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.