12.1 Introduction

Climate change is happening, and human activity is the cause. What are we going to do about it? Bill McKibben calls this “the most important question that there ever was.” It is a practical question, but it also raises some philosophical issues. My goal in this chapter is to examine these philosophical issues. They include matters of self-interest and rational choice, and they include moral issues about the value of nature, the nature of human values, and difficult issues about international justice and intergenerational morality.

A number of writers have pointed out that climate change has remarkable spatial and temporal characteristics. It is a global problem and a paradigm of what game theorists call the Prisoner's Dilemma. The fundamental characteristic of a Prisoner's Dilemma is that if each agent successfully pursues its rational best interests, the result is collectively worse for each of them than some other possible result. I will discuss this issue in Section 12.3 below.

The temporal problem is an illustration of intergenerational asymmetry, or what some philosophers call the “tyranny of the present.” In each generation, people must decide whether they will collectively accept some costs in order to reduce greater harms and costs in the future or continue to pursue short-term gains and pass the problem on to the next generation. Because future people do not exist, they cannot bargain, reciprocate, compensate, reward, or punish us for what we do. I will discuss the implications of this asymmetry in intergenerational morality in Sections 12.4 and 12.5.

Both of these philosophical problems are familiar, and I will have little to add to the technical analysis of them. Once one understands and accepts the central facts about climate change, moreover, it is easy enough to formulate principles that tell us what we must do to avoid causing the worst harms and to mitigate the future harms we have already caused.