Diseased thinking: dissolving questions about disease by Scott Alexander

welcome to the nonlinear library, where we use text-to-speech software to convert the best writing from the rationalist and ea communities into audio.
this is: Diseased thinking: dissolving questions about disease, published by Scott Alexander on the effective altruism forum.
Related to: Disguised Queries, Words as Hidden Inferences, Dissolving the Question, Eight Short Studies on Excuses
Today's therapeutic ethos, which celebrates curing and disparages judging, expresses the liberal disposition to assume that crime and other problematic behaviors reflect social or biological causation. While this absolves the individual of responsibility, it also strips the individual of personhood, and moral dignity
-- George Will, townhall.com
Sandy is a morbidly obese woman looking for advice.
Her husband has no sympathy for her, and tells her she obviously needs to stop eating like a pig, and would it kill her to go to the gym once in a while?
Her doctor tells her that obesity is primarily genetic, and recommends the diet pill orlistat and a consultation with a surgeon about gastric bypass.
Her sister tells her that obesity is a perfectly valid lifestyle choice, and that fat-ism, equivalent to racism, is society's way of keeping her down.
When she tells each of her friends about the opinions of the others, things really start to heat up.
Her husband accuses her doctor and sister of absolving her of personal responsibility with feel-good platitudes that in the end will only prevent her from getting the willpower she needs to start a real diet.
Her doctor accuses her husband of ignorance of the real causes of obesity and of the most effective treatments, and accuses her sister of legitimizing a dangerous health risk that could end with Sandy in hospital or even dead.
Her sister accuses her husband of being a jerk, and her doctor of trying to medicalize her behavior in order to turn it into a "condition" that will keep her on pills for life and make lots of money for Big Pharma.
Sandy is fictional, but similar conversations happen every day, not only about obesity but about a host of other marginal conditions that some consider character flaws, others diseases, and still others normal variation in the human condition. Attention deficit disorder, internet addiction, social anxiety disorder (as one skeptic said, didn't we used to call this "shyness"?), alcoholism, chronic fatigue, oppositional defiant disorder ("didn't we used to call this being a teenager?"), compulsive gambling, homosexuality, Aspergers' syndrome, antisocial personality, even depression have all been placed in two or more of these categories by different people.
Sandy's sister may have a point, but this post will concentrate on the debate between her husband and her doctor, with the understanding that the same techniques will apply to evaluating her sister's opinion. The disagreement between Sandy's husband and doctor centers around the idea of "disease". If obesity, depression, alcoholism, and the like are diseases, most people default to the doctor's point of view; if they are not diseases, they tend to agree with the husband.
The debate over such marginal conditions is in many ways a debate over whether or not they are "real" diseases. The usual surface level arguments trotted out in favor of or against the proposition are generally inconclusive, but this post will apply a host of techniques previously discussed on Less Wrong to illuminate the issue.
What is Disease?
In Disguised Queries , Eliezer demonstrates how a word refers to a cluster of objects related upon multiple axes. For example, in a company that sorts red smooth translucent cubes full of vanadium from blue furry opaque eggs full of palladium, you might invent the word "rube" to designate the red cubes, and another "blegg", to designate the blue eggs. Both words are useful because they "carve reality at the joints" - they refer to two completely separate classes of things which it's practically useful to k...