“Perception is reality,” Republican political consultant Lee Atwater is famously quoted as saying. That’s never been more true than it is today, as fake news and online conspiracy theories allow people to pick and choose the reality in which they live.

It’s time to start pushing back against these hoaxes more vigorously, and help young people acquire and refine the skills they’ll need to effectively identify and separate fake news from the real thing. By the looks of it, they’re going to be dealing with more and more of it.

For a by-the-numbers look at the proliferation of fake news, Buzzfeed’s Craig Silverman had the organization compare election stories from mainstream news outlets on Facebook with items published by hoax sites and hyperpartisan blogs.

Those pieces — which included a false report that Pope Francis had endorsed Donald Trump, as well as a story falsely claiming Hillary Clinton had sold weapons to ISIS — generated more than 8.7 million shares, reactions and comments, BuzzFeed found. Over the same time period (the final three months of the election), the 20 best-performing election stories from the news outlets only generated 7.36 million shares, reactions and comments.

The idea that these false and misleading reports don’t produce real world consequences was shattered on Sunday when Edgar M. Welch spent about 45 minutes roaming around Comet Ping Pong pizza in Washington, D.C., with an AR-15 assault rifle, in a vain and monstrously dangerous attempt to investigate a fake news story with which he had become obsessed.

Welch, of North Carolina, had apparently bought the story — this one claiming Clinton and Comet’s owner had conspired to run a sex-slave ring — hook, line and sinker. He fired at least one bullet inside the business and pointed his weapon at at least one employee before ultimately surrendering to police outside.

Friends of Mr. Welch have said they don’t believe he intended to shoot anyone, but their assessment, like the hoax that sent him to Comet in the first place, is simply post-factual speculation. The truth is we’re simply lucky no one — including Welch, who has two daughters — was injured or killed.

Sickeningly, a new conspiracy theory emerged on Monday claiming that Welch’s incident was either staged or a hoax itself. The sex slave conspiracy theory surrounding Comet pizza isn’t dead either, apparently.

As scary as all of this is, it’s even more troubling when you consider how ill-equipped young people apparently are when it comes to sussing out fake news online. A Stanford University study of 7,804 students (middle school through college age) found that the vast majority couldn’t tell the difference between fake and real news online.

The study, published last month, found a staggering 82 percent of middle schoolers couldn’t distinguish between “sponsored content” and real news stories online. For many students the issue of credibility was settled not by who was providing the information, but by things like whether or not a large picture was attached to the story.

The researchers were so troubled by their findings that they summed up students’ abilities to discern the credibility of online news stories in one word: “bleak.”

It’s easy to shrug off admonitions against fake news and conspiracy-mongering when its effects are seemingly academic. Who cares that a bunch of reporters and editors are upset their version of the truth is getting less play?

If you believe that, then you’re part of a problem that has, for years, fostered self-serving maliciousness and a “no-holds-barred” version of political discourse online. On Sunday, it graduated to creating a real-world, life-threatening situation for dozens of people.

This is not a healthy, sane or safe state of affairs for our country. And it is up to each and every one one of us to repudiate the trolls and scammers peddling this corrosive trash.