Big Takeaways and Key Ideas:
 

Why are we so bad at detecting lies? You’d think we’d be good at it.  Logic says that it would be very useful for human beings to know when they are being deceived.  Evolution, over millions of years, should have favored people with the ability to pick up the subtle signs of deception.  But it hasn’t. (pg. 72)

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We have a default to truth: our operating assumption is that people we are dealing with are honest. (pg. 73)

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To snap out of truth-default mode requires a “trigger.”  A trigger is not the same as a suspicion or the first sliver of doubt.  We fall out of truth-default mode only when the case against our initial assumption becomes definitive.  We do not behave, in other words, like sober-minded scientists, slowly gathering evidence of the truth or falsity of something before reaching a conclusion.  We do the opposite. We start by believing. And we stop believing only when our doubts and misgivings rise to the point where we can no longer explain them away.  (pg. 74)

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You believe someone not because you have no doubts about them.  Belief is not the absence of doubt. You believe someone because you don’t have enough doubts about them. (pg. 78)

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Lies are rare.  And those lies that are told are told by a very small subset of people.  That’s why it doesn’t matter so much that we are terrible at detecting lies in real life.  Under the circumstances, in fact, defaulting to truth makes logical sense. (pg. 100)

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The advantage to human beings lies in assuming that strangers are truthful.  The trade-off between truth-default and the risk of deception is a great deal for us.  What we get in exchange for being vulnerable to an occasional lie is efficient communication and social coordination.  The benefits are huge and the costs are trivial in comparison. Sure, we get deceived once in a while. That is just the cost of doing business.  Because we trust implicitly, spies go undetected, criminals roam free, and lives are damaged. But the point is that the price of giving up on that mindset is much higher.  (pg. 100)

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The consequence of not defaulting to truth is if you don’t begin in a state of trust, you can’t have meaningful social encounters. (pg. 104)

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We default to truth - even when that decision carries terrible risks - because we have no choice.  Society cannot function otherwise. And in those rare instances where trust ends in betrayal, those victimized by default to truth deserve our sympathy, not our censure. (pg. 141)

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The transparency problem ends up in the same place as the default-to-truth problem.  Our strategies for dealing with strangers are deeply flawed, but they are also socially necessary.  We need the criminal-justice system and the hiring process and the selection of babysitters to be human.  But the requirement of humanity means that we have to tolerate an enormous amount of error. That is the paradox of talking to strangers.  We need to talk to them. (pg. 166)

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When a liar acts like an honest person, or when an honest person acts like a liar, we’re confused.  In other words, human beings are not bad lie detectors. We are bad lie detectors when the person we’re judging is mismatched. (pg. 176)

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Alcohol has a myopia effect - it’s principal effect is to narrow our emotional and mental fields of vision.  It creates a state of shortsightedness in which superficially understood, immediate aspects of experience have a disproportionate influence on behavior and emotion.  Alcohol makes the thing in the foreground even more salient and the thing in the background less significant. If someone who is drinking is at a football game surrounded by rabid fans, the excitement and drama going on around him will temporarily crowd out his pressing worldly concerns.  But if the same person is in a quiet corner of the bar, drinking alone, he will get more depressed. Now there’s nothing to distract him. Drinking puts you at the mercy of your environment. It crowds out everything except the most immediate experiences. (pg. 207)

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When your blood alcohol level gets to approximately 0.15 the hippocampus simply shuts down entirely.  It’s when individuals experience a black out and there is nothing to recall. At approximately the 0.15 mark, the hippocampus shuts down and memories stop forming, but it is entirely possible that the frontal lobes, cerebellum, and amygdala can continue to function more or less normally. (pg. 217)

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Police officers in the United States not only have at their disposal a virtually limitless list of legal reasons to stop a motorist; they are also free to add any other reasons they might dream up, as long as they seem reasonable.  And once they’ve stopped a motorist, police officers are allowed, under the law, to search the car, so long as they have reason to believe the motorist might be armed or dangerous. (pg. 306)

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To assume the best about another is the trait that has created modern society.  Those occasions when our trusting nature gets violated are tragic. But the alternative - to abandon trust as a defense against predation and deception - is worse.  (pg. 342)