Johan van Benthem is University Professor of Logic at the University of Amsterdam, Henry Waldgrave Stuart Professor of Philosophy at Stanford University, and Weilun Visiting Professor at Tsinghua University, Beijing. He is the author of Language in Action (1991) and Exploring Logical Dynamics (1996) and an editor of the Handbook of Modal Logic (2006), the Handbook of Spatial Logics (2007) and Philosophy of Information (2008).