Alqassas Ahmad, A unified theory of polarity sensitivity: Comparative syntax of Arabic. New York: Oxford University Press, 2021. Pp. x + 246.

Negative sensitive items (NSIs) have been the subject of much discussion in the syntactic as well as semantic literature for at least the last forty years since the publication of Ladusaw’s (1980) seminal work. The subject particularly is of great significance as it has consequences on topics including the syntactic and semantic composition of indefinites, the nature and locus of negation, how semantic domains are further restricted by syntactic constraints (i.e. the division of labor between syntax and semantics in licensing), and the domain of application of Agree and Merge as primitive syntactic operations, to mention a few. This book contributes to the growing body of literature on the issue by presenting interesting and new empirical facts from an understudied language, namely Arabic. One of the challenges to any researcher working on the topic of NSIs in Arabic is the scarcity of data, especially because Arabic encompasses many varieties so different that they are often described as different languages. Although there is much work on NSIs in Romance and other Indo-European languages, one can hardly find any serious work that presents the landscape of NSIs in (the major varieties of) Arabic. Chapter 2, ‘Classification of PSIs and their lexical categories’, walks the reader through all categories of NSIs from different varieties of Arabic, including Egyptian, Moroccan, Jordanian, Qatari, and Standard. As with other languages, Arabic has two major classes of NSIs: negative polarity items (NPIs) and negative indefinites (NIs). The latter can also include elements that can be construed as negative concord items (NCIs). Perhaps of great interest is the fact that Arabic exhibits elements that contribute a negative interpretation in absence of overt negation, such as NCIs in preverbal position (Wala ħada idʒa ‘No one came.’) and NCIs in fragment answers (A:Miin idʒa? ‘Who came?’ B:Wala ħada! ‘No one!’). These elements pose a challenge to previous work and motivate a new analysis that departs from restricting licensing to c-command in the domain of a negative marker (NM). A point of strength of the empirical part of this monograph is the richness of data sources. In particular, Alqassas hinges on introspection for the data drawn from his own dialect (Jordanian), cited examples from the other colloquial varieties, and corpus data for the standard variety (Qur’an corpus). The issue of reliability of data