"Truth is the recognition of reality; reason, man's only means of knowledge, is his only standard of truth." -- Ayn Rand
Truth is the product of recognition(i.e., indentification)of the facts of reality. Man identifies and integrates the facts of reality by means of concepts. He retains concepts in his mind by means of definitions. He organizes concepts into propositions -- and the truth or falsehood of his propositions rests, not only on their relation to the facts he asserts, but also on the truth of falsehood of his designations of essential characteristics." -- Ayn Rand
"The truth or falsehood of all of man's conclusions, inferences, thought and knowledge rests on the truth or falsehood of his definitions." -- Ayn Rand
How would she know with certainty whether the thoughts (chemical secretions?) in her head correspond to external realities?