The “nominalists” . . . hold that all our ideas are only images of concretes, and that abstractions are merely “names” which we give to arbitrary groupings of concretes on the basis of vague resemblances. . . . (There is also the extreme nominalist position, the modern one, which consists of declaring that the problem [of universals] is a meaningless issue, that “reality” is a meaningless term, that we can never know whether our concepts correspond to anything or not, that our knowledge consists of words — and that words are an arbitrary social convention.)
Denying that concepts have an objective basis in the facts of reality, nominalists declare that the source of concepts is a subjective human decision: men arbitrarily select certain characteristics to serve as the basis (the “essentials”) for a classification; thereafter, they agree to apply the same term to any concretes that happen to exhibit these “essentials,” no matter how diverse these concretes are in other respects. On this view, the concept (the term) means only those characteristics initially decreed to be “essential.” The other characteristics of the subsumed concretes bear no necessary connection to the “essential” characteristics, and are excluded from the concept’s meaning.
Observe that, while condemning Plato’s mystic view of a concept’s meaning, the nominalists embrace the same view in a skeptic version. Condemning the essence-accident dichotomy as implicitly arbitrary, they institute an explicitly arbitrary equivalent. Condemning Plato’s “intuitive” selection of essences as a disguised subjectivism, they spurn the disguise and adopt subjectivism as their official theory — as though a concealed vice were heinous, but a brazenly flaunted one, rational. Condemning Plato’s supernaturally-determined essences, they declare that essences are socially-determined, thus transferring to the province of human whim what had once been the prerogative of Plato’s divine realm. The nominalists’ “advance” over Plato consisted of secularizing his theory. To secularize an error is still to commit it.
Its form, however, changes. Nominalists do not say that a concept designates only an entity’s “essence,” excluding its “accidents.” Their secularized version is: A concept is only a shorthand tag for the characteristics stated in its definition; a concept and its definition are interchangeable; a concept means only its definition.
It is the Platonic-nominalist approach to concept-formation, expressed in such views as these, that gives rise to the theory of the analytic-synthetic dichotomy.
The nominalist view that a concept is merely a shorthand tag for its definition, represents a profound failure to grasp the function of a definition in the process of concept-formation. The penalty for this failure is that the process of definition, in the hands of the nominalists, achieves the exact opposite of its actual purpose. The purpose of a definition is to keep a concept distinct from all others, to keep it connected to a specific group of existents. On the nominalist view, it is precisely this connection that is severed: as soon as a concept is defined, it ceases to designate existents, and designates instead only the defining characteristic.
And further: On a rational view of definitions, a definition organizes and condenses — and thus helps one to retain — a wealth of knowledge about the characteristics of a concept’s units. On the nominalist view, it is precisely this knowledge that is discarded when one defines a concept: as soon as a defining characteristic is chosen, all the other characteristics of the units are banished from the concept, which shrivels to mean merely the definition. For instance, as long as a child’s concept of “man” is retained ostensively, the child knows that man has a head, two eyes, two arms, etc.; on the nominalist view, as soon as the child defines “man,” he discards all this knowledge; thereafter, “man” means to him only: “a thing with rationality and animality.”
On the nominalist view, the process of defining a concept is a process of cutting the concept off from its referents, and of systematically evading what one knows about their characteristics. Definition, the very tool which is designed to promote conceptual integration, becomes an agent of its destruction, a means of disintegration.