Then there are the dimensions of those vices. People often criticize Trump for “vulgarity,” but that makes it sound as if he merely uses the wrong fork or decorates gaudily. To insinuate that a rival candidate’s father was involved in assassinating a president, or to go after the candidate’s wife’s looks, or to attack a reporter for being disabled—and then lie about all of these offenses: These are novelties in a presidential race. So is a candidate’s having established a business that is credibly alleged to have been an essentially fraudulent enterprise preying on the vulnerable.

A voter should care about a candidate’s character for two reasons. The first relates to job performance. Would the candidate seek the common good and exercise mature judgment in office? No president hits those marks every time, but some people inspire more confidence than others.

The second concerns our culture. Trump’s success in the presidential race so far reflects a cultural rot: It would once have been impossible for someone like him to win the nomination. But it also deepens that rot. If we elevate a man we know to be cruel, impulsive, insecure, vain and dishonest to the most powerful position in our country, that choice helps to define our own character and shape our expectations for one another. It also means that our political debate will be dumber, nastier and more content-free.