By Daniel J. Levitin, from his introduction to Weaponized Lies (Dutton Books, March 2017)

I’m going to start by saying two things that will surely make some people very mad. First, the language we use has begun to obscure the relationship between facts and fantasy. Second, this is a dangerous by-product of a lack of education in our country that has now affected an entire generation of citizens. These two facts have made lies proliferate in our culture to an unprecedented degree. It has made possible the weaponizing of lies so that they can all the more sneakily undermine our ability to make good decisions for ourselves and for our fellow citizens.

What has happened to our language? The Oxford Dictionary’s Word of the Year for 2016 was post-truth, which they define as an adjective “relating to or denoting circumstances in which objective facts are less influential in shaping public opinion than appeals to emotion and personal belief.” It was selected because its usage skyrocketed during that year. I believe we need to get back to using plain old “truth” again—and fast. And we need to reject the idea that truth doesn’t exist anymore.

There are not two sides to a story when one side is a lie.

We are all being more than a bit too careful in how we refer to falsehoods. Perhaps in an effort to avoid personal confrontations, an effort to “just get along,” we have started to use euphemisms to refer to things that are just plain whack-a-do crazy. The lie that the Washington, DC, pizza shop Comet Ping Pong was running a sex-slave operation spearheaded by Hillary Clinton led Edgar M. Welch, twenty-eight, of Salisbury, North Carolina, to drive miles from his home to Washington, DC, and fire his semiautomatic weapon inside the pizzeria on Sunday, December 4, 2016 (just days after “post-truth” became the word of the year). The New York Daily News called the lie a “fringe theory.”

A theory, by the way, is not just an idea—it is an idea based on a careful evaluation of evidence. And not just any evidence—evidence that is relevant to the issue at hand, gathered in an unbiased and rigorous fashion.

Other euphemisms for lies are counterknowledge, half-truths, extreme views, alt truth, conspiracy theories, and, the more recent appellation, “fake news.”

Critical thinking trains us to take a step back, to evaluate facts and form evidence-based conclusions.

The phrase “fake news” sounds too playful, too much like a schoolchild faking illness to get out of a test. These euphemisms obscure the fact that the sex-slave story is an out-and-out lie. The people who wrote it knew that it wasn’t true. There are not two sides to a story when one side is a lie. Journalists—and the rest of us—must stop giving equal time to things that don’t have a fact-based opposing side. Two sides to a story exist when evidence exists on both sides of a position. Then, reasonable people may disagree about how to weigh that evidence and what conclusion to form from it. Everyone, of course, is entitled to their own opinions. But they are not entitled to their own facts. Lies are an absence of facts and, in many cases, a direct contradiction of them.

Truth matters. A post-truth era is an era of willful irrationality, reversing all the great advances humankind has made. Maybe journalists don’t want to call “fake news” what it is, a lie, because they don’t want to offend the liars. But I say offend them! Call them on the carpet.

Other euphemisms for lies are counterknowledge, half-truths, extreme views, alt truth, conspiracy theories, and, the more recent appellation, “fake news.”

Perhaps a better formulation is: What has been happening to our educational systems and institutions in the run-up to this post-truth era? The number of books students read on average declines steadily every single year after second grade. Already fifteen years ago, the U.S. Department of Education found that more than one in five adult Americans were not even able to locate information in text or “make low-level inferences using printed materials.” We have apparently failed to teach our children what constitutes evidence and how to evaluate it. This is worthy of our outrage. Edgar Welch, the Comet Ping Pong shooter, told authorities that he was “investigating” the conspiracy theory after reading about it online. Our information infrastructure is powerful. It can do good or it can do harm. And each of us needs to know how to separate the two.

We are a social species, and we tend to believe what others tell us.

Welch may have thought in one way or another that he was investigating, but there is no evidence that any true investigating took place. It appears that this ignorant citizen does not know what it is to compile and evaluate evidence. In this case, one might look for a link between Hillary Clinton and the restaurant, behaviors of Clinton that would suggest an interest in running a prostitution ring, or even a motive for why she might benefit from such a thing (certainly the motive could not have been financial, given the recent kerfuffle over her speaking fees). He might have observed whether there were child prostitutes and their customers coming in and out of the facility. Or, lacking the mentality and education to conduct one’s own investigation, one could rely on professionals by reading what trained investigative journalists have to say about the story.

The fact that no dedicated professional journalist gives this any credence should tell you a lot. I understand that there are people who think that journalists are corrupt and co-opted by the government. The U.S. Bureau of Labor Statistics reports that there are 45,790 reporters and correspondents. The American Society of News Editors, an independent trade group, estimates there are 32,900 reporters working for the nearly 1,400 daily newspapers in the United States. Some journalists may well be corrupt, but with this many of them, it’s very unlikely that they all are.

