Abstract

Mathematics has had its share of historical shocks, beginning with the discovery by Hippasus the Pythagorean that the integers could not possibly be the elements of all things. Likewise with Kurt Gödel’s Incompleteness Theorems, which presented a serious (even fatal) obstacle to David Hilbert’s formalism, and Bertrand Russell’s own discovery of the paradox inherent in his intuitively simple set theory. More recently, Paul Benacerraf presented a problem for the foundations of arithmetic in “What Numbers Could Not Be” and “Mathematical Truth.” Drawing out difficulties he found in mathematical realism, Benacerraf ended up proposing his own structuralist view of mathematics, according to which numbers could not be considered objects at all, but mere placeholders, wholly defined in terms of the structures within which they were found. While we do not intend to work through the intricacies of structuralism or other types of mathematical nonrealism, or even of any of the many other competing theories in contemporary philosophy of mathematics, our question concerns problems one finds in an earlier, and perhaps more naïve, view of mathematics which, though a realism of its own, begins with seemingly more problematic assumptions than these. Classically expressed, the question is: do numbers exist in the world, whether as substances or as attributes of things? These are among the things Benacerraf holds numbers could not be; still, we hope to dispel some of the confusion which might bring one prematurely to reject this account. Most precisely, we wish to address the problem whether there can be a science of arithmetic, as that term is understood by Aristotle and Thomas Aquinas.