Mr. Trump has put my doubts to rest.

What doubts, you ask?

Well, doubts about how he would accomplish the many things he has promised his fans and admirers he will do.

Like how he will make our country really, really, really Tony-the-Tiger great again.

Or how he will build the huge, expensive wall between us and Mexico, the one he insists Mexico will pay for, even though Mexico says, sorry, amigo.

And how he will defeat ISIS. I’d worried that in assuring us he would destroy the Islamic State without saying how, he was a little like Richard Nixon with his secret plan to end the Vietnam War.

Until this week, all we had to rely on was Mr. Trump’s assurances that he’s smarter than everyone else and can negotiate much, much better deals.

Why, silly as it now sounds, I’d even had the heretical thought that some of the Sunday show hosts might want to press him a little harder on the hows and not just take “believe me’’ for an answer. Though I know if they did, Mr. Trump probably wouldn’t call in to their programs anymore, so I guess, all things considered, it’s better to be polite.

Still, I was dubious.

But no longer.

Why? Because this week, it’s all become clear. When he needs to accomplish difficult tasks, Mr. Trump will simply morph into:

The Incredible Sulk.

After long keeping his superhero side a secret, Mr. Trump finally revealed that impressive alter ego this week, when confronted with an adversary more steely, menacing, and dangerous than any an American president has yet faced.

Megyn Kelly.

Mr. Trump knows she can’t trusted. And he’s on to her tactics.

First Megyn uses her beguiling beauty to lure people onto Fox News — and then, once they’re there, she fixes her mesmerizing stare upon them and subjects them to terrible attacks. Like, say, repeating some of the, um, observations someone has made about women. Things like his noting that this one or that is a “fat pig’’ or a “dog’’ or a “slob’’ or “disgusting.’’ Or his saying to another, “It must be a pretty picture, you dropping to your knees.’’

When you’re dealing with someone so unscrupulous that she’ll use your own words against you, there’s really no other recourse than to go into super sulk mode and declare you won’t be part of any debate if she is.

And look at the results! Not since Achilles moped in his tent rather than join the battle against the Trojans has a fit of self-pity so commanded public attention.

Further, if anyone has any doubt about the Churchillian power of the Trumpian will, they need only watch his Wednesday appearance on “The O’Reilly Factor.’’ His face frozen in a principled pout, Mr. Trump resolutely resisted all of Bill’s compliments, all his cajolery, all his coaxing that he rise above his Megyn-mangled feelings and do the Fox News debate for the sake of “the folks.’’

Why, I haven’t seen such high-minded resolve since Newtie shut down the government because Bill Clinton’s team made him exit the back door of Air Force One when they returned to Washington after Yitzhak Rabin’s funeral.

Just think about the power of a presidential pout as a tool of international diplomacy!

People will stop bad-mouthing America pretty darn quick, I’ll tell you that.

And if Kim Jong Un thinks his temperamental-teenager-with-an-atomic-bomb act will confound Mr. Trump, he’s got a thing or two to learn about world-class tantrums.

So after this week, can we all agree that the question of whether Mr. Trump has the right temperament to be president has now been definitively answered?

Scot Lehigh can be reached at lehigh@globe.com. Follow him on Twitter @GlobeScotLehigh.