Ah, of course, because it's more important to signal one's pure, untainted epistemic rationality than to actually get anything done in life, which might require interacting with outsiders.
"Pick a side and stick with it, supporting your friends and bashing your enemies at every cost-effective opportunity" is the dominant strategy in factional politics much the same way tit-for-tat is dominant in iterative prisoner's dilemma. Generosity to strangers and mercy to enemies are so heavily encouraged because in the absence of that encouragement they're the rare, virtuous exception.
Yes, obviously we have to interact with outsiders. That's what makes them outsiders, rather than meaningless hypothetical aliens beyond our light-cone. The que...
Another month has passed and here is a new rationality quotes thread. The usual rules are: