Читать книгу The Philosophy of Philosophy - Timothy Williamson - Страница 18

Suppose that there was once plenty of water on the planet Mars; it was clearly not dry. Ages passed, and very gradually the water evaporated. Now Mars is clearly dry. No moment was clearly the first on which it was dry or the last on which it was not. For a long intermediate period it was neither clearly dry nor clearly not dry. Counting the water molecules would not have enabled us to determine whether it was dry; other measures would have been equally inconclusive. We have no idea of any investigative procedure that would have resolved the issue. It was a borderline case. No urgent practical purpose compels us to ask whether Mars was dry then, but only a limited proportion of thought and talk in any human society is driven by urgent practical purposes. We should like to know the history of Mars. When necessary, we can always use words other than “dry.” Nevertheless, we reflect on the difficulty of classifying Mars as dry or as not dry at those intermediate times, even given exact measurements. We may wonder whether it was either. We ask ourselves:

Was Mars always either dry or not dry?

Henceforth I will refer to that as the original question. More precisely, I will use that phrase to designate that interrogative sentence, as used in that context (the word “question” can also be applied to what interrogative sentences express rather than the sentences themselves).

The original question is at least proto-philosophical in character. It is prompted by a difficulty both hard to identify and hard to avoid that we encounter in applying the distinctions in our repertoire. It hints at a serious threat to the validity of our most fundamental forms of deductive reasoning. Philosophers disagree about its answer, on philosophical grounds explored below. A philosophical account of vagueness that does not tell us how to answer the original question is thereby incomplete. Without an agreed definition of “philosophy,” we can hardly expect to prove that the original question or any other is a philosophical question; but when we discuss its answer, we find ourselves invoking recognizably philosophical considerations. More simply, I’m a philosopher, I find the original question interesting, although I think I know the answer, and I have no idea where one should go for an answer to it, if not to philosophy (which includes logic). But before we worry about the answer, let us examine the original question itself.

The question queries just the supposition that Mars was always either dry or not dry, which we can formalize as a theorem of classical logic, ∀t (Dry(m, t) ∕ ¬Dry(m, t)).² In words: for every time t, either Mars was dry at t or Mars was not dry at t. The question is composed of expressions that are not distinctively philosophical in character: “Mars,” “always,” “either … or …,” “not,” “was,” and “dry.” All of them occur in a recognizably unphilosophical question such as “Was Mars always either uninhabited or not dry?,” which someone might ask on judging that Mars is both uninhabited and dry and wondering whether there is a connection. Although philosophical issues can be raised about the words in both questions, it does not follow that merely in using those words one is in any way engaging in philosophy. One difference between the two questions is that it is not obviously futile to try to argue from the armchair that Mars was always either dry or not dry, whereas it is obviously futile to try to argue from the armchair that Mars was always either uninhabited or not dry.

The original question does not itself ask whether it is metaphysically necessary, or knowable a priori, or analytic, or logically true that Mars was always either dry or not dry. It simply asks whether Mars always was either dry or not dry. Expressions such as “metaphysically necessary,” “knowable a priori,” “analytic,” and “logically true” do not occur in the original question; one can understand it without understanding any such philosophical terms of art. This is of course neither to deny nor to assert that it is metaphysically necessary, or knowable a priori, or analytic, or logically true that Mars was always either dry or not dry. For all that has been said, the proposition may be any combination of those things. But that is not what the original question asks.

In other circumstances, we could have answered the original question on philosophically uninteresting grounds. For instance, if there had never been liquid on Mars, then it would always have been dry, and therefore either dry or not dry. In order to pose a question which could not possibly be answered in that boring way, someone who already grasped one of those philosophically distinctive concepts might ask whether it is metaphysically necessary, or knowable a priori, or analytic, or logically true that Mars. The meaningfulness of the philosophical jargon might then fall under various kinds of suspicion, which would extend to the question in which it occurred. But the original question itself cannot be correctly answered in the boring way with respect to the originally envisaged circumstances. Its philosophical interest, however contingent, is actual.

