What is The Myth of Mental Illness: Foundations of a Theory of Personal Conduct about?

Thomas Szasz's thesis, first published in 1961, is that mental illness is a category error. Illness, properly understood, is a deviation from a biological norm — a lesion, an infection, a demonstrable structural or biochemical abnormality. Mental illness, by contrast, is defined by deviation from social, ethical, or legal norms. Because the two types of deviation are fundamentally different, calling the second type an "illness" imports medical authority into what is actually a moral and political judgment. Szasz does not deny that people suffer or behave strangely; he denies that their suffering is best understood as disease.

Szasz develops his argument through a close reading of the history of psychiatry, particularly Freudian theory. He argues that Freud's achievement was to create a systematic framework for understanding "problems in living" — difficulties with work, relationships, sexuality, and meaning — but that framing these problems as diseases subject to medical treatment was a category mistake with serious social consequences. Psychiatric diagnosis, he argues, is a tool for social control masquerading as medical science: it allows the state and families to coerce individuals under the neutral-seeming authority of medical necessity.

The book distinguishes between genuine brain diseases — epilepsy, syphilitic psychosis, organic deliria — which Szasz considers legitimate medical conditions, and functional psychiatric diagnoses — schizophrenia, hysteria, neurosis — which he treats as constructs that describe unwanted behavior rather than identifiable pathology. This distinction became both the most influential and most contested part of his argument: critics noted that the brain-behavior boundary is not as sharp as Szasz implied, and that later neuroscience has identified biological correlates for many conditions he classified as mythological.

Szasz was a practicing psychiatrist and a committed libertarian, and the book's ethical argument is as important as its medical one. He insists that individuals have the right to be treated as moral agents responsible for their conduct, rather than as patients whose agency is suspended by diagnosis. Involuntary commitment and compulsory treatment are, on his account, forms of imprisonment obscured by medical language. The Myth of Mental Illness remains a provocative, rigorous, and deeply uncomfortable challenge to psychiatric orthodoxy.