Abstract

In this work we will argue that legal reasoning is best understood as an instance of defeasible reasoning. So, it is important to distinguish between defeasible and not defeasible rule of inference. Perhaps the paradigmatic example is modus ponens. Given a legal rule R, R has the following form: A →B, where A refers to a factual condition and B refers to a legal consequence. So, if A holds, then B is the case. But in some situations, exceptions can arise, and this means that B only holds probably. So, there are not conclusive modus ponens in law, defeatable.