The precautionary principle: a new approach to public decision-making?

The precautionary principle recommends preventing possible harm to human health and environment. It has gained support in the international community as a higher-order legal principle that should guide public policy and the formulation of specific laws. But it is also the target of much criticism, with many arguing that the principle is vacuous, inconsistent or based on an excessively conservative attitude towards risk. I argue that the value of the precautionary principle is that it emphasises aspects of good decision-making that go beyond the scope of formal decision theory, and are often neglected in practice. It is best conceived as providing guidelines for formulating a decision problem, as opposed to challenging standard decision rules. To this effect, the principle advocates assessment of acts relative to feasible alternatives, and proper representation of all potential outcomes of acts (including those outcomes that are probabilistic or scientifically uncertain). In terms of determining suitable outcome utilities and burdens of proof, I claim that the precautionary principle appeals to ethical ideals associated with ‘sustainable development’. I finally outline some general implications of the principle for environmental decision-making.