Guggenheim Museum curator Nancy Spector probably thought she was being pretty clever.

The White House’s Office of the Curator contacted the Guggenheim back in September to ask — as every previous administration has done with other famous museums — for the loan of a work of art to put on display at the executive mansion. But instead of granting the request to send Vincent Van Gogh’s “Landscape With Snow” to the White House, Spector offered something else: a gold toilet.

The 18-karat fixture titled “America” has been installed at one of the museum’s rest rooms for the past year and has been used by more than 100,000 visitors. The artist Maurizio Cattelan thinks the expensive piece of plumbing is a metaphor for the country President Trump wants to make great again and chuckled when asked for comment about the incident by The Washington Post, which broke the story last week.

The Guggenheim isn’t talking. But perhaps its leadership thinks the insult to the presidency or perhaps the allusion to the reported splendor of Trump’s Fifth Avenue penthouse home will do it some good with liberal donors whose hatred of the president knows no bounds.

Yet the truth is, the incivility of the Guggenheim’s response to the White House’s loan request is as great as, if not far greater than, anything Trump has tweeted. He is surely responsible for helping to coarsen our political discourse. But if this is what the people entrusted with some of the treasures of Western civilization think passes for correct behavior or even humor, then Trump’s behavior may be the least of our society’s troubles.

Those who run the museums that help make New York City great are making a terrible mistake that goes beyond bad manners. What’s really troubling is that in substituting political uniformity for philanthropy, they are abandoning their mission to educate the public and to preserve the heritage of the West.

The same lesson applies to what is going on across Central Park from the Guggenheim, at the Museum of Natural History.

During the summer, some liberal activists were campaigning to remove the iconic statue of President Theodore Roosevelt from its place in front of the museum because of the great Rough Rider’s sins against 21st-century notions of political correctness. But the impulse to purge is now moving inside the museum as a combination of activists and leftist academics are seeking to remove one of the institution’s most generous donors from its board.

Rebekah Mercer has been a member of the museum’s board since 2013. But since the family foundation created by her hedge-fund magnate father, Robert, also donates to a variety of conservative causes — including a couple that don’t follow the current liberal party line on global warming — many on the left believe she and other conservatives must be shamed and driven out of public life.

Like the contempt for Trump, the desire to silence those with differing views on that topic of inquiry is fashionable. But, contrary to the drive to label all such dissenters as “science deniers,” it’s also profoundly anti-science, since serious study requires a willingness to question conventional wisdom or the consensus of the majority, not totalitarian purges of critics.

Unfortunately, Mercer’s foes think they can win because a previous campaign against another generous conservative donor, David H. Koch, led to his cutting ties with the museum, even though he later denied it was connected to protests.

It ought to be apparent to those running these museums that while behaving in this manner will win them applause in certain upscale Manhattan neighborhoods, enforcing political litmus tests for donors is a dangerous game to play for those who depend on the kindness of strangers for financial survival.

Conservatives tend to be adept at making money and, as the history of New York has shown, their willingness to give it away to enhance the lives of everyone made the city’s cultural legacy possible.

It should also be obvious that, in substituting politics for taste and free inquiry, they’re abandoning their mandate to expand knowledge and preserve our culture.

Liberals may look down their noses at the right. But by legitimizing vulgar insults to the presidency and attempting to purge conservatives and their ideas from the public square, they are discrediting themselves, not Trump or the Mercers.

Jonathan S. Tobin is editor in chief of the JNS.org, the Jewish News Syndicate, and a contributing writer for National Review.

Twitter: @jonathans_tobin