In January, when The New York Times asked Donald Trump whether there were any limits on his global powers, he replied, “Yeah, there is one thing. My own morality. My own mind.” Since whatever morality he ever possessed has long since departed, the remaining question is whether he has also lost his mind. Given that, in the course of his war on Iran, he has chosen to present himself to the world as a genocidal maniac—posting on Truth Social that “a whole civilization will die tonight, never to be brought back again. I don’t want that to happen, but it probably will”—the answer may seem all too obvious.

Yet to arrive at it we have to tease out the relationships that are always at the heart of his persona: the complex connections between performance and reality, method and madness, bombast and bombs. With Trump, these oppositions are never absolute. The borders between them are always porous.…