In the last chapter I rejected the ‘ecocentric’ perspective of many green thinkers, according to which the range of our morally permissible actions is limited or constrained by values in nature that are independent of the interests of humans and other sentient creatures. In this chapter I will examine the claim that nature constrains our actions in another way: by presenting us with a set of non-moral facts which we must acknowledge and adapt to for the sake of our own well-being. This idea of natural limits as material constraints upon human action and especially upon economic growth expresses the important truth that the range of actions open to us, and the effects of those actions, depend in part upon facts about the world that are beyond our control. I will argue, however, that even when natural limits are understood in this factual sense, they remain dependent upon human evaluations, interests and activities to a greater extent than has often been recognised in environmental thought.

The claim that there are definite limits to growth to which society must adapt has been central to the development of environmental thought and remains one of its most important themes. The dramatic and shocking (though subsequently disputed) conclusions drawn from this claim in the late 1960s and early 1970s played an important part in bringing environmental issues to public prominence, and the same contention underlies the claim of green parties to possess a distinct political ideology.