The dissertation analyses the capacity of contractualism and natural law to justify environmental intergenerational duties.

For three decades, climate change has been a major political concern. As a fundamental threat to environmental sustainability, climate change is believed to threaten the long-term welfare of humankind. It thus seems imperative to affirm long-term duties regarding future people’s environment. Furthermore, contractualism and natural law are two important moral theories in contemporary political life. While the former seems influential among political liberals, natural law seems more appealing to political conservatives. It is thus of interest how both of these theories can be used to argue for environmental intergenerational duties. Yet, natural law has been particularly understudied in this regard.

The point of departure of the study is the so-called non-identity problem, formulated by Derek Parfit. As concerns future generations, what we do not only affects the quality of people’s lives, but also who will come to exist. If future people come to exist as a consequence of how we live our lives, including the choice of living unsustainably, a degraded environment will be worse for no one. For so-called person-affecting theory, such as contractualism, non-identity seems to imply that there is nothing morally objectionable about leaving future people with an unsustainable environment.

First, the dissertation demonstrates recent attempts in contractualism, in the vein of John Rawls and Thomas Scanlon, to solve the non-identity problem on person-affecting terms. It is shown that these attempts either fail to affirm environmental intergenerational duties or implicitly abandon a person-affecting view.

Second, the dissertation explores a natural law approach to the non-identity problem, employing a recent account of natural law suggested by John Finnis. While natural law can be considered of import in contemporary political decision-making, it has hardly ever been used to ground environmental intergenerational duties. This dissertation shows how an impersonal application of natural law could be used in attempts to circumvent the non-identity problem, i.e. to affirm environmental intergenerational duties, and treats possible objections to such an account. It is argued that the requirement to consider so-called basic values, also in cases when no individual would be worse off by one’s act, should render it at least morally objectionable to leave future generations with an unsustainable environment.

Third, a new kind of objection to environmental intergenerational duties is discussed in depth. The objection applies to theories that, although they may accept an impersonal view in morals, subscribe to a person-affecting restriction in politics. On some interpretations, this limited restriction can be ascribed to both contractualism and natural law. This may imply a specifically institutional non-identity problem. It conveys the possibly paralysing conclusion that, even if there are environmental intergenerational duties in a moral sense, we are not permitted to use political institutions to enforce them.

Again, contractualism is used to demonstrate the possible difficulties in overcoming this kind of problem. With regard to natural law, the dissertation explores how the use of institutions could be justified impersonally by reference to the common good and the idea of intergenerational community. In this view, experiences that link us to previous generations justify institutional responsibility for the future.