A central assumption behind psychiatric diagnoses is that a disease has an objective existence in the world, whether discovered or not, and exists independently of the gaze of psychiatrists or anyone else. In other words, neolithic people had post-traumatic stress disorder as have people in all epochs since. However, the story of post-traumatic stress disorder is a telling example of the role of society and politics in the process of invention rather than discovery.

The diagnosis is a legacy of the American war in Vietnam and is a product of the post-war fortunes of the conscripted men who served there. They came home to find that they were being blamed for the war. Epithets like “babykiller” and “psychopath” were thrown at them by some who had watched on television the US military's atrocities against defenceless peasants. This reception was a primary factor in the well publicised difficulties—such as antisocial behaviour—that some military personnel had in readjusting to their peacetime roles. Those who were seen by psychiatrists were diagnosed as having an anxiety state, depression, substance misuse, personality disorder, or schizophrenia; these diagnoses were later supplanted by post-traumatic stress disorder.

Early proponents of the diagnosis of post-traumatic stress disorder were part of the antiwar movement in the United States; they were angry that military psychiatry was being used to serve the interests of the military rather than those of the soldier-patients. The proponents lobbied hard for veterans to receive specialised medical care under the new diagnosis, which became the successor to the older diagnoses of battle fatigue and war neurosis. The new diagnosis was meant to shift the focus of attention from the details of a soldier's background and psyche to the fundamentally traumatogenic nature of war. This was a powerful and essentially political transformation: Vietnam veterans were to be seen …