An axiom is a statement that identifies the base of knowledge and of any further statement pertaining to that knowledge, a statement necessarily contained in all others, whether any particular speaker chooses to identify it or not. An axiom is a proposition that defeats its opponents by the fact that they have to accept it and use it in the process of any attempt to deny it.
Existence exists — and the act of grasping that statement implies two corollary axioms: that something exists which one perceives and that one exists possessing consciousness, consciousness being the faculty of perceiving that which exists.
If nothing exists, there can be no consciousness: a consciousness with nothing to be conscious of is a contradiction in terms. A consciousness conscious of nothing but itself is a contradiction in terms: before it could identify itself as consciousness, it had to be conscious of something. If that which you claim to perceive does not exist, what you possess is not consciousness.
Whatever the degree of your knowledge, these two — existence and consciousness — are axioms you cannot escape, these two are the irreducible primaries implied in any action you undertake, in any part of your knowledge and in its sum, from the first ray of light you perceive at the start of your life to the widest erudition you might acquire at its end. Whether you know the shape of a pebble or the structure of a solar system, the axioms remain the same: that it exists and that you know it.
To exist is to be something, as distinguished from the nothing of nonexistence, it is to be an entity of a specific nature made of specific attributes. Centuries ago, the man who was — no matter what his errors — the greatest of your philosophers, has stated the formula defining the concept of existence and the rule of all knowledge: A is A. A thing is itself. You have never grasped the meaning of his statement. I am here to complete it: Existence is Identity, Consciousness is Identification.
“You cannot prove that you exist or that you’re conscious,” they chatter, blanking out the fact that proof presupposes existence, consciousness and a complex chain of knowledge: the existence of something to know, of a consciousness able to know it, and of a knowledge that has learned to distinguish between such concepts as the proved and the unproved.
When a savage who has not learned to speak declares that existence must be proved, he is asking you to prove it by means of non-existence — when he declares that your consciousness must be proved, he is asking you to prove it by means of unconsciousness — he is asking you to step into a void outside of existence and consciousness to give him proof of both — he is asking you to become a zero gaining knowledge about a zero.
When he declares that an axiom is a matter of arbitrary choice and he doesn’t choose to accept the axiom that he exists, he blanks out the fact that he has accepted it by uttering that sentence, that the only way to reject it is to shut one’s mouth, expound no theories and die.