Bill Moyers interviewed Robert Jay Lifton last week on the concerns expressed about the current president by a number of mental health professionals.

The central point is that a psychiatrist has a “duty to warn” when they perceive a risk of harm, but this duty is balanced by the Goldwater Rule, which warns against diagnosis outside of a clinical setting.

Dr. Lifton has written the foreword to The Dangerous Case of Donald Trump, a collection of essays by psychiatrists assessing the mental health of Donald Trump. It will be published October 3 by St. Martin’s Press.