  However, many proponents of modal schemes argue that the latter feature is not appropriately expressed by saying that quantum mechanics, modally conceived, is incomplete. They object that this incompleteness terminology is apt to suggest a defect of the theory, and the need for completion (by hidden variables). But modal theorists maintain that their interpretations of quantum mechanics are not in need of additions, because these interpretations already contain everything that can reasonably be expected from theories describing a fundamentally probabilistic (indeterministic) world. First, modal schemes completely specify which observables are definite-valued. Second, they fix the possible values that may be taken by these observables and they provide the probabilities with which these values may be realized. Since it is a core modal principle that the actualization of properties in the quantum world is a fundamentally probabilistic (indeterministic) process, nothing more than this probabilistic description is possible. From this viewpoint, insisting that modally interpreted quantum mechanics is necessarily incomplete is tantamount to stipulating that any probabilistic theory must be incomplete by definition—even if it applies to a fundamentally probabilistic world. But that appears an inappropriate use of terminology.