Donald Trump at CPAC2015 in February. (Jahi Chikwendiu/The Washington Post)

Tonight’s Republican presidential debate, starring Donald Trump, might be the most feverishly anticipated August political event since the one that took place 157 years ago in Ottawa, Ill.

The debate between Abraham Lincoln and Stephen A. Douglas, like the six others that followed in 1858, is remembered today for the seriousness of its subject — slavery — and the forensic skill with which these two candidates for Illinois’s U.S. Senate seat addressed it.

Yet the Lincoln-Douglas debates were also a traveling circus. Thousands of spectators, playing hooky from their monotonous farms, flocked to each small-town venue from the surrounding countryside. Bands played. Cannons boomed. The candidates literally led parades to the stage.

Cheers, applause and heckling repeatedly interrupted the candidates’ speeches, which were abundantly seasoned with humor and theatrical gesticulation.

In short, those dismayed by the fact that a casino-magnate-turned-reality-TV-star could sprint ahead of the GOP presidential field should remember that American political campaigns are, were and always have been entertainment. Not like entertainment. Entertainment.

This drives Europeans (and bien-pensant types on this side of the Atlantic) nuts, but it makes some sense given our history. Causal factors include not only the lack of alternative diversions in early America, but also an electoral system that encourages candidates to promote themselves as individuals, rather than fitting into a party list as in a European democracy.

Political scientist Seymour Martin Lipset, the great analyst of American exceptionalism, emphasized the United States’ greater religious enthusiasm compared with Europe — which, he argued, fosters a sense that “social and political dramas [are] morality plays,” or “battles between God and the Devil.” What could be more entertaining than that?

Wasn’t it just 12 years ago that Arnold Schwarzenegger got elected governor of California, promising to vanquish high taxes like he’d dispatched that jungle monster in “Predator”? Even sober, sensible Minnesota once put a pro wrestler (and “Predator” co-star!), Jesse Ventura, in the governor’s mansion.

There’s a downside, of course — but before getting to that, pause to consider the benefits, or, if you prefer, the functionality, of politics-as-entertainment. Simply put, the path to a voter’s brain leads through the gut, and the heart. If you want people to think, first you have to make them feel.

Shakespeare’s most profound insights would have gone to waste if his plays weren’t exciting, funny and moving. Similarly, lots of good ideas — civil rights, women’s suffrage, winning the Cold War — might have wound up on democracy’s cutting-room floor, if their advocates had bored everyone.

Now for the downside: Demagogy is entertaining, too. Furthermore, even if entertainment is at its most functional during campaign season, it’s less so when the time comes for actual governance. That’s the tedious part, especially in the United States, with its separation of powers, multiple veto points and all the other checks and balances that make it hard (intentionally so) to convert campaign promises into policy reality.

It’s a rare leader who’s as good at governance as he or she was on the hustings. However, the most successful American politicians — Ronald Reagan and Franklin D. Roosevelt come to mind — understand the distinctions and adjust to them.

Donald Trump seems unlikely to fit into their category, much less that of a Lincoln. To be sure, his business career has taught him to “play to people’s fantasies,” as he wrote in “The Art of the Deal.” “People may not always think big themselves, but they can still get very excited by those who do. That’s why a little hyperbole never hurts. People want to believe that something is the biggest and the greatest and the most spectacular.”

In the case of the perpetually out-of-sorts GOP “base,” what they want to believe is that Trump’s the guy who’s finally going to cut through all the BS in Washington, grab Mexico by the lapels and, while he’s at it, teach China a thing or two.

One wonders if so many of the GOP’s groundlings would still flock to Trump’s banner if they were aware of how consciously he is manipulating them, and their anger.

Then again, maybe, at some level, they understand that The Donald’s straight-shooter routine, like those of Schwarzenegger and Ventura, is basically just an act. They know it would end, as Arnold’s and Jesse’s did, in compromise and frustration if he’s elected — assuming he doesn’t flame out long before that.

He likely will flame out, too, partly because his message — “Down with everybody else,” basically — lacks enough positive notes to keep it interesting.

Meanwhile, though, his supporters are having too much fun watching Trump do his thing, while the media flip out and the GOP establishment squirms. It’s August; what else is on?

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