As Marcia Angell, former editor of The New England Journal of Medicine, observed last year in The New York Review of Books, “there are no objective signs or tests for mental illness…and the boundaries between normal and abnormal are often unclear. That makes it possible to expand diagnostic boundaries or even create new diagnoses in ways that would be impossible, say, in a field like cardiology.” In other words, mental illnesses are whatever psychiatrists say they are, writes Jacob Sullum.

How “scientific” is that? Not very.