He may, however, be making a mistake a lot of aspiring politicians do: overestimating how many supporters he has.

Over the years I have met many no-chance presidential candidates who say similar things: People are always urging them to run. One of those candidates said he had taken a trip to a small town in Alaska and been greeted at the port by people with signs telling him to run. I don’t think these stories are made up.

But it is a very big country, and the people who come up to these politicians are a tiny self-selected sample. Ten people could tell him to run every day for the next year, and they would add up to 0.003 percent of the country’s voters. But even if the rational brain of a man being so flattered can grasp the point, the emotional brain might not.