All the fears of our age seem to have found shelter in one word: precaution. Yet the conceptual underpinnings of the notion of precaution are extremely fragile.
Let us recall the definition of the precautionary principle formulated in the Maastricht treaty:
The absence of certainties, given the current state of scientific and technological knowledge, must not delay the adoption of effective and proportionate preventive measures aimed at forestalling a risk of grave and irreversible damage to the environment at an economically acceptable cost.
A first serious deficiency which hamstrings the notion of precaution is that it does not properly gauge the type of uncertainty with which we are confronted at present. The very formulation of the precautionary principle makes it clear that it places itself from the outset within the framework of epistemic uncertainty, i.e. a form of uncertainty that resides in the mind of the knowing subject rather than in the objective properties of the outside world. The presupposition is that we know we are in a situation of uncertainty. It is an axiom of epistemic logic that if I do not know p, then I know that I do not know p. Yet, as soon as we depart from this framework, we must entertain the possibility that we do not know that we do not know something. In cases where the uncertainty is such that it entails that the uncertainty ...