Final answer:
Thomas Szasz controversially argued that mental illness is a myth and that behaviors diagnosed as insanity are merely differences that do not conform to societal norms. His position challenges the medical model of mental health represented by the DSM, although psychiatry has evolved to recognize serious mental illnesses which have substantial impacts on lives.
Step-by-step explanation:
Thomas Szasz is renowned for his controversial assertion that mental illness is a myth, suggesting that what is often diagnosed as insanity is merely a set of behaviors that deviate from societal norms and bother other people. This stance is encapsulated in Szasz's work, "The Myth of Mental Illness: Foundations of a Theory of Personal Conduct", where he posits that many behaviors classified as mental illnesses are in fact just differences not conforming to the expectations of society. Szasz's view challenges the conventional medical model of psychiatric disorders, which is typified by the Diagnostic and Statistical Manual of Mental Disorders (DSM), an authoritative text that outlines the symptoms and classifications of mental disorders utilized by the American Psychiatric Association.
In the historical context, certain behaviors and orientations, such as homosexuality, which were once pathologized and classified as mental illnesses, have been reevaluated as natural variations of human behavior. This exemplifies the societal and medical shift from pathologizing to normalizing certain behaviors, reflecting Szasz's critique about the subjectivity in labeling deviance and mental illness. However, it's important to recognize that the field of psychiatry has significantly evolved, and today, mental illnesses like schizophrenia, depression, and anxiety are widely recognized as serious nervous system disorders that affect millions and have considerable impact on daily life.