One of my favourite seminar topics I pose for my students is for them to apply the precautionary principle to the precautionary principle.
It is a basic, axiomatic tenet of environmentalism that the precautionary principle is an essential aspect of all public policy deliberation. Yet many are unaware of the ramifications of the precautionary principle and, more so, its common application in the restriction of human activity, rather than as a tool to assist in decision making.
Here is a good post on the precautionary principle, a link to an originating, thoughtful essay and a series of interesting comments that illustrate the myriad of ways in which the precautionary principle is (and isn't) understood to be working.
All of which is a great excuse for this quote from Samuel Johnson: Nothing will ever be attempted if all possible objections must first be overcome.