In philosophy, the fundamentals are metaphysics and epistemology. On the basis
of a knowable universe and of a rational faculty’s competence to grasp it, you
can define man’s proper ethics, politics and esthetics. (And if you make an
error, you retain the means and the frame of reference necessary to correct
it.) But what will you accomplish if you advocate honesty in ethics, while
telling men that there is no such thing as truth, fact or reality? What will
you do if you advocate political freedom on the grounds that you feel it is
good, and find yourself confronting an ambitious thug who declares that he
feels quite differently?
The layman’s error, in regard to philosophy, is the tendency to accept
consequences while ignoring their causes—to take the end result of a long
sequence of thought as the given and to regard it as “self-evident” or as an
irreducible primary, while negating its preconditions.