I don’t know about you, but ever since I can remember – from my early teens – I have been bemused about the endless rituals we humans perform; and even more so about what can and can’t be said about these rituals, especially when the rituals involve obvious hypocrisies or are illogical.

Review: When Everyone Knows That Everyone Knows: Common Knowledge and the Science of Harmony, Hypocrisy and Outrage – Steven Pinker (Allen Lane)

Do you see what I just did with my opening paragraph?

Obviously, through a brief personal reflection, I tried to give you a general sense of what much of Steven Pinker’s book When Everyone Knows That Everyone Knows is about: namely, that we often perform perplexing rituals for the sake of harmony, and if we draw attention to the quizzical aspects of those rituals – if we make these aspects common knowledge – we can get into trouble.

But I also did something else. I started with the innocuous, “I don’t know about you…”

Now hold on tight. This gets complicated very fast. Just like Pinker’s book.

The thing is, I do believe that many people are bemused by the rituals we perform and the silences we must keep. But I wouldn’t say that this phenomenon is itself common knowledge.

More accurately, I wouldn’t say that I know that you know that this is common knowledge. And I also wouldn’t say that I know that you know that I know that this is common knowledge.

In drawing attention to this phenomenon, however, I am, like Pinker, helping to make this phenomenon, which involves common knowledge, common knowledge.

I’m not joking. Well, actually, I am joking. But the joke is accurate. Pinker’s book goes on like this for hundreds of pages. Reading it is a discombobulating but glorious experience. Section after section takes us down one, then another, then another layer of reflexivity.

In doing so, the book brings to light the endless ways that common knowledge – knowledge that everyone knows that everyone knows – affects our individual lives and society.

Indeed, having read Pinker’s book, my sense is that tussling with “common knowledge” is just about the most common thing we humans do – it’s up there with breathing and sleeping.

Though it isn’t exactly common knowledge that this is the case.

Common knowledge is not exactly knowledge in the sense of established and widely accepted facts. Pinker is not talking about Einstein’s General Theory of Relativity or other well-established truths, like calculus or maybe even the law of supply and demand, though such truths do come into it.

Rather, common knowledge refers to beliefs that are commonly held, and that people........

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