Why Posterity Matters is the first comprehensive philosophical examination of our duties to future generations. It appears at a time when it is becoming increasingly obvious that we can no longer exploit the environment without causing risks for posterity.Dr de-Shalit argues that our obligations towards new generations are a matter of justice, not of charity or supererogation. It becomes our duty to consider them when we distribute access to natural resources, decide on environmental policies and plan budgets. This raises problems for conventional theories of justice. Why Posterity Matters puts forward a new communitarian theory of intergenerational justice, which can serve as the moral basis for environmental policy.