Culture | Crowd force

You’re not as smart as you think you are

Human cleverness arises from distributing knowledge between minds, making people think they know more than they do

The Knowledge Illusion: Why We Never Think Alone. By Steven Sloman and Philip Fernbach. Riverhead; 296 pages; $28. Macmillan; £18.99.

DO YOU know how a toilet works? What about a bicycle, or a zipper? Most people can provide half answers at best. They struggle to explain basic inventions, let alone more complex and abstract ones. Yet somehow, in spite of people’s ignorance, they created and navigate the modern world. A new book, “The Knowledge Illusion” sets out to tackle this apparent paradox: how can human thinking be so powerful, yet so shallow?

Steven Sloman and Philip Fernbach, two cognitive scientists, draw on evolutionary theory and psychology. They argue that the mind has evolved to do the bare minimum that improves the fitness of its host. Because humans are a social species and evolved in the context of collaboration, wherever possible, abilities have been outsourced. As a result, people are individually rather limited thinkers and store little information in their own heads. Much knowledge is instead spread through the community—whose members do not often realise that this is the case.

The authors call this the illusion of understanding, and they demonstrate it with a simple experiment. Subjects are asked to rate their understanding of something, then to write a detailed account of it, and finally to rate their understanding again. The self-assessments almost invariably drop. The authors see this effect everywhere, from toilets and bicycles to complex policy issues. The illusion exists, they argue, because humans evolved as part of a hive mind, and are so intuitively adept at co-operation that the lines between minds become blurred. Economists and psychologists talk about the “curse of knowledge”: people who know something have a hard time imagining someone else who does not. The illusion of knowledge works the other way round: people think they know something because others know it.

The hive mind, with its seamless interdependence and expertise-sharing, once helped humans hunt mammoths and now sends them into space. But in politics it causes problems. Using a toilet without understanding it is harmless, but changing the health-care system without understanding it is not. Yet people often have strong opinions about issues they understand little about. And on social media, surrounded by like-minded friends and followers, opinions are reinforced and become more extreme. It is hard to reason with someone under the illusion that their beliefs are thought through, and simply presenting facts is unlikely to change beliefs when those beliefs are rooted in the values and groupthink of a community.

The authors tentatively suggest that making people confront the illusion of understanding will temper their opinions, but this could have the opposite effect—people respond badly to feeling foolish. Messrs Sloman and Fernbach show how deep the problem runs, but are short on ideas to fix it.

“The Knowledge Illusion” is at once both obvious and profound: the limitations of the mind are no surprise, but the problem is that people so rarely think about them. However, while the illusion certainly exists, its significance is overstated. The authors are Ptolemaic in their efforts to make it central to human psychology, when really the answer to their first question—how can human thought be so powerful, yet so shallow?—is the hive mind. Human ignorance is more fundamental and more consequential than the illusion of understanding. But still, the book profits from its timing. In the context of partisan bubbles and fake news, the authors bring a necessary shot of humility: be sceptical of your own knowledge, and the wisdom of your crowd.

This article appeared in the Culture section of the print edition under the headline "Mind meld"

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