Talking about Knowledge Johan van Benthem Abstract: In current studies of knowledge at the interface of logic and epistemology, philosophical positions and logical systems lore meet in new ways. This little piece, a programmatic sequel to van Benthem 2011 ("Logical Dynamics of Information and Interaction") and a prequel to Baltag et al. 2015 ("The Music of Knowledge"), adds some further perspectives and issues to this mix from dynamic­epistemic logics of information and inquiry. Its aim is to show that we can have a yet richer agenda of epistemic themes, and a richer view of the interplay of logic and epistemology, when we make epistemic action a major focus on a par with knowledge or belief per se. To appear in C. Baskent, L. Moss & E. Pacuit, eds., "Rohit Parikh Volume", Outstanding Contributions to Logic, Springer. Keywords: knowledge, relevant alternatives, belief, logic