Television has always sought to create the illusion of intimacy. But at Monday night’s up-close-and-uncomfortably-personal debate between Hillary Clinton and Donald Trump, it will be no illusion.

After months of the candidates lambasting each other from afar in stump speeches, commercials, and tweets, the distance between Clinton and Trump will abruptly narrow to the width of a debate stage at Hofstra University on Long Island as they approach the decisive phase of an exceptionally vicious campaign.

TV viewers — perhaps more than 100 million of them, according to some estimates — could well be treated, or subjected, to a display of interpersonal dynamics more tense and flat-out weird than any in the history of televised presidential debates. Richard Nixon’s sweaty countenance when he faced off against John F. Kennedy in 1960, the sight of George H.W. Bush impatiently checking his watch during a 1992 debate with Bill Clinton and Ross Perot, or Al Gore’s elaborate sighs in 2000 as he listened to George W. Bush answer questions, will be nothing compared with this charged encounter between Trump and Clinton, who just a decade ago sat in the front row at Trump’s third wedding.

For television itself, Monday’s debate could represent a rare convergence of two contrasting strands of the medium’s identity: the putatively high-minded side that congratulates itself for making room on prime time for political forums, and the spectacle-driven side that would like nothing better than a good wallow in the mud consisting of equal parts “Survivor’’-style endurance test, soap-opera histrionics, and Jerry Springer-esque confrontation.

And us? As we settle in front of our televisions, we’ll engage in the intellectual equivalent of split-screen viewing, absorbing the answers Clinton and Trump give to policy questions while also keeping a close eye on their behavior and the general vibe. How excruciatingly awkward will their ritual handshake be? What is revealed by their body language during the debate? How many times do the candidates snort, sneer, or roll their eyes? Can we really rule out the possibility of a Bronx cheer?

Potential scenarios are endless, because seldom have two nominees genuinely despised each other as much as Trump and Clinton seem to, and never has a candidate been as willing to buck campaign norms as Trump has.

Hard feelings invariably emerge as campaigns drag on, but the antagonism between these two registers as visceral, almost primal, born of mutual contempt. The styles of the flamboyant real estate mogul and the cautious former secretary of state who is the first woman nominee of a major political party could not be more dissimilar. Their contest is like a real-life version of Showtime’s “Billions,’’ in which a rule-flouting hedge-fund manager is pursued and confronted by a relentless US attorney who is determined to bring him down.

Just as Trump has upended long-held assumptions about what’s permissible in behavioral and policy terms during a presidential campaign, so, too, is the Republican nominee poised to topple planted assumptions about presidential debates.

Ad hominem attacks were a Trumpian trademark long before he entered politics, and he has indulged that trait even more as a presidential candidate. During the GOP primary campaign he crossed all previously recognized lines of decorum in his attacks on his primary rivals (“Little Marco,’’ “Lyin’ Ted,’’ etc.). Then he turned his vitriol on the woman he calls “Crooked Hillary,’’ even going so far as to publicly muse about scenarios involving violence against her. For her part, Clinton has made no secret of her scorn for Trump, this week saying that his statements about Muslims make him tantamount to a “recruiting sergeant for the terrorists.’’

There is an element of unpredictability and suspense hanging over Monday night that is usually the province of sporting events. Trump has proven willing to say virtually anything. The ultra-disciplined Clinton will probably try to stay on the high ground and project an “I’m the adult here’’ demeanor, but it could be that Trump’s personality represents a challenge for which no amount of debate prep is adequate.

The nation will watch it all play out in real time, perhaps while pondering how far we’ve come since the first televised presidential debate in US history, JFK-Nixon in 1960. That showdown coincided with television’s coming of age, and JFK’s mastery of the medium, combined with Nixon’s lack of same, proved decisive.

Ever since then, TV debates have offered a chance for candidates to revise or polish their images before voters cast their ballots. Conducted within explicitly or implicitly agreed-upon boundaries, with the candidates often relying on talking points they honed on the campaign, the debates have usually possessed a formal, even semi-scripted quality.

Consequently, the defining moments have tended to be moments of spontaneity, principally gaffes like Gerald Ford’s premature liberation of Eastern Europe in 1976 or Admiral James Stockdale’s “Who am I? Why am I here?’’ soliloquy in the 1992 vice presidential debate. Indeed, gaffe-watching has been the favorite spectator sport when these debates are televised.

But does the traditional idea of a “gaffe’’ really apply to Trump? What can he say Monday night that is more incendiary that what he has already said over the past 15 months? This could be the rare spectacle of a candidate who has, in effect, gaffe-proofed himself. Those of us watching at home Monday night may have to revise our usual debate scorecards.

Don Aucoin can be reached at aucoin@globe.com.