Donald Trump both disbelieves and believes in falsehoods, so that when he did thrive on his longstanding - the claim that Obama was not born in the United States - he's crazy like a fox in manipulating it because it gave him his political entrée onto the national stage. In order to make your falsehoods powerful, you have to believe in them in some extent. And that's why we simplify things if we say that Trump either believes nothing in his falsehoods and is just manipulating us like a fox or he completely believes them.

Trump has a mind that in many ways is always under duress, because he's always seeking to be accepted, loved. He sees himself as constantly victimized by others and by the society, from which he sees himself as fighting back. So there's always an intensity to his destructive behavior that could contribute to his false beliefs.

The language of the totalist environment is characterized by the thought-terminating cliché. The most far-reaching and complex of human problems are compressed into brief, highly reductive, definitive-sounding phrases, easily memorized and easily expressed. These become the start and finish of any ideological analysis.

People with what we call mental illness can indeed serve well, and people who have no discernible mental illness - and that may be true of Trump - may not be able to serve, may be quite unfit. So it isn't always the question of a psychiatric diagnosis. It's really a question of what psychological and other traits render one unfit or dangerous.

One reason that I embarked on a study of Nazi doctors was that in this personal journey, I had the feeling increasingly that I did want to do a Holocaust study and that increasingly I wanted it to be of perpetrators, which I thought was more needed.

With the nuclear threat we know that if sufficient weapons are used, human civilization - all of humankind - could be extinguished literally by "nuclear winter." So we have to see ourselves as part of the ultimate human group, just as we have to do with global warming.

For anyone with the traits - of feeling himself victimized, of seeking to be the strongman who resolves everything, yet sees truth only through his own self and negates all other truth outside of it - is bound to become more malignant when he has power. Power then breeds an intensification of all this because the power can never be absolute power - to some extent it's stymied - but the isolation while in power becomes even more dangerous. Think of it as a vicious circle. The power intensifies these tendencies and the tendencies become more dangerous because of the power.