From Merchants of Doubt, by Naomi Oreskes and Erik M. Conway:
All scientific work is incomplete—whether it be observational or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not confer upon us a freedom to ignore the knowledge we already have, to postpone action that it appears to demand at a given time. Who knows, asks Robert Browning, but the world may end tonight? True, but on available evidence most of us make ready to commute on the 8:30 next day.
“A demand for scientific proof is always a formula for inaction and delay, and usually the first reaction of the guilty. The proper basis for such decisions is, of course, quite simply that which is reasonable in the circumstances.” Or as Bill Nierenberg put it in a candid moment, “You just know in your heart that you can’t throw 25 million tons a year of sulfates into the Northeast and not expect some … consequences.”