Know it alls

There's more to common knowledge than meets the eye. Steven Pinker sets out to enlighten us.

- BY DANYL MCLAUCHLAN

Think of a dreadful secret about yourself, something shameful that nobody knows. Now imagine someone close to you stumbles across the horrible truth and you don't know they know; they've kept it to themselves. From your perspective that relationship is completely normal. Yet if you find out that they know, and they find out that you know they know, everything changes. The secret hasn't altered, nor has the number of people exposed to it. What's different is the knowledge about that knowledge. It was private, and now it's common knowledge, public to both of you. And that makes all the difference.

This is Steven Pinker's 12th book. The first two were academic works on his area of expertise, language and cognition, subjects he's researched and taught at Harvard for many years. These were followed by a string of popular bestsellers - The Language Instinct, How the Mind Works, The Blank Slate.

In 2011, he took a turn towards the political with The Better Angels of our Nature, a controversial interdisciplinary argument that pre-modern, pre-industrial societies were significantly more violent than most people imagined, and that moderns enjoy long, safe lives thanks to government, commerce and expanding moral norms. He's advanced his pro-modernity position in Enlightenment Now and Rationality, which made a doomed attempt to teach the world to think clearly. Four years and one Trump reelection later, we have When Everyone Knows That Everyone Knows.