Mr Trump is also wilfully divisive.
All politicians attack their opponents, but presidents see it as their duty to unite the country after a tragedy.
Only Mr Trump would think the Tree of Life synagogue shooting a chance to hit back at the media and the Democrats for criticising him.
Only he would suggest that, rather than tone down his explosive rhetoric, he might just “tone it up”.
Such divisiveness matters because, when your opponents are simply bad people, the compromise that is the foundation of all healthy politics becomes hard within parties and almost impossible between them.
Mr Trump is not the only politician to wallow in division—just the most powerful and one of the most accomplished.
Before he was elected, more than half of Democrats told pollsters that they were afraid of Republicans and almost half of Republicans said the same about Democrats.
After a Republican congressman was shot by an unstable gunman last summer, leading Democrats expressed “outrage” at the idea that their rhetoric had played any part.
Yet they used the attempted bombings and the synagogue shooting to begin a debate about the precise degree of presidential responsibility for domestic terrorism.
America’s democracy is robust—it was designed to be.
However, one by one, its institutions are being infected with toxic polarisation.
Congress caught the bug in the 1990s, when Newt Gingrich was Speaker.
The media have also fallen victim to partisan scepticism—certainly among audiences, if not also among contributors.
Just 11% of strong Trump supporters believe the mainstream media, whereas 91% of them trust Mr Trump, a CBS News poll found in the summer.
Among Democrats those beliefs tend to be reversed.
Now the Supreme Court is perceived to be partisan, too.
Democrats see the recent confirmation of Brett Kavanaugh to the court as the ramming through of a partisan who has lied, possibly about a sexual assault, and who will be incapable of putting the law above his party.
Republicans, by contrast, see it as a triumph over a monstrous Democratic conspiracy to keep a decent man down.
A dishonest executive, conniving with a fawning legislature and empowered by a partisan judiciary: were it to come to that, America truly would be in grave trouble.