How does the Precautionary Principle address the question of uncertainty?
TS: It is important to acknowledge various kinds of uncertainty. One kind of uncertainty is statistical. This has to do with not knowing the exact value of a single variable like, for example, off-gassing from a building material. But we can measure it and ultimately reduce the uncertainty considerably. Another kind of uncertainty is model uncertainty. This arises from inadequate understanding of the relationships among variables in a system. How, for example, will that off-gassing affect building occupants over time? This is far more complex and difficult to study. As models become more complex, uncertainty evolves into indeterminacy. This leads to fundamental uncertainty. Here we deal not only with indeterminacy but often fail to know what we don’t know. We may not even know what questions to ask. Precaution takes a respectful approach to complex systems, acknowledges the limits of science, and is wary of arrogance. A precautionary approach looks for early warning signs and opportuni
