of such things; such knowledge may itself be philosophically useful (indeed, Johnston uses it for his philosophical purposes).6 6 On essentialism see, for example, Kripke (1980), French, Uehling, and Wettstein (1986), Fine (1994, 1995) and Wiggins (2001). For a good statement of the outlook of contemporary metaphysics see Zimmerman (2004).
2 Taking Philosophical Questions at Face Value
How often are philosophical questions implicitly about thought or language when they are not explicitly so? As a case study, I will take a question closely related to the problem of vagueness, because it looks like a paradigm of a philosophical question that is implicitly but not explicitly about thought and language. For vagueness is generally conceived as a feature of our thought and talk about the world, not of the world itself. Admittedly, some philosophers find tempting the idea of mind-independently vague objects, such as Mount Everest, vague in their spatiotemporal boundaries and mereological composition, if not in their identity. That kind of vagueness is not my concern here. I will consider an example of a quite standard type, involving a vague predicate.1 Yet the reconstrual of the question as implicitly about thought or language turns out to be a mistake. If it is a mistake here, in such favorable conditions, it is a mistake far more widely.
1
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
