Mr. Trump has been playing himself instinctually as a character since the 1980s; it’s allowed him to maintain a profile even through bankruptcies and humiliations. But it’s also why, on the rare occasions he’s had to publicly attempt a role contrary to his nature — calling for healing from a script after a mass shooting, for instance — he sounds as stagey and inauthentic as an unrehearsed amateur doing a sitcom cameo.

His character shorthand is “Donald Trump, Fighter Guy Who Wins.” Plop him in front of a camera with an infant orphaned in a mass murder, and he does not have it in his performer’s tool kit to do anything other than smile unnervingly and give a fat thumbs-up.

This is what was lost on commentators who kept hoping wanly that this State of the Union or that tragedy would be the moment he finally became “presidential.” It was lost on journalists who felt obligated to act as though every modulated speech from a teleprompter might, this time, be sincere.

The institution of the office is not changing Donald Trump, because he is already in the sway of another institution. He is governed not by the truisms of past politics but by the imperative of reality TV: Never de-escalate and never turn the volume down.

This conveniently echoes the mantra he learned from his early mentor, Roy Cohn: Always attack and never apologize. He serves up one “most shocking episode ever” after another, mining uglier pieces of his core each time: progressing from profanity about Haiti and Africa in private to publicly telling four minority American congresswomen, only one of whom was born outside the United States, to “go back” to the countries they came from.

The taunting. The insults. The dog whistles. The dog bullhorns. The “Lock her up” and “Send her back.” All of it follows reality-TV rules. Every season has to top the last. Every fight is necessary, be it against Ilhan Omar or Debra Messing. Every twist must be more shocking, every conflict more vicious, lest the red light grow bored and wink off. The only difference: Now there’s no Mark Burnett to impose retroactive logic on the chaos, only press secretaries, pundits and Mike Pence.

To ask whether any of this is “instinct” or “strategy” is a parlor game. If you think like a TV camera — if thinking in those reflexive microbursts of adrenaline and testosterone has served you your whole life — then the instinct is the strategy.

And to ask who the “real” Donald Trump is, is to ignore the obvious. You already know who Donald Trump is. All the evidence you need is right there on your screen. He’s half-man, half-TV, with a camera for an eye that is constantly focused on itself. The red light is pulsing, 24/7, and it does not appear to have an off switch.

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