They go together: if I know that you and I can have a discussion and agree to disagree, rather than having it escalate it to an emotionally charged argument that affects our relationship, then I'm more likely to express my thoughts thruthfully.
This presumes a level of objective truth that is almost never available within the confines of casual conversation. I find the failure mode of a stubborn "truth-seeker" far more obnoxious in most settings than the failure mode of someone saying "huh, that's interesting, I'll have to look into that more" even when they're pretty sure they're right.
Surely you realize how much of an oxymoron that is.
Follow an unrealistic and impractical standard, just as your forefathers have. Why? Because it is righteous and good.
There's no point in finding the truth. Perhaps if your knowledge seeking gives you positive neurochemical feedback, more power to you, but to denigrate all of society for not conforming to your ideals is a very ugly personality trait.
It's not hard to tell if someone is actually seeking dialectic and wants to pursue the truth. The vast majority of people are making smalltalk and may as well be discussing professional basketball.
The tack I've come to lately is to say "I don't think we currently have sufficient information available to adequately resolve this issue" - it works like a charm, and people seem to like you more when you say that, compared with "let's agree to disagree"