However, this seems to have been forgotten and the popular notion today, which is commended by psychiatrists, is that "mental illness" is "like any other illness". Szasz argues that this is a fundamental mistake even on the premise that "mental illness" is due to brain malfunction: "for those who regard mental symptoms as signs of brain disease, the concept of mental illness is unnecessary and misleading. If they mean that people so labelled suffer from diseases of the brain, it would seem better, for the sake of clarity, to say that and not something else."
Szasz does not believe that most types of so-called "mental illness" can be understood as brain malfunction and he points out that psychiatric diagnosis rarely takes place on that basis, in contrast to medical diagnosis: "we call people physically ill when their body-functioning violates certain anatomical and physiological norms; similarly, we call people mentally ill when their personal conduct violates certain ethical, political, and social norms".
Matters that the book deals with are (citing chapter headings): "Mental Health as Ideology", "What Psychiatry can and cannot do", "The Insanity Plea and the Insanity Verdict", "Involuntary Mental Hospitalisation", "Psychiatric Classification as a Strategy of personal constraint".
"When I assert that mental illness is a myth, I am not saying that personal unhappiness and socially deviant behaviour do not exist; what I am saying is that we categorise them as diseases at our own peril." This is Thomas Szasz's thesis, and this book gives clear, precise arguments for the author's case. It has none of the sloppy thinking or professional dogmatism that categorises so many books on such subjects, nor does Thomas Szasz ever take refuge in jargon. It is a book which will require a fair amount of thought, and will repay careful study.