Hans Sluga is William and Trudy Ausfahl Professor of Philosophy at the University of California, Berkeley. His publications include Gottlob Frege (1980), Heidegger's Crisis, Philosophy and Politics in Nazi Germany (1994) and Wittgenstein (2011). He is also the editor of The Philosophy of Frege (1993) and the co-editor of The Cambridge Companion to Wittgenstein (with David Stern, Cambridge, 1996).