[3.5.3.] Quine’s Criterion of Ontological Commitment.

 

Quine’s answer to the question about Pegasus (that there is no entity that is Pegasus, not even an unactualized possible) and his rejection of realism about universals illustrates the view he expresses in his famous slogan:

 

“To be is to be the value of a variable.” (139)

 

Here Quine is referring to variables in symbolic logic.

 

In symbolic logic, a variable is a lower case letter (x, y, z...) that can represent some individual or other:

 

(x)(Mx É Ax) [For all x, if x is a mammal, then x is an animal; i.e., all mammals are animals]

 

“(x)” is known as the universal quantifier; it is read: “for all x”

 

“É” represents “if ... then...”

 

“M” represents being a mammal; “A” represents being an animal.

 

($x)(Px · Tx)  [There is an x such that x is a philosopher and x is tall, i.e. some philosophers are tall.]

 

“($x)” is known as the existential quantifier; it is read: “there is an x such that”

 

“·” represents “and”

 

In both of the above sentences, “x” is a variable, and so it does not refer to any specific thing.

 

In proclaiming “to be is to be the value of a variable,” Quine is giving a criterion of ontological commitment:

·         this is not a criterion of what there actually is;

·         it is a criterion of what a theory says there is;

·         what there actually is is what a true theory says there is.

 

He states the criterion as follows: “a theory is committed to those and only those entities to which the bound variables of the theory must be capable of referring in order that the affirmations made in the theory be true.” (138)

 

The criterion is this: in order to tell what types of thing a given theory says exist…

1.      translate the statements of the theory into statements of symbolic logic.^[1]

2.      locate the statements that begin with an existential quantifier “($x),” which is read “there is an x such that...”

3.      figure out what things must exist in order for those statements to be true: the theory is committed to the existence of those things and only those things.

 

Quine gives two illustrations:

 

(1) “Some dogs are white.”                  ($x)(Dx · Wx)            

 

In order for this to be true, there must be white dogs; so this statement says there are white dogs. It does not say that there is any such thing as doghood or whiteness.

 

(2) “Some species are cross-fertile.”    ($x)(Sx · Cx)

 

In order for this to be true, there must be cross-fertile species. Since a species is an abstraction, this statement commits us to admitting abstract objects into our ontology.

 

If you don’t want to admit species into your ontology, then you are obligated to show how this sentence can be translated into other statements that are not committed to the existence of species.

 

 

[3.5.4.] Semantic Ascent.

 

“Semantic ascent” is Quine’s phrase for his method of resolving disagreements in ontology.

 

Suppose that two people, X and Y, have different ontologies: one of them believes that Pegasus is, the other believes that Pegasus is not.

 

According to Quine, it is difficult, maybe even impossible, to settle this disagreement by talking about Pegasus.

 

A better strategy is to make a semantic ascent: ascend from a conversation about Pegasus to a conversation about the word “Pegasus.” As Quine puts it:

 

In so far as our [i.e., Quine’s and McX’s] basic controversy over ontology can be translated upward into a semantical controversy about words and what to do with them, the collapse of the controversy into question-begging may be delayed. (140)^[2]

 

This illustrates a view of language shared by many of the most prominent figures in the analytic tradition (Frege, Russell, Wittgenstein, Carnap...): philosophical problems can be settled or resolved by focusing on language.

 

But Quine gives the following warning: the fact that we can make a semantic ascent when discussing ontology does not mean that “what there is depends on words.” (140) We may be able to settle ontological questions by focusing on language, but that does not mean that ontological questions are merely linguistic questions. They remain questions about what there is, not about language:

 

                It is no wonder, then, that ontological controversy should tend into controversy over language. But we must not jump to the conclusion that what there is depends on words. Translatability of a question into semantical terms is no indication that the question is linguistic. To see Naples is to bear a name which, when prefixed to the words ‘sees Naples’, yields a true sentence; still there is nothing linguistic about seeing Naples. (140)

 

 

[3.5.5.] Competing Ontologies.

 

So how do we go about deciding what our ontology will be? How do we decide, from among the different possible conceptual schemes, which one to adopt?

 

In beginning to answer this question, Quine once again alludes to Ockham’s razor:

 

… we adopt, at least insofar as we are reasonable, the simplest conceptual scheme into which the disordered fragments of raw experience can be fitted and arranged. (140, emphasis added)

 

But a bare appeal to simplicity will not result in the selection of a single ontology from among all the ontologies we could choose:

 

            But simplicity, as a guiding principle in constructing conceptual schemes, is not a clear and unambiguous idea; and it is quite capable of presenting a double or multiple standard. (140)

 

For example, consider two competing conceptual schemes (and their accompanying ontologies), each of which is “simple” in its own way:

 

phenomenalism (df): the ontological view according to which there are only mental items and events (Quine: “individual subjective events of sensation and reflection”); what appear to be physical objects are actually mere phenomena.

 

physicalism (df.): the ontological view according to which there are only physical objects.

 

Says Quine, there is a sense in which phenomenalism is very simple: it uses “the most economical set of concepts adequate to the play-by-play reporting of immediate experience.” (140)

 

But there is also a sense in which physicalism is very simple:

 

By bringing together scattered sense events and treating them as perceptions of one object, we reduce the complexity of our stream of experience to a manageable conceptual simplicity. The rule of simplicity is indeed our guiding maxim in assigning sense data to objects: we associate an earlier and a later sensum [a sensum is an object of sensation] with the same so-called penny, or with two different so-called pennies, in obedience to the demands of maximum simplicity in our total world-picture. (140)

 

“…from a phenomenalistic point of view, the conceptual scheme of physical objects is a convenient myth, simpler than the literal truth and yet containing that literal truth as a scattered part.” (140)

 

So, although Quine has come out against the conceptual scheme that includes universals as independently existing entities (i.e., he has come out against realism), the article ends without Quine having declared in favor of any specific ontological scheme. In fact, he takes a very liberal attitude towards the issue of deciding among simple conceptual schemes:

 

                Here we have two competing conceptual schemes, a phenomenalistic one and a physicalistic one. Which should prevail? Each has its advantages; each has its special simplicity in its own way. Each, I suggest, deserves to be developed. (140)

…the question of what ontology actually to adopt still stands open, and the obvious counsel is tolerance and an experimental spirit. Let us by all means see how much of the physicalistic conceptual scheme can be reduced to a phenomenalistic one; still, physics also naturally demands pursuing, irreducible in toto though it be. Let us see how, or to what degree, natural science may be rendered independent of platonistic mathematics and delve into its platonistic foundations. (141, emphasis added)

 

 

Stopping point for Monday March 9. For next time, begin reading “Realism vs, Anti-Realism” by Loux (pp.250-57, stop at the section entitled “Dummett’s Realism”). Note that at the beginning of this reading, he refers back to the book’s introduction, in which he had described two different conceptions of metaphysics:

1.      the traditional conception: metaphysics is concerned with “being qua being” [i.e., it is concerned with being as being, with being itself]. This is how Aristotle defined being.

2.      a modern conception: metaphysics is concerned with “human conceptual structures.”