Quine on Matters OntologicalRoger Gibson
 Willard Quine has been writing about ontology for almost as long as he has been writing philosophy -- approximately 65 years. For the most part he has focused his attention on the epistemology of ontology, and as a consequence of those epistemological ruminations he has taken a substantive stand on what there is. On the epistemological side Quine famously maintains that (a) everything to which we concede existence is a posit , (b) to be is to be the value of a variable, (c) no entity without identity, and (d) reference is indeterminate (or inscrutable), i.e., the doctrine of ontological relativity. On the substantive side Quine is (tentatively) committed to a bifurcated, but thoroughly extensional, ontology of (concrete) physical objects and (abstract) classes.
 Ironically, Quine's long-time interest in the epistemology of ontology has led him to a doctrine of ontological indifference: under certain conditions different ontologies can serve a particular theory equally well. Nevertheless, he steadfastly maintains that the ontology of current physical theory consists exclusively of physical objects and classes. How can Quine have it both ways: ontological indifference and ontological preference? Answering this question will not only shed light on Quine's views on matters ontological, it will also shed light on his philosophy in general.
II. Ontological Indifference
(a) Posits and Reification
 Quine maintains that "[e]verything to which we concede existence is a posit..." (1960: 22). Macroscopic bodies--sticks and stones--posits? Microscopic bodies--neutrinos and quarks--posits? Abstract objects--classes and numbers--posits? But what is a posit? As Quine explains, a posit is a result of a linguistic process of reification:
The reification of bodies comes in stages in one's acquisition of language, each successive stage being more clearly and emphatically an affirmation of existence. The last stage is where the body is recognized as identical over time, despite long absences and interim modifications. Such reification presupposes an elaborate schematism of space, time, and conjectural hidden careers or trajectories on the part of causally interacting bodies. Such identifications across time are a major factor in knitting implications across the growing fabric of scientific hypotheses.Reification is a topic that Quine has written about extensively and in some detail, but in Pursuit of Truth he gives two especially illuminating, brief, examples of the kind of thing he has in mind:
At more sophisticated stages in the development of language and science, implications are enhanced by positing further objects, no longer observable; thus subvisible particles, also numbers and other classes. (1992a: 7)
(1) A white cat is facing a dog and bristling.
Four simple observation sentences underlie this. One is 'Cat', or, on the analogy of the ontologically innocent 'It's raining', 'It's catting'. The others are 'White', 'Dog-facing', and 'Bristling'. But (1) cannot be rendered as a mere conjunction of these four, because the conjunction is too loose. It tells us only that the four things are going on in the same scene. We want them all in the same part of the scene, superimposed. It is this tightening that is achieved by subjecting the four-fold conjunction to existential quantification, thus:
Something is catting and is white and is dog-facing and is bristling,which is to say (1). An object has been posited, a cat....
For purposes of that context, a cat of the moment would suffice; no need of an enduring cat. To illustrate the need for an enduring cat I must go beyond observation sentences and suppose that we have somehow worked our way far enough up into scientific theory to treat of time; earlier and later. Suppose then that we want to convey this thought:
(2) If a cat eats a spoiled fish and sickens, then she will thereafter avoid fish.
We cannot treat this as a simple 'if-then' compound of two self-sufficient component sentences. Like the 'and' of the preceding example, the 'if-then' connection is too weak. It has to be the same cat in both sentences, and hence an enduring cat. Our sentence is really a universally quantified con ditional:
Everything is such that if it is a cat and it eats a spoiled fish and it sickens then it will avoid fish..... My examples offer a crude notion of how it may be that reification and reference contribute to the elaborate structure that relates science to its sensory evidence. At its most rudimentary level, reification is a device for focusing observation sentences convergently; thus (1). Anaphora, clinching cross-reference, continues to be its business also at more sophisticated levels, as in (2). (1992b: 29-31)
 Putting reification aside, however, we might ask what prompts Quine to think of objects in terms of posits in the first place? The answer is, because current scientific theory maintains that surface irritations exhaust our clues to an external world, and even all possible surface irritations woefully underdetermine physical theory. Furthermore, the objects posited (sticks and stones, neutrinos and quarks, classes and numbers) are justified only insofar as they contribute to the smooth running of the engine of scientific method. Thus does Quine's epistemology of ontology have a naturalistic origin: natural science.
(b) Criterion of Ontic Commitment.
 Despite the role reification plays in Quine's account of posits, his view is not that posits are linguistic, but what we say about them is. Furthermore, he maintains that while ordinary language if often about posits, it does not contain an implicit ontology: "We must recognize... that a fenced ontology is just not implicit in ordinary language. The idea of a boundary between being and nonbeing is a philosophical idea, an idea of technical science in a broad sense" (1981: 9). It is up to scientists and philosophers to draw explicit ontological lines; but how?
