As Mr. Carter became the national scapegoat, the qualities that once made him the antidote to Richard Nixon — his piety, simplicity, openness, gentleness — could now be coded as impotence. By July 1980, thanks to his perceived mishandling of the crisis, his disapproval rating hit 77 percent, higher than Nixon’s worst, in part because “Carter did not project the image of being a ‘real man,’ ” as the political scientist John M. Orman argued in “Comparing Presidential Behavior: Carter, Reagan, and the Macho Presidential Style.” Picking up on the nastier implications, various right-wingers over the years have derided Mr. Carter as “the first female president.” Even Mr. Carter himself has admitted, ruefully, “I could’ve been re-elected if I’d taken military action against Iran, shown that I was strong and resolute and, um, manly and so forth.”

Mr. Trump, I contend, carries Mr. Carter with him everywhere, as a kind of anti-self. If Mr. Carter was deliberative, Mr. Trump must be reactive; where Mr. Carter was essentially sermonic, a devotee of Reinhold Niebuhr, the great theologian of human limits, Mr. Trump is comedic-demagogic, a fan of Norman Vincent Peale, the pop-evangelist behind “positive thinking.” In picking the most extreme, unlawful, norm-violating option, and killing General Suleimani, Mr. Trump was acting according to one of his political life’s clearly discernible logics: to be the antithesis of “the first female president.”

Mr. Trump has set his life so firmly against moral development, it makes sense that he remains fixed in the past. It makes sense, too, given his personal history, that he remains fixed exactly here, in the transition from 1979 to, say, 1983 — from a weak, feminized and, in the end, reviled Jimmy Carter, to a can-do, decisive and ultimately triumphant Ronald Reagan. (This is a cartoon; but Mr. Trump thinks in cartoons.) It was this transition that helped turn “Trump into Trump” — from a comparatively minor fish in the Manhattan real estate pond into the world’s greatest popinjay.

Mr. Trump, of course, may be so impulsive as to lack a coherent self. But what reason there is to his actions as president comes, it seems to me, from his commitment to live as the anti-Carter. To enhance the theory’s traction, it will help to look at an even more specific turning point.

Mr. Carter’s so-called “malaise” speech is famously remembered as a lay sermon that fell flat, but it was a crafted performance meant to address, overtly and covertly, three political questions. First, what to do with the plurality of voters who had lost faith in American government? An alarming number of these “long-term pessimists,” as one adviser labeled them, had gravitated in the ’68 and ’72 presidential elections to George Wallace, an avowedly racist candidate. Mr. Carter’s solution, from the ’76 primaries on, was to position himself as the perpetual outsider. By running against the Washington establishment, he could appeal to cynicism while avoiding racial demagogy. True to form, Mr. Carter began his speech that night by deriding the “isolated world of Washington.”