In this paper, the unexpected behavior of object negative quantifiers in some diagnostic tests of sentential negation is accounted for within a Minimalist framework assuming that: (i) negative quantifiers decompose into negation and an existential quantifier; (ii) negative quantifiers are multidominant phrase markers, as Parallel Merge allows the verb to c-select their existential part but not their negative part, thus giving negation remerge flexibility; (iii) tag questions involve or-coordination of TPs, and neither/so clauses involve and-coordination of TPs; (iv) two positions for sentential negation are available in English, one below TP (PolP2), and one above TP (PolP1). Activation of either PolP1 or PolP2 in the absence of other scope-taking operators corresponds to two distinct grammars. If PolP1 is active, the negative part of an object negative quantifier remerges in its Specifier valuing the [upol: ] feature of Pol1 as negative ([upol:neg]) while skipping the TP-domain. As no negative formal feature is present in the TP, a negative question tag is required, as well as so-coordination, too-licensing and Yes, I guess so ‘expression of agreement’. Conversely, if PolP2 is active, the negative part of the object negative quantifier remerges in the TP-domain (in Spec, PolP2), thus requiring a positive question tag, neither-coordination, either-licensing, and No, I guess not.