Romanides proceeds to argue that Barlaam was clearly a Christian Platonist and not a nominalist. The first philosophers to explicitly describe nominalist arguments were the Stoics, especially Chrysippus. In "Ideas Have Consequences", Weaver analyzed William of Occam's 14th century notions of nominalist philosophy. Burgess distinguished two types of nominalist reconstructions. William Lane Craig has proposed an nominalist argument influenced by the philosophy of mathematics. Dignaga formulated a nominalist theory of meaning called "apoha", or theory of exclusions. He was an extreme nominalist who saw the three divine persons as separately existing. Armstrong rejects nominalist accounts of properties that attempt to align properties simply with classes.