Some cognitive states — e.g. states of thinking, calculating, navigating — may be partially external because, at least sometimes, these states depend on the use of symbols and artifacts that are outside the body. Maps, signs, writing implements may sometimes be as inextricably bound up with the workings of cognition as neural structures or internally realized symbols (if there are any). According to what Clark and Chalmers [1998] call active externalism, the environment can drive and so partially constitute cognitive processes. (...) Where does the mind stop and the rest of the world begin? If active externalism is right, then the boundary cannot be drawn at the skull. The mind reaches – or at least can reach --- beyond the limits of the body out into the world. (shrink)