For Trump, the showman, the exercise will actually be quite easy. He will be the cool version of himself – the one we saw standing with Mexico's president Enrique Peña Nieto last month – speaking in moderate tones, sounding almost diplomatic. He will most certainly not display the hot version of his character – the one we saw in Phoenix later that same day as he railed about immigration.

Clinton, too, will keep it cool. This is not her first rodeo, and she's not likely to be thrown by Trump's bull. Her strategy will be to promote her vast knowledge of facts, while politely noting at every opportunity that Trump is careless, if not downright deceptive, in his handling of the same.

Never have finalists in a presidential election been so different, which is why this debate looms so large. But it is the very nature of those differences that will make the outcome frustratingly vague.

They differ in style and character and in background and experience. They each have resumes with heavy baggage. Nothing in a debate will change that, nor is it likely to sway most voters.

In the simplistic debate format actual issues will be boiled down to generalities that will make Trump and Clinton seem surprisingly alike, even though they are not. ISIS? Bad. Jobs? Need more. Taxes? Let's reform. Infrastructure? (That's a favorite.) Gotta fix it!

If policy questions require more detail, the go-to answer is: "On my website I have outlined a 10-point plan to deal with (fill in blank). It's all there."

And what about the moderator, Lester Holt of NBC News? Will he be able to make something meaningful out of this? No.

Holt, a mild-mannered veteran journalist, is not known as a combative interviewer. And now, after weeks in which both campaigns have issued warnings about how he must strive for fairness, he's likely to play it straight, maybe too straight.

You'll know where this is headed with the very first question. If Holt goes for the headlines – "Mr. Trump, your companies have filed numerous times for bankruptcy..." or, "Secretary Clinton, your handling of emails has caused many voters to question..." – then we're headed for a brawl with little meaning.

If, on the other hand, Holt goes for substance – "Let's begin by having each of you state the three concrete steps you would take to deal with ISIS" – then we're on a better track, but one that will devolve into stump dialogue, with little chance of affecting voters' thinking.

Following the debate, you'll hear numerous cable-TV pundits declare that, "Both candidates scored some points, but only enough to reinforce their base."

You'll read that the debate had the largest audience ever, out scoring "Monday Night Football."

You'll watch as Hillary Clinton tells Rachel Maddow, "I believe we got our message across and, come November, it will be up to the voters to decide."

And you'll listen as Donald Trump tells Sean Hannity, "I won!"

(c) Peter Funt. Distributed by Cagle syndicate.