One of the most important insights to emerge slowly over the past hundred years is that the actions of the current generation—that is, what we do—could have profound and far-reaching effects for future generations. It was during the debate over nuclear power that this insight took firm root in the public consciousness since it brought with it a much longer time perspective than any previous generation has had to consider. For example, it is expected that high-level waste needs to be isolated from people and nature for 100,000 years—a mind-bogglingly long time. More recently—at least in this time perspective—climate change has emerged as the cardinal challenge. It raises new and important but very difficult questions about how we should morally evaluate different alternatives that will have consequences far into the future.
In the discussion of how to evaluate different outcomes, the number of individuals and who these individuals are have usually been taken for granted. The focus has been on the how to distribution benefits and burdens among an already given group of people. When we consider future generations, however, we cannot take the affected group as a given, since our actions not only affect the living conditions of future people, but also the number of people and who these people will be. In Gustaf Arrhenius's talk, he discusses some of the problems this raises for the moral evaluation of different futures.