Frankly, he has my sympathies, and I say this speaking as one who is now officially and technically a fucking scientific racist, and is hating every minute of it. The increase in knowledge doesn't even seem worth the sacrifice; we're talking about differences in average IQ between 95, 105, 110, 115. For one such as I, who's got an IQ of 168, this degree of difference seems unimpressive, and, frankly, worth ignoring/not worth knowing.

"You're telling me all these massive groups of people have these slight differences in average between them? About one standard deviation? Of what use could this information possibly be?" "Let's forbid entrance to my particular country to immigrants from the inferior races, namely, people of 'african' and 'hispanic' ancestry; it's cheaper than giving everyone an IQ test. Is this not a clever idea that advances my nation's interest and saves taxpayer money?"

And then I sigh at the stupidity of people with high IQ's, myself included.

Nevertheless, pianoforte, you're definitely overreacting. Do give your friend Arthur some references on Ethical Injunctions and remind him of our Litanies. Even if you did nothing, I do not expect Arthur, or any lesswronger for that matter, to present a level of threat worth having actual cold sweats over.

Here's another argument you can give him; social justice seeks to achieve just ends, and to do so requires just means, an image of justice as well as a just system. To seek social justice is to seek righteousness, and to seek to be right; it demands that you be scrupulously rational. Since You Provably Can't Trust Yourself, you should not, cannot allow yourself to employ the methods of evil, of which irrationality, stupidity and incoherence are the very essence. Throughout my life, I have been in contact with all kinds of people who invested huge amounts of effort in struggling for the betterment of mankind, and, whenever they started thinking in martial terms, of Us Versus Them (see Robbers-Cave experiment), of a struggle where one allows oneself all dirty tricks because so does "the other side", Arguments Are Soldiers, and they lose themselves and their ability to identify the truth when it doesn't fit their narrative. And that's a huge handicap.

Keeping a clear mind and remaining open to the truth, no matter how inconvenient, is, I think, the only way to live through one's life, and remain sane to the very end. Once you forfeit your sanity, no matter your successes, you have lost.