Abstract

Under what conditions can we justify actions which impose risk on some group of people on the grounds that they belong to a set of actions that, together, do not impose risk on that same group of people? Answering this question is important for evaluating various practices, including the practice of offsetting carbon emissions. We've recently defended an answer to this question, which carries the practical implication that whether emitting and offsetting is permissible can depend on the form that the offsetting takes. If you offset by sequestering, such that you remove as much carbon from the atmosphere as you put in (for example by planting trees), then according to our view you can successfully offset. But when you offset by forestalling—preventing others from putting additional carbon into the atmosphere (for example by paying them not to emit, or providing them with more energy efficient stoves), you typically cannot. After explaining our view and considering some objections that others have presented to it, we introduce and discuss an important distinction between various harms to which your conduct can be causally related.