UNIVERSAL

in epistemology and logic, a quality or property which each individual member of a class of things must possess if the same general word is to apply to all members of that class. Universals are the qualities of individual things, or particulars. For example, the quality of redness (a universal) is possessed by all red objects (which are particulars). But does redness exist apart from particular red things? In a way it does, since, like a particular, redness has a name that is a noun. But in other ways universals are quite unlike particulars. For example, redness, unlike red objects, cannot be picked up, and primeness, unlike prime numbers, cannot be multiplied. Then do universals exist at all? This question has been debated since the time of Plato. The debate over the status of universals stems from the ancient Greek theory of forms or ideas, which Plato held to have a real existence distinct from their manifestations in individual objects; ideal beauty must exist, he thought, as a precondition of its manifesting itself, albeit imperfectly, in certain things recognized as beautiful. Aristotle was rather less positive, arguing that forms or universals exist but only in the particulars in which they are discerned. Although both Plato and Aristotle were realists in holding that universals are real, there was a difference between them, later summed up in the phrases universalia ante rem (Plato's belief in universals before the thing) and universalia in re (Aristotle's belief in universals in the thing). Christian scholastic philosophers of the Middle Ages were influenced on the one hand by Augustine's identification of the Platonic forms with archetypes in the mind of God and on the other by a passing reference by Boethius, a late Roman scholar, in his commentary on Porphyry's Isagoge, to the questions whether genera and species are substances or are set in the mind alone; whether they are corporeal or incorporeal substances; and whether they are separate from the things perceived by the senses or set in them. The Platonic-Augustinian position, extreme realism, is reflected in the works of the Pseudo-Dionysius the Areopagite, of John Scotus Erigena, of Anselm, of Guillaume de Champeaux, and of Gilbert de La Porre. The Aristotelian position, moderate realism, is reflected in the writings of Albertus Magnus and of Thomas Aquinas. The medieval minority's opposition to realism granted existence to universals only as mental concepts. Conceptualist arguments were put forward by Roscelin, by Abelard, and by William of Ockham; but Roscelin and Ockham were so uncompromising that their antagonists equated their conceptualism with nominalism (i.e., with the contention that universals are merely words or names arbitrarily applied to similar things for convenience). Modern scholars, however, doubt that there were any medieval nominalists, for extreme nominalism cannot explain man's perception of similarities. In the 17th century, however, the materialist philosopher Thomas Hobbes defended a moderate nominalism based on the close connection between thought and speech. Later philosophers, divided between those who upheld the validity of ontology (the theory of being) and those concerned only with logic and with linguistic analysis, shifted the perennial debate about universals into fields of epistemology barely explored by the scholastics. Thus, modified forms of all four viewsPlatonic, Aristotelian, conceptualist, and nominalistare still defended.