The rhetoric of grammar: Scalar reasoning and polarity sensitivity

Polarity items are linguistic forms whose distributions are sensitive to negation and other polarity contexts. This dissertation offers a compositional account of what it means to be a polarity item and why polarity items are sensitive to polarity. The grammar of polarity sensitivity is shown to be grounded in a general cognitive ability for scalar reasoning, and in the ways this ability is systematically exploited for rhetorical ends in actual discourse.; The basic claim is that polarity contexts are defined by their scalar properties. Polarity items are analyzed as scalar operators, forms which must be interpreted with respect to an appropriately structure scalar model, and polarity sensitivity is shown to arise from the interaction of two sorts of scalar semantic features, quantitative and informative value. The first defines a polarity item's position within a scalar ordering. The second determines the informational strength of the proposition to which a polarity item contributes its meaning. Both features are grounded in the logic of scalar reasoning and in the rhetoric of interpersonal communication. Their combination within a single form effectively limits it to contexts allowing the appropriate sorts of scalar inferences. The theory predicts four basic sorts of polarity items based on the interaction of these two scalar properties. All four sorts are well-attested in English and other languages, and a wide array of apparently dissimilar polarity items is shown to conform to the basic predictions of the theory.; Polarity licensing itself turns out to be pragmatic in nature. It is demonstrated that polarity contexts cannot be adequately defined in terms of structural constraints on formal representations, whether syntactic or semantic. Rather, polarity licensing depends on the pragmatic availability of an appropriate scalar construal for a given construction.; An important result of this work is that the apparently arbitrary constraints on polarity items actually reflect normal processes of human reasoning and interpersonal communication. This conclusion undermines the thesis that grammar constitutes an autonomous module of cognition. Rather, at least in the case of polarity items, grammar reflects the conventional adaptation of general cognitive abilities for specific communicative ends.