with me now is the chairman of psychiatry, and the author of shrinks, the untold story of psych itry. first of all, do you believe the ongoing rash of gun violence is a mental health issue. >> in part it is, but not entirely. if you tack about violent crime in the united states, about 4% of the violent crimes are committed by people who commit mental illnesses. if you talk about the massacres, the proportion of those, and untreated mental illness goes up to 20%. so if people don't get treatment. they are prone to do the kind of unfathomable act of violence to a greater degree, and this is what attracts the public and media's attention. >> what about p.t.s.d., soldiers diagnosed with post-traumatic stress disorder, should they be able to get a gun. >> it depends what your criterion is. first of all, i think the issue trying to be addressed by the senator's bill, and the issue of gun control is really very limited. it's trying to - it's trying to chase the horses after they left the barn, instead of closing the door. >> you think it will not work. >> it will be a step in the right direc