Cleo Condoravdi - Polarity Reversal in Counterfactuals
Positive polarity items (PPIs) are generally not acceptable within the scope of clause-mate negation, but they can systematically appear in the scope of negation in certain environments. Baker (1970) introduced the term 'polarity reversal' for the phenomenon of licensing under the reverse polarity and identified the antecedent of counterfactual conditionals as one such environment, exemplified by (1) and (2).
(1) If she had not arrived already, we would have postponed the meeting.
(2) If she weren't pretty smart, she wouldn't have dealt with the situation so well.
Baker?s generalization, reflected in his licensing principle, was that PPIs can be in the scope of clausal negation in the antecedent of a subjunctive conditional if and only if the conditional presupposes the rejacent of the negation, e.g. in (1) that she had already arrived. Schwartz & Bhatt (2006), taking this generalization for granted, postulated the existence of a special negation that presupposes its prejacent. But this turns out to be the wrong generalization. Though the prejacent of the negation being entailed by the context is sufficient for polarity reversal, it is not necessary. A conditional with polarity reversal in the antecedent is acceptable when the negated clause is compatible with the context, or even presupposed, as long as the entire antecedent is counterfactual.
In this talk, I take as my starting point the more fine-grained view of polarity sensitivity due to Krifka (1995) and Chierchia (2006), and show that polarity reversal follows from the lexical semantics of a polarity sensitive expression and the interpretation of counterfactual conditionals. A crucial factor is that in making a counterfactual assumption, you not only give up propositions that are inconsistent with it, but also certain contextually entailed propositions, which are consistent with the counterfactual assumption but whose truth depends on the truth of the proposition contradicted by the counterfactual assumption. Thus the phenomenon of polarity reversal sheds light on the role the information in a context plays in determining what you hold constant and what you give up when interpreting counterfactuals.