Balancing is one of the main issues in current debates on legal argumentation and constitutional review. The discussion has polarized into two competing theses. On the one view, balancing is both irrational and subjective. When courts “weigh” conflicting constitutional rights, they actually make a preferential choice that cannot be rationally justified. On a different view, balancing is a rational form of argumentation grounded in the very structure of constitutional rights and principles. In this paper we argue that none of these theses is true. By analyzing the inferential structure of balancing we show that it is composed by multiple inferential steps. One must consider what inferential commitments are undertaken in the balancing process, and by what conditions these commitments can be discursively satisfied in a given constitutional system. In particular, we address the problem of the external justification of balancing, namely the justification of its premises.