Much of what we are able to accomplish in our day-to-day lives depends on the ability to act and think in concert with others. Often this involves not only the capacity to perceive together the surrounding world—we must also know that we perceive together. In other words, there must be perceptual common knowledge. Philosophical questions mount quickly: How is this kind of knowledge possible? How does it arise? What does its possibility show us about our sociality? What does it suggest about the world around us?

In The Shared World: Perceptual Knowledge, Demonstrative Communication, and Social Space (MIT Press, 2019), Axel Seemann develops an account perceptual common knowledge that is both philosophically subtle and empirically informed.