This paper proposes a new explanation for the oddness of presuppositional and negative islands, as well as the puzzling observation that these islands can be obviated by certain quantificational elements. The proposal rests on two independently motivated assumptions: (i) the idea that the domain of manners contains contraries and (ii) the notion that degree expressions range over intervals. It is argued that, given these natural assumptions, presuppositional and negative islands are predicted to lead to a presupposition failure in any context.