Scott Alexander (reading by Solenoid Entity / Astral Codex Ten podcast host)

Predictive processing can tell us that in a different context, sensations can be perceived differently.

But what makes this particular context switch so jarring?

Normally I would interpret this as a moral prohibition.

The sensations are pleasant, but he's morally opposed to them.

But even if this person was a progressive with no moral objection to homosexuality, even if he was one of those high decoupler types who say bestiality is fine as long as the animal consents and enjoys it,

he might still feel this pseudo-moral repugnance.

And of course there's no moral law against having sex with an ugly person.

That suggests there's some set of unconscious rules about which kinds of sexual pleasure are allowed.

Probably this comes from a combination of genetic instincts and cultural mores, just like everything else.

But the exact genesis is sort of obscure, and instincts and mores sure do get channeled along some unusual paths.

I wrote about some of this in my Sadly Porn review, but upon contact with any real people, our society's stylized description of sex – people get pleasure from genital contact with others, especially hot others – fractures into a dizzying array of inexplicable weirdness.

The first layer is people who can only get pleasure from unusual sex positions or orifices, or people wearing certain clothing, or taking certain roles.

Fine, you can explain that by some kind of weird classical conditioning.

Then there are the people who prefer masturbation to real sex, or at least get different things out of both.

Fine, you can explain that by peculiarities of different ways of stimulating genital nerves.

Then there are the people who can only get pleasure from some very specific scenario, imagining that they're an antebellum slave owner and their partner is a runaway slave who they're punishing, or that their partner is their brother and they're committing incest.

or that their partner is their disciplinarian teacher who always gave them bad grades, but secretly it was because they loved them the whole time and wanted them to get strong enough to be a good spouse.

Then there's the dirt common phenomenon of people who can only take pleasure in sex if they know their partner is enjoying it too, and the thankfully rarer phenomenon of people who can only take pleasure if their partner isn't enjoying it.

There's people who can only enjoy hate sex, or make-up sex, or who want their partner to be hard to get, or who pursue someone until they say yes and then they're not interesting anymore, or who only date abusers even though they hate it, etc, etc, etc.

Physics is stuck in an annoying equilibrium where the standard model works for almost everything and then occasionally we come across some exotic domain where it totally falls apart and we know that reality must be something deeper and weirder.