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Must we always follow reason? Do I need a rational argument for why I should fall in love, cherish my children, enjoy the pleasures of life? Isn’t it sometimes OK to go crazy, to be silly, to stop making sense? If rationality is so great, why do we associate it with a dour joylessness? Was the philosophy professor in Tom Stoppard’s play Jumpers right in his response to the claim that “the Church is a monument to irrationality?”

The National Gallery is a monument to irrationality! Every concert hall is a monument to irrationality! And so is a nicely kept garden, or a lover’s favour, or a home for stray dogs! . . . If rationality were the criterion for things being allowed to exist, the world would be one gigantic field of soya beans!

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Here I’ll take up the professor’s challenge. We will see that while beauty and love and kindness are not literally rational, they’re not exactly irrational, either. We can apply reason to our emotions and to our morals, and there is even a higher-order rationality that tells us when it can be rational to be irrational.

Stoppard’s professor may have been misled by David Hume’s famous argument that “reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.” Hume, one of the hardest-headed philosophers in the history of Western thought, was not advising his readers to shoot from the hip, live for the moment, or fall head over heels for Mr. Wrong.1 He was making the logical point that reason is the means to an end, and cannot tell you what the end should be, or even that you must pursue it. By “passions” he was referring to the source of those ends: the likes, wants, drives, emotions, and feelings wired into us, without which reason would have no goals to figure out how to attain. It’s the distinction between thinking and wanting, between believing something you hold to be true and desiring something you wish to bring about. His point was closer to “There’s no disputing tastes” than “If it feels good, do it.”2 It is neither rational nor irrational to prefer chocolate ripple to maple walnut. And it is in no way irrational to keep a garden, fall in love, care for stray dogs, party like it’s 1999, or dance beneath the diamond sky with one hand waving free.3

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Cheesecake is fattening, unattended kids get into trouble, and cutthroat ambition earns contempt—you can’t always get what you want.

Still, the impression that reason can oppose the emotions must come from somewhere—surely it is not just a logical error. We keep our distance from hotheads, implore people to be reasonable, and regret various flings, outbursts, and acts of thoughtlessness. If Hume was right, how can the opposite of what he wrote also be true: that the passions must often be slaves to reason?

In fact, it’s not hard to reconcile them. One of our goals can be incompatible with the others. Our goal at one time can be incompatible with our goals at other times. And one person’s goals can be incompatible with others’. With those conflicts, it won’t do to say that we should serve and obey our passions. Something has to give, and that is when rationality must adjudicate.

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People don’t want just one thing. They want comfort and pleasure, but they also want health, the flourishing of their children, the esteem of their fellows, and a satisfying narrative on how they have lived their lives. Since these goals may be incompatible—cheesecake is fattening, unattended kids get into trouble, and cutthroat ambition earns contempt—you can’t always get what you want. Some goals are more important than others: the satisfaction deeper, the pleasure longer lasting, the narrative more compelling. We use our heads to prioritize our goals and pursue some at the expense of others.

While Odysseus had himself tied to the mast and rationally relinquished his option to act, his sailors plugged their ears with wax and rationally relinquished their option to know. At first this seems puzzling. One might think that knowledge is power, and you can never know too much. Just as it’s better to be rich than poor, because if you’re rich you can always give away your money and be poor, you might think it’s always better to know something, because you can always choose not to act on it. But in one of the paradoxes of rationality, that turns out not to be true. Sometimes it really is rational to plug your ears with wax.4 Ignorance can be bliss, and sometimes what you don’t know can’t hurt you.

An obvious example is the spoiler alert. We take pleasure in watching a plot unfold, including the suspense, climax, and denouement, and may choose not to spoil it by knowing the ending in advance. Sports fans who cannot see a match in real time and plan to watch a recorded version later will sequester themselves from all media and even from fellow fans who might leak the outcome in a subtle tell. Many parents choose not to learn the sex of their unborn child to enhance the joy of the moment of birth. In these cases we rationally choose ignorance because we know how our own involuntary positive emotions work, and we arrange events to enhance the pleasure they give us.

