The precautionary principle as multi-period games where players have different thresholds for acceptable uncertainty

ABSTRACT The precautionary principle (PP) is formalized assuming multiple players (branches of government, interest groups, etc.). Each player has a different threshold for acceptable uncertainty. A flow chart illustrates how a threat impacts uncertainty. Thereafter each player, starting with the most precautionary, assesses whether the uncertainty is below its threshold. Replying yes implies no command and execution of action, and vice versa when replying no. One game is played in each time period through the flow chart, followed by a feedback loop causing a new and possibly lower threat and uncertainty. The process continues as long as at least one player experiences uncertainty above its threshold. The flow chart is illustrated with a 2  ×  2 game displaying equilibria through three time periods where both players, one player, and no players are precautionary. Illustrations are made involving pollution, climate change, genetically modified food, new drugs, and nuclear proliferation. A nuclear power example with three players illustrates equilibria with varying degrees of being precautionary.