Complex Technology, Complex Calculations: Uses and Abuses of Precautionary Reasoning in Law

Abstract

After a honeymoon period in environmental law, the so-called “precautionary principle” has received sustained criticism. This paper does not try to rescue the precautionary principle as such. However, it is argued, using Pascal’s Wager, that there are conditions under which precautionary reasoning is valid, which provides a general principle for the limiting case. Although the limiting principle does not apply straightforwardly to the principle that those accused of criminal offences should not be convicted unless found guilty beyond all reasonable doubt, this case suggests an alternative principle that employs precautionary reasoning in a proportionate manner. To apply the limiting principle involves difficult judgments about the relative undesirability of options presented and the proportionality of the precautionary response. Nevertheless, it is argued that the limiting principle provides a strong argument against the death penalty, and that precautionary reasoning is more widely involved in legal reasoning than generally appreciated; e.g., wherever the burden of proof is placed more strongly on one party, where the threshold in relation to a particular option is raised, and, perhaps, in slippery slope and floodgates arguments.