Emil Kirkegaard proposes a semi-objective definition of “mental illness”.

He’s partly responding to me, but I think he mangles my position; he seems to think I admit mental illnesses are “just preferences” but that which preferences are valid vs. diseased can be decided by “what benefits my friends”.

I mostly don’t think mental illnesses are just preferences! I’ve been really clear on this! But Emil is right that I don’t deny that there can be a few cases where it’s hard to distinguish a mental illness from a preference - the clearest example is pedophilia vs. homosexuality. Both are “preferences” for sex with unusual categories of people. But I would - making a value judgment - call pedophilia a mental illness: it’s bad for patients, bad for their potential victims, and bad for society. Also making a value judgment, I would call homosexuality an unusual but valid preference: it’s not my thing, but seems basically okay for everyone involved.

(I wouldn’t describe this as “benefiting my friends” - I’m against children getting raped whether they’re my friends or not. I think this dig was unworthy of Emil, and ask that he correct it.)

https://www.astralcodexten.com/p/contra-kirkegaard-on-evolutionary