G'day, humans. Welcome to the safe space for dangerous ideas. Stephen Pinker. He might be one of the

world's best known cognitive psychologists, a public intellectual who for decades has used his fame

to help us understand how we think, how we develop language, how our behaviour is shaped by

evolution and biology. He is a professor of psychology at Harvard University. His most recent book

is a hugely entertaining reflection on social norms, on cooperation, on outrage cycles and

social media pylons, sudden political shifts, and

moral panics. It's called When Everybody Knows, that Everybody Knows. And Pinker joins me to

discuss echo chambers and bank runs and media bias and why we hoarded toilet paper during COVID.

I hope you enjoy as much as I did, the one and only, Stephen Pinker.

I think everyone is aware of the general contours of the problem of people being in echo chambers at the moment, Stephen.

You know, part of the success of this show is its attempt to help people who would

normally be in different bubbles of group think to understand what the hell the other one is

talking about. What I think is really interesting in your new book is the fact of noticing

that it isn't just the fact of the echo

chamber that's a problem. It's also that everyone being on the same page that everybody is

on the same page is the crucial sort of missing component. It's not enough for everybody to

just be consuming the same worldview. They need to know that everybody else is also consuming the worldview for it to have currency.

Why?

Because that state of knowing, common knowledge is the technical term, a little bit different than the way it's used in ordinary conversation.

But common knowledge where everyone knows that everyone knows something. You know, I know it, something, you know it, I know that you know it, you know it, everyone knows that everyone knows something.

You know, I know it, something, you know it, I know that you know it, you know that I know it,

I know that I know it, and so on, is necessary for coordination, for people to be on the same

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