  Reductionist ontological naturalism and non-modal structuralism about set theory face an immediate problem: there are apparently far fewer entities in spacetime than there are sets. Even on the most liberal assumptions (spacetime points and arbitrary regions thereof exist, some smallish infinity of entities may be collocated at any of these points or regions), the size of spacetime and the objects in it is a relatively low infinite cardinality (surely no more than ω—even that is generous). Thus there are not enough spatiotemporal entities to interpret set theory literally nor to make a structural interpretation of set theory non-vacuously true, and hence to ensure that set-theoretic falsehoods come out false rather than true. See Paseau (2008) for discussion of this and other problems for set-theoretic reductionism.