ࡱ> 5@ 0Ibjbj22 &XX+wxxx ***8bt< y+"@@@*******$k,R.`+x###+XB@@@3+(((#x@x@*(#*(((xx(@ %-*$'(*dI+0y+(/$(/(44(4/x(r( i!++ (( Lecture 2 Words and Truth Gary Ebbs University of Illinois at Urbana-Champaign garyebbs@uiuc.edu May 14, 2004 1. Introduction In the first lecture I presented the framework for my approach to clarifying logic, truth and rational inquiry. I began by assuming that our interest in clarifying rational inquiry is motivated in part by our desire for fruitful collaborations with other inquirers. I explained how our desire for fruitful collaborations with other inquirers motivates us to clarify our agreements and disagreements, to paraphrase our words and sentences in the notation of modern logic, and to formulate logical laws by using a truth predicate defined by Tarski's methods for sentences and words of our own language. I also described what I call our practical judgments of sameness of denotation, which result when we combine our practice of taking other's words to be the same as our own, and apply our own disquotational definitions of denotation to those words. I emphasized that our practical judgments of sameness of denotation go hand-in-hand with our practical identifications of agreements, disagreements, discoveries and proofs. I then raised a central question for our understanding of rational inquiry: How are our disquotational definitions of truth related to our practical judgments of sameness of denotation? Our formal methods of defining truth by themselves tell us nothing about the relationship between the resulting definitions and our practical judgments of sameness of denotation. According to the standard view, these judgments are either (i) determined by independently specifiable facts, hence objective, or (ii) subjective. Unfortunately, neither of these alternatives is acceptable. Attempts to specify facts that determine our practical judgments of sameness of denotation have so far failed, but the alternative of regarding such judgments as subjective leads to the unattractive conclusion that our agreements, disagreements, discoveries, and proofs are all ultimately subjective. To overcome these difficulties I propose that we view our practical judgments of sameness of denotation as objective, hence factual, even though they are not determined by independently specifiable facts. This proposal requires that we reject the standard view that we cannot see our practical judgments of sameness of denotation as objective unless they are determined by independently specifiable facts. Unfortunately, there is a deeply entrenched conception of words that makes it difficult to accept my proposal. In this lecture I will (first) identify the standard conception of words, (second) explain how it creates the illusion that our practical judgments of sameness of denotation are either (i) determined by independently specifiable facts, hence objective, or (ii) subjective, and (third) explain in more detail why neither of these alternatives is acceptable. In lecture 3, I will present an alternative conception of words that fits with my proposal that we view our practical judgments of sameness of denotation as objective, yet not determined by independently specifiable facts. 2. Fact, factual, and fundamental To clarify these points, I will assume a conception of facts and factuality that does not bring with it the idea of items in the world to which our sentences must correspond if they are to be true. On this conception, truth is defined disquotationally, and a fact is just a true sentence. There are no indispensable uses of the words factIt is a fact that snow is white, for instance, is equivalent to, and can be replaced, by Snow is whiteand there are no items in the world to which our sentences must correspond if they are to be true. A sentence we can use is factual if and only if it is disquotationally true or false. This is not to say that every meaningful sentence is factual. According to the conception of factuality that I will assume, some sentences we accept are part of a discourse that is fundamental to our understanding of a given subject matter at a given time, in the sense that we have no grip on that subject matter at that time apart from our acceptance of some of those sentences, so we cannot help but regard them as factual. W. V. Quine held, in particular, that theory in physics is an ultimate parameterthat there is no legitimate perspective independent of physics from which to question our physicists theories, and so we regard the sentences of physics as factual. We can regard other sentences as factual only if their truth or falsity is settled by the truth or falsity of sentences that are fundamental to our understanding of their subject matter. Hence, according to the Quinean conception of factuality, (C) If S is a sentence we can use, then S is factual (true or false) if and only if (a) S is part of a discourse that is fundamental to our understanding of Ss subject matter, or (b) the truth or falsity of sentences of such a discourse determine that S is true or false. This conception of factual fits with my proposal that we understand truth disquotationally, but it does not by itself show that our practical judgments of sameness of denotation are factual. It is also independent of any particular view of which discourses are fundamental to our understanding of a given subject matter. 3. Two senses of language use and the spelling-plus-ex-use conception of words To clarify the motivations for the standard view, we must first distinguish two senses of "language use." One understanding of this phrase is linked with the logical distinction between the use and mention of linguistic expressions. Consider the sentence Beijing is a city, but Beijing is not a city. When we affirm this sentence, we use the first occurrence of the word Beijing to mention (refer to) Beijing, and we use Beijing to mention (refer to) the word Beijing. In this context, our understanding of language use is performative: our only way of conveying what it is to use a word in this sense is actually to use itto perform a particular linguistic act that shows what it is to use the word. When logicians explain the logical distinction between using and mentioning words, they identify words by their spelling alone, and regard them as strings of letter-types. According to this orthographic conception, the ink marks Beijing, Beijing, for example, instantiate two tokens of the word spelled B-e-i-j-i-n-g. The orthographic conception of words is deeply entrenched and widely accepted. One reason is that it provides precise formal criteria of identity for words. Another reason is