Pragmatic responses to under-informative some-statements are not scalar implicatures

A highly emblematic paradigm in experimental pragmatics consists in presenting participants with an existentially quantified sentence of the form Some X are Y in a context in which all X are obviously Y. Participants who reject such sentences as false or infelicitous are said to adopt a 'pragmatic' instead of a 'logical' reading of some, and to derive the scalar implicature Some, but not all X are Y. Although there are several competing accounts of scalar implicatures, virtually all of them assume that a participant who responds pragmatically to an under-informative some-sentence mentally entertains a linguistic representation of the negation of a stronger alternative (All X are Y). Yet, there is no evidence that judging an under-informative some-sentence false or infelicitous actually involves the derivation of the some, but not all scalar implicature. We report three experiments consisting of a sentence-picture verification task followed by a forced choice between two paraphrases of the sentence initially assessed. These experiments robustly show that hearers who reject an under-informative some-sentence do so without explicitly entertaining a some, but not all implicature. Our results represent a strong challenge for grammatical accounts of scalar implicature, which all presuppose a mechanism of negation of stronger alternatives, and force a drastic reinterpretation of processing data on scalar implicatures. More generally, our findings show that one should not conflate psychological models of pragmatic processing with a reconstructed link between sentences and their potential meanings.