When psychiatrist Marco Ramos of Yale University prescribes antidepressants to patients in distress and they ask him how they work, Ramos admits: We don't really know. And too often, they don't work at all. Despite decades of brain research and billions of dollars spent, psychiatry has made little progress in understanding mental illness. Listen as Ramos explains to EconTalk's Russ Roberts how the myth of the biological basis for mental illness began, why it stubbornly persists, and why honesty about what we know and don't know is the best policy.