that it is strongly suggested by Tarski's method of defining truth and denotation, which requires (as a regulative ideal) that we paraphrase ambiguous words of our language by unambiguous words, so that we can identify and distinguish between the words and sentences of the resulting regimented part of our language by spelling alone. Starting with these observations about the usefulness of identifying and distinguishing between words by their spelling, we are naturally tempted to take two additional steps that are not as innocentwe are tempted to think that (i) any utterance can be viewed as an utterance of tokens of word-types, considered as strings of letters, and (ii) different tokens of a given string of letters can have different denotations. It is then natural to wonder what makes it the case that tokens of strings of letters, which appear lifeless and insignificant, have the denotations we ordinarily take them to have. The only plausible answer, it seems, is that we use these tokens in ways that give them certain denotations. The idea is that we can identify tokens of words by means of their spelling, and describe facts that explain or metaphysically determine the denotations, if any, that the tokens have. In this context, our understanding of language use is supposed to be descriptive or explanatory, not performative, and hence in principle available to us whether or not we are in a position to use the words whose denotations we are trying to describe or explain. (To save words, I will henceforth write language ex-use and ex-use in place of language use in the descriptive or explanatory sense and use in the descriptive or explanatory sense, respectively. For language use in the performative sense and use in the performative sense, I will often simply write language use and use.) In short, it seems that facts about how we ex-use tokens of strings of letters determine whatever denotations those tokens have. On this view, the words that interest us in logic are not just strings of letters, but tokens of strings of letters that have particular denotations (or equivalence classes of such tokens). The orthographic conception of words therefore naturally inclines us to adopt what I call the spelling-plus-ex-use conception of words, according to which tokens of a given word w may have different denotations, and tokens of a given sentence s may have different truth-values, where the differences in denotation are determined in part by differences in the way the tokens of w or s are ex-used. 4. Two metaphysical principles If we adopt the spelling-plus-ex-use conception of words and sentences, we will be forced to conclude that our disquotational definitions of denotation and truth for our own words and sentences are factual only if they are determined by facts about how we ex-use our words and sentences. For instance, when we accept instances of the pattern (D) (D) _____ is true of x if and only if x is a ______, such as robin is true of x if and only if x is a robin, we must identify the words within single quotation marks by their spelling alone. But, again, it seems that different tokens of a given word w, considered as a string of letters, may have different denotations determined by differences in the way those tokens are ex-used. (Strictly speaking, on the spelling-plus-ex-use conception of words, only tokens of strings of letters can be ex-used. To simplify my exposition, however, I will often take the phrase ex-use a word (string of letters) as short for ex-use a token of a given word (string of letters).). If we adopt the spelling-plus-ex-use conception of words, we will infer that sentences constructed from the pattern (D) are not fundamental to our understanding of their denotation. We will therefore conclude (in accord with (C)) that if such sentences are factual, their truth or falsity is uniquely determined by the truth or falsity of sentences that describe how the words they contain are ex-used. We will also be tempted to suppose that we can use our words to state their own denotations disquotationally only if the sentences that we use to do this are factual, hence only if there are facts (about how we ex-use the words that occur in those sentences) that determine the denotations of those words. Moved by such reasoning, many philosophers accept the following metaphysical principle (P1) If our disquotational specifications of the denotations of our words are factual, then the denotations thus specified are uniquely determined by facts about how we ex-use the words. The reasoning behind this principle has consequences for our understanding of practical judgments of sameness of denotation. Suppose such judgments are factual. Then in particular the denotation that I specify disquotationally by affirming robin is true of x if and only if x is a robin is uniquely determined by facts about how I ex-use the word spelled r-o-b-i-n, and the denotation that you specify disquotationally by affirming robin is true of x if and only if x is a robin is uniquely determined by facts about how you ex-use r-o-b-i-n. So when I take your word robin to be the same as my word robin, and hence to be true of all and only robins, this practical judgment of sameness of denotation is correct or incorrect according as the denotation that is uniquely determined by facts about how I ex-use r-o-b-i-n is the same as the denotation that is uniquely determined by facts about you how you ex-use r-o-b-i-n. The relevant facts here include facts about how I apply tokens of r-o-b-i-n to things in my environment, and facts about how my tokens of r-o-b-i-n are related to other speakers tokens of r-o-b-i-n, all described independently of my practical judgments of sameness of denotation. Hence on this conception of words, our practical judgments of sameness of denotation are not fundamental to our understanding of denotation: the relevant facts about language ex-use can be described independently of all our practical judgments of sameness of denotation, including my practical judgment that your tokens of r-o-b-i-n have the same denotation as my tokens of r-o-b-i-n. This reasoning can be generalized to apply to any practical judgment of sameness of denotation. Suppose that a speaker S makes a practical judgment of sameness of denotation at time t if and only if there are word-tokens w1 and w2 such that w1 is ex-used by S at t, w2 is ex-used by S at some time before t or by another speaker at or before t, S takes w1 and w2 to be spelled or pronounced in the same way, and without reflection S takes w2 to have the same denotation as w1. Then the reasoning in the previous paragraph suggests