By the same logic, we can understand our negative emotions and starve ourselves of information that we anticipate would give us pain. Many consumers of genetic testing know they would be better off remaining ignorant of whether the man who calls himself their father is biologically related to them. Many choose not to learn whether they have inherited a dominant gene for an incurable disease that killed a parent, like the musician Arlo Guthrie, whose father, Woody, died of Huntington’s. There’s nothing they can do about it, and knowledge of an early and awful death would put a pall over the rest of their lives. For that matter most of us would plug our ears if an oracle promised to tell us the day we will die.

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We also preempt knowledge that would bias our cognitive faculties. Juries are forbidden to see inadmissible evidence from hearsay, forced confessions, or warrantless searches—“the tainted fruit of the poisoned tree”—because human minds are incapable of ignoring it. Good scientists think the worst of their own objectivity and conduct their studies double blind, choosing not to know which patients got the drug and which the placebo. They submit their papers to anonymous peer review, removing any temptation to retaliate after a bad one, and, with some journals, redact their names, so the reviewers can’t indulge the temptation to repay favors or settle scores.

We keep our distance from hotheads, implore people to be reasonable, and regret various flings, outbursts, and acts of thoughtlessness.

In these examples, rational agents choose to be ignorant to game their own less-than-rational biases. But sometimes we choose to be ignorant to prevent our rational faculties from being exploited by rational adversaries—to make sure they cannot make us an offer we can’t refuse. You can arrange not to be home when the Mafia wiseguy calls with a threat or the deputy tries to serve you with a subpoena. The driver of a Brink’s truck is happy to have his ignorance proclaimed on the sticker “Driver does not know combination to safe,” because a robber cannot credibly threaten him to divulge it. A hostage is better off if he does not see the faces of his captors, because that leaves them an incentive to release him. Even misbehaving young children know they’re better off not meeting their parents’ glares.

Rational ignorance is an example of the mind-bending paradoxes of reason explained by the political scientist Thomas Schelling in his 1960 classic The Strategy of Conflict. In some circumstances it can be rational to be not just ignorant but powerless, and, most perversely of all, irrational.

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In the game of Chicken, made famous in the James Dean classic Rebel Without a Cause, two teenage drivers approach each other at high speed on a narrow road and whoever swerves first loses face (he is the “chicken”). Since each one knows that the other does not want to die in a head-on crash, each may stay the course, knowing the other has to swerve first. Of course when both are “rational” in this way, it’s a recipe for disaster (a paradox of game theory). So is there a strategy that wins at Chicken? Yes—relinquish your ability to swerve by conspicuously locking the steering wheel, or by putting a brick on the gas pedal and climbing into the back seat, leaving the other guy no choice but to swerve. The player who lacks control wins. More precisely, the first player to lack control wins: if both lock their wheels simultaneously …

Though the game of Chicken may seem like the epitome of teenage foolishness, it’s a common dilemma in bargaining, both in the marketplace and in everyday life. Say you’re willing to pay up to $30,000 for a car and know that it cost the dealer $20,000. Any price between $20,000 and $30,000 works to both of your advantages, but of course you want it to be as close as possible to the lower end of the range and the sales rep to the upper end. You could lowball him, knowing he’s better off consummating the deal than walking away, but he could highball you, knowing the same thing. So he agrees that your offer is reasonable but needs the OK from his manager, but when he comes back he says regretfully that the manager is a hardass who nixed the deal. Alternatively, you agree that the price is reasonable but you need the OK from your bank, and the loan officer refuses to lend you that much. The winner is the one whose hands are tied. The same can happen in friendships and marriages in which both partners would rather do something together than stay home, but differ in what they most enjoy. The partner with the superstition or hang-up or maddeningly stubborn personality that categorically rules out the other’s choice will get his or her own.

Suicide terrorists who believe they will be rewarded in paradise cannot be deterred by the prospect of death on Earth.