[First we must] regiment our notation, admitting only general and singular terms, singular and plural predication, truth functions, and the machinery of relative clauses; or, equivalently and more artificially, instead of plural predication and relative clauses we can admit quantification. Then it is that we can say that the objects assumed are the values of the variables.... (1981: 9-10)In other words, to be is to be the value of a variable of some theory. This criterion of ontic commitment is trivial since it settles merely the question of what some suitably regimented theory says there is, leaving untouched the substantive question of what there is. Furthermore, the criterion is parochial
in that it applies directly only to theories constructed within the framework of our classical quantification theory, or predicate logic. Theories with access to other resources present a problem of foreign exchange. Failing translation into my adopted standard, I can only say that the word 'exists' has a different usage, if any, in that quarter. Given translation, on the other hand, that criterion simply carries over. (1995: 33)Specifying a theory's ontic commitments, however, can be a little tricky:
Our question was: what objects does a theory require? Our answer is: those objects that have to be values of variables for the theory to be true. Of course a theory may, in a sense, require no objects in particular, and still not tolerate an empty universe of discourse either, for the theory might be fulfilled equally by either of two mutually exclusive universes. If for example the theory implies '(Ex)(x is a dog)', it will not tolerate an empty universe; still the theory might be fulfilled by a universe that contained collies to the exclusion of spaniels, and also vice versa. So there is more to be said of a theory, ontologically, than just saying what objects, if any, the theory requires; we can also ask what various universes would be severally sufficient. The specific objects required, if any, are the objects common to all those universes. (1969: 96)In propounding his criterion of ontic commitment, Quine's key insight is that the existential quantifier of classical quantification, '(Ex)', or 'There exists an object x such that', is fashioned so as to have existential import. According to Quine, statements as diverse as 'There is a brick house on Elm Street', 'There is a top quark', and 'There is a prime number between ten and twenty' express the same sense of existence, though the evidence for the three statements differ. Thus, macroscopic objects, microscopic objects, and abstract objects, if they exist, exist in the same sense of the term.
 However, the central ontological role that Quine assigns to the variable of classical quantification is rendered otiose for theories having finite and denumerable universes of discourse: "Once the size [of the universe of discourse] is both finite and specified... ontological considerations lose all force; for we can then reduce all quantifications to conjunctions and alternations and so retain no recognizably referential apparatus" (1976: 216). What Quine has in mind here is that in a finite and specified universe each object would have a name. If so, then universal quantifications, e.g., '(x)Fx', can be defined as continued conjunctions, e.g., '(Fa & Fb & . . . & Fn)', while existential quantifications, e.g., '(Ex)Fx', can be defined and continued alternations, '(Fa v Fb v ... v Fn)'. Here there is no significant role for quantification to play.
Variables... disappear, and with them the question of a universe of values of variables. And the very distinction between names and other signs lapses in turn, since the mark of a name is its admissibility in positions of variables. Ontology thus is emphatically meaningless for a finite theory of named objects.... (1969: 62)(c) Object Identity and Extensionalism.
 According to Quine, "[w]e have an acceptable notion of class, or physical object, or attribute, or any other sort of object, only insofar as we have an acceptable principle of individuation for that sort of object. There is no entity without identity" (1981: 102). For example, classes are identical when their members are identical; physical objects are identical when they occupy the same regions of space-time. Attributes are a different matter. "The positing of attributes is accompanied by no clue as to the circumstances under which attributes may be said to be the same of different" (1969: 19). Indeed, there is no room for such intensional "objects" among the values of the variables of Quine's austere, extensional, language of science. But we should remind ourselves that, for Quine, this not on account of their being abstract objects; after all, Quine countenances classes and they are abstract objects par excellence.
(d) Proxy Function Argument
 We have already noted that different, even mutually exclusive, universes of discourse can fulfill the same theory. Our example was a theory that implied '(Ex)(x is a dog)' and which was fulfilled by a universe that contained collies to the exclusion of spaniels, and also vice versa. Quine's so-called proxy function argument generalizes the point:
A proxy function is any explicit one-to-one transformation, f, defined over the objects in our purported universe. By 'explicit' I mean that for any object x, specified in an acceptable notation, we can specify fx. Suppose now we shift our ontology by re-interpreting each of our predicates as true rather of the correlates fx of the objects x that it had been true of. Thus, where 'Px' originally meant that x was a P, we reinterpret 'Px' as meaning that x is f of a P. Correspondingly for two-place predicates and higher.... We leave all of the sentences as they were, letter for letter, merely reinterpreting. The observation sentences remain associated with the sensory stimulations as before, and the logical interconnections remain intact. Yet the objects of the theory have been supplanted as drastically as you please. (1992b: 31-32)The epistemological moral of the proxy function argument "is that there can be no evidence for one ontology over against another, so long anyway as we can express a one-to-one correlation between them. Save the structure and you save all" (1992a: 8). But what does this conclusion portend for reference and ontology?
