I think it misses the word for the trees to put the emphasis on a libertarian bent. The British and American class systems are perfectly capable of enforcing the same rules for prestige and polite discussion in order to favour some preferred hegemonic power without endorsing libertarian values. Indeed libertarianism as a movement most certainly adopts those rules because - for all that it may derive political support from (primarily white) guys of all sorts of backgrounds - it’s a fundamentally aristocratic proposition, right down to almost absurdist details such as its propensity to distribute land amongst an elite who employ lesser beings to work it.

In the case of rationalism, the emphasis should instead be on control: Yudkowsky built his system to control what was and wasn’t acceptable thinking, ostensibly for the benefit of the thinker. Its departures from actually very good patterns of thinking are what take it into cult territory, as the rigidity of the rules meets the hard wall of reality, and forces adherents to choose between reality and fantasy.

And as I say below to David, sure, there were other trends in play (most especially - as I note above as well - the tendency for America’s moral arc to bend towards racism). But I’d push back on suggesting that IQ-fetishism is distinct from naive biologism. Rather, IQ-fetishism itself is an expression of naive biologism (as we can see tracing its antecedents through back to Herbert Spencer), because you don’t get IQ-fetishism without the spectres of relativism and nurturism which, politically, it purports to counter-act - “IQ” is a supposedly sound, stable, measurable, cognitive category, where the alternative is understood to be a tangled mess of occult entities which cannot be reduced to any structure in the brain (and IQ holds out the promise of being reducible to g, which is in its whole conception reducible to a structure in the brain).

In this way the speculative futurism is simply of a piece with the biologism: once you reduce everything to (this very peculiar and highly naive, already science-fictional, concept of) the physical, you can manipulate it to generate whatever future you want. By the same token, the eugenic and fascistic trend in science-fiction pursues the same conceptual route. But it is only with the right historical ingredients, and the right players to activate those ingredients - which is to say an unequal society and the tendency to have people who want to naturalise that inequality - that the mixture becomes potently racist, and Yudkowsky, so to speak, is the one building the pot to specification.