One of the likely characteristics of someone who sets out to be a "rationalist" is a lower-than-usual tolerance for flaws in reasoning. This doesn't strictly follow. You could end up, say, rejecting your religion, just because you spotted more or deeper flaws in the reasoning, not because you were, by your nature, more annoyed at a flaw of fixed size. But realistically speaking, a lot of us probably have our level of "annoyance at all these flaws we're spotting" set a bit higher than average.
That's why it's so important for us to tolerate others' tolerance if we want to get anything done together.
For me, the poster case of tolerance I need to tolerate is Ben Goertzel, who among other things runs an annual AI conference, and who has something nice to say about everyone. Ben even complimented the ideas of M*nt*f*x, the most legendary of all AI crackpots. (M*nt*f*x apparently started adding a link to Ben's compliment in his email signatures, presumably because it was the only compliment he'd ever gotten from a bona fide AI academic.) (Please do not pronounce his True Name correctly or he will be summoned here.)
But I've come to understand that this is one of Ben's strengths—that he's nice to lots of people that others might ignore, including, say, me—and every now and then this pays off for him.
And if I subtract points off Ben's reputation for finding something nice to say about people and projects that I think are hopeless—even M*nt*f*x—then what I'm doing is insisting that Ben dislike everyone I dislike before I can work with him.
Is that a realistic standard? Especially if different people are annoyed in different amounts by different things?
But it's hard to remember that when Ben is being nice to so many idiots.
Cooperation is unstable, in both game theory and evolutionary biology, without some kind of punishment for defection. So it's one thing to subtract points off someone's reputation for mistakes they make themselves, directly. But if you also look askance at someone for refusing to castigate a person or idea, then that is punishment of non-punishers, a far more dangerous idiom that can lock an equilibrium in place even if it's harmful to everyone involved.
The danger of punishing nonpunishers is something I remind myself of, say, every time Robin Hanson points out a flaw in some academic trope and yet modestly confesses he could be wrong (and he's not wrong). Or every time I see Michael Vassar still considering the potential of someone who I wrote off as hopeless within 30 seconds of being introduced to them. I have to remind myself, "Tolerate tolerance! Don't demand that your allies be equally extreme in their negative judgments of everything you dislike!"
By my nature, I do get annoyed when someone else seems to be giving too much credit. I don't know if everyone's like that, but I suspect that at least some of my fellow aspiring rationalists are. I wouldn't be surprised to find it a human universal; it does have an obvious evolutionary rationale—one which would make it a very unpleasant and dangerous adaptation.
I am not generally a fan of "tolerance". I certainly don't believe in being "intolerant of intolerance", as some inconsistently hold. But I shall go on trying to tolerate people who are more tolerant than I am, and judge them only for their own un-borrowed mistakes.
Oh, and it goes without saying that if the people of Group X are staring at you demandingly, waiting for you to hate the right enemies with the right intensity, and ready to castigate you if you fail to castigate loudly enough, you may be hanging around the wrong group.
Just don't demand that everyone you work with be equally intolerant of behavior like that. Forgive your friends if some of them suggest that maybe Group X wasn't so awful after all...