Reference and ontology recede thus to the status of mere auxiliaries. True sentences, observational and theoretical, are the alpha and omega of the scientific enterprise. They are related by structure, and objects figure as mere nodes of the structure. What particular objects there may be is indifferent to the truth of observation sentences, indifferent to the support they lend to the theoretical sentences, indifferent to the success of the theory in its predictions. (1992b: 31)Does this mean that we never know the reference of our terms or the objects that are the values of our variables? No at all; by following the norm of homophonic translation at home, we learn along with our fellow English speakers that 'rabbits' refers to rabbits and that dogs are among the values of the variables of a theory that entails '(Ex)(x is a dog)'. But after having acquired our mother tongue, according to the proxy function argument we are free to supplant our home ontology by a strange and distant one without detriment to our theory; ontology is indifferent.
III. Ontological Preference
 We have been recounting the story of how Quine's epistemology of ontology led him to ontological indifference. Moreover, this story is a naturalistic one insofar as it presupposes the ontology of current science. For it is science that teaches us that surface irritations exhaust our clues to an external world. And it is this same science that talks of nerve endings, molecules striking eardrums, light rays striking retinas, and so on. But isn't such talk undercut by Quine's chief epistemological finding, ontological indifference? Aren't nerve ending, molecules, eardrums, light rays, retina, and so on, just figments of an empty structure of theory?
Naturalism itself is what saves the situation. Naturalism looks only to natural science, however fallible, for an account of what there is and what what there is does. Science ventures its tentative answers in man-made concepts, perforce, couched in man-made language, but we can ask no better. The very notion of object, or of one and many, is indeed as parochially human as the parts of speech; to ask what reality is really like, however, apart from human categories, is self-stultifying. It is like asking how long the Nile really is, apart from parochial matters of miles or meters. (1992a: 9)Thus, Quine's ontology of epistemology is as thoroughly naturalistic as the epistemology of ontology that presupposed it. Quine's "tentative ontology continues to consist of quarks and their compounds, also classes of such things, classes of such classes, and so on, pending evidence to the contrary" (1992a: 9).
 Quine's motive for advocating the peaceful coexistence of ontological indifference and ontological preference is beautifully summed up in Word and Object where he writes:
Everything to which we concede existence is a posit from the standpoint of a description of the theory-building process, and simultaneously real from the standpoint of a description of the theory that is being built. Nor let us look down on the standpoint of the theory as make-believe; for we can never do better than occupy the standpoint of some theory or other, the best we can muster at the time. (1960: 22)The only point that need be added to round out this summary of Quine's position is that, by his lights, the best theory we can muster at this time belongs to science.
 Details of Quine's position aside, I think that it is hard for most philosophers to feel at ease with the prospect of the peaceful coexistence of Quine's ontological indifference and his ontological preference. There is a stubborn tendency to think that nobody, not even Quine, can have it both ways. If objects are posits then they aren't real, and if objects are real then they aren't posits. My own view is that this stubborn tendency arises in large part from the fact that most philosophers are heirs to a long tradition that has done little to discourage the idea that philosophers practice their trade from a vantage point of cosmic exile. That, by itself, doesn't mean that such philosophers are mistaken, of course. Nevertheless, I believe they are. I think that a thoroughgoing naturalism that repudiates such first philosophy in favor of a naturalistic human perspective is closer to the mark, comes closer to making philosophical progress. Needless to say, pointing out the pragmatic value of taking the naturalistic turn is unlikely satisfy the fantastic yearnings of our colleagues in cosmic exile. They will, no doubt, and not without reason, view the naturalistic philosopher as having sold out, that is, as having given up being a Philosopher. We are left, then, with two conceptions of philosophy.
Roger F. Gibson
Quine, W. V. (1960) Word and Object. Cambridge, MA: The MIT Press.
----- (1992a) "Structure and Nature." The Journal of Philosophy, LXXXIX, No.1: xx-xxx.
----- (1992b) Pursuit of Truth (revised edition). Cambridge, MA: Harvard University Press.
----- (1981) Theories and Things. Cambridge: Harvard University Press.
----- (1995) From Stimulus to Science. Cambridge: Harvard University Press.
----- (1969) Ontological Relativity and Other Essays. New York: Columbia University Press.
----- (1976) The Ways of Paradox and Other Essays (Revised and enlarged edition). Cambridge, MA: Harvard University Press.
©1997 Roger F. Gibson
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