As it happens there is social science on this question, too, and it finds that conservatives are more alert to threats than liberals are. One 2012 study by researchers at the University of Nebraska, Lincoln, showed liberals and conservatives a collage of photographs, and conservatives lingered longer on dangerous or repulsive images — car crashes, excrement — than liberals did.

Which brings us to Orlando, Fla. Let’s acknowledge two plain and straightforward truths. One, Mr. Trump handled the situation shockingly, embarrassingly. From that tweet in which he accepted “congrats for being right on radical Islamic terrorism” to his big post-attack speech, which was somehow at once offensive and plodding, he made it about him. When he did try to sound vaguely like a leader, spooning out kind words for the L.G.B.T. community (which he of course cherishes), he sounded ridiculous, about as genuine as some of those Southern congressmen did expressing their solidarity with New Jerseyans after Hurricane Sandy before they voted against the emergency funding.

Two — and this is important — the Orlando tragedy wasn’t just a straightforward terrorist attack. It was also a hate crime, since it was directed at one community (or two — Latino and L.G.B.T.). According to a CBS News poll, 57 percent of Americans thought it was both, but among those who chose one or the other, more saw it as a hate crime (25 percent) than an act of terror (14 percent). That the act didn’t “read” to people as a strictly terrorist act may mean it didn’t fire the same set of synapses in most people that an attack that just killed Americans randomly might have. And the fact that Congress is preparing to take a couple of ritualistic gun-control votes nudges the psychic needle even further in the hate-crime direction.

But acknowledging those caveats, I want to advance a theory: Americans in 2016 may have a less reactive response to terrorism than they had 15 years ago. When 9/11 happened, it was so shocking and new; most people had simply thought that something like that could never happen in the United States. A decade and a half later, we have joined the world, the weary and beleaguered world, and learned that anything can happen anywhere, anytime.

We may also have figured out, or most of us may have, that the bluster and gasconade of the fear-mongers hasn’t really done us much good. George W. Bush said “bring ’em on”; and bring it on they did, pitching us into hell. Maybe after these last 15 years of war, a lot of Americans hear Mr. Trump’s rhetoric and plans and think, “That’s the last thing we need.”

It’s also the case that Hillary Clinton, by contrast, looked and sounded like a president ought to. The reputation for hawkishness that she spent her Senate years cultivating didn’t hurt, as backdrop. And while she may not have said anything terribly memorable, in a week such as the one past, maybe that’s the point: Just say the obvious and comforting things a president is supposed to say. Observing her comportment last week, one could easily picture her representing the nation at grave moments. The same could hardly be said of Mr. Trump.