No, it’s not. The Enlightenment gave us a lot of ideas about the metaphysics of truth and knowledge that have been challenged, to put it mildly, in the last century. To be more clear, a lot of very respectable philosophy has been done by thinkers like Wittgenstein, Husserl, Sartre, Davidson, etc., that undercuts the validity of any claim to Truth. Postmodernism is a fairly extreme form of a lot of that work, but it has its moments.
And that’s the point. You said that you feel a duty to correct falsehoods, when there are plausible arguments to be made that what you consider falsehoods are mostly accidental to your time and place and perspective; at the very least, bounded by your particular circumstances.
These are certainly arguable positions. It’s not the case that Relativism won out against Transcendentalism, and someone forgot to tell you. But it’s perfectly plausible to view truth as something less than absolute, yet more than perfectly subjective. In that sense, one can be suspicious of those who argue from on high, claiming perfect rationality. One doesn’t throw out logic, but one also doesn’t sacrifice intuition and experience. One is also aware of the limits of rational argumentation, as we Dopers often are when arguing that moon landings really did happen, but our only argument is that the overwhelming preponderance of evidence is on our side.
“Principle of Charity” comes from Donald Davidson, who said something along the lines of first understanding something with maximum internal coherence–in other words, first grasp how that thing makes sense to itself, before criticizing it. In philosophical argumentation, this leads to the corrolary that one doesn’t defeat a thesis unless one defeats the most charitable interpretation of that thesis. In feminist terms, it means listening without judging to someone expressing something from an alien viewpoint, and seeking to understand that expression in its own terms. It doesn’t mean all criticism is suspended; it means giving the benefit of the doubt to an expression of a viewpoint different from one’s own, and being wary of judging it by one’s own, inapplicable experience.
“Oppressed Groups” in feminist discourse is pretty much anyone who is from a community that is not the dominant, mainstream community. In our case, that’s white, heterosexual men. Again, one can argue about the degree and validity of the label “oppressed”, but that misses the point–if those people are, in some sense, oppressed, then, according to the principle of charity, it behooves us to listen uncritically first to be sure that we’re not silencing them with our power, when we think it’s our rationality.
(and the battle of the emoticons begins…)