Perhaps the laws of political gravity are about to take hold in the case of Donald Trump. But the lesson of this appalling primary season cautions against discounting Trump’s appeal — which prompts another Trump column, this one on the utter incoherence of his policy views.

It’s not simply that Trump is wrong on policy. Ted Cruz is wrong on policy. Trump is wrong on policy and argues for policy positions glaringly inconsistent with his asserted principles. All politicians do this, sure. But Trump’s incoherence is classically Trumpian — huge, glitzy, unembarrassed.

That phenomenon was on vivid display last week, as world leaders gathered for a summit on nuclear nonproliferation. On this topic, Trump stands, or says he does, with the global consensus. He raised the issue in his discussion with The Post’s editorial board, in response to a question about whether he believes in man-made climate change.

“The biggest risk to the world, to me . . . is nuclear weapons,” Trump said. “That is a disaster, and we don’t even know where the nuclear weapons are right now. . . . The biggest risk for this world and this country is nuclear weapons, the power of nuclear weapons.”

Okay, and — leaving aside the strange suggestion that authorities don’t know where the nukes are — give Trump credit for emphasizing the nuclear risk.

The GOP presidential candidates talked about the charges against Donald Trump's campaign manager, Muslims in the U.S. and more, and backed away from past pledges to support whomever becomes the nominee during the CNN town hall on March 29. (Jenny Starrs/The Washington Post)

Except, jump ahead a few days, to Trump’s interview with the New York Times and his CNN town hall. Given Trump’s argument that the United States should withdraw military protections from Japan and South Korea, the Times’s David E. Sanger and Maggie Haberman asked: Should those countries be able to obtain their own nuclear weapons?

Trump’s answer managed to combine his concerns about proliferation with opening the door to more. “There’ll be a point at which we’re just not going to be able to do it anymore,” he said. “Now, does that mean nuclear? It could mean nuclear. It’s a very scary nuclear world. . . . At the same time, you know, we’re a country that doesn’t have money.”

So the United States can’t afford a nuclear deterrent? The cost of maintaining and modernizing the U.S. nuclear arsenal was $24 billion in 2015, and is expected to total about $350 billion over the next decade, according to the Congressional Budget Office.

The cost of Trump’s proposed tax cuts is around $1 trillion — annually. I’m no billionaire, but that doesn’t seem like a smart balance of spending priorities.

CNN’s Anderson Cooper pushed Trump further on the conflict between his anti-proliferation stance and his willingness to allow more proliferation — during which Trump opened the door to a nuclear Saudi Arabia, closed it, and then cracked it open again.

Cooper: “So you have no problem with Japan and South Korea having . . . nuclear weapons.”

Trump: “At some point we have to say, you know what, we’re better off if Japan protects itself against this maniac in North Korea, we’re better off, frankly, if South Korea is going to start to protect itself . . .”

Cooper: “So if you said, Japan, yes, it’s fine, you get nuclear weapons, South Korea, you as well, and Saudi Arabia says we want them, too?”

Trump: “Can I be honest with you? It’s going to happen, anyway. . . . It’s only a question of time.”

This is a radical position, even contained to South Korea and Japan. “That would be an incredible catastrophe,” said Kingston Reif of the Arms Control Association. “We have a big enough problem with stability in that region without introducing two new nuclear weapons states.”

The cornerstone of U.S. nuclear policy for decades has been to prevent additional countries from acquiring nuclear capability. The more countries with nuclear weapons, the greater the risk of use, and of technology and material falling into the wrong hands. China would likely respond by increasing its nuclear arsenal. Other countries would lobby to go nuclear. U.S. influence in the region — on trade rules that Trump cares about, for example — would wane.

“No contender for the presidency of the United States in either party has ever said that since nuclear weapons were invented,” Michael Green of the Center for Strategic and International Studies, who served on the National Security Council under George W. Bush and advised the Jeb Bush campaign, said of Trump’s view. “It would cost us enormously . . . in terms of the steps we’d have to take to defend ourselves against a much more weaponized world.”

There are other examples of Trumpian incoherence, but perhaps none so striking, and so dangerous if taken seriously.

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