Proportionality, Comparability, and Parity: A Discussion on the Rationality of Balancing

This article analyses the rationality of the principle of proportionality as a justificatory method for solving cases involving conflicts of constitutional principles. It addresses the “problem of comparability”: a set of arguments claiming that proportionalists fail to understand what happens when constitutional principles collide. The problem of comparability suggests that balancing cannot be done if some conflicts of constitutional principles are, in reality, cases of noncomparability, incommensurability, incomparability, or vagueness. In this article, I challenge the views of both proportionalists and their skeptics. Against the skeptics, I argue that proportionality can survive the challenge posed by the problem of comparability. Against the proportionalists, I submit that proportionality cannot be understood as a system of tradeoffs between degrees of satisfaction of principles. If comparison among constitutional principles is to be rational, we need a different approach to normativity—one that allows for the possibility of parity.