Le principe de précaution n'est pas un catastrophisme

In spite of early confusion, the precautionary principle is very different from the principle of abstention that asks the promoter to bring the certain proof of safety of a product or a technology before it can be authorized, and the authorities to forbid any product or technology for which there is a scientific doubt. The main idea brought by the precautionary principle is that of earliness in taking account of potential threats of huge and irreversible damage to the environment. But this idea of earliness is counterbalanced by the requirement that precautionary measures are provisional and proportionate. Thus the precautionary principle is all but a catastrophism; moreover it is for good reasons that this principle has maintained itself far away from various forms of catastrophism. After having sketched the main components of the precautionary principle, the paper discusses different types of catastrophism and shows their lack of self-consistency. A special consideration is given to the thoughts of Hans Jonas and Jean-Pierre Dupuy, but also to a specific involuntary type of catastrophism that results from an inappropriate frame of assessment that focuses only on potential damages and gives the same consideration to all non-refuted hypotheses.