Not Born Yesterday explains how we decide who we can trust and what we should believe — and argues that we're pretty good at making these decisions. Hugo Mercier demonstrates how virtually all attempts at mass persuasion — whether by religious leaders, politicians, or advertisers — fail miserably. Drawing on recent findings from political science and other fields ranging from history to anthropology, Mercier shows that the narrative of widespread gullibility, in which a credulous public is easily misled by demagogues and charlatans, is simply wrong.

Why is mass persuasion so difficult? Mercier uses the latest findings from experimental psychology to show how each of us is endowed with sophisticated cognitive mechanisms of open vigilance. Computing a variety of cues, these mechanisms enable us to be on guard against harmful beliefs, while being open enough to change our minds when presented with the right evidence. Even failures — when we accept false confessions, spread wild rumors, or fall for quack medicine — are better explained as bugs in otherwise well-functioning cognitive mechanisms than as symptoms of general gullibility. In this lively and provocative conversation Shermer and Mercier discuss:

• If we're not as gullible as we've been led to believe, then why do so many people apparently believe in ESP, astrology, the paranormal, the supernatural, conspiracy theories, and the like?
• Epistemic Vigilance and skepticism
• why most Germans did not believe in Nazi ideology
• honest signaling, costly signaling, and virtue signaling
• Malcolm Gladwell's book Talking to Strangers and why the "default to truth" theory is wrong.
• folk biology and why creationism is intuitive and evolutionary theory counterintuitive
• conspiracy theories and why we believe them (or not)
• the real meaning of conformity experiments in which people appear to go along with the group
• why people join cults … or ISIS.
• why people belong to religions, and
• why we are not living in a post-truth era, and why access to accurate information has never been so good.

Hugo Mercier is a cognitive scientist at the Jean Nicod Institute in Paris and the coauthor of The Enigma of Reason. He lives in Nantes, France. Twitter @hugoreasoning

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