In this paper, we observe that although all positive indefinites, in particular some-pronouns and some-NPs, qualify as Positive Polarity Items (PPIs), they do not exhibit a uniform behavior when occurring in the so-called ‘rescuing contexts’ as only the former are possible. In order to solve this puzzle, we will propose that anti-licensing and rescuing contexts respectively pertain to narrative/descriptive and argumentative discourse, and correlate with different ways in which sentential negation translates: in narrative/descriptive contexts, sentential negation is interpreted as quantificational negation and in argumentative contexts as propositional negation. Given this hypothesis, the contrast between some-pronouns and some-NPs in rescuing contexts can be explained by observing that the former are weak indefinites, whereas the latter are strong indefinites. Weak positive indefinites can take scope within propositional negation, whereas strong positive indefinites cannot do so. In anti-licensing contexts, on the other hand, sentential negation is interpreted as quantificational negation, which bans any kind of positive indefinite (due to an extended version of Collins & Postal's (2004) Determiner Sharing condition on polyadic quantification).