What Are Numbers?

Plato claimed that numbers exist in some mind-independent abstract heaven. Nominalists claim that there is no such heaven. Clearly, we can’t see, hear, taste or feel numbers. But if there are no numbers what is mathematics all about? John and Ken count on a great discussion with Gideon Rosen from Princeton University, co-author of A Subject With No Object: Strategies for Nominalistic Interpretation of Mathematics.