 There are a few different arguments that have been brought against mathematical platonism, but the most important—and the most famous—is what is known as the epistemological argument against platonism. This argument goes back at least to Plato. In contemporary times, it received its most classical statement in a paper by Paul Benacerraf (1973), although most philosophers of mathematics agree that Benacerraf’s formulation of the argument is problematic because of its reliance on an implausible causal theory of knowledge. A better way to formulate the argument is as follows: