Abstract
The great evolutionist Ernst Mayr coined the term “population thinking” to encourage biologists to shift their focus from prototypical individual organisms toward the parameters that characterize populations as a whole. Economists are trained to cultivate a similar mind-set, as captured by concepts like “general equilibrium.” Clinicians in psychiatry and psychology may question the relevance of such aggregate-level concepts for their work. But in my research on the analysis of national substance abuse policies, I've come to appreciate that population thinking is a valuable adjunct to the more traditional clinical focus on the client or patient. Clinical treatment innovations can have broader social effects, both desirable and undesirable. The clinical trial paradigm is a tremendously powerful engine for medical progress, but as I hope to illustrate through the following brief case studies, this paradigm is not always well suited for exploring these broader consequences.