Where does the necessity that seems to accompany causal inferences come from? “Why [do] we conclude that … particular causes must necessarily have such particular effects?” In 1.3.6 of the Treatise, Hume entertains the possibility that this necessity is a function of reason. However, he eventually dismisses this possibility, where this dismissal consists of Hume’s “negative” argument concerning induction. This argument has received, and continues to receive, a tremendous amount of attention. How could causal inferences be justified if they are not justified by reason? If we believe that p causes q, isn’t it reason that allows us to conclude q when we see p with some assurance, i.e. with some necessity?