Everyone, of course, is entitled to their own opinions. But they are not entitled to their own facts.

Facebook is making an effort to live up to its social responsibilities as a source of information by “making it easier for its 1.8 billion members to report fake news.” In other words, to call a lie a lie. Perhaps other social media sites will take an increasingly curatorial role in the future. At the very least, we can hope that their role in weaponizing lies will decrease.

Many news organizations looked into where the story of the sex-slave pizzeria originated. NBC reported on a thriving community of “fake news” fabricators in the town of Veles, Macedonia, who could well have been the source. This region was in communist Yugoslavia until 1991. BuzzFeed and the Guardian found more than 100 fake news domain names originating there. Young people in Veles, without any political affiliation to US political parties, are pushing stories based on lies so that they can garner significant payments from penny-per-click advertising on platforms such as Facebook. Teenagers can earn tens of thousands of dollars in towns that offer little economic opportunity. Should we blame them for the gunshots in the pizzeria? Social networking platforms? Or a US educational system that has created citizens complacent about thinking through the claims we encounter every day?

The best defense against sly prevaricators, the most reliable one, is for every one of us to learn how to become critical thinkers.

You might object and say, “But it’s not my job to evaluate statistics critically. Newspapers, bloggers, the government, Wikipedia, etc., should be doing that for us.” Yes, they should, but they don’t always, and it’s getting harder and harder for them to keep up as the number of lies proliferates faster than they can knock them down. It’s like a game of whack-a-mole. The Pizzagate story received more than one million hits, while its debunking by Snopes received fewer than 35,000. We are fortunate to have a free press; historically, most nations have had much worse. We should never take the media’s freedom and integrity for granted. Journalists and the companies that pay them will continue to help us identify lies and defuse them, but they can’t accomplish this on their own—the lies will win if we have a gullible, untrained public consuming them.

Of course most of us would not believe that Hillary Clinton was running a sex-slave ring out of a Washington, DC, pizzeria. But this book isn’t just about such absurdities. Do you really need this new drug or is the billion-dollar marketing campaign behind it swaying you with handpicked, biased pseudo-data? How do we know if a celebrity on trial is really guilty? How do we evaluate this investment or that, or a set of contradictory election polls? What things are beyond our ability to know because we aren’t given enough information?

A post-truth era is an era of willful irrationality, reversing all the great advances humankind has made.

The best defense against sly prevaricators, the most reliable one, is for every one of us to learn how to become critical thinkers. We have failed to teach our children to fight the evolutionary tendency toward gullibility. We are a social species, and we tend to believe what others tell us. And our brains are great storytelling and confabulation machines: given an outlandish premise, we can generate fanciful explanations for how they might be true. But that’s the difference between creative thinking and critical thinking, between lies and the truth: the truth has factual, objective evidence to support it. Some claims might be true, but truthful claims are true.

A Stanford University study of civic online reasoning tested more than 7,800 students from intermediate school through college for eighteen months, ending June 2016. The researchers cite a “stunning and dismaying consistency. Overall, young people’s ability to reason about the information on the Internet can be summed up in one word: bleak.” They were horrible at distinguishing high-quality news from lies. We need to start teaching them to do so now. And while we’re at it, the rest of us could use a refresher course. Fortunately, evidence-based thinking is not beyond the grasp of most twelve-year-olds, if only they are shown the way.

The most important component of the best critical thinking that is lacking in our society today is humility.

Many said that Pizzagate was a direct result of fake news—but let’s call it like it is: lies. There is no “news” in fake news. Belief in lies can be harmless, such as belief in Santa Claus or that these new jeans make me look thin. What weaponizes the lies is not the media nor Facebook. The danger is in the intensity of that belief—the unquestioning overconfidence that it is true.

Critical thinking trains us to take a step back, to evaluate facts and form evidence-based conclusions. What got Welch into a situation of discharging a firearm in a DC pizza parlor was a complete inability to understand that a view he held might be wrong. The most important component of the best critical thinking that is lacking in our society today is humility. It is a simple yet profound notion: If we realize we don’t know everything, we can learn. If we think we know everything, learning is impossible. Somehow, our educational system and our reliance on the Internet has led to a generation of kids who do not know what they don’t know. If we can accept that truth, we can educate the American mind, restore civility, and disarm the plethora of weaponized lies threatening our world. It is the only way democracy can prosper.

DANIEL J. LEVITIN is the James McGill Professor of Psychology and Neuroscience at McGill University in Montreal and is the Dean of Social Sciences at the Minerva Schools at KGI. Before becoming a neuroscientist, he was a record producer with gold records to his credit and a professional musician. He splits his time between Montreal, Quebec, and the San Francisco Bay Area.