Leading up to the 2016 presidential election, I repeatedly heard politicians, pundits and voters predict or at least express hope that, if elected, Donald Trump would “rise to the occasion” or “surround himself with good people.” It infuriated me. As a mental health practitioner, I knew this would not happen. More than his policy or populist rhetoric, it was Donald Trump’s instability I feared. Most disturbing to me was few people did.

People assume that psychiatric diagnosis is a subjective science open to interpretation, but this is far from the case. Human behavior operates on a continuum. In many cases (but certainly not all) it’s a matter of degree and frequency that separates abnormal from normal. When taking Abnormal Psychology in college, we were warned of psychiatry’s own version of “medical student syndrome.”

Perhaps this is why it’s easy to justify Trump’s deviances. It’s when you take into account the…