You need to clarify your intentions/success criteria. :) Here's my What Actually Happened technique to the rescue:
(a) You argued with some (they seem) conventional philosophers on various matters of epistemology.
(b) You asked LessWrong-type philosophers (presumably having little overlap with the aforementioned conventional philosophers) how to do epistemology.
(c) You outlined some of the conventional philosophy arguments on the aforementioned epistemological matters.
(d) You asked for neuroscience pointers to be able to contribute intelligently.
(e) Most of the responses here used LessWrong philosophy counterarguments against arguments you outlined.
(f) You gave possible conventional philosophy countercounterarguments.
This is largely a failure of communication because the counterarguers here are playing the game of LessWrong philosophy, while you've played, in response, the game of conventional philosophy, and the games have very different win conditions that lead you to play past each other. From skimming over the thread, I am as usual most inclined to agree with Eliezer: Epistemology is a domain of philosophy, but conventional philosophers are mostly not the best at—or necessarily the people to go to in order to apprehend—epistemology. However, I realise this is partly a cached response in myself: Wanting to befriend your coursemates and curry favour from teachers isn't an invalid goal, and I'd suspect that in that case you wouldn't be best be served by ditching them. Not entirely, anyway...
Based on your post and its language, I identify at least the three following subqueries that inform your query:
(i) How can I win at conventional philosophy?
(ii) How can I win by my own argumentative criteria?
(iii) How can I convince the conventional philosophers?
Varying the balance of these subqueries greatly affects the best course of action.
If (i) dominates, you need to get good at playing the (language?) game of the other conventional philosophers. If their rules are anything like in my past fights with conventional philosophers, this largely means becoming a beast of the 'relevant literature' so that you can straightblast your opponents with rhetoric, jargon, namedropping, and citations until they're unable to fight back (if you get good enough, you will be able to consistently score first-round knockouts), or so that your depth in the chain of counter^n-arguments bottoms them out and you win by sheer attrition in argumentdropping, even if you take a lot of hits.
If (ii) dominates, you need to identify what will make you feel like you've won. If this is anything like me in my past fights with conventional philosophers, this largely means convincing yourself that while what they say is correct, their skepticism is overwrought and serves little purpose, and that you are superior for being 'useful'.
If (iii) dominates, the approach depends upon of what you're trying to convince them. For example, whether the position of which you're trying to convince them is mainstream or contrarian completely changes your argumentative approach.
In the case of (d), the nature of the requested information is actually relatively clear, but the question arises of what you intend to do with it. Is it to guide your own thinking, or mostly to score points from the other philosophers for your knowledge, or...? If it's for anything other than improving your own arguments by your own standards, I would suggest (though of course you have more information about the philosophers in question) that you reconsider how much of a difference it will make; a lot of philosophers at best ignore and at worst disdain relevant information when it is raised against their positions, so the intuition that relevant information is useful for scoring points might be misguided.
Where you speak of seeing yourself shifting/having shifted and moving away from an old position (foundationalism) or towards a new one (coherentism) and describing your preference for foundationalism as irrational, it seems like you probably should just go ahead and disavow foundationalism. Or at least, it would if I were confident such affiliations were useful; I'm not. See conservation of expected evidence.
This is an excellent post.
I have naturally read the material here, but am still not sure how to act on two questions.
1: I've been arguing out the question of Foundationalism v.s Coherentism v.s other similiarly basic methods of justifying knowledge (e.g. infinitism, pragmatism). The discussion left off with two problems for Foundationalism.
a: The Evil Demon argument, particularly the problem of memory. When following any piece of reason, an Evil Demon could theoretically fool my reason into thinking that it had reasoned correctly when it hadn't, or fool my memory into thinking I'd reasoned properly before with reasoning I'd never done. Since a Foundationalist either is a weak Foundationalist (and runs into severe problems) or must discard all but self-evident and incorrigible assumptions (of which memory is not one), I'm stuffed.
(Then again, it has been argued, if a Coherentist were decieved by an evil demon they could be decieved into thinking data coheres when it doesn't. Since their belief rests upon the assumption that their beliefs cohere, should they not discard if they can't know if it coheres or not? The seems to cohere formulation has it's own problem)
b: Even if that's discarded, there is still the problem of how Strong Foundationalist beliefs are justified within a Strong Foundationalist system. Strong Foundationalism is neither self-evident nor incorrigible, after all.
I know myself well enough to know I have an unusually strong (even for a non-rationalist) irrational emotive bias in favour of Foundationalism, and even I begin to suspect I've lost the argument (though some people arguing on my side would disagree). Just to confirm, though- have I lost? What should I do now, either way?
2: What to say on the question of skepticism (on which so far I've technically said nothing)? If I remember correctly Elizier has spoken of philosophy as how to act in the world, but I'm arguing with somebody who maintains as an axiom that the purpose of Philosophy is to find truth, whether useful or useless, in whatever area is under discussion.
3: Finally, how do I speak intelligently on the Contextualist v.s Invariantist problem? I can see in basic that it is an empirical problem and therefore not part of abstract philosophy, but that isn't the same thing as having an answer. It would be good to know where to look up enough neuroscience to at least make an intelligent contribution to the discussion.