We like to pretend that presidents exert vast control over the country, commanding not only the direction of American politics but also the laws and policies of the country and even the state of the economy.

When presidents fail to control events to our liking, critics often suggest that the problem is the chief executive’s failure to try hard enough or act tough enough. I’ve called this pattern the Green Lantern theory of the presidency after the comic book superheroes who wield special rings with powers that are limited only by the hero’s willpower.

Mr. Trump is the purest Green Lantern candidate we’ve seen in recent years. He cleverly exploits the appeal of presidential omnipotence by contrasting his supposedly decisive style of business leadership as a real estate magnate with the compromises, inertia and policy failures that are inevitable in politics.