Neumayer (1999) argues that economics cannot tell which policies should be favoured to tackle climate change because economic projections are partly based on unscientific beliefs. Calculations of discount rates, for example, depend on choices concerning whether environmental damage can be compensated by growth in material benefits, in other words whether the loss of natural capital can be compensated by an increase in man-made capital. He claims that the question of substitutability cannot be settled scientifically, but only within the political decision-making process.
Granted that we do not know what future generations prefer, I still think it is a mistake to argue that the validity of the “perfect substitutability paradigm” boils down to a matter of belief only. If we do not know for sure what future people want - but we try to act with their interest in mind even though they cannot yet represent themselves - surely the best course of action is to keep as many options open as possible. Given that natural capital offers the raw materials for man-made capital, preserving natural capital allows future generations to make decisions about the form their capital takes. If we use up “more than our share” of natural resources, we might end up curbing future generations’ options.
In contrasts to Neumayer, I argue that proponents of strong sustainability do not need to show that individuals have lexicographic preferences with respect to environmental amenities. Strong sustainability can be favoured without the need to view the environment as a superior good, and without claiming that anything that inflicts harm on future generations is unjustified and cannot be compensated for. The distinction between luxury emissions and subsistence emissions (Shue 1993) could be employed to analyse how widely and equally the benefits of emissions are shared.