We could generalize the original question in various ways. We might ask whether everything is always either dry or not dry. Then we might notice that discussing that question is quite similar to discussing whether everything is either old or not old, and so on. We might, therefore, ask whether for every property everything either has it or lacks it. The coherence of such generalizing over properties might itself fall under various kinds of suspicion, which would extend to the question in which it occurred. Someone might even doubt whether there is such a property as dryness. But the original question itself does not attempt such generality. That it has the same kind of philosophical interest as many other questions does not imply that it has itself no philosophical interest. If that interest is obscured by problematic features of the apparatus with which we try to generalize it, we can refrain from generalizing it, and stick with the original question. In order not to be distracted by extraneous issues that arise from the apparatus of generalization, not from the original question, we do best to stick with the original question in its concrete form.³ We can still help ourselves not to be distracted by unimportant features of the question, if we remember that there are many other questions of a similar form.

What is the original question about? “About” is not a precise term. On the most straightforward interpretation, a sentence in a context is about whatever its constituents refer to in that context. Thus, taken at face value, the original question is about the planet Mars, the referent of “Mars” in this context; perhaps it is also about dryness, the referent of “dry,” and the referents of other constituents too. Since the original question contains no metalinguistic expressions, it is not about the name “Mars” or the adjective “dry.” Evidently, the original question is not explicitly about words.

Is the original question implicitly about language? Someone might claim so on the grounds that it is equivalent to questions that are explicitly about language, such as these:

Is the sentence “Mars was always either dry or not dry” true? (Does it express a truth as used in this context?)

Did Mars always belong either to the extension of the word “dry” or to the anti-extension of “dry” (as the word “dry” is used in this context)? (1970: 11).

But parallel reasoning would lead to the conclusion that the unphilosophical question “Was Mars always either uninhabited or not dry?” is also implicitly about language, since it is equivalent to these questions:

Is the sentence “Mars was always either uninhabited or not dry” true? (Does it express a truth as used in this context?)

Did Mars always belong either to the extension of the word “uninhabited” or to the anti-extension of “dry” (as the word “dry” is used in this context)?

Indeed, we could make parallel arguments for all everyday and scientific questions. Since they are not all about language in any distinctive sense, the reasoning does not show that the original question was about language in any distinctive sense. Even if the equivalences did show that the original question was in some sense implicitly about language, they could be read in both directions: they would also show that the explicitly metalinguistic questions were in an equally good sense implicitly not about language.

The equivalences between the questions are in any case uncontroversial only if the corresponding disquotational biconditionals are:

 (T1) “Mars was always either dry or not dry” is true if and only if Mars was always either dry or not dry.

 (T2a) For any time t, Mars belongs to the extension of “dry” at t if and only if Mars is dry at t.

 (T2b) For any time t, Mars belongs to the anti-extension of “dry” at t if and only if Mars is not dry at t.

On the face of it, these biconditionals express at best contingent truths. For perhaps the word “dry” could have meant wet, in which case Mars would have belonged to the extension of “dry” when wet and to the anti-extension of “dry” when dry: for we use the word “dry” to mean dry even when we are talking about circumstances in which it would have meant something else, because we are not talking in those circumstances. If so, T2a and T2b do not express necessary truths. Similarly, perhaps the sentence “Mars was always either dry or not dry” could have failed to express a truth even though Mars was always either dry or not dry, since “always” could have meant never. On this reading, T1 does not express a necessary truth. We should not assume that a useful notion of aboutness would transfer across merely contingent biconditionals. Perhaps we can instead interpret T1, T2a, and T2b as expressing necessary truths by individuating linguistic expressions so that their semantic properties are essential to them; whether that requires treating the quoted expressions as necessary existents is a delicate matter. In any case, some theorists of vagueness have denied even the actual truth of biconditionals such as T1, T2a, and T2b; they might respond to the original question in one way and to the explicitly metalinguistic questions in another.⁴ Thus the questions are not pragmatically, dialectically or methodologically equivalent within the context of debates on vagueness. For present purposes, we need not resolve the status of the disquotational biconditionals, because we have already seen that the sense in which they make the original question implicitly about words is too indiscriminate to be useful.

