Agrippa's trilemma

Guillaume Hansali
Guillaume Hansali
Agrippa's trilemma

A new series?

I don’t think I have mentioned this anywhere, but I’ve been studying philosophy online lately. To be more exact, I’m studying Oxford’s courses from the department of continuing education.
Back in August, I studied their Introduction to Philosophy and Political Philosophy courses, and I’m now doing Theory of Knowledge (Epistemology) and Philosophy of Science.

There is a lot to digest, and I thought it would be beneficial for me to write on my blog about what I’ve learned to consolidate my understanding of the topics covered.
Toward the end of the courses, I will have to submit essays, and I will make sure to publish them on the blog as well. If you were wondering what those two essays (essay 1, essay 2) were coming from, they were the final assignments of the two previous courses I studied in August.

The courses are structured in 10 weekly units covering one main topic each. They both started two weeks ago, but I was on vacation in France with my family and couldn’t find the courage to summon my philosopher self. So I’ll be starting with Unit 3! (don’t worry, I reviewed the first two units before).

Without further due, in this post, I’ll be talking about Agrippa’s trilemma.

Agrippa’s trilemma

If you are a geek with good taste, you may have watched the episode of Big Bang Theory where Sheldon announces out of the blue to Leonard that he’ll be moving out because he has to keep a secret from Penny, and invokes the Münchausen’s Trilemma, also commonly called Agrippa’s Trilemma. If you ever wondered what it was about, continue reading.

To explain the trilemma, we need first to talk about knowledge.
Propositional knowledge (knowledge about the truth or falsehood of a given proposition or statement) is commonly defined as justified true belief. To know that a proposition is true, you first need to believe that it is. It then needs to actually be true. And lastly, you need to be able to justify your belief; otherwise, it could just be a lucky guess like guessing numbers at the lottery and be lucky to be right.

The last part raises an interesting problem.
How can we justify a particular belief? We need reasons. I believe A because of B. For example, I believe it is midday because the sun is bright.
But how do I know that the sun is bright? How do I know it is the sun I’m seeing? How do I know that the sun is supposed to be bright at midday? Etc.

Each of these justifications entails a need for further justification, which invites the following question: how much further do we need to go to have enough justification for a belief?

Agrippa’s trilemma suggests that there aren’t any acceptable answers to the question above. When it comes to justification, we only have three unacceptable possibilities:

(1) our beliefs are unjustified; A => B => ?
(2) we need an infinite regress of justifications, ie, a chain of further justifications that continues ad infinitum; A => B => C => D => … => ∞
(3) justification is circular, ie, there exists a chain of justification that folds back onto itself; A => B => C => D => … => A, or as Sheldon says in the episode: “I’m moving out because I’m moving out”.

(1) is unacceptable because that would mean we either can’t have knowledge, or we can’t justify that we do;
(2) is unpractical because we can’t be sure about our beliefs unless we go down the chain of justifications, but it is infinite, and we are finite beings; and
(3) is shaky because justification circularity doesn’t give us any level of confidence in our beliefs.

Solutions to the trilemma?

There are three commonly recognized solutions or counter-arguments to the trilemma.

Infinitism accepts the idea of infinite regress in the chain of justifications. Each belief we have may be justified by another belief, which in turn may be further justified by yet another belief, ad infinitum.
Interestingly enough, the number of possible ideas is most likely finite (our universe is finite), so I wonder how that would work epistemologically speaking.
Proponents of infinitism would say that justification is a continuous (never-ending) process and that we can always go deeper in the chain, increasing our confidence as we do.

Coherentism embraces justification circularity as long as the circle is wide enough and the circularity is not too obvious. Our beliefs support each other in a coherent web.
Circularity is often criticized by philosophers and considered a logical fallacy called “begging the question”; if you claim that God exists because if he didn’t exist there would be no god (I’m moving out because I’m moving out), you’re committing an obvious case of circularity.
Supporters of coherentism argue that we shouldn’t focus on the fact that A ultimately goes back to A; what matters is the warrant that emerges from the mutually supportive beliefs (stronger together!).
I personally find this proposal the most plausible, and above all, the most practical! Science is a good example of coherentism with many laws and theories based on each other (although we do have a few axioms too!)

Foundationalism doesn’t assume infinite regress and states that there exist fundamental beliefs that do not need further justification and that all other beliefs can draw on them. These beliefs serve as a foundation to our knowledge; they are, in a way unjustified justifiers (a little bit like the unmoved mover in the cosmological argument, but I digress).
While this is probably the most widely accepted solution due to its intuitiveness, it nonetheless opens the door to another conundrum: how to decide what qualifies as a fundamental belief?
That question, of course, leads to the criterion problem, namely, is there a sufficient condition for a belief to be justified?

But that’s a different topic!

So there it is, in a nutshell, Agrippa’s trilemma.
Now you can geek out about the episode of Big Bang Theory!

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