Rationality: What It Is, Why It Seems Scarce, Why It Matters

by Steven Pinker

Rationality ought to be the lodestar for everything we think and do. (If you disagree, are your objections rational?) Yet in an era blessed with unprecedented resources for reasoning, the public sphere is infested with fake news, quack cures, conspiracy theories, and “post-truth” rhetoric.

Though the problems are daunting, solutions exist, and our species has the intellectual wherewithal to find them. Yet among our fiercest problems today is convincing people to accept the solutions when we do find them.

as a cognitive scientist I cannot accept the cynical view that the human brain is a basket of delusions. Hunter-gatherers—our ancestors and contemporaries—are not nervous rabbits but cerebral problem solvers.

we’re so smart: smart enough to have discovered the laws of nature, transformed the planet, lengthened and enriched our lives, and, not least, articulated the rules of rationality that we so often flout.

This book grew out of a course I taught at Harvard which explored the nature of rationality and the puzzle of why it seems to be so scarce. Like many psychologists, I love to teach the arresting, Nobel Prize–winning discoveries of the infirmities that afflict human reason, and consider them to be among the deepest gifts to knowledge that our science has contributed.

the benchmarks of rationality that people so often fail to measure up to should be a goal of education and popular science. Just as citizens should grasp the basics of history, science, and the written word, they should command the intellectual tools of sound reasoning. These include logic, critical thinking, probability, correlation and causation, the optimal ways to adjust our beliefs and commit to decisions with uncertain evidence, and

the yardsticks for making rational choices alone ...

the distinction between two modes of believing: the reality mindset and the mythology mindset.

though it may seem paradoxical to lay out rational arguments for rationality itself, it’s a timely assignment. Some people pursue the opposite paradox, citing reasons (presumably rational ones, or why should we listen?) that rationality is overrated, such as that logical personalities are joyless and repressed, analytical thinking must be subordinated to social justice, and a good heart and reliable gut are surer routes to well-being than tough-minded logic and argument. Many act as if rationality is obsolete—

In an era in which rationality seems both more threatened and more essential than ever, Rationality is, above all, an affirmation of rationality.

The cognitive wherewithal to understand the world and bend it to our advantage is not a trophy of Western civilization; it’s the patrimony of our species.

The San of the Kalahari Desert

They reason their way from fragmentary data to remote conclusions

more Homer Simpson than Mr. Spock,

But evolutionary psychologists, mindful of the ingenuity of foraging peoples, insist that humans evolved to occupy the “cognitive niche”: the ability to outsmart nature with language, sociality, and know-how.14 If contemporary humans seem irrational, don’t blame the hunter-gatherers.

It is a kit of cognitive tools that can attain particular goals in particular worlds.

To understand what rationality is, why it seems scarce, and why it matters, we must begin with the ground truths of rationality itself: the ways an intelligent agent ought to reason, given its goals and the world in which it lives. These “normative” models come from logic, philosophy, mathematics, and artificial intelligence, and they are our best understanding of the “correct” solution to a problem and how to find it. They serve as an aspiration for those who want to be rational, which should mean everyone. A major goal of this book is to explain the most widely applicable normative tools of reason;

The many ways in which ordinary people fall short of these benchmarks have become famous through the Nobel Prize–winning research of Daniel Kahneman, Amos Tversky, and other psychologists and behavioral economists.

in many cases there is a method to people’s madness.

problem may have been presented to them in a deceptive format,

the normative model may itself be correct only in a particular environment, and people accurately se...

one,

the model may be designed to bring about a certain goal, and, for better or worse, people...

some of today’s florid outbursts of irrationality may be understood as the rational pursuit of goals other than an objective understanding of the world.

Though explanations of irrationality may absolve people of the charge of outright stupidity, to understand is not to forgive.

Three Simple Math Problems

The lesson of the Cognitive Reflection Test is that blunders of reasoning may come from thoughtlessness rather than ineptitude.

Human intuition doesn’t grasp exponential (geometric) growth,

A Simple Logic Problem

How can humans make it through the day with an inability to apply the most elementary rule of logic? Part of the answer is that the selection task is a peculiar challenge.

bake together the content relevant to the problem with the rules of logic

augment the ecological rationality we are born and grow up with—our horse sense, our street smarts—with the broader-spectrum and more potent tools of reasoning perfected by our best thinkers

A Simple Probability Problem

Let’s Make a Deal.

Monty Hall,

something about the Monty Hall dilemma is designed to bring out the stupid in our System 1. But in this case System 2 is not much brighter.

the easier something is to visualize, the likelier it seems.

the conjunction fallacy, in which a conjunction is more intuitively probable than either of its elements.

“the Linda problem”:

The Moral from Cognitive Illusions

They lead to incorrect answers, yes, but they are often correct answers to different and more useful questions.

excellent as our cognitive systems are, in the modern world we must know when to discount them and turn our reasoning over to instruments—the tools of logic, probability, and critical thinking that extend our powers of reason beyond what nature gave us.

Rationality is uncool.

postmodernism and critical theory (not to be confused with critical thinking) hold that reason, truth, and objectivity are social constructions that justify the privilege of dominant groups.

“the ability to use knowledge to attain goals.”

A rational agent must have a goal, whether it is to ascertain the truth of a noteworthy idea, called theoretical reason, or to bring about a noteworthy outcome in the world, called practical reason (“what is true” and “what to do”).

William James

With the filings the path is fixed; whether it reaches the end depends on accidents. With the lover it is the end which is fixed; the path may be

modified indefinitely.

With this definition the case for rationality seems all too obvious: do you want things or don’t you? If you do, rationality is what allows you to get them.