 Whatever the merits of the Boolos translation, plural quantification is nowadays generally distinguished from second-order quantification on the grounds that they bind expressions of different syntactic and semantic categories—while predicates are unsaturated in Frege’s terminology and contain argument places to be completed by expressions of an appropriate syntactic category, plural terms are often thought to be akin to saturated singular terms. Different variations on this theme may be found, for example, in Higginbotham 1998; Oliver &amp; Smiley 2001; Rayo &amp; Yablo 2001; Williamson 2003, 2013. This is a book, which includes an extensive discussion of important differences in the behavior of plural and second-order quantification in modal contexts. Plural quantification has consequently become the subject of its own study.