Jens Timmermann is Reader in Moral Philosophy at the University of St Andrews. He is the author of Kant's Groundwork of the Metaphysics of Morals: A Commentary (Cambridge University Press, 2007) and Sittengesetz und Freiheit (2003). He is the editor of Kant's Critique of Practical Reason: A Critical Guide (with Andrews Reath, Cambridge University Press, 2010) and of Kant's Groundwork of the Metaphysics of Morals: A Critical Guide (Cambridge University Press, 2009).