Knowledge is in the form of words , not sense data. This is the answer to the riddle of claims that Marx and Lenin's theory of reflection is flawed . By "reflection" they do not mean as in a mirror, but represented as symbols or signs in French. Sense data are had by individual Organisms or bodies . Words and symbols are social facts, shared by humans.
Symboling is using something to represent something it is not abitrarily and conventionally. A symbol does not imitate or resemble that which it represents. This is the basic contradiction in all words and knowledge. Something is identified with something it is NOT. The sound sequence or sequence of letters d-o-g is not the animal it is identified with. "Dog" is not dog. A is not A. All language is contradictory at its root. Thus, the truth of dialectics :All dialects are fundamentally contradictory.