All knowledge is circularly justified

This seems like a restatement of Where Recursive Justification Hits Bottom [LW · GW].

https://en.m.wikipedia.org/wiki/Münchhausen_trilemma

It's worth remembering that we are some 90% animal brains (and 98.8% chimps), so if you dig deeper, you hit the limits of introspection and slide into rationalizing without realizing it. I guess it's what you are saying. Best we can do as aspired (post-)rationalists is to point at the vague blob of intuition and call it intuition/subconscious/instincts rather than "knowledge".

You might like the work of Roderick Chisholm on this topic. He spent a good deal of effort on addressing the issue of epistemic circularity (the issue created by the problem of the criterion) and gives what is, in my opinion, one of the better and more technical treatments of the topic. His work also lets us make a distinction between particularism (making minimal leaps of faith) and pragmatism (making any leaps of faith), which I find useful because in practice most people seem to be pragmatists (they have other things to do than wrestle with epistemology) while thinking they are particularists because their particular leaps of faith (the facts they assume without justification) are intuitive to them and they can't think of a way to make them smaller.

I haven't read a lot about it, 'but this seems related to a kind of problem in philosophy that I know as 'grounding problems'. E.g., the question of 'how do we ground truth?' On Wikipedia, the article I found to describe it calls it the symbol grounding problem. On the Stanford Encyclopedia of Philosophy, this kind of problem are known as problems of metaphysical grounding. For rationalists, one application of the question of metaphysical grounding is to what makes propositions true. That constitutes my reading on the subject, but those links should provide further reading resources. Anyway, the connection between the question of how to ground knowledge, and this post, is that if knowledge can't be grounded, it seems by default it can only be circularly justified. Another way to describe this issue is to see it as a proposition that all worldviews entail some kind of dogma to justify their own knowledge claims.

Have you checked out any work on coherentist theories of epistemic justification? I definitely haven't done the work to have an opinion on this, but I remember this dichotomy (foundationalism v. coherentism) being referred to in old introductory epistemology coursework.

I don't think 1) is so safe a bet. THere is atleast the possibility of an infinite chain to be ruled out. Furthermore if this refers to actual chains of questions of "why?" there can be other kinds of termination points. You can encounter confusion and you can encounter lack of imagination ("What you can question that?").

Wittgenstein has an argument about a table on how to consult a table and how it seems problematic that you would need inifinte tables in order to use one. Instead there is some level where you just are competent, able to perform the operations without instruction. Intuition as a word would suggest that there is some abstract thing that you just feel is "true". But other kind of termination is where you just function that way. One can for example understand the function of a eye cell as thought (atleast on the primitive level) that happens upon photon collision. "In the mind world" there is no preceding thought. It just happens just like a cosmic ray would bug out and malfunction an inner brain piece (which would in effect onlyh be a photoreceptor for a very different wavelength off-ocurse withouyt supporting structures like lenses etc).

But loopiness doesn't need to imply circularity. If you start with some system, make it reflect on itself until it stabilises the end result might seem circular. However it might be possible to reverse engineer the reflection and there are reflection balances that have only a finite history. With chicken and egg you find dinosaurs which is a story much longer than the lifespan of a chicken but still some finite generation number. With parents you can go back to start of sexual reproduction. With off-spring you can go back to multicellular-life. With lineage you can go back to start of cell membranes. With reproduction you can go to auto-catalysm. Progressively surprisingly longer stories but they end up being linear instead of the initial seeming circular nature. And there is a direction to the loopiness, it's only loopy towards "the future". Thus when you are tracking where a thought comes from or its justification (if it not constructive in the sense that the discovery process builds an entity that didn't exist before (ie you make up the why as you answer the question instead of discovering something preexisting)) you know you are going "in the wrong direction" and the circularity could end at any step.

Edit note: Removed large amounts of trailing whitespace that I presume were not intentional.

If circular justification has some non zero level of validity, then you might as well use it. But it's not clear that it has non zero validity.