This article shows that the deontic modals must, should and supposed to are all Positive Polarity Items which can raise in order to avoid being in an anti-licensing environment; it also establishes that should has a dual nature, i.e., it is not just a PPI, but it is also a neg-raising predicate, which can achieve wide scope through a homogeneity inference, and that supposed to, also a PPI, exhibits a neg-raising behavior under certain pragmatic conditions which shed new light on the neg-raising phenomenon.