Of all the ironies in academia, this one felt particularly unlikely: I was asked to introduce Steven Pinker and moderate the Q&A for his latest book, When Everyone Knows That Everyone Knows... : Common Knowledge and the Mysteries of Money, Power, and Everyday Life.

The problem? Pinker and I inhabit different intellectual universes.

If you could map cognitive science onto physics, Pinker's world operates like Newtonian mechanics: clean lines, predictable trajectories, universal laws. Language, in his framework, is an instinct, a distinct module that evolved in our species. It works in clear causal chains and direct relationships. Common knowledge (that recursive structure where I know that you know that I know) is something we can identify, analyze, and deliberately construct to solve coordination problems.

My world looks more like quantum mechanics and relativity. Language, to me, is composed of bits and pieces cobbled together from our evolutionary history. As Elizabeth Bates noted, "It is a new machine built out of old parts," fragments borrowed from tool use, the lucky accident of our vocal anatomy, the expansion of our brains. These elements converged into something we call language, but it's fundamentally messy, embodied, and emergent. We are, like so many other animals on this planet, sensing our way through the world, listening, moving, feeling, and from all those sensations, we construct a model of other minds and our own.

Both Pinker and I acknowledge that our models are flawed. But here's where we diverge: I think the world is far more malleable and far less precise than his framework allows. Even when we establish norms (when something becomes "what everyone knows that everyone knows"), they shift with dizzying speed. This flow of information, what I call the informational singularity, makes knowing what constitutes shared truth unexpectedly treacherous.

During the........

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