Münchhausen trilemma

In epistemology, the Münchhausen trilemma is a thought experiment intended to demonstrate the theoretical impossibility of proving any truth, even in the fields of logic and mathematics, without appealing to accepted assumptions. If it is asked how any given proposition is known to be true, proof in support of that proposition may be provided. Yet that same question can be asked of that supporting proof, and any subsequent supporting proof. The Münchhausen trilemma is that there are only three ways of completing a proof: The circular argument, in which the proof of some proposition presupposes the truth of that very proposition The regressive argument, in which each proof requires a further proof, ad infinitum The dogmatic argument, which rests on accepted precepts which are merely asserted rather than defended The trilemma, then, is the decision among the three equally unsatisfying options. Karl Popper's suggestion was to accept the trilemma as unsolvable and work with knowledge by way of conjecture and criticism. The name Münchhausen-Trilemma was coined by the German philosopher Hans Albert in 1968 in reference to a trilemma of "dogmatism versus infinite regress versus psychologism" used by Karl Popper. It is a reference to the problem of "bootstrapping", based on the story of Baron Munchausen (in German, "Münchhausen") pulling himself and the horse on which he was sitting out of a mire by his own hair. Like Munchausen, who cannot make progress because he has no solid ground to stand on, any purported justification of all knowledge must fail, because it must start from a position of no knowledge, and therefore cannot make progress. It must either start with some knowledge, as with dogmatism, not start at all, as with infinite regress, or be a circular argument, justified only by itself and have no solid foundation, much like the absurdity of Münchhausen pulling himself out of the mire without any independent support. In contemporary epistemology, advocates of coherentism are supposed to accept the "circular" horn of the trilemma; foundationalists rely on the axiomatic argument.