ABSTRACT
I shall discuss in this Chapter the modern form of a very old problem, much discussed by the scholastics, but still, in our day, far from being definitively solved. The problem, in its broadest and simplest terms, is this: “How shall we define the diversity which makes us count objects as two in a census?” We may put the same problem in words that look different, e.g. “what is meant by a ‘particular’?” or “what sort of objects can have proper names?”
