Date of Original Version
Abstract or Description
This paper makes three points. (1) Drug-related measures, such as the number of users, have changed rapidly over time, suggesting that they are not merely symptoms of underlying trends in the economy, demographics, or other aggregates that change more slowly. (2) Drug markets are subject to a wide range of feedback effects that can induce non-linearity into dynamic behavior. (3) There are at least five classes of epidemic models that reflect such non-linear dynamic behavior. Some of those classes tend to be optimistic about the ability of drug control interventions to reduce use; others are pessimistic. It is hoped that this discussion and, in particular, the typology, can inform and elevate the debate about drug policy, but it is unlikely to resolve that debate because of the inability to demonstrate empirically which class(es) are most accurate.