In part one, I identify the core logical structure of the precautionary principle and distinguish it from the various key concepts that appear in the many different formulations of the principle. I survey these concepts and suggest a program of further conceptual analysis. In part two, I examine a particular version of the precautionary principle dubbed “the catastrophe principle” and criticize it in light of its similarities to the principle at work in Pascal’s Wager. I conclude with some suggestions for (...) advocates of the precautionary principle who wish their formulation to avoid the pitfalls confronting the catastrophe principle. (shrink)