NOMINALISM. The philosophical view of nominalists is based on the conviction that in human discourse only names (nomina), nouns, or words are "universal," not things, common natures, or ideas, as claimed by the realists. The problem of universals, first raised in logic, concerned the status of terms that are predicable of many subject-terms. The problem raised other questions that had to be answered in psychology or epistemology, with serious ramifications in theology. The logical problem of universals was heatedly debated in the eleventh and twelfth centuries in response to Abelard; the larger problem was debated even more heatedly in the fourteenth and fifteenth centuries in response to Ockham and his followers.

In the early Middle Ages logicians encountered the problem of universals in teaching Aristotle's Categories and Porphyry's Isagoge (Introduction). In the Categories Aristotle listed ten classes of terms that are predicable of subject-terms in discourse (substance and...