We have a linear idea of medical progress. Each year medical science makes a new discovery. Each year we develop a new treatment. Each year we improve. And by and large that’s true. But not always. Progress can not only be slow, it can sometimes be halted or even reversed for a while if the medical establishment commits itself to a course that turns out to be mistaken. And in one field in particular, psychiatry, where it is the mind that seems to be ill, the terrain is littered with failed treatments, professional disputes, unresolved controversies and — above all — a lack of confidence in diagnosing disease.

The world of postwar American psychiatry is the backdrop for Susannah Cahalan’s The Great Pretender. Cahalan,