Faced with political opponents, proponents of climate justice should consider how politically feasible different principles of climate justice are. I focus in this chapter on the political feasibility of an “ability to pay principle” as a proposal for dividing the burdens of past emissions and emissions from the global poor. I argue that a formulation of an ability to pay principle with a voluntarist scope, restricted only to agreed upon collective goals, is significantly more politically feasible than one with a (...) preventative scope, which focuses on preventing a very bad outcome. A voluntarist ability to pay principle can much more clearly be justified to both constrained policy makers and reactionary citizens as a solution to a collective action problem among states that have already bound themselves to collectively solving the problem. A voluntarist principle also has a stronger precedent as a principle of international law. Thus, those philosophers concerned with the political feasibility of an ability-to-pay principle should carefully consider using a voluntarist rather than a preventative formulation. The chapter proceeds as follows. First, I outline what I mean by “political feasibility” and distinguish it from other conceptions of feasibility. Second, I explore the different rationales for a preventative ability to pay principle. Third, I introduce my voluntarist formulation of the ability to pay principle. I then reply to objections to that formulation, arguing that the drawbacks of a voluntarist formulation are not as dire as they might appear. (shrink)