Science and public policy: what’s proof got to do with it?

In recent years, it has become common for opponents of environmental action to argue that the scientific basis for purported harms is uncertain, unreliable, and fundamentally unproven. In response, many scientists believe that their job is to provide the “proof” that society needs. Both the complaint and the response are misguided. In all but the most trivial cases, science does not produce logically indisputable proofs about the natural world. At best it produces a robust consensus based on a process of inquiry that allows for continued scrutiny, re-examination, and revision. Within a scientific community, different individuals may weigh evidence differently and adhere to different standards of demonstration, and these differences are likely to be amplified when the results of inquiry have political, religious, or economic ramifications. In such cases, science can play a role by providing informed opinions about the possible consequences of our actions (or inactions), and by monitoring the effects of our choices.