What Is The Münchhausen Trilemma?


The Münchhausen trilemma is a problem in the branch of philosophy known as epistemology; the Münchhausen trilemma, also known as Agrippa’s trilemma, reveals that any theory of knowledge cannot be certain and that all beliefs are unjustified.

In other words, justified beliefs, which are beliefs founded on reason and logic, cannot be obtained, as the Münchhausen trilemma demonstrates the impossibility of justified premises.

There have been numerous attempts to establish justified beliefs, but none have been satisfactory thus far. And so, the Münchhausen trilemma thought experiment is still a problem for any theory of knowledge

The Münchhausen trilemma leads us to unjustified beliefs and deprives us of certainty in knowledge because it stops us from forming a theory of knowledge via fallacious reasoning: e.g.,

(X → X) = arbitrary assumption
([X → Y] ^ [Y → ∞]) = infinite regress or unjustified premise
([X → Y] ↔ [Y → X]) = circular reasoning

When we rid our philosophy from arbitrary assumptions, unjustified premises, or circular reasoning, as the trilemma so dictates, we likewise have to obviate all notions of justified belief and certainty because all known origin points for any theory of knowledge involve some form of the above mentioned fallacies.

To see how the Münchhausen trilemma demonstrates that any theory of knowledge cannot be proven, consider the various responses, written below, that one can give when their worldview is questioned.

To give an example of the Münchhausen trilemma, we will use realism as the theory of knowledge to be skeptical towards.

Briefly, a realist believes the contents of perception are mind-independent and exist objectively outside the person; they believe we have a one-to-one correspondence between our minds and reality. Thus, the realist has justified beliefs, since he or she sees a real world. Their theories of knowledge are objectively the case.


When we ask the realist, who believes they see reality objectively so, how they have derived that belief, they can respond with an appeal to sense perception. They construct their theory of knowledge on the grounds of perception.

An appeal to sense perception simply means that the realist relies on their senses to know things; for example, “I know there is a book on my desk, because I can see it“.


So, the realist can say, “I know the apple is red because I can verify that claim up against my senses; that is, I can see that the apple is plainly red”.

The Problem Of Perception

However, as the Münchhausen trilemma so encourages us to do, when we ask the realist how they can rely on their sense-perceptions for their theory of knowledge, trouble arises; unjustified beliefs begin to emerge.

Since we have a first-person perspective onto the world, which means we live within experience, we cannot step outside our own point of view.

That means, we cannot verify whether our sensory experiences are accurate or not; we cannot know if sensory experience corresponds to a real world environment or not. And that is a problem for anyone who wants epistemic justification from sense perception.

Relying on sense perceptions for a theory of knowledge, the realist has to argue, “apples are red if I perceive them to be red, and I perceive the apple to be red; therefore, apples are red”. This is circular reasoning, as it appeals to sense perception to verify something found in sense perception.

Untitled Diagram.jpg (1).jpg

So, if the realist appeals to sense perception, then, as the Münchhausen trilemma predicted, they have a fallacious starting point for their worldview.


Another possible response to the Münchhausen trilemma is to appeal to yet more premises; that is, when someone asks the realist, “how do you know reality exists independently of the mind,” the realist can produce an infinite regression of premises.

An infinite regression is when we use one premise to infer another premise, and then we repeat that ad infinitum. Doing so builds a theory of knowledge known as infinitism.

Some people believe infinite regressions are valid, as they produce no fallacies insofar as they maintain consistency, but infinite regressions cannot be used for justifications anymore than “I don’t know” can be used to justify knowledge.

The reason being, we have to assume that the next premise inside the infinite regression is valid, which is not a justification its self.

Or, as equally bad, we have to accept that an unverified premise is grounds for justification; that uncertainty leads to a valid theory of knowledge.

Thus, when the realist relies on an infinite regression for a theory of knowledge, they have no means to justify their worldview, which demonstrates further the problems put forth by the Münchhausen trilemma.

(more on infinite regression)


The last response a realist can give to the Münchhausen trilemma, so as to justify their theory of knowledge, is to simply use arbitrary reasoning: axioms.

Axioms are assertions or tautologies, of which embrace circular reasoning. They are true by virtue of someone’s declaration that they are true.

So, when people question the foundations of realism, like whether there is a correspondence between the mind and reality, or whether our sense perceptions are valid or not, the realist can just assume so.

The realist can assume sensory perceptions are valid, or the realist can assume they are perceiving an objective reality. And from there, they can construct a theory of knowledge around those assumptions.

But the problem herein be that a counter-worldview can follow precisely the same line of reasoning and suppose a different set of assumptions, from which they derive negations of the realists worldview.

So, arbitrary assumptions fail to provide a cogent justification, which means the Münchhausen trilemma has thusly demonstrated the impossibility of certainty.


The Münchhausen trilemma leads to unjustified beliefs because we are unable to provide justification for our evidence and beliefs; that is, when we look at the premises for world-views like realism, and then ask what justification these premises have, we will engage in: arbitrary assumptions, infinite regression, or circular reasoning.

And those responses to the trilemma will always be the case, as we can only give more premises, perceptions, or axioms to respond to skepticism; these fallacies are ingrained into human nature.

Put otherwise, no one will solve the münchhausen trilemma because humans have to reason from fallacious starting points; therefore, justified beliefs and certainty are impossible.


