 Much of the recent interest in plural quantification in logic and philosophy began with Boolos(1984), who provided a plural interpretation of monadic second-order quantification. Boolos wanted to defend second-order axiomatizations of set theory against the charge that second-order quantification over the domain of all sets is incoherent, since there is no set of all sets. In response, he explained how to interpret the second-order quantifier, \(\forall X\), over the domain of all sets in terms of the plural quantifier “some sets”, and how to interpret atomic formulas of the form \(Xx\) in terms of the plural locution “is one of”. The fact that plural locutions are systematically used and perfectly understood in natural language, Boolos thought, helped address the charge of incoherence. The Boolos translation is described in detail in the entry on  plural quantification.