 Once one is accustomed to comparing the naturalness of properties, it is natural to want to extend such comparisons to propositions. For example, the proposition that some things are green should count as more natural than the proposition that some things are grue. While the use of ‘natural’ to apply to propositions is rare, talk of propositions—or of proposition-like entities like hypotheses, theories, accounts, proposals, etc.—as being more or less simple is ubiquitous, in science as well as philosophy, and arguably amounts to the same thing.