I offer an account of _a fortiori_ arguments in the context of a Toulmin-style theory of argumentation schemes. _A fortiori_ arguments contain a comparison of the strength of two or more arguments involving scalar inferences. We can distinguish two kinds of _a fortiori_ arguments depending on whether those scalar inferences connect the premises and the conclusion or the backing and the warrant of the arguments. The first pattern has been studied by rhetoricians and the second pattern by legal argumentation theorists.