universal
- Related Topics:
- realism
- nominalism
- term
- particular
- conceptualism
universal, in philosophy, an entity used in a certain type of metaphysical explanation of what it is for things to share a feature, attribute, or quality or to fall under the same type or natural kind. A pair of things resembling each other in any of these ways may be said to have (or to “exemplify”) a common property. If a rose and a fire truck are the same colour, for example, they both exemplify redness, or the property of being red. Realists take this way of talking about universals to be strictly and literally true: the property shared—redness—is a third entity, distinct from both the rose and the truck. The two things resemble each other in virtue of standing in the same relation (“exemplification”) to this third entity, which is called a “universal” because it extends over, or is located in, many distinct things. Nominalists, on the other hand, reject universals, claiming that there is no need to posit an extra, rather strange entity—the universal “redness”—simply to account for the fact that roses and fire trucks resemble one another.
The problem of universals—whether there are any and, if so, what exactly they are—was a dominant theme in ancient Greek philosophy, in medieval Scholasticism, and in Western philosophy during the modern period (the 17th through the 19th centuries). Although debates about universals no longer lead to fisticuffs (as they were said to do among the Scholastics), they remain central to contemporary metaphysics. Realists are still opposed by nominalists, and realists themselves are still sharply divided between those who adhere to something like Plato’s conception of universals and those who favour Aristotle’s. Realists also remain divided between those who posit a plenitude of universals and those who accept very few. This division in turn reflects a fundamental disagreement among realists over why one should believe in universals in the first place.
Platonic and Aristotelian realism
According to a traditional interpretation of the metaphysics of Plato’s middle dialogues, Plato maintained that exemplifying a property is a matter of imperfectly copying an entity he called a form, which itself is a perfect or pure instance of the property in question. Several things are red or beautiful, for example, in virtue of their resembling the ideal form of the Red or the Beautiful. Plato’s forms are abstract or transcendent, occupying a realm completely outside space and time. They cannot affect or be affected by any object or event in the physical universe.
Few philosophers now believe in such a “Platonic heaven,” at least as Plato originally conceived it; the “copying” theory of exemplification is generally rejected. Nevertheless, many modern and contemporary philosophers, including Gottlob Frege, the early Bertrand Russell, Alonzo Church, and George Bealer are properly called “Platonic” realists because they believed in universals that are abstract or transcendent and that do not depend upon the existence of their instances.
Aristotle denied that exemplifying a universal is anything like copying it. He parted company with all Platonic realists by affirming that: (1) the properties of material things are “immanent”—i.e., “in” the things that exemplify them, in a nearly literal, spatial way; and (2) properties do not exist independently of the things that exemplify them. Both of these ideas survived in some contemporary theories. Thus, the entities that Alfred North Whitehead called “objects” seem to be universals weaving their way through space-time, numerically the same wherever or whenever they appear. Universals are also immanent according to defenders of the so-called “bundle” theory—philosophers such as David Hume and the later Russell, who said that individuals are just bundles of universals. An individual stop sign, for example, consists of the universals eight-sidedness, redness, hardness, and so on. Because the sign is spatially and temporally located and contains nothing but universals, universals themselves must be in space and time—they cannot be there merely “by courtesy,” in virtue of being exemplified by something that is really in space and time. In the theory defended by the contemporary Australian philosopher David Armstrong, universals are perhaps not quite as immanent as they are according to the bundle theorists, but they nevertheless obey an Aristotelian “principle of instantiation,” insofar as no universal can exist without instances.
Medieval and early-modern nominalism
The problem of universals was arguably the central theme of medieval Western philosophy. Just before the medieval period, St. Augustine defended a version of Platonism, identifying Platonic forms with exemplars timelessly existing in the mind of God. Although many medieval philosophers were Aristotelian realists of one sort or another, a few developed varieties of nominalism. William of Ockham, for example, claimed that things “share features in common” in virtue of the fact that objective relations of resemblance hold among them. But he denied that the holding of such relations requires that there be anything literally the same within the things themselves. Ockham explained the human ability to think and talk in general terms by appealing to mental entities, or concepts, which serve as “natural signs” of the many things to which they apply.
Ockham’s conceptualism won few converts among medieval philosophers. But conceptualism of one sort or another, combined with nominalism, was central to the philosophies of the 17th- and 18th-century British empiricists John Locke, George Berkeley, and Hume.
It should be noted that there is much inconsistency in the application of the terms “conceptualism” and “nominalism.” In this article “nominalist” is used as a name for all opponents of realism, some of whom have typically been called “conceptualists.” It would be least misleading to reserve the term “conceptualism” for certain theories about the ability to think and talk in general terms—theories that are not, strictly speaking, in competition with realism or nominalism but that, in practice, usually accompany the latter.
Plenitudinous theories and sparse theories
The distinction between plenitudinous and sparse theories of universals (a distinction that cuts across the distinction between Platonic and Aristotelian realism) did not become a major issue in philosophy until the 20th century. According to the plenitudinous view, there is a universal corresponding to almost every predicative expression in any language—including not only relatively natural predicates, such as “…is red,” “…is round,” and “…is a dog,” but also more-complex and less-natural predicates, such as “…is either red or round or a dog.” Sparse theories posit universals only for certain very special predicates, typically those used in the fundamental theories of physics, such as “…is an electron” and “…has negative charge.”
