The addiction literature is fraught with conceptual confusions, stalled debates, and an unfortunate lack of clear and careful attempts to delineate the phenomenon of addiction in a way that might lead to consensus. My dissertation has two overarching aims, one metaphysical and one practical. -/- The first aim is to defend an account of addiction as the systematic disposition to fail to control one’s desires to engage in certain types of behaviors. I defend the inclusion of desires and impaired control (...) in the definition, and I flesh out the notion of systematicity central to my dispositionalist framework. I engage the so-called ‘disease vs. choice’ debate, criticizing its presupposition that we are dealing here with a dichotomy and arguing that the movement towards a middle ground is the right track to take. I explain how the dispositionalist account can capture this middle ground and how it serves to expand upon existing views, in particular by filling in the metaphysical details. -/- The second aim is to show how the account I defend can help to unify the extant views and disciplinary perspectives in the literature. Both the dispositionalist aspect of my framework and the methodology adopted (applied ontology and systematic metaphysics) can move the literature towards both substantive and methodological unification. This will help to clear up conceptual confusions, resolve (or sometimes dissolve) apparently intractable disputes, situate different research perspectives with respect to each other, facilitate interdisciplinary dialogue, and help to frame important questions about addiction. Finally, I offer the beginnings of an ontology of addiction, which will provide a terminologically well-structured guide to the addiction literature in a way that will facilitate more effective and efficient communication and data management across disciplines. (shrink)