 Thus, for each framework (no matter whether it describes empirical objects, abstract objects, or a mix of both), one can formulate both simple and complex existential statements. According to Carnap, each simple existential statement is either empirical or analytic. If a simple statement is empirical, its truth value can be determined by a combination of empirical inquiry and consideration of the linguistic rules governing the framework; if the simple existential statement is analytic, then its truth value can be determined simply by considering the linguistic rules governing the framework. Whereas the simple existential statements that require empirical investigation assert the existence of possible concrete entities (like ‘tables’ or ‘unicorns’), the simple existential statements that are analytic assert the existence of abstract entities. Let us call this criterion for asserting the existence of abstract objects the criterion of linguistic rules.