Abstract

Pythagoreanism, the claim that ‘all is number’, is rarely taken seriously these days as a candidate for the sober metaphysical truth. This is a mistake. I distinguish various versions of Pythagoreanism. Some such versions are unmotivated, some are subject to serious objections, and some are both. But, I argue, there is a robust version of Pythagoreanism—according to which there is a true theory whose ontology and ideology are wholly mathematical from which every truth follows—that is both well-motivated and not subject to any serious objection. Given that fact, Pythagoreanism ought to be a serious metaphysical contender.