Risk, Uncertainty and Catastrophe Scenarios

Some scholars, most notably Martin Weitzman (2009; 2011) have warned that there is an uncertain chance of runaway climate change that could devastate the planet. At least since Hans Jonas’s The Imperative of Responsibility (1981), some have argued that even low-probability existential risks should be treated in a fundamentally different way. How should we act when we believe that there is some chance of a catastrophe, but cannot make reliable probability estimates (Elster 1979; Haller 2002; Gardiner 2005)? How much should we worry about worst-case scenarios? What should we do when experts disagree about whether catastrophe is possible?