The Limits of Practical Possibility
One aim of political philosophy is to describe a socio-political ideal: a picture of the best that society could possibly be. In developing an account of this kind, however, we operate under a number of constraints. For example, because we recognize that universal benevolence cannot be achieved, we do not propose an ideal in which humans have this characteristic. Or because we recognize that no populace will perfectly obey the law, we build a system of sanctions into the complete account. We aim, in other words, at what John Rawls calls a “realistic utopia”: a picture of the world where our highest aspirations for human society are balanced by our understanding of what humans can actually achieve.2 Framing the search for a realistically achievable socio-political ideal as a question, it might be asked: “What would an ideal society look like under favorable but practically possible conditions?” This is a big, old question and my aim in this chapter is not to answer it. Instead, I intend to clarify the idea of practical possibility, a concept without which this big question cannot be properly understood, let alone answered.