I was argued into supporting eugenics about two years or so back, and then I was argued out of it, so I felt like I ought to write up my reasons for being anti-eugenics as a sort of perspective from someone who has been there. (Definitions: “eugenics” here means noncoercive eugenics, such as free birth control to people with certain traits or encouraging people who are carriers of certain genetic diseases not to breed. It does not mean forcibly sterilizing people, much less killing them. I am also not discussing the deliberate genetic engineering of designer babies, because the technology isn’t here yet.)

The most important reason, I think, is that humans suck at eugenics.

Normally, the example people give here is Nazis. However, I promised I would not talk about Nazis. So instead let’s talk about dairy cows.

Today’s dairy cows produce ten times as much milk as cows a few decades ago, due primarily to heavy selective breeding. This heavy selective breeding leads to mastitis, an extremely painful infection of the udder. And it’s endemic: in 2007, 79% of farms that reported permanently removing cows from their herds did so because of mastitis. And that doesn’t even count all the cows with subclinical mastitis: if it doesn’t interfere with milk production, the cow can continue to suffer for the rest of her life.

“Okay,” you might say. “That’s great, but we don’t actually care about whether dairy cows live in constant pain. We do, presumably, care about whether our children live in constant pain.”

People also care about whether their dogs live in constant pain.

Thousands of cavalier king charles spaniels have brains too big for their skulls, which leave them in constant pain. The cute face of pugs put them at risk of respiratory problems such as brachycephalic obstructive airway syndrome, which can make it impossible for them to breathe. Pugs’ large, deepset eyes leave them at risk of conjunctivitis. For more information, I highly recommend the documentary Pedigree Dogs Exposed.

Owners love dogs. I’m sure everyone has known someone who has spent hundreds of dollars they couldn’t really afford to try to save their dog. And yet breeders– people who have literally devoted their lives to taking care of dogs– made their beloved animals live lives of tremendous pain.

For cuteness.

Humans have, so far, not managed to show that they can consistently outperform Azathoth. Indeed, we have yet to consistently pass the “does not cause excruciating lifelong pain” bar. I admit it’s a controversial position, but I feel if we are going to be doing something to human babies, we should be very very sure we do not accidentally cause excruciating lifelong pain.

Beyond that concern, I see a lot of people saying that they want to breed out traits which have no purpose: depression, schizophrenia, autism, mental handicaps, various physical genetic diseases. At which point I yell “aaaaaa! Chesterton’s Fence!”

Let’s take schizophrenia: obviously genetic, obvious and very large costs to fitness. Actual schizophrenics spend too much time hallucinating black mold to raise children very often. Other disorders genetically linked to schizophrenia, such as schizotypal personality disorder, literally have “lack of interest in sex or other human beings” as a diagnostic symptom.

Nevertheless, the genes for schizophrenia have stuck around for thousands of years. There has to be something that outweighs the enormous fitness cost of those genes. And we don’t know what it is. If we did, perhaps we could knowingly make the tradeoff. But we literally have no idea what we are trading off against. For all we know, it’s creativity. Or g factor. Or the human ability to be conscious.

If a Lovecraftian god builds a fence and you don’t know why it’s there, don’t knock down the fence.

There are some genetic diseases where “why is this still around?” has an obvious explanation. Huntingdon’s hits people after they’ve had kids. Tay-Sachs carriers are fully capable of having children and mostly marry other Jews, who are more likely to be Tay-Sachs carriers as well. Eliminate those as much as you like. But if you don’t have a good explanation for why something obviously fitness-reducing is still present in the population, Thou Shalt Not Fuck With Azathoth.

Finally, there is something called the disability paradox. If asked to rate disabled people’s quality of life, most people will say that their quality of life is very low. However, most disabled people report that they have relatively high quality of life. In fact, some studies suggest that lower quality of life for disability is mediated by ability to participate in activities rather than to the impairments themselves. If you’re in a wheelchair and you can work a job, have friends, and enjoy an interesting hobby, you’re probably going to be about as happy as anyone else. If you’re in a wheelchair and you’re stuck at home all day and you’re lonely and you don’t feel like you contribute anything to society, then you won’t.

Now, perhaps you will argue that people who aren’t disabled see the true horror of disability, while disabled people have to put a bright spin on things in order to get through the day. That is maybe true. On the other hand, it does bring up the question of why all the people with no jobs, no friends, and no hobbies haven’t put a bright spin on things too.

In addition, disabled people have actually been disabled, which seems like a bit of a relevant consideration when you’re talking about whether the lives of disabled people are worth living. They have first-hand experience with the situation. They understand the qualia far more than some random person who is offering up their opinion based on, what, Lifetime movies? If more than half of disabled people are looking at their lives and going “actually, my quality of life is moderate to high,” that seems like reasonable evidence that their quality of life is, in fact, moderate to high.

In fact, some disabled people are so in support of disability that they compare medical treatment of disability to genocide. I do not offer this up as an argument against cochlear implants. I am just pointing out that this is pretty strong evidence that many Deaf people, at least, are perfectly happy being Deaf.

Furthermore, if we assume that most disabled people are in fact basically happy– and far more could be happy if, instead of eugenics, we concentrated our resources on expansions of assistive tech, accommodations, and disability rights advocacy– then we probably shouldn’t do selective breeding to eliminate disabilities, for much the same reason that we shouldn’t do selective breeding to eliminate red hair or attached earlobes or that weird ankle thing everyone in my family has. There’s no point to eliminating a trait that people can have perfectly happy lives with.

I will put out my position here: I think that the anti-disability opinion of abled people is nothing more than a cognitive bias. I suspect it goes both ways– depression is much, much worse than people who have never been depressed think it is; being in a wheelchair is much, much better– and that, in fact, the opinions of people who do not have a disability about how bad that disability is are uncorrelated with how unhappy the people with that disability are. Which has obvious problems for a naive selective breeding program run by abled people. If we do choose to engage in selective breeding to eliminate disabilities, it should be based on careful quality of life research with disabled people themselves, not the prejudices of the abled.