Introduction: Current perspectives on positive polarity.

Polarity sensitivity has been an established key topic of linguistic research for more than half a century. The study of polarity phenomena can be extremely revealing about the internal structure of a language, as they usually involve an interaction at the interface between syntax, semantics and pragmatics. In the past, most attention was paid to negative polarity items. However, recent years have witnessed a growing interest in positive polarity items. As a continuation of this trend, this issue collects four papers dedicated to positive polarity items, which enrich the empirical domain with novel observations from different languages and appeal to diverse theoretical concepts such as scalarity and presupposition in their modeling of positive polarity. The results show that positive polarity is a distributional phenomenon that has different sources and most likely cannot be modeled in a unifying way, although there may be subsets of positive polarity items that allow unifying accounts. [ABSTRACT FROM AUTHOR]