The nominalists’ denial that universals are things and Ockham’s reduction of the categories to substance and quality were both attempts to reduce the number of types of things. (Although it should be noted that the
Reduction of the categories and antirealism about univer-sals are, and in the Middle Ages were sometimes taken to be, logically independent).
Ockham’s reductivist program is often associated with his principle of parsimony (‘‘Ockham’s Razor’’). But Ockham did not invent this principle (indeed, one can find versions of the principle in Aristotle), nor was he the only philosopher in the thirteenth and fourteenth centuries who made use of the principle. Moreover, the importance of the principle of parsimony is often overestimated. As one commentator observes, no one advocated the postulation of unnecessary entities (Spade 1999:102). The real dispute was over precisely what entities were necessary.
Much like contemporary forms of antirealism, medieval antirealists tried to determine what words actually pick out things and what words only appear to pick out things (cf. Normore 1985). Sentences that only appeared to commit someone to a certain kind thing were paraphrased into statements that did not commit one to things of this type. So, for example, sentences that seemed to commit one to quantities were transformed into sentences about substances and qualities existing in this or that way.
But some commentators have wondered whether medieval antirealists actually achieved ontological economy. Ockham, for example, seems to have substituted an ontology of modes for one of things. Even if that accusation does not stick (see Adams 1987:306-310), it still appears that Ockham’s program cannot reduce away objective temporal, spatial, and causal ordering. Yet, Ockham insists that these features of reality are not things (Spade 1999:106-111). Abelard had a similar problem. He insisted that no thing is a universal, and yet universality is grounded in objective ‘‘agreements’’ between individual things (cf. Tweedale 1976:204-209). Hence, in practice, those with antirealist tendencies often tacitly employed a “two-tiered” ontology (Spade, op cit.).
World History
