many philosophers denied the validity of his proof, which sent them back to square one. Subsequent skeptics have struggled with solipsism. A solipsist cannot be satisfied with the evidence that anything exists except the Self.
Nevertheless, a Rationalist school calling itself Cartesian formed in later generations, claiming knowledge in all fields. All these great philosophers, Malebranche, Liebnitz, and Wolff, however, can be considered like a great branch of a tree which was sawn off at the base arid from which, of course, nothing further ever grew.
The Empiricists, the other great philosophic school of the century after Descartes, eventually prevailed over the Rationalists. These English empiricists were every bit as exacting as Descartes in analyzing away common sense and ordinary appearance. John Locke (1632-1704) with his tabula rasa
concept of the clean slate did not himself abandon all knowledge, but the logical consequence was the sweeping skepticism of David Hume (1711-1776). Even before the Enlightenment of the 18th century had led to the Age of Revolution (starting 1789), all the premises upon which reform had been deduced had been demolished. Philosophy had contracted back into deliberations on how
we can know, but the world went on believing what
it believed to be knowledge, anyway.The epistemologist par excellance beyond all compare was Immanuel Kant (1724-1804). Though he agreed with Hume that all basis for rational certainty had been destroyed, Kant nevertheless constructed laboriously a way to knowledge based upon the mind's perception of phenomena. On the one hand, this would seem to be Rationalism revived, and in Hegelianism this does seem to have occurred. On the other hand, Kant acknowledged complete skepticism about things-in-themselves. Kant's philosophy really was an "as-if" (Vaihinger's "als ob") epistemology whose legitimate successor is the philosphy of science known as "conventionalism." Putting aside Kant's pretentiousness, his philosophy was that we perceive experience in preconceived categories of understanding. At worst this seems like glorified prejudice, better as a defense of innate knowledge within the human intellect, perhaps even as resurrection of the Platonic theory of Forms, the universal ideas.
In Hegel and all his successors, in the 19th century as in the 18th century, a great branch of philosophy claiming great knowledge ended up with no current representatives. Hegelianism and the other optimistic creeds of Progress crashed into the catastrophic suffering of World War I and various civil wars, famines, revolutions, Great Depression, Naziism, and World War II thereafter.
As a consequence, 20th century philosophy has been very restrained in its pretensions. No great systems have arisen. All have sought to find one of various ways of knowing. How do we go about finding truth? Pragmatists say, "Does it work?" Existentialists take each life experience as it comes. Other Irrationalists assume some presumptions as if they were true, usually based on tradition of feeling. Philosophy of science alone has been assertive, but in doing this as Logical Positivism has turned against all other knowledge. Here it is asserted that anything besides science, being unverifiable, is unknowable and even meaningless. Linguistic Analysis in England tends to focus so much on word study that knowledge itself is secondary. What proofs they have made famous have been, ironically, the most demanding and unattainable form of all knowledge, the proving of a negative. Several proofs have been put forth of the non-existence of God. If so, Descartes has been stood on his head, for only the existence of God could rescue Descartes from solipsism.
The failure of Descartes' epistemology has led to the emergence of philosophies which seek to avoid the issues. Scottish and English Realist philosophers have attempted to vindicate common sense in a modified form, but implicitly they acknowledged Descartes' critique. Scholasticism reemerged as Neo-Thomism in the 19th century, completely ignoring Descartes. Other French Catholic philosophers such as Olle-Laprune and Blondel, however, have solved to their satisfaction the problem of skepticism by simply attributing ill-will to unbelievers. (Of course, the charge can as easily be reversed, to find fault with believers for letting the will override the intellect.) This in itself is a most important contribution to skepticism in epistemology. It revives the demon theory in full force, whether hypothesized (as by Descartes) as an external deceiver or presumed to be inborn sin.
In the course of 2000 years, therefore, we have dropped from asking "What is Truth?" to merely "How is truth found?"-and still no answer is heard.