Abstract: Cass Sunstein's Laws of Fear (2005) is an influential attack on the Precautionary Principle (PP). At its heart is a quick conceptual argument. Sunstein argues that, applied consistently, the PP leads to incoherent, paralyzing policy outcomes, unlike Cost-Benefit Analysis (CBA). Sunstein claims that many regulators are able to apply the PP only because they are hostage to pervasive cognitive biases causing them to reason inconsistently. These biases affect the majority of the population, so they also affect ordinary applications of CBA. To establish that we biased cognizers should prefer CBA to the PP, Sunstein would need to demonstrate that the actual policy outcomes that the PP leads to, when applied by biased cognizers, are inferior to those that are recommended by the application of CBA. No such demonstration is made in Laws of Fear, so the work suffers from an evidential gap. I consider four ways in which Sunstein might try to quickly rejig his conceptual argument against the PP to meet my criticisms and I argue that none would succeed. However, I argue that a ‘slow' argument against the PP, which draws on empirical evidence about the possibility of ameliorating bias, alongside conceptual considerations, has good prospects of success.

Steve Clarke is a Research Fellow on the Programme on the Ethics of the New Biosciences, and is a researcher on the new AHRC funded Research Project ‘Cognitive Science and Religious Conflict'.