Donald Trump has repeatedly emphasized the value of being “unpredictable,” and has established a pattern of firing off ill-conceived threats that do make him appear slightly unhinged. His apparent hope is that this sort of behavior will persuade both allies and adversaries will do his bidding, for fear that this irrational and impulsive man will fly off the handle and do something terrible. In other words, Trump appears to subscribe to the so-called madman theory of diplomacy.