Our president has descended to the level of ridiculing Senator Bob Corker for his five-foot-seven height.  You might think he is demeaning the presidency with behavior like this. Or you might, along with some of his advisers, be concerned that he is “further fracturing his relationship with congressional Republicans just a week before a vote critical to his tax cutting plan.” But if you think he is behaving stupidly, you ought to reconsider your position.
“Stupid” is a word that gets thrown around too much. We often use it for things that aren’t stupid exactly, but are things we disagree with, or even things we don’t understand. So we often say that a political figure has said something “stupid” as a way of strongly registering our disapproval. And we might say that a politician is going about the business of improving the economy in a “stupid” manner, although, unknown to us, his aim is not to improve the economy at all.
But how could making fun of Senator Corker’s height not be a stupid thing for President Trump to do? Even if he is not worried about demeaning the office he holds, he does need Congress to enact any legislation he desires, and it doesn’t seem wise to alienate its members in an ongoing argument that loses substance as it progresses.
This is confusing only so long as we think that Donald Trump has any objective in mind beyond being the president. But he does not. Ideologically and philosophically he is an empty suit. When he considers what ideas to adopt, he considers only two things: what will benefit him personally, and what will get him elected.
Thus, even though he was notably vocal about repealing the Affordable Care Act, he came up with nothing substantial himself in the way of a replacement. Congress, having gotten used to major initiatives of that kind coming from the White House, proved to have atrophied initiative muscles, and was unable to come up with a replacement that wasn’t palpably worse.
Substance, of course, isn’t Mr. Trump’s bailiwick. He is a salesman. He is very, very good at it. He is a serial philanderer who sold himself as the Evangelical candidate. He is a one-percenter, calling for “supply-side” tax cuts, who sold himself as a champion of the working class. He is a draft evader who sold himself as a patriot who would “make America great again.” And like all good salesmen, he knows that, above all, he has to sell himself.
He sells himself largely by knowing what will attract attention to himself. Allowing himself to be a curiosity, he manipulated the news media into giving him a good deal of free advertising during the primaries. He did this because he knows what attracts media attention. It is not a set of great ideas that attracts that attention, but those things that will enhance ratings and advertising revenue. A detailed and scholarly analysis on how to improve the economy or improve foreign relations won’t do that. Calling your political opponents names like “Crooked Hillary,” “Pocahontas,” “Crazy Bernie,” “Little Marco,” “Lyin’ Ted,” “Low Energy Jeb,” or “or Cryin’ Chuck” will do that. 
In behaving this way, he shocks the pundits, but only confirms what most Americans, with no small justification, already think about the political class. The pundits are outraged, but that very outrage garners media attention. Meanwhile he gives voice to the frustrations deeply held by a large segment of the populace.
There are risks to this strategy, of course. One thinks that, at some point, he will have to deliver with some substantial improvements. But he doesn’t seem overly concerned about that. During the campaign he said that his health plan would cover everyone. “I am going to take care of everybody,” he said. “I don’t care if it costs me votes or not. Everybody’s going to be taken care of much better than they’re taken care of now.”  Not only that, but he said that “the government’s gonna pay for it.” But once he was president he got behind GOP plans that would have resulted in millions fewer being covered.  He apparently felt that he would later be able to sell himself around the inconsistency. Perhaps he was right. He is a genius at media manipulation.
There are areas, however, where his aptitude will be of little use. He is trying the same strategy in his dealings with North Korea, even going so far as to deride Kim Jong Un with the epithet “Rocket Man” on the floor of the United Nations.  But the North Korean dictator’s position of power doesn’t depend on the American electorate, and a miscalculation here could have consequences more dire than lost votes.
If Secretary of State Rex Tillerson really called Trump a “moron,”  he was mistaken. Mr. Trump’s political opponents should not make the same error, or they are likely to see the same electoral results in 2020.