The Realism of Aquinas

Abstract In his book On Universals, Nicholas Wolterstorff examines Aquinas’ theory of universals and concludes that it suffers from “a crucial and incurable ambiguity, or incoherence.” Wolterstorff charges Aquinas with denying that there is anything two distinct things have in common while maintaining that forms or natures may be the forms or natures of several distinct things. Aquinas’ resolution of the apparent contradiction is said to consist of the assertion that forms or natures exist outside the mind only as individualized in singulars and exist as universals only when they are abstracted from such things by some intellect. Universals are then concepts abstracted from distinct singulars which are similar but not identical. But in that case, Wolterstorff shows, it is not one nature which is abstracted but several and so-called universal concepts cease to have any foundation in reality.’