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Scientists have stepped up their investigations into fake news in recent months, and amid all the analyses, studies and meetings, some have raised the possibility that a lot of people simply don't care whether the claims they embrace are true. "Post-truth" has become a hot topic for researchers from a variety of fields, including Nobel prize-winning chemists: The annual Lindau Nobel Laureate Meeting in Germany this summer took as a theme "Science in a Post-Truth Era."

Skeptics have long studied why people wrongly believe in astrology, ESP and all manner of weird things, but not caring about truth at all would seem to fly in the face of basic human curiosity. People send probes to other planets, dig up dinosaur bones, and build powerful microscopes to find out the truth about inner and outer space. We follow crime stories because we want to learn what really happened. Shouldn't curiosity act as a guardrail to keep us from falling into a post-truth world?

Astrophysicist Mario Livio makes a key observation in his new book, "Why?: What Makes Us Curious": To be truly curious requires a middling level of knowledge. If you know absolutely nothing, then you don't know what to be curious about. If you know everything, you have no reason to inquire. So children who have never heard of dinosaurs can't be curious about them, and very few adults are curious about how many pennies are in a dollar.

I realized, however, that it's not actual knowledge but people's perception of their own knowledge that encourages or stifles curiosity. That observation snapped into place for me at an event at the MIT Media Lab. In a talk, Putin biographer Masha Gessen noted that one striking similarity between Putin and Trump is their utter lack of curiosity. I asked her to elaborate, and she said that both men think they already know everything. That perception of superior knowledge comes through in Trump's habit of saying "Nobody knows it better than me" when discussing a variety of subjects -- taxes, trade, visas, infrastructure, social media, uranium sales, and "nuclear horror," to name a few.

So curiosity requires a level of humility. But how far does the problem of ego inflation go? In his new book "The Death of Expertise," author Tom Nichols makes a case that there's a raging epidemic of egomania in the United States. "Most cases of ignorance can be overcome if people are willing to learn," he writes. "Nothing, however, can overcome the toxic confluence of arrogance, narcissism and cynicism that Americans now wear like full suit of armor against the efforts of experts and professionals."

Nichols is not convinced that curiosity matters to the bulk of the public. Sure, he said, some people are curious -- the engineers and scientists and artists of the world. But he doesn't see curiosity as an important driver of human behavior. "People don't go on Reddit to learn stuff -- they go there to win," he said. If they read newspaper or magazine stories at all, he argues, it's not to satisfy a thirst for knowledge, but to look smart or to collect likes on Facebook.

Of course, not everyone takes such a dim view of human curiosity. In another book about expertise, "If I Understood You, Would I Have This Look on My Face?", the actor and science advocate Alan Alda takes for granted that many people are hungry for knowledge. But to engage that curiosity, he argues, experts have to pay attention to their audiences to gauge where they fall on that spectrum of intermediate knowledge. By listening and communicating, experts can avoid talking over people's heads or repeating things they already know -- both mistakes scientists sometimes make.

Alda is himself a curious character. He became involved in science communication after hosting the television show "Scientific American Frontiers." He realized that scientists often find themselves onstage or in front of cameras struggling to explain their research, and thought his expertise in acting and improvisation might prove useful. Now he's adapting his ideas for business leaders and other experts.

One lesson from improvisation, he says, is that real communication is an exchange, and what you say should depend on what you see and hear from the other party. When I spoke with Alda, he made the memorable observation that everyone knows things you don't know -- whether you're speaking to an astrophysicist or the person who cuts your hair or delivers your pizza. They have different experiences. They've seen the world from different angles. If people can engage their curiosity, it doesn't matter who is smarter. What matters is that both parties leave the encounter smarter than they were before.

William Moerner, a Nobel Laureate in chemistry, is one of those curious people. I was interviewing him about various topics after he had spoken at the meeting of Nobel winners in Germany, when the U.S.'s decision to cancel a national commission on forensic science came up. He wanted to know what I knew. He had a notebook and pen in hand, and by the end of our chat, he may have asked as many questions and jotted as many notes as I had.

While he'd been onstage during the panel discussion, another journalist asked him why he wasn't more outraged, given the way the U.S. government was sidelining science. Indeed, the world (and especially the world of social media) seems to demand indignation. But outrage hinges on certainty -- not on that intermediate level of knowledge that stimulates investigation and curiosity. Moerner's response? At times like this, he said, "Someone needs to be rational."

Faye Flam is a Bloomberg View columnist. She has written for the Economist, the New York Times, the Washington Post, Psychology Today, Science, New Scientist and other publications. She has a degree in geophysics from the California Institute of Technology, and has been a Knight-Wallace fellow at the University of Michigan.