Extending Lewisian Modal Metaphysics from a Specific Quantum Gravity Perspective

In this essay I propose a metaphysical model of extension of Lewisian modal metaphysics in light of the physical content and formal articulation of quantum string theory. The broad rationale behind the project is that of showing that, although endorsing the metaphysical commitment of quantum string theory to the nonfundamentality of space and time, an attempt of preserving crucial features of Lewisian modal metaphysics (assigning a fundamental role to spatiotemporal relations) is not only possible but also has interesting philosophical implications. My extension applies to two Lewisian accessibility structures, the similarity accessibility and the nomological one. As it turned out in the essay, the formal scheme, constructed by extrapolating parts of the theory’s formal articulation and physical content, calibrates a metaphysical accessibility structure extending Lewisian similarity, because of fully carrying its structural properties. It also calibrates a metaphysical accessibility structure tentatively extending Lewisian nomological accessibility, because of only partially carrying its structural properties. So, the two Lewisian accessibility structures can be regained from the two extensions, even though the nomological one only partially. Then, the bottom line is that the extended metaphysical accessibility structures (especially the one extending Lewisian similarity) appear to be somehow “more fundamental” than the Lewisian ones in virtue of the fact that some of their crucial properties smoothly reflect the discreteness of the fundamental quantum nature of reality.