Ideasinhat is a business development analyst and longtime reader of academic literature. He writes books and essays on science and philosophy, and posts them to this website. The essays, as with the books, cover topics from psychology, philosophy, and cognitive science to economics, politics, and law.

15 thoughts on “What Is The Münchhausen Trilemma?

  1. You can’t really make this argument as a true skeptic, however. To make these arguments consistently you have to assume some standard. I.e. “we can only say we know something if our belief in it is properly justified” which is itself a kind of axiom, a kind of arbitrary assumption that we have to employ.

    I’m not an expert on theories of justification but I find phenomenological conservatism not a bad way of looking at the problem. It avoids the practical issues associated with infinitism and avoids any kind of repulsive circular reasoning. We simply have to find a way of having “axioms” (which isn’t necessarily the right term) which aren’t arbitrary. My basic beliefs aren’t arbitrary to me if they seem prima facie true. They may seem wrong or arbitrary to others, however. So the problem is still there that people with 100% diverging intuitions will still butt heads. Nevertheless, relying on seemings is not an arbitrary starting point for me.

    I mean, in this article you said that circular reasoning places us on fallacious grounds for developing a foundation for our worldview but this appears to be nothing but an appeal to a seeming. The true radical skeptic could never make such an argument since they cannot have a standard which dictates that circular reasoning isn’t allowed. The only reason that circular reasoning would not be allowed is if we appeal to the fact that it seems wrong or invalid.

    1. Yeah, you are right. Besides, as a complete skeptic everything can be made to sound like it is a belief based on fallacy or non-justified, but that isn’t enough to convince us at all of the “unrealness” of our beliefs. It’s just used to confuse us but brings nothing new to the table. The author of this post seems ignorant of much of philosophy. He hasn’t said anything new, and this “Trilemma” is nothing more than Skepticism for children 101.

    2. Well by that logic a true skeptic truly can not be sure of anything. In order for anyone to use logic and to propose ideas axioms must be accepted.

      1. Axioms are fine. Certainty is not. In the book I wrote, I conclude that pragmatism wins because, as someone else commented, a pragmatism who is motivated by skepticism doesn’t have to butt heads with anyone. They know all absractions are unjustified assertions, and so they do not have to worry about being right or true. Instead, they can focus on how the world presents itself.

        I.e., whether we call murder evil or not has little impact on whether I want the specific behavior of not wanting others to murder. Put elsewise, whether the notion “murder is evil” is actually true or not doesn’t matter. All I want is a specific set of behaviors.

        Most people cannot see that skepticism leads to less focus on abstraction and more focus on action because they have personal emotions wedded to their own ability to reason to the truth/ A lot of people don’t have good arguments based on certainty, they have arguments motivated by their emotions and refuse to accept that by railing against skeptics: i.e., saying they are dumb, or skeptics fail to be self aware about their own arbitariness.

        Skeptics accept arbitrariness and see no problem, and for me it seems to lead to a pragmatism about action.

  2. >>>Put otherwise, no one will solve the münchhausen trilemma because humans have to reason from fallacious starting points
    You say this is a fallacy. But at the same time you cannot justify why it is fallacious. There are some justified beliefs. We can think of logic as a constraint that needs no justification by itself, because to abandon logic is to abandon communication and proper basics like distinctions. We have no choice to abide by logic, these is no abandoning it. It’s impossible.

    One solution to this “problem” is to just ignore this as a problem altogether. It’s not a problem if it is not of immediate consequence to anything in so far as what matters to us works. We value what we value and it doesn’t matter what you believe. You still cannot deny you experience things. You cannot deny you exist, that data “is”. These are proper basics that we cannot (or have yet not) gotten around. The idea that because we cannot linguistically express these justifications is not proof that are no justifications.

    So let us embrace the shackles that is logic and epistemic certainty that chain us to the ground and remember that is really about maneuvering phenomenological experience. If not, what else could it be? Until we “know”, it doesn’t matter.

    1. “We can think of logic as a constraint that needs no justification by itself, because to abandon logic is to abandon communication and proper basics like distinctions. We have no choice to abide by logic, these is no abandoning it. It’s impossible.”
      The fact that we have no choice but to abide by logic doesn’t mean it is therefore justified. Not being able to disprove something isn’t the same as proving it.

      “It’s not a problem if it is not of immediate consequence to anything in so far as what matters to us works.”
      Lmao, so all of philosophy then.

      1. “The fact that we have no choice but to abide by logic doesn’t mean it is therefore justified.”
        Constraints like logic which are a consequence from experiences don’t need justifications because they are experiences. Like I said, I don’t need to prove to you that I am experiencing sight, touch, smells and so on. It doesn’t matter that I am hallucinating, the experience is still happening.

        The assertion that everything needs a deductive proof is absurd. I never said it can be justified. I said it “needs no justification”.

  3. “humans have to reason from fallacious starting points” What about I think therefore I am.

    1. I don’t see how the “therefore, I am” follows. In fact, some people even deny the “I”. In addition to all of that, “I am” doesn’t get you to “apples are red,” as far as I can tell!

  4. You only think your believe in the MÜNCHHAUSEN TRILEMMA. You cannot even prove the trilemma exists.

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