Link: https://slatestarcodex.com/2019/12/04/symptom-condition-cause/

On my recent post on autism, several people chimed in to say that "autism" wasn't a unitary/homogenous category. It probably lumps together many different conditions with many different causes. It's useless to speculate on the characteristics of "autism" until it can be separated out further.

I get this every time I talk about a psychiatric condition. The proponents of this view seem to think they're speaking a shocking heresy that overturns the psychiatric establishment. But guys, we know this kind of stuff. Psychiatric diagnoses don't have to perfectly match underlying root causes to be useful.

Suppose a patient comes to you with difficulty breathing, excessive sweating, anxiety, and extreme discomfort when lying down flat. You recognize these as potential signs of pulmonary edema, ie fluid in the lungs. You do an x-ray, confirm the diagnosis, and prescribe symptomatic treatment – in this case, supplemental oxygen. All of this is good work.

But you can have fluid in your lungs for lots of different reasons. Most of the time it's heart failure, but sometimes it's kidney failure, pneumonia, drug overdose, smoke inhalation, or altitude sickness. Some of these causes will have slightly different symptoms, which an alert doctor can notice.