Agrippa the Skeptic

The Münchhausen trilemma by Agrippa the Skeptic

The Münchhausen trilemma by Agrippa the Skeptic

Philosophy with The VALiens: The Münchhausen trilemma by Agrippa the Skeptic

The Münchhausen Trilemma (after Baron Münchhausen, who allegedly pulled himself and the horse on which he was sitting out of a swamp by his own hair), also called Agrippa’s Trilemma (after Agrippa the Skeptic), is a philosophical term coined to stress the purported impossibility to prove any truth even in the fields of logic and mathematics. It is the name of an argument in the theory of knowledge going back to the German philosopher Hans Albert, and more traditionally, in the name of Agrippa.


If we ask of any knowledge: “How do I know that it’s true?”, we may provide proof; yet that same question can be asked of the proof, and any subsequent proof. The Münchhausen Trilemma is that we have only three options when providing proof in this situation:

  • The circular argument, in which theory and proof support each other (i.e. we repeat ourselves at some point)
  • The regressive argument, in which each proof requires a further proof, ad infinitum (i.e. we just keep giving proofs, presumably forever)
  • The axiomatic argument, which rests on accepted precepts (i.e. we reach some bedrock assumption or certainty)

The first two methods of reasoning are fundamentally weak, and because the Greek skeptics advocated deep questioning of all accepted values they refused to accept proofs of the third sort. The trilemma, then, is the decision among the three equally unsatisfying options.

In contemporary epistemology, advocates of coherentism are supposed to be accepting the “circular” horn of the trilemma; foundationalists are relying on the axiomatic argument. Views that accept the infinite regress are branded infinitism.

Agrippa and the Greek skeptics

The following tropes for Greek skepticism are given by Sextus Empiricus, in his Outlines of Pyrrhonism. According to Sextus, they are attributed only “to the more recent skeptics” and it is by Diogenes Laertius that we attribute them to Agrippa. The tropes are:

  1. Dissent – The uncertainty of the rules of common life, and of the opinions of philosophers.
  2. Progress ad infinitum – All proof requires some further proof, and so on to infinity.
  3. Relation – All things are changed as their relations become changed, or, as we look upon them from different points of view.
  4. Assumption – The truth asserted is merely a hypothesis.
  5. Circularity – The truth asserted involves a vicious circle (see regress argument, known in scholasticism as diallelus)

[165] According to the mode deriving from dispute, we find that undecidable dissension about the matter proposed has come about both in ordinary life and among philosophers. Because of this we are not able to choose or to rule out anything, and we end up with suspension of judgment. [166] In the mode deriving from infinite regress, we say that what is brought forward as a source of conviction for the matter proposed itself needs another such source, which itself needs another, and so ad infinitum, so that we have no point from which to begin to establish anything, and suspension of judgment follows. [167] In the mode deriving from relativity, as we said above, the existing object appears to be such-and-such relative to the subject judging and to the things observed together with it, but we suspend judgment on what it is like in its nature. [168] We have the mode from hypothesis when the Dogmatists, being thrown back ad infinitum, begin from something which they do not establish but claim to assume simply and without proof in virtue of a concession. [169] The reciprocal mode occurs when what ought to be confirmatory of the object under investigation needs to be made convincing by the object under investigation; then, being unable to take either in order to establish the other, we suspend judgment about both.

With reference to these five tropes, the first and third are a short summary of the ten original grounds of doubt which were the basis of the earlier scepticism.[1] The three additional ones show a progress in the sceptical system, and a transition from the common objections derived from the fallibility of sense and opinion, to more abstract and metaphysical grounds of doubt.

According to Victor Brochard “the five tropes can be regarded as the most radical and most precise formulation of skepticism that has ever been given. In a sense, they are still irresistible today.”

Agrippa and Big Bang Theory

Agrippa and Big Bang Theory

The Münchhausen trilemma is also mentioned on the TV show “The Big Bang Theory”, in the 2008 episode “The Bad Fish Paradigm

— article taken from —


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