Arguing a Contrario

This chapter offers a new account of arguments a contrario. It is divided into six sections. Section 1 presents the argument a contrario as it is commonly seen by legal practitioners and theorists. Practitioners and theorists diverge in how they see it: while the former think of the argument as a ‘product of logic and common sense,’ the latter view it with suspicion. Section 2 explains why: according to the standard theoretical account, the argument a contrario boils down to a logical fallacy. But there are reasons, Section 3 suggests, to resist the standard account. Section 4 shows where the standard account goes wrong. Sections 5 and 6 give a new account of arguments a contrario.