We can argue more directly that the original question is not implicitly about the word “dry” by appeal to a translation test. For consider the translation of the original question into another language, such as Serbian:

 Da li je Mars uvek bio suv ili nije bio suv?

The Serbian translation is not implicitly about the English word “dry.” But since the questions in the two languages mean the same, what they are implicitly about (in the same context) should also be the same. Therefore, the original question is not implicitly about the word “dry.” By similar reasoning, it is not about any word of English or any other language. Of course, given the informality of the notion of implicit aboutness, the argument is not fully rigorous. Nevertheless, the translation test emphasizes how far one would have to water down the notion of reference in order to reach a notion of implicit aboutness on which the original question would be implicitly about a word.

The translation test does not show that the original question is not implicitly about a concept, something like the meaning of a word rather than the word itself, for the English word “dry” and its Serbian synonym “suv” both express the concept dry. But what basis is there for the claim that the original question is implicitly about the concept dry? We might argue that the original question is in some sense equivalent to a metaconceptual question:

Did Mars always belong either to the extension of the concept dry or to the anti-extension of dry?

For we might apply the notions of extension and anti-extension to concepts by means of biconditionals similar to T2a and T2b respectively:

 (TC2a) For any time t, Mars belongs to the extension of dry at t if and only if Mars is dry at t.

 (TC2b) For any time t, Mars belongs to the anti-extension of dry at t if and only if Mars is not dry at t.

TC2a and TC2b can express necessary truths more easily than T2a and T2b can, for the apparently contingent relation between words and their meanings has no straightforward analogue for concepts. Concepts are individuated semantically: rather than merely having meanings, they are meanings, or something like them.⁵ Nevertheless, the argument that the original question is implicitly about the concept dry in virtue of being equivalent to the metaconceptual question wildly overgeneralizes, just like the argument that the original question is implicitly about the word “dry” in virtue of being equivalent to the metalinguistic question. For parallel reasoning would lead to the conclusion that the unphilosophical question “Was Mars always either uninhabited or not dry?” is implicitly about the concept dry, and likewise for any other unphilosophical question. Since those questions are not about concepts in any distinctive sense, the original reasoning does not show that the original question is about concepts in any distinctive sense. Even if the equivalences did show that the original question was in some sense implicitly about thought, they can be read in both directions: they would also equally show that the explicitly metaconceptual questions were in an equally good sense implicitly not about thought.

A Fregean might argue: the original question is explicitly about the concept dry, because it contains the predicate “… is dry” (in the past tense), which refers to the concept dry. In that sense, the question “Was Mars always either uninhabited or not dry?” would also be explicitly about the concept dry. However, the Fregean is not using the word “concept” with its contemporary meaning, on which concepts are something like mental or semantic representations, closer to the realm of sense than to that of reference. The Fregean referent of a predicate (a Fregean concept) is simply the function that maps everything to which the predicate applies to the true and everything else to the false: it could be treated as the extension of the predicate, except that in Fregean terms it is a function rather than an object. If the predicate refers to the property of dryness or to the set of dry things, then the original question is about the property of dryness or the set of dry things, but that has no tendency to show that it is about thought. Similarly, the Fregean claim has no tendency to show that the question is about thought, for the Fregean concept is in the realm of reference, not in the realm of thought. Like the property and the set, it is no sense but something to which a sense may determine reference. Since it is no sense, it is no constituent of a thought, on the Fregean view, nor is it a concept in the current sense of “concept.”

Thought and talk are not always about thought or talk. To judge by its overt compositional structure, the original question in particular is not about thought or talk. It is no metalinguistic or metaconceptual question. We have seen no reason to regard its overt structure as at all misleading in that respect. Our provisional conclusion must therefore be that the original question, although at least proto-philosophical, is not about thought or language in any distinctive sense. It does not support the linguistic or conceptual turn, interpreted as a conception of the subject matter of philosophy.