Powers for Dispositionalism: A Metaphysical Ground for New Actualism

Abstract

In this dissertation, I develop a metaphysics of powers to ground Dispositionalism, the theory of the source of modality according to which all alethic modal truths are grounded in dispositional properties instantiated in the actual world. I consider a number of key theses that powers metaphysics display, and investigate which can be incorporated in the metaphysical base of Dispositionalism, and how.
In the first part I examine the interaction of two core principles of powers ontologies: Directedness, the thesis that powers ‘point at’ their manifestations, and Independence, the thesis that powers can fail to manifest. These two principles are in tension: there is an argument, known as Too Much Possibility, to the effect that they are inconsistent. I examine various strategies to resist the argument. These involve Physical Intentionality, numerical identity between power and manifestation, process ontologies, and platonic universals. I conclude that they are all unsatisfactory. 
In the second part, I develop a ‘minimal metaphysics of powers’ that is immune from the threat of Too Much Possibility. This involves considering unmanifested manifestations to be akin to (a suitably re-vamped version of) Mere Logical Existents. I argue that the best way to avoid the tension at the heart of powers ontologies is to conceive of unmanifested manifestations as non-essentially non-spatiotemporally located entities. I then consider some consequences of minimal metaphysics: I examine which ontological category the manifestations of power can belong to, and what are the prospects of grounding metaphysical, as opposed to natural, modality.
Finally, in the third part, I investigate whether further key theses of powers ontologies can be incorporated into the minimal metaphysics. This leads to discuss the relationship of the minimal metaphysics with grounding and dependency relations, the metaphysics of time, the truthmaking principle, and tendential theories of powers.