Like much of what Mr. Trump says, his statement could be dismissed as an offhand remark, thrown out in the heat of a contentious exchange with reporters. The president, after all, declared a day earlier that “racism is evil” — that the Ku Klux Klan, neo-Nazis and white supremacists “are repugnant to everything we hold dear as Americans.”

Yet Mr. Trump’s refusal Tuesday to pass an explicit moral judgment on the violence in Charlottesville seemed a genuine reflection of his beliefs. Certainly, it is similar to his refusal to condemn the tactics of autocrats like President Rodrigo Duterte of the Philippines or President Vladimir V. Putin of Russia.

“There are a lot of killers,” Mr. Trump said to Bill O’Reilly on Fox News early this year when he was asked about his reluctance to condemn the Russian leader. “You think our country’s so innocent?”

In fact, Mr. Trump’s predecessors, going back to George Washington, have all tried, with varying degrees of success, to summon Americans to a higher moral purpose.

Abraham Lincoln, in his second inaugural address, called on Americans, bitter after years of civil war, to bind up their wounds “with malice toward none; with charity for all; with firmness in the right.”