What is the non-identity problem?

It is the puzzle that many of our choices determine which particular people will later exist, so those future people cannot easily claim they were made worse off than they would otherwise have been, complicating the idea that we harm them.

What does 'sustainability' require, ethically?

Accounts differ. 'Strong' sustainability holds that critical natural capital must be preserved, while 'weak' sustainability allows substituting produced capital for natural capital so long as overall opportunity is maintained; which is correct is debated.

Future Generations and Sustainability

This topic concerns whether and what present people owe to future generations, and how the ideal of sustainability expresses obligations toward people not yet born.

Definition

The study of moral obligations of present generations toward future ones, and of sustainability as a normative ideal for the use and preservation of resources over time.

Scope

This topic covers intergenerational justice and the ethics of sustainability: whether future people can have rights against us, the non-identity problem, how to discount or weigh future welfare, what 'sustainability' requires regarding natural and produced capital, and the relation between present obligations and uncertainty about future needs. It surveys the philosophical literature and its principal puzzles, describing the arguments rather than recommending policies.

Core questions

Can people who do not yet exist hold rights or be owed duties now?
How does the non-identity problem complicate claims that we can harm future people?
Should the welfare of future generations be discounted, and if so on what basis?
What must be sustained for development to count as sustainable?

Key theories

The non-identity problem: Derek Parfit observes that policies affecting the long-term future also change who will exist, so a future person cannot straightforwardly be said to be harmed by a policy that was a condition of their existence, challenging person-affecting accounts of harm.
Sustainability as intergenerational justice: Brian Barry analyses sustainability as a requirement of justice across generations, arguing that later generations should not be left with worse opportunities than earlier ones enjoyed.

History

Concern with obligations to posterity gained philosophical rigor with Rawls's discussion of a 'just savings principle' (1971) and, decisively, Parfit's Reasons and Persons (1984), which framed the non-identity problem. The 1987 Brundtland Report's definition of sustainable development linked these debates to environmental policy.

Debates

Whether future people can have rights: Some argue that rights require existing right-holders, so duties to future generations cannot be grounded in their rights; others, like Gosseries, defend the coherence of future rights or recast the duties in non-rights terms.

Key figures

Derek Parfit
Brian Barry
Axel Gosseries
John Rawls

Seminal works

parfit1984
barry1997

Frequently asked questions

What is the non-identity problem?: It is the puzzle that many of our choices determine which particular people will later exist, so those future people cannot easily claim they were made worse off than they would otherwise have been, complicating the idea that we harm them.
What does 'sustainability' require, ethically?: Accounts differ. 'Strong' sustainability holds that critical natural capital must be preserved, while 'weak' sustainability allows substituting produced capital for natural capital so long as overall opportunity is maintained; which is correct is debated.