Philosophers have been writing about addiction continually since the 1990s, and a number of much older, broader philosophical theories are of direct relevance to the study of addiction. Yet the developments in the philosophical study of addiction have seldom been incorporated into the science of addiction. In this paper I focus upon two issues in the scientific literature: the disease classification of addiction and the claim that addictive behaviour is compulsive. While each of these views is open to debate on empirical grounds, there is a long history of philosophical work which must be engaged if these claims are to be justified in a philosophical sense. I begin by showing how the conceptual work of philosophers such as Boorse and Nordenfelt can be used to critique the claim that addiction is a disease. Following this, I demonstrate how deep philosophical concepts of freedom and willpower are embedded into scientists' claims about compulsion in drug addiction. These concepts are paradoxical and difficult, and they have consumed numerous contemporary philosophers of mind, such as Audi, Arpaly, Frankfurt, Mele, Wallace and Watson, among many others. I show how problems can arise when scientists sidestep the work of these philosophers, and I explain where scientists should seek to include, and sometimes exclude, philosophical concepts. CONCLUSIONS Many philosophical concepts and theories can be of use to addiction science. The philosophical work must be understood and acknowledged if the science is to progress.