Is Addiction a Heterogeneous Condition? Reflections on Pickard's 'The Purpose in Chronic Addiction'

摘要

Both the traditional disease model of addiction and Pickard's "purposive" model (Pickard 2012) attempt to define the motivational influence exerted by substances of abuse on agents that influence the agents' behavior toward further substance consumption. Such a definition would seem to take the form "For all substances S that cause addiction/dependence, there exists a kind of motivational influence M such that agents affected by M are more inclined to engage in substance-related behaviors B." In these terms, the argument between Pickard and proponents of the disease model is over the nature of M, and evidence such as the epidemiological data cited by Pickard and neurological changes cited by disease theories (e.g., Everitt and Robbins 2005) are attempts to support differing conceptions of M. Specifically, the disease model argues that -M is a change in control from mechanisms underlying voluntary to those underlying compulsive action, whereas Pickard argues that M is a combination of five factors that converge around a putative reason or "purpose" for the agent to consume the substance.