“[There is] a widespread approach to ideas which Objectivism repudiates altogether: agnosticism. I mean this term in a sense which applies to the question of God, but to many other issues also, such as extra-sensory perception or the claim that the stars influence man’s destiny. In regard to all such claims, the agnostic is the type who says, “I can’t prove these claims are true, but you can’t prove they are false, so the only proper conclusion is: I don’t know; no one knows; no one can know one way or the other.”The agnostic viewpoint poses as fair, impartial, and balanced. See how many fallacies you can find in it. Here are a few obvious ones: First, the agnostic allows the arbitrary into the realm of human cognition. He treats arbitrary claims as ideas proper to consider, discuss, evaluate—and then he regretfully says, “I don’t know,” instead of dismissing the arbitrary out of hand. Second, the onus-of-proof issue: the agnostic demands proof of a negative in a context where there is no evidence for the positive. “It’s up to you,” he says, “to prove that the fourth moon of Jupiter did not cause your sex life and that it was not a result of your previous incarnation as the Pharaoh of Egypt.” Third, the agnostic says, “Maybe these things will one day be proved.” In other words, he asserts possibilities or hypotheses with no jot of evidential basis.The agnostic miscalculates. He thinks he is avoiding any position that will antagonize anybody. In fact, he is taking a position which is much more irrational than that of a man who takes a definite but mistaken stand on a given issue, because the agnostic treats arbitrary claims as meriting cognitive consideration and epistemological respect. He treats the arbitrary as on a par with the rational and evidentially supported. So he is the ultimate epistemological egalitarian: he equates the groundless and the proved. As such, he is an epistemological destroyer. The agnostic thinks that he is not taking any stand at all and therefore that he is safe, secure, invulnerable to attack. The fact is that his view is one of the falsest—and most cowardly—stands there can be.”

“So it is best to keep an open mind and be agnostic. At first sight that seems an unassailable position, at least in the weak sense of Pascal's wager. But on second thoughts it seems a cop-out, because the same could be said of Father Christmas and tooth fairies. There may be fairies at the bottom of the garden. There is no evidence for it, but you can't prove that there aren't any, so shouldn't we be agnostic with respect to fairies?”

“As a philosopher, if I were speaking to a purely philosophic audience I should say that I ought to describe myself as an Agnostic, because I do not think that there is a conclusive argument by which one can prove that there is not a God. On the other hand, if I am to convey the right impression to the ordinary man in the street I think that I ought to say that I am an Atheist, because, when I say that I cannot prove that there is not a God, I ought to add equally that I cannot prove that there are not the Homeric gods.”

“Here there comes a practical question which has often troubled me. Whenever I go into a foreign country or a prison or any similar place they always ask me what is my religion.I never know whether I should say "Agnostic" or whether I should say "Atheist". It is a very difficult question and I daresay that some of you have been troubled by it. As a philosopher, if I were speaking to a purely philosophic audience I should say that I ought to describe myself as an Agnostic, because I do not think that there is a conclusive argument by which one prove that there is not a God.On the other hand, if I am to convey the right impression to the ordinary man in the street I think I ought to say that I am an Atheist, because when I say that I cannot prove that there is not a God, I ought to add equally that I cannot prove that there are not the Homeric gods.None of us would seriously consider the possibility that all the gods of homer really exist, and yet if you were to set to work to give a logical demonstration that Zeus, Hera, Poseidon, and the rest of them did not exist you would find it an awful job. You could not get such proof.Therefore, in regard to the Olympic gods, speaking to a purely philosophical audience, I would say that I am an Agnostic. But speaking popularly, I think that all of us would say in regard to those gods that we were Atheists. In regard to the Christian God, I should, I think, take exactly the same line. ”

“It is often said, mainly by the 'no-contests', that although there is no positive evidence for the existence of God, nor is there evidence against his existence. So it is best to keep an open mind and be agnostic. At first sight that seems an unassailable position, at least in the weak sense of Pascal's wager. But on second thoughts it seems a cop-out, because the same could be said of Father Christmas and tooth fairies. There may be fairies at the bottom of the garden. There is no evidence for it, but you can't prove that there aren't any, so shouldn't we be agnostic with respect to fairies?”

“If there are no self-evident first principles, as a foundation for reasoning to conclusions that are not immediately apparent, how can you construct any kind of a philosophy? If you have to prove even the basic axioms of your metaphysics, you will never have a metaphysics, because you will never have any strict proof of anything, for your first proof will involve you in an infinite regress, proving that you are proving what you are proving and so on, into the exterior darkness where there is wailing and gnashing of teeth. If Descartes thought it was necessary to prove his own existence by the fact that he was thinking, and that his though therefore existed in some subject, how did he prove that he was thinking in the first place? But as to the second step, that God must exist because Descartes had a clear idea of him – that never convinced me, then or at any other time, or now either. There are much better proofs for the existence of God than that one.”