I've always avoided epistemology since it didn't excite me the way ethics and politics did. It is, however, becoming clear to me just how intertwined all these philosophical branches are. You start digging at the roots of one and you find those roots travel quite a ways underground and flower into a whole different plant that you thought was quite unconnected.
So yesterday, during a discussion of science, global warming, and whom to trust, one of my brighter students expressed quite succinctly the epistemological principles I've been trying to articulate in my discussions with him:
"So, Mr. Watson, is that why you say the principles of knowledge are community and time?"
Yup. Community because you're ignorant, and time because it takes a while to communicate and get things through your thick head. That's overly simplistic, but a start.
Now the other interesting thing is that this "community" that you need in order to truly know things has to be a functioning, just, full, working political community. Anything less than this disables you from truly learning the truth about something because you never know what a person means when he says something. You both must have a common conception of overarching, higher goods that you are all aiming at -- I think these are what Charles Taylor calls "hypergoods" -- in order to trust his utterances, since a person can say what is simplistically true but mean something entirely different by it.
For example: someone might say: "Check out this huge cookie. It's really good. I'll trade you the cookie for your Rice Crispie® bar." And you might be tempted to make the trade since you like chocolate chip cookies more than you like Rice Crispie® treats. But that's only a fair trade if you two share the same hypergoods. In this case the hypergood of fullness of life through deliciousness of dessert. If it turns out that the vendor of cookies is your enemy and he doesn't have your fullness of life through deliciousness of dessert at heart, then what he means by "good cookie" is one that will poison you with strychnine and accomplish his unshared hypergood, which is fullness of life through your horrible demise. (I assume you do not share his longing for your own horrible demise.)
Unless you and he share common concepts and ideals of life, you don't mean by primitive terms like "good" what he means by those terms. Thus you can't believe anything he says. Thus you can't learn from him anything you don't already know.