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 states 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 having to choose one of three equally unsatisfying options.

A loose equivalent can be seen in the response to a young child repeatedly applying "but why?" to answers they receive. One can either end up admitting "but why" could go on forever (regressive argument), that the "why" eventually loops back to where you started (circular argument), or that at some point the answer to why becomes "it just is" (dogmatic argument).