When you encounter someone who expresses a political or social opinion that you find absolutely abhorrent, it is instructive to consider the extent to which this person is making a mistake, and the extent to which they simply have different values from you. Is this opinion something that they would immediately relinquish, if only they knew they knew the true facts of which they are now ignorant?—or is it reflective of some quality essential to their agency, a basic motive far too sacred to be destroyed by the truth?
(Of course, it is also instructive to consider whether you're making a mistake. But that is not the subject of this post.)
Some would say that it is useless to consider such questions, that human cognition doesn't separate cleanly into beliefs and values, and that even if such a thing could be done, it is futile for any present-day human to consider the matter, given our ignorance of our own psychology. And yet, the question still seems to make sense to me. If I can't know, I can guess. And I don't guess the same thing every time.
It's hard to say which extreme is more terrifying. In one scenario, you want to cry out to them, "Oh, you fool! You beautiful, beautiful fool! I love you and I want to be your friend, trust that I will always want to be your friend, but don't you see that the path you're taking can only lead to disaster? If you give me some time I can explain my reasoning precisely, but all the evidence points to the same conclusion: you must turn back now, I beg you, for the sake of everything we hold dear!"
But you know that wouldn't work, so you say nothing.
In the other scenario, you instinctively know that appeals to emotion or common goals would be a waste of precious time, so you frantically search an argument, some sequence of facts and reasoning that will convince them, convince any halfway-rational creature, to stop doing this terrible thing—but it's clear that no such argument exists. Any fact or reason you could offer would only be interpreted as evidence about reality, incorporated into their world-model, and used to persue their monstrous goals that much more efficiently.
You say nothing, but as you look into your enemy's eyes as they hasten the destruction of your world, you can't shake the feeling of having been understood.