"If the worst-case scenario played itself out - not the potential or likely, but the worst - would that be acceptable?" This is the advise that James M. Wilson offers clinical scientists. This comes from experience of the saddest kind. In 1999, James M. Wilson was the head of the institute that ran a gene therapy experiment that resulted in death of a 18 year old boy. (See! That's the thing. You get to hear a lot about the miracles of stem cell therapy. How many times have you heard voices of sanity that says, "Slow down! Reflect!") - you can read all about it; just click on the link above. If you think about it, the above warning is applicable to all those who are in the position to influence. Whether it is IPCC, or World Leaders, or CEO of a company, or a Project Manager or a Parent. The question remains the same: Would the worst-case scenario be acceptable to you? One might argue that this could lead to paralytic inaction. On the other hand, this could well turn out to be the basis of meaningful, positive action.