Threats are another arena in which a lack of control can afford a paradoxical advantage. The problem with threatening to attack, strike, or punish is that the threat may be costly to carry out, rendering it a bluff that the target of the threat could call. To make it credible, the threatener must be committed to carrying it out, forfeiting the control that would give his target the leverage to threaten him right back by refusing to comply. A hijacker who wears an explosive belt that goes off with the slightest jostle, or protesters who chain themselves to the tracks in front of a train carrying fuel to a nuclear plant, cannot be scared away from their mission.

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The commitment to carry out a threat can be not just physical but emotional.5 The narcissist, borderline, hothead, high-maintenance romantic partner, or “man of honor” who considers it an intolerable affront to be disrespected and lashes out regardless of the consequences is someone you don’t want to mess with.

A lack of control can blend into a lack of rationality. Suicide terrorists who believe they will be rewarded in paradise cannot be deterred by the prospect of death on Earth. According to the Madman Theory in international relations, a leader who is seen as impetuous, even unhinged, can coerce an adversary into concessions. In 1969 Richard Nixon reportedly ordered nuclear-armed bombers to fly recklessly close to the USSR to scare them into pressuring their North Vietnamese ally to negotiate an end to the Vietnam War. Donald Trump’s bluster in 2017 about using his bigger nuclear button to rain fire and fury on North Korea could charitably be interpreted as a revival of the theory.

The problem with the madman strategy, of course, is that both sides can play it, setting up a catastrophic game of Chicken. Or the threatened side may feel it has no choice but to take out the madman by force rather than continue a fruitless negotiation. In everyday life, the saner party has an incentive to bail out of a relationship with a madman or madwoman and deal with someone more reasonable. These are reasons why we are not all madpeople all the time (though some of us get away with it some of the time).

Promises, like threats, have a credibility problem that can call for a surrender of control and of rational self-interest. How can a contractor convince a client that he will pay for any damage, or a borrower convince a lender that she will repay a loan, when they have every incentive to renege when the time comes? The solution is to post a bond that they would forfeit, or sign a note that empowers the creditor to repossess the house or car. By signing away their options, they become trustworthy partners. In our personal lives, how do we convince an object of desire that we will forsake all others till death do us part, when someone even more desirable may come along at any time? We can advertise that we are incapable of rationally choosing someone better because we never rationally chose that person in the first place—our love was involuntary, irrational, and elicited by the person’s unique, idiosyncratic, irreplaceable qualities.6 I can’t help falling in love with you. I’m crazy for you. I like the way you walk, I like the way you talk.

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The paradoxical rationality of irrational emotion is endlessly thought-provoking and has inspired the plots of tragedies, Westerns, war movies, mafia flicks, spy thrillers, and the Cold War classics Fail Safe and Dr. Strangelove. But nowhere was the logic of illogic more pithily stated than in the 1941 film noir The Maltese Falcon, when detective Sam Spade dares Kasper Gutman’s henchmen to kill him, knowing they need him to find the jewel-encrusted falcon. Gutman replies:

That’s an attitude, sir, that calls for the most delicate judgment on both sides, because as you know, sir, in the heat of action men are likely to forget where their best interests lie, and let their emotions carry them away.

Steven Pinker is the author, most recently, of Rationality: What It Is, Why It Seems Scarce, Why It Matters. He is the Johnstone Family Professor in the Department of Psychology at Harvard University. His other books include How the Mind Works and The Better Angels of Our Nature.

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From Rationality by Steven Pinker, published by Viking, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2021 by Steven Pinker.


1. Cohon, R. The passions and intentional action. In Coventry, A.M. & Sager, A. (Eds.), The Humean Mind Taylor & Francis (2018).

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2. Though that’s not what he literally believed about taste in art and wine, as expressed in “Of the standard of taste” (Gracyk 2020). His point here was only that goals are inherently subjective.

3. Bob Dylan, “Mr. Tambourine Man.”

4. Gigerenzer, G. & Garcia-Retamero, R. Cassandra’s regret: The psychology of not wanting to know. Psychological Review 124, 179–196 (2017)

5. Frank, R.H. Passions within reason: The strategic role of the emotions W.W. Norton & Company, New York, NY (1988)

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6. Pinker, S. How the Mind Works W.W. Norton & Company, New York, NY (1997/2009).

Lead image: vchal / Shutterstock

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