 Standard logic treats all predicate expressions alike—the predicates can be interpreted as any subset of the domain of quantification. If any of the claims discussed above about sortals are correct, then the sortal predicates have distinctive properties, and a more sophisticated logical treatment might provide philosophical illumination. One obvious and agreed on principle is that in general the negation of a sortal predicate is not a sortal. This contrasts with the predicates of standard logic where if F is a predicate, so is \(\neg F\), (not-F).