 For McCall (1967), contrariety is a quasi-modal notion akin to logical impossibility, \(\Box \neg\), in that \(\Box \neg A\) entails \(\neg A\) but not vice versa, but as pointed out by an anonymous reviewer, there is no intrinsic modal component of contrariety; all that is necessary is that contrariety is a non-truth-functional one-place connective. (See Humberstone 1986, 2003, 2005; Bogen 1991; and Vakarelov 1989a for additional considerations.)