Modal Interpretation of Quantum Mechanics and Classical Physical Theories

Abstract

In 1990, Bas C. van Fraassen defined the modal interpretation of quantum mechanics as the consideration of it as a pure theory of the possible, with testable, empirical implications for what actually happens. This is a narrow, traditional understanding of modality, only in the sense of the concept of possibility (usually denoted in logic by the C. I. Lewiss symbol 3) and the concept of necessity 2 defined by means of 3. In modern logic, however, modality is understood in a much wider sense as any intensional functor (i.e. non-extensional or determined not only by the truth value of a sentence). In the recent (independent of van Fraassen) publications of the author (1997), an attempt was made to apply this wider understanding of modality to interpretation of classical and quantum physics. In the present lecture, these problems are discussed on the background of a brief review of the logical approch to quantum mechanics in the recent 7 decades. In this discussion, the new concepts of sub-modality and super-modality of many orders are used.