Human action is not a figment of our imaginations, nor is it a social construct. Praxeology describes real and purposeful actions by people who act on what they know or what they believe to be true.

In physics, therefore, postulated explanations have to be hypothesized in such a way that they or their consequents can be empirically tested. Even then, the laws are only tentatively rather than absolutely valid. . . . On the other hand, economics, or praxeology, has full and complete knowledge of its original and basic axioms. These are the axioms implicit in the very existence of human action, and they are absolutely valid so long as human beings exist.

Man is born with no innate knowledge of what ends to choose or how to use which means to attain them. Having no inborn knowledge of how to survive and prosper, he must learn what ends and means to adopt, and he is liable to make errors along the way. But only his reasoning mind can show him his goals and how to attain them.

Of course, a person may say that he denies the existence of self-evident principles or other established truths of the real world, but this mere saying has no epistemological validity. As Toohey pointed out, “A man may say anything he pleases, but he cannot think or do anything he pleases. He may say he saw a round square, but he cannot think he saw a round square. He may say, if he likes, that he saw a horse riding astride its own back, but we shall know what to think of him if he says it.”