In this book, Michael Huemer and Bryan Frances debate whether – and how – we can gain knowledge of the world outside of our own minds. Starting with opening statements, the debate moves through two rounds of replies. Frances argues that we lack knowledge because, for example, we cannot rule out the possibility that we are brains in vats being artificially stimulated in such a way as to create an illusion of living in the real world. Huemer disagrees that we need evidence against such possibilities in order to gain knowledge of the external world, maintaining instead that we are entitled to presume that things are as they appear unless and until we acquire specific grounds for thinking otherwise. The authors go on to discuss how one should think about controversial issues wherein the experts persistently disagree. Frances argues that we should generally withhold judgment about such issues or at least greatly reduce our confidence. Huemer agrees that people are often overconfident about controversial issues but tries to carve out exceptions wherein one can rationally hold on to controversial views. Accessible whilst also detailed and substantial, this thoughtful debate is suitable for readers at all levels, from those encountering the topic for the first time through those who are deeply familiar with the issues. Key Features: Showcases arguments from two leading philosophers in standard form and in clear language Presents definitions in an easily accessible form Summary boxes recap key arguments Includes an annotated bibliography and glossary of all specialized vocabulary