 would count as a logical constant (Gómez-Torrente 2002, 21), assuming that it is epistemically necessary that there are no male widows. It may be tempting to solve this problem by appealing to a distinctively logical modality—requiring, for example, that logical constants have permutation-invariant extensions as a matter of logical necessity. But we would then be explicating the notion of a logical constant in terms of an obscure primitive notion of logical necessity which we could not, on pain of circularity, explicate by reference to logical constants. (McCarthy 1998, §3 appeals explicitly to logical possibility and notices the threat of circularity here.)