Future Generations, Obligations to

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Unless something goes drastically wrong in the next few centuries, future people will greatly outnumber those currently alive. The actions of present generations have potentially enormous impact on those who will live in the future. Perhaps the most significant impact is that society's decisions affect who those future people will be–and even if there will be any future people at all.

Despite its obvious importance, intergenerational ethics has not loomed large in traditional moral philosophy. Only since the 1960s have philosophers really begun to grapple with the complexities involved. Much of the discussion has been highly technical, focusing on logical puzzles regarding the value of existence and on the possibility of comparing the lives of different possible individuals. But underlying these difficult-to-understand technicalities are some of the deepest moral questions. What makes life worth living? What do we owe to our descendants? How do we balance their needs against our own?

The Non-Identity Problem

In his classic discussion of the present generation's obligations to future generations, Derek Parfit distinguished two kinds of moral choice. In a Same People Choice, society's actions affect what will happen to people in the future, but not which people will come to exist. If an individual's actions does affect who will exist in the future, then one is making a Different People Choice. Parfit claimed that Different People Choices are much more frequent than one might expect and that many traditional moral theories cope much better with Same People Choices than with Different People Choices. Taken together, these two claims constitute Parfit's Non-Identity Problem, so called because in a Different People Choice, those who would come to exist in one possible outcome are not (numerically) identical to those who would come to exist in an alternative possible outcome.

Suppose the cheapest way to meet the energy needs of the present generation is to build a power plant in a presently unoccupied desert. Experts know that the plant will be safe for several generations but will then leak radiation, harming those living nearby. The choice is made to build this plant, rather than to build a safer, more expensive one somewhere else. To many this behavior seems outrageous. Several common moral principles, however, imply that there is nothing wrong with the decision. Suppose one thinks that an act is wrong only if it wrongs some particular person, that people are wronged only if they are harmed, and people are harmed only if they end up worse off than they would otherwise have been. Now apply these principles to the choice of energy policy. Suppose the lives of those who suffer from radiation poisoning are worth living overall. If the safer plant was chosen, those future people would never have existed, because their great-grandparents, who moved to the desert to build the plant, would never have met. So the future people have no complaint, because the choice has not harmed them.

Philosophers have responded to the Non-Identity Problem in three distinct ways: (1) Some deny that present-day society has any obligations to future people. For instance, David Heyd is a defender of a "generocentric" position, where the behavior of the present generation is constrained only by obligations to contemporaries and to themselves. (2) "Person-affecting theorists" argue that society does have obligations to particular future people, even if our actions create those people and their lives are worth living. One common approach appeals to rights. If future people have a right to an unpolluted atmosphere, then our current practices might violate that right, even though the resulting people have lives worth living. (3) Utilitarians argue that society should make future humans as happy as possible, regardless of their identity.

The Repugnant Conclusion

Utilitarianism avoids the Non-Identity Problem by treating Different People Choices and Same People Choices analogously. In either case, individuals seek to maximize the happiness of whoever exists. Unfortunately, utilitarianism faces other problems, especially in Different Number Choices, where society decides how many people there will be.

In describing Different Number Choices, Parfit imagined a choice between two possible futures, A and Z. In A, there are 10 billion people, all of whom have wonderful lives. In Z, there is a much larger number of people, all of whom have lives that are "barely worth living." Parfit argued that if the second population is sufficiently large, then traditional utilitarianism must prefer Z, because it contains more happiness.

This "Repugnant Conclusion" is the organizing problem of contemporary utilitarian value theory. Some utilitarians reply that the value of a possible outcome should be a function of the average happiness, as well as total happiness. Others embrace the Repugnant Conclusion but argue that the Z future cannot be as bad as Parfit suggested. Debate often focuses on the precise specification of the "zero level"–the point below which a life ceases to be worth living. By definition, the people in Z live just above that zero level. If the zero level is set at a comparatively high level, then life in the Z world might be reasonably worthwhile. Some philosophers argue that, in this case, it would not be repugnant to prefer Z to A.

The Unequal Circumstances Problem

The quality of life of future generations is largely dependent on society's decisions. By contrast, the quality of life for present generations is not affected at all by decisions of future generations. Present generations can do a great deal to posterity, but posterity cannot do anything to them. Western political philosophy has often discussed justice in terms of mutually advantageous reciprocal interaction, either in the actual world or in some hypothetical choice situation. Traditional political theories thus find it hard to generate any obligations to future generations.

Some theorists expand the traditional social contract, imagining a contract between different generations, perhaps built on a series of contracts between overlapping generations. Others reject the individualism of much contemporary political philosophy, arguing that only a holistic approach can provide an adequate framework for thinking about our obligations to future generations. If members of the present generation view their own lives as bound together with those of their ancestors and descendants in an intertemporal community, then it is easier to see how they might have obligations to future people.

See also: Environmental Ethics; Generational Accounting; Intergenerational Transfers.


Barry, Brian. 1977. "Justice between Generations." In Law, Morality, and Society: Essays in Honour of H. L. A. Hart, ed. P. M. S. Hacker and J. Raz. Oxford: Clarendon Press.

——. 1978. "Circumstances of Justice and Future Generations." In Obligations to Future Generations, ed. Richard Sikora and Brian Barry. Philadelphia: Temple University Press.

Heyd, David. 1992. Genethics: Moral Issues in the Creation of People. Berkeley: University of California Press.

Kim, Tae-Chang, and Ross Harrison, eds. 1999. Self and Future Generations: An Intercultural Conversation. Cambridge, Eng.: White Horse Press.

Mulgan, Tim. 1999. "Teaching Future Generations." Teaching Philosophy 22: 259–273.

Parfit, Derek. 1984. Reasons and Persons. Oxford: Oxford University Press.

Tim Mulgan