"The precautionary principle...

... is based on the belief that there is no down side to taking action. "

This is precisely the phrase I've been looking for in many conversations I have had in the past. It captures exactly what I want to say, from my initial sense of "somethign is wrong about that idea but I can't put my finger on it" all the way through the evolution into my current full-blown opposition to nearly everything espoused by someone who would embrace the so-called "precautionary principle."

I got there via The Anarchangel's article: Anthropogenic Global Warming is a Politically Motivated Scam

Both are worth reading.