In epistemology, the Münchhausen trilemma is a thought experiment used to demonstrate the impossibility of proving any truth, even in the fields of logic and mathematics. If it is asked how any knowledge is known to be true, proof may be provided. Yet that same question can be asked of the proof, and any subsequent proof. The Münchhausen trilemma is that there are only three options when providing proof in this situation: The circular argument, in which theory and proof support each other. The regressive argument, in which each proof requires a further proof, ad infinitum. The axiomatic argument, which rests on accepted precepts.

If there are no provable truths, then this trilemma isn't one either, by its definition, so why is this an acknowledged thought experiment.

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    The same for every skeptical claim that asserts (i.e. produce a statement as a true one) that there are no true assertions. Commented Jun 7, 2019 at 10:41
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    The structure of the argument in the trilemma is different. It is if there was such a thing as provable truth then it would be impossible to prove it (without accepting axioms, etc.). It is similar to a proof by contradiction: assuming proofs are possible leads to one. Like many skeptical arguments, it accepts what the opponent believes (for the sake of the argument), only to refute it. If one already doubts provability of all claims they no longer need the trilemma, and universal doubt is not a claim (it is refraining from any claims) and so is not subject to it.
    – Conifold
    Commented Jun 7, 2019 at 11:26

1 Answer 1


A different way of phrasing Munchausen's trilemma (MT) might help explain what the problem is and why your attempt at a solution is inadequate. MT states that if proof is necessary for knowledge and if we accept standard rules about arguments, then nothing can be proven and knowledge is impossible. Stating that proof is possible doesn't make that problem go away without an explanation of how proof is possible.

There is a solution to MT, which involves saying that proof is unnecesssary and we can use guessing controlled by criticism to create knowledge instead, see Why is the Münchhausen trilemma an unsolved problem?

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