So I get that the left disagrees with Donald Trump’s plan to respond to the Orlando terrorist attack — and the San Bernardino shooting, and the Boston Marathon bombing, and the terrorist attacks of September 11, 2001 — with a temporary moratorium on Muslim immigration to America.

I can understand all the objections to Mr. Trump’s idea. It would be hard to implement, because would-be immigrants might just lie about their religion. It might prevent the entry into America of moderate Muslims who can help combat extremist violence. It would get the American government into the business of religious discrimination. It wouldn’t necessarily stop the terrorism, because some of the extremists are born here.

What I don’t understand, though, is what constitutes the left’s preferred alternative to Mr. Trump’s plan.

Gun control? Even the New York Times, not exactly the National Rifle Association newsletter, was reporting on its home page that, “A vast majority of guns used in 16 recent mass shootings were bought legally and with a federal background check.” That suggests that requiring “smart” guns with some kind of fingerprint lock, or closing the “gun show loophole” that allows for private sales of guns without background checks, wouldn’t do much to solve the mass shooting problem.

Unless one also wants to ban fertilizer or pressure-cooker sales, or require federal background checks for purchases of those, even solving the gun issue entirely might just push the problem toward bombs. In Israel, terrorists have been wreaking havoc recently with kitchen knives. The death toll is smaller than in a bombing or mass shooting, but the effects on victims, their families, and the tourism economy are nonetheless severe.

A statement from Hillary Clinton responding to the Orlando terrorist attack spoke of “defeating international terror groups, working with allies and partners to go after them wherever they are.” Sounds good to me. But when George W. Bush tried to do this in Iraq and Afghanistan, the left accused him of dragging America into a deadly quagmire that would only create more terrorists. More than a dozen years into this war, victory doesn’t appear near. Maybe America lacks the stomach to pursue this war with the sustained relentlessness that would be required to win it.

Mrs. Clinton’s statement also spoke of “hardening our defenses at home.” Yet the city that set up the most hard defenses — New York City under the skilled and courageous leadership of Mayor Michael Bloomberg and his police commissioner Ray Kelly — has been met with the worst kind of derision from the left. The New York Times ran one, two, three separate editorials heaping contempt on Mr. Bloomberg, Mr. Kelly, and the NYPD for its surveillance programs, which the Times called unconstitutional.

Columbia University honored the Associated Press with a Pulitzer Prize for its articles criticizing the NYPD’s anti-terror programs, and the Times then promptly hired away Matt Apuzzo, one of the reporters who led the AP’s anti-NYPD effort. Columbia and the Pulitzer board also showered a separate prize on James Risen and Eric Lichtblau of the Times for their articles exposing wiretapping and cellphone data collection as a counterterrorism program at the federal level.

More mental health funding? That proposal is sometimes heard after mass shootings. But most mentally ill individuals are nonviolent. Sorting the nonviolent ones from the violent ones is tricky, and leftist legal groups have spent years making it harder to restrain or institutionalize people against their will.

What options are left? No politician is openly advocating simply shrugging and tolerating a certain level of terrorist violence as the price we pay for living in a free society. It’s too humbling for any politician to concede that there are some problems that can’t be solved at an acceptable price. Or, to take some of the blame away from the politicians, it’s not a message that voters are particularly eager to hear.

Mr. Stoll is editor of FutureOfCapitalism.com.