As we celebrate Christmastime amid an unnecessary and indefinite government shutdown and the worst December for the stock market since 1931, I’m reminded once again of my long-standing prediction: The Trump presidency will end poorly because character is destiny.

I’ve said it so often, I occasionally need to be reminded that I didn’t coin the phrase.

The Greek philosopher Heraclitus did, when he observed “ethos anthropoi daimon,” most often translated as “man’s character is his fate.”

Character is one of those topics, like culture or morality, that everyone strongly supports yet also argues about. When James Q. Wilson, one of the greatest social scientists of the last half-century, turned his scholarly attention to character, many of his colleagues in academia were repulsed.

Even though every one of them surely believed in some notion of good character, it was assumed that to talk of it, let alone seek a definition of it or a plan for how to cultivate it, would be an exercise in lending aid and comfort to the moralizers of the right.

But Wilson had a more humble and universal definition than his colleagues might have expected: decency, politeness, self-restraint, commitment, honesty, cooperativeness and the ability to think of others’ well-being.

Weirdly, it’s gotten to the point that when I say President Trump is not a man of good character, I feel like I should preface it with a trigger warning for many of my fellow conservatives.

Most of the angry responses are rooted in the fact they do not wish to be reminded of this obvious truth.

But others seem to have convinced themselves that Trump is a man of good character, and they take personal offense at the insult, even though I usually offer it as little more than an observation.

This latter group rushes to rebut the claim, citing banal or debatable propositions: He loves his children! He’s “loyal to a fault!” He’s authentic!

Never mind that many bad men love their children, that loyalty to people or causes unworthy of loyalty is not admirable, and that authentic caddishness is not admirable. Never mind, too, that he is not remotely loyal, to his wives or the people who work for him.

What’s most worrisome is that these defenders are redefining good character in Trump’s image, and they end up modeling it.

Still others assume that I am referencing the president’s style, specifically his insults and Twitter addiction. They overlook that his insults are not merely an act, but rather the product of astonishing levels of narcissism, insecurity and intellectual incuriosity. His Twitter feed is simply a window into his id.

The president who became a celebrity by telling reality-show contestants “you’re fired” has not fired any of his Cabinet officials face-to-face, or even on the phone. He relies on others, or on Twitter, to deliver the news. He loves controversy because it keeps him in the center ring, but he hates confrontation.

The driving force behind nearly all of the controversies that have bedeviled his administration is his personality, not his ideology.

To be sure, ideology plays a role. It amplifies the anger from both his left-wing critics and his transactional defenders. Many of the liberal critics shrieking about the betrayal of the Kurds implicit in his decision to withdraw from Syria would be applauding if a President Clinton had made the same decision. And many of the conservatives celebrating the move would be condemning it.

But his refusal to listen to advisors; his inability to bite his tongue; his demonization and belittling of senators who vote for his agenda; his rants against the 1st Amendment; his praise for dictators and insults for allies; his need to create new controversies to eclipse old ones; and his inexhaustible capacity to lie and fabricate history: All this springs from his nature.

Over the weekend, former New Jersey Gov. Chris Christie offered an odd defense of the president. He’s like a “72-year-old relative,” Christie said on ABC’s “This Week.” “When people get older, they become more and more convinced of the fact that what they’re doing is the right thing.”

Christie has a point. But the reason Trump won’t change has little to do with age and everything to do with character.