  Of all the considerations favoring non-reductive realism, perhaps none is more compelling than the intuition that relations have a different nature or “quiddity” from that of ordinary categorial accidents. As we have seen, medieval philosophers recognize that predications involving relative terms (such as ‘x is taller’) are incomplete in a way that monadic or absolute predications (such as ‘x is white’) are not. They also recognize, moreover, that unlike absolute terms relative terms come in pairs or sets. Every relative term has a correlative, and the meaning of the one (say, ‘taller’) cannot be understood in isolation from the meaning of the other (‘shorter’). These facts about relative terms and predication are often thought to show that their significata have a distinct nature or quiddity from the ordinary, absolute accidents that serve as their foundations. Here again it is useful to quote Harclay: