Preface

I am a hippopotamus enthusiast. The hippopotamus is not only my favorite kind of animal but also my favorite kind of material object. When I was an undergraduate, I had a fine arts instructor who, like most people in my life, knew about my fondness for hippos. One day this instructor came into class and announced that he was going to show the class “the most wonderful hippo.” He took us to the nearby sculpture studio, where a visiting artist had molded a statue of a hippo out of clay. My instructor was right: it was a wonderful hippo. (Well, it was a wonderful representation of a hippo.) I do not know much about molding clay statues, but I will assume that, at some point, the artist began with a piece of clay that was merely an undistinguished lump, and then she gradually molded it into a hippo-like shape. This apparently innocuous case of artistic labor generates a well-known puzzle. On the one hand, there is a very good reason to think that the statue and the piece of clay it was molded from are the same object: they are located in exactly the same place at exactly the same time, and they are made of exactly the same matter. Normally, we do not think that two different objects can be in exactly the same place at exactly the same time and made of exactly the same matter. On the other hand, there is also a very good reason to think that the statue and the piece of clay are two different objects: they seem to differ from each other in certain ways. For example, it seems as though the piece of clay existed before it was molded into a statue-like shape, whereas it seems as though the statue did not yet exist at that time. So are the statue and the piece of clay one and the same object, or two different objects?1