Called by professional philosophers “the indispensability argument for mathematical realism,” it basically asserted the existence of mathematical entities. W.V.O. Quine (1908–2000) and Hilary Putnam (1926-) argued that we have to commit to the existence of, or “have ontological commitments to,” things that are indispensable for the best science. Mathematical entities qualify as indispensable. Therefore, we must commit to their existence.