At least two sorts of arguments for the existence of universals support the conclusion that, in the words of G.E. Moore (1873–1958), “if there are any at all, there are tremendous numbers of them.” Arguments of the first sort claim that a plenitude of universals is a logical consequence of a resolute opposition to idealism, according to which reality is in some fundamental way mental or mind-dependent. Arguments of the second sort find a plenitude of universals behind the phenomenon of “abstract reference.”
Plenitudes from anti-idealism
The logical realism of Frege, Russell, and Moore
The term “realism” is sometimes used to mean anti-idealism. In the late 19th and early 20th centuries, several of the philosophers who made major advances in formal logic (most importantly Frege and Russell) were realists in this sense, in part because they held that the entities studied by logic are objective and mind-independent. Most other philosophers and psychologists during this period, however, believed that the subject matter of logic consists of thoughts or judgments and is therefore subjective and mind-dependent, a conception that fitted nicely with idealist metaphysics. In opposition to this view, Frege, who identified thoughts with the meanings of sentences in a logical or natural language, pointed out that more than one person can have the very same thought and that many of the thoughts that people have would be true or false whether or not there were in fact people to have them. (The German mathematician Bernhard Bolzano also made this point.) For these reasons, thoughts must be objective (shareable by many persons) and mind-independent. Russell and Moore called thoughts in this sense “propositions.”
Whereas an idealist would take propositions to be made up of ideas, Russell and Moore insisted that propositions contain the very things in the world that the sentences expressing them are about. Attention to the logical forms of sentences suggested an argument for plenitudes of universals based on this theory of propositions.
The new logic pioneered by Frege and Russell divided all meaningful sentences into names (“Jones,” “World War II,” “New York”), predicates (“…is red,” “…runs,” “…is to the left of…”), and various logical connectives and operators (“and,” “or,” “not,” and the existential and universal quantifiers: “For some…,” or “There is [at least one]…,” and “For all…,” or “Everything is…”). The nonlogical parts of sentences—i.e., the names and predicates—introduce the subject matter of a sentence, the things in the world that it is about. A name can refer to the same individual in various sentences, and so the same individual can be a part of many propositions. A predicate too can be used in different sentences to mean the same thing. Russell and Moore concluded that a meaningful predicate also must stand for a thing that can be part of many propositions. Since a predicate can be true of many different things, what a predicate stands for must be a universal—i.e., something that characterizes many individuals.
It follows from this line of reasoning that there is a universal corresponding to each predicate (or set of synonymous predicates) in a language. The forms of predication suggest important distinctions between universals. One-place predicates, such as “…is round,” can be converted into a sentence with the addition of only one name, so they express monadic universals exemplified by single things. Two-place predicates, such as “…is next to…,” require two names to turn them into a full sentence, so they express relational universals exemplified by pairs. More-complex predicates correspond to relational universals exemplified by larger numbers of things.
Nominalist criticism
Nominalists were not impressed by the claim that, if subject-predicate sentences are to be about the real world, there must be an entity in the world referred to by each predicate. A person who sincerely utters a sentence such as “Jones is hungry” or “Robinson is next to Smith” seems to be committed to the existence of entities corresponding to the names “Jones,” “Robinson,” and “Smith.” In other words, normally one could infer from these utterances that there exists something (namely, Jones) that is hungry and that there exist two things (namely, Robinson and Smith) that are next to each other. But are similar inferences warranted concerning the predicates? It is unclear that the parallel existence claims even make sense. Certainly, one cannot say: “there exists something (namely, … is hungry) that Jones is” or “there exists something (namely, … is next to …) that Robinson and Smith are.”
The predicates can be nominalized, resulting in “hunger” and “being next to,” which do seem like proper names for universals. Frege, Russell, and Moore thought that a predicate such as “…is hungry” in the sentence “Jones is hungry” represents a universal, in this case hunger, which is part of the subject matter of the proposition expressed by the sentence. In that case, “Jones is hungry” would imply “there exists something (namely, the universal hunger) that Jones has or exemplifies.” But then what of the new relational predicates “…has…” and “…exemplifies…”? Insistence upon treating all predicates as though they were like names in this way would justify drawing the further conclusion, “there is something (namely, the relational universal exemplification) that holds between Jones and the universal hunger.” Again, however, the new relational predicate “…holds between…and…” must be treated in the same way. The realist is now faced with an infinite regress, which leads to a dilemma: either every truth implies an infinite series of relational universals, or there are meaningful predicates that can be used to characterize things without commitment to corresponding universals.
A few brave realists—e.g., Russell—accepted the infinite series, but most did not. If the infinite series is rejected, however, then the Russell-Moore argument for universals from anti-idealism is seriously weakened. Once the realist admits that not all predicates need universals in order to be meaningful, it is open to the nominalist to ask why any predicate does.
Despite this difficulty, anti-idealism continues to inspire arguments for the existence of a plenitude of universals. Both Bealer and the Austrian-born philosopher Gustav Bergmann noted the fundamental subject-predicate structure of thought, and each gave a unique argument from anti-idealism to the conclusion that there are genuine, mind-independent universals corresponding to most predicates.
