In 2006, soon after returning from military service in Ramadi, Iraq, during the bloodiest period of the war, Captain Matt Stevens of the Vermont National Guard began to have a problem with PTSD, or post-traumatic stress disorder. Stevens's problem was not that he had PTSD. It was that he began to have doubts about PTSD: the condition was real enough, but as a diagnosis he saw it being wildly, even dangerously, overextended.