How can the deflationary nominalist explain the possibility of mathematical knowledge, given the abstract nature of mathematical objects? On this version of nominalism, this problem vanishes. Mathematical knowledge is ultimately obtained from what follows from mathematical principles. Given that mathematical objects do not exist, they play no role in how mathematical results are known (Azzouni 1994). What is required is that the relevant mathematical result be established via a proof. Proofs are the source of mathematical knowledge.