Precaution without paralysis: A theory for decision-making under extreme events

Traditional approaches to risk management in conservation decision making often break down in the face of extreme events. How do you plan for a very unlikely event with a very undesirable outcome? Though a fundamental tenet of conservation, the precautionary principle can provide little guidance in these cases: modest precaution provides an insufficient buffer against extreme perturbations. Decision-theoretic approaches similarly founder on action paralysis as soon as a given action has potentially unacceptable consequences, however unlikely. I will illustrate these challenges using examples from marine fisheries and suggest a new approach for addressing this uncertainty by learning from the past.