Donald Trump seems to have forgotten the saw that those who live in glass houses should never throw stones.

The thrice-married, privileged scion and businessman, whose bankruptcies and ill-gotten gains from short-changing contractors and business partners, should be the last person to accuse Hillary Clinton of being “crooked.” Trump is, as U.S. Supreme Court Justice Ruth Bader Ginsburg put it, “ a faker.” If the man had one genuine bone in his overstuffed body, I doubt his current wife would be pilfering words from a Michelle Obama speech. She the foreign-born trophy wife who follows the Donald’s lead.

More remarkable, a philosophically bankrupt Republican Party, though embarrassed by his and her antics, seems not to care about the fraud the Trumps are guilty of perpetrating. For the GOP, all that glitters is accepted as gold. “ Trust me,” Trump intones, and the sheep blindly follow the New York phony populist. And remember, the last time Americans elected a Republican businessman as president, he got us into two wars and the worst economic mess since the Great Depression. When George W. Bush left office after two seemingly interminable terms, his public approval rating was in the low 20s.

Bush at least tried to govern. True, he was frequently intimidated by his vice president, the snarling lip from Wyoming — and also a businessman, as in Haliburton. But W declared himself “the decider” and occasionally acted the role he assigned himself. Trump, on the other hand, has not denied reports that he intends to serve as the chair of the board and let his vice president, the gay-bashing Christian conservative from Indiana, serve as chief executive officer, that is, actually run the “company.”

If so, this move, no doubt approved by Russian president and autocrat Vladimir Putin, at least shows that Trump knows himself well enough to understand that he has no idea how government works. Let Mike Pence take the blame for economic and security policies that, if enacted, could bankrupt America. Trump would remain above it all because he has no idea what “all” means.

Frightening enough, but as worrisome is Trump’s “fortress America.” Despite his international experience — building a golf course in Scotland and overseeing Miss Universe pageants — Trump boasts an “America First” program that relegates alliances, treaties and immigration to disposable policies that he feels entitled to ignore, modify, or scuttle. NATO, the European Union, free-trade pacts all can be cherry-picked, according to Trump, based on his isolationist attitude of “what have you done for us recently?”

The Republican-leaning Wall Street Journal editorialized July 22 that “Mr. Trump’s comments this week casting doubt on the U.S. commitment to NATO suggests he thinks allies can be bullied like real-estate lenders.” And the WSJ adds, “Mr. Trump knows remarkably little about most policy questions, and he does not sweat the details. That means he’d be more dependent on his advisors than most Presidents, if he’s willing to listen to them.”

If there ever was a time in recent history when America needed an informed, skilled and practiced internationalist in the White House, this is it. The art of the deal in these perilous times requires not a bully but a skilled diplomat who understands that global leadership is, alas, America’s burden of responsibility. Retreating behind literal and metaphoric walls runs the very great risk of ceding greater power to North Korea, Iran, Islamic State and Russia.

“Boil Mr. Trump’s platform down to its essence,” Lexington writes in The Economist, “and he is offering to shield his angry, unhappy supporters from global competition, whether by beating it back with protectionism, trade wars, and a fortified border, or by an ‘America First’ foreign policy that would hand in America’s badge as a global policeman.”

Like it or not, America’s status as the leader of the free world bears costs, as well as benefits. Trump does not understand this simple reality and, therefore, is unfit to serve as our president.

Roger Bowen of Prospect Harbor is president emeritus of the State University of New York at New Paltz.