that (P2) If a given speakers practical judgment that w1 has the same denotation as w2 is factual then (a) the facts about how w1 is ex-used uniquely determine the denotation of w1, (b) the facts about how w2 is ex-used uniquely determine the denotations of w2, and (c) the denotation, if any, that is uniquely determined by the facts about how w2 is ex-used is the same as the denotation, if any, that is uniquely determined by the facts about how w2 is ex-used. Again, on the standard view, our practical judgments of sameness of denotation are not fundamental to our understanding of denotationthe relevant facts about ex-use are independent of all of our practical judgments of sameness of denotation. The spelling-plus-ex-use conception of words leads us to accept (P1) and (P2), which imply that our practical judgments of sameness of denotation are not fundamental in the sense explained above. If our practical judgments of sameness of denotation are factual, hence objective, then (P2) implies that they are uniquely determined by facts about language ex-use that can be described independently of them, which means that they are not fundamental. Most philosophers dont see any alternative to the spelling-plusex-use conception of words, and so they feel driven to conclude that our practical judgments of sameness of denotation are either not factual or not fundamental, even if these judgments appear to be factual and fundamental from our perspective as participants in rational inquiries. I mentioned earlier that this standard view has unacceptable consequences. In the rest of this lecture I will explain some of these unacceptable consequences in more detail. In lecture 3 I will sketch an alternative conception of words that enables us to regard our practical judgments of sameness of denotation as fundamental. 5. The causal-historical theory of denotation There are many theories about what facts determine the denotations of our words. Here I will focus on what is perhaps the most famous of these theories--causal-historical theory of denotation due to Saul Kripke and Hilary Putnam. In outline, the causal-historical theory is that the denotation of a name or a kind term is initially determined by an "ostensive definition" that may partly rely on causal connections to samples or things that the name or term is to denote. Once the denotation of a word is established in this way, speakers of the language can be credited with using that word if and only if they are connected by an appropriate causal chain with other speakers who use the word, and they are minimally competent in its use. "Appropriate" and "minimally competent" are place-holders for specifications of the causal chains and competencies that are supposed to determine the truth or falsity our practical judgments of sameness of denotation. There is no consensus about how to specify these supposed chains and competencies, and many philosophers concede that there are kind terms (such as names of biological species) that pose challenges for the causal-historical theory. Nevertheless, many philosophers still think that by citing causal-historical facts we can explain why the denotation of our word gold, for instance, did not change as a result of our discovery that gold is the element with atomic number 79. Even in this paradigm case, however, as I shall now try to show, the truth or falsity of our practical judgments of sameness of denotation is not determined by causal-historical facts. 6. A thought experiment The historical background for my argument is that platinum was not discovered until the mid-18th century, when chemists called it white gold because of its striking similarities to what they previously called gold. Platinum has a higher melting point than gold. But like gold, Platinum dissolves in aqua regia, which was named for its ability to dissolve gold. In the mid-17th century, a chemist applying this acid test to a sample of platinum might have concluded that it should be called gold. We now know that platinum and gold are different elements: platinum is the element with atomic number 78, and gold is the element with atomic number 79. With this in mind, suppose that there is a Twin Earth that is indistinguishable from Earth up until 1650, when large deposits of platinum are uncovered in Twin South Africa, and that once it is established by Twin Earth chemists that the newly uncovered metal dissolves in aqua regia, members of the Twin English speaking community call it gold, treating it in the same way we treat gold: the platinum is mined as gold, hammered (and later melted) together with gold to produce coins and bars that are valued by Twin Earthlings just as we value gold. Everyone on Twin Earth trusts the Twin Earth chemists judgment that the newly uncovered metal is properly called gold. Suppose also that on Twin Earth chemistry develops in almost exactly the same way in which it develops on Earth, except that when Twin Earth chemists investigate what they call gold, they conclude that there are two kinds of goldtheir word gold denotes x if and only if x is (a bit of) the element with atomic number 78 or x is (a bit of) the element with atomic number 79. Recall that Twin Earth is just like Earth with a slightly different future after platinum is first uncovered in Twin South Africa in 1650. To see the possibility of this Twin Earth senario, it is enough to imagine a few accidental differences between the two communities that allow for the accidental uncovering of large amounts of platinum on Twin Earth. The crucial point is that just as members of our English speaking community take for granted that the denotation of the English word gold did not change as a result of the discovery that it denotes x if and only if x is (a bit of) the element with atomic number 79, so members of the Twin English speaking linguistic community take for granted that the denotation of their Twin English word gold did not change as a result of their discovery that it denotes x if and only if x is (a bit of) the element with atomic number 78 or x is (a bit of) the element with atomic number 79. Members of the two communities have different beliefs about what their word form gold denotes, and they take these beliefs for granted even when they are evaluating utterances made by using gold before 1650. For instance, suppose that in 1649 John Locke and his twin on Twin Earth both uttered the words There are huge deposits of gold in those hills, with Locke indicating South African hills, and Twin Locke indicating the corresponding Twin South African hills, both of which contain platinum but no gold. We take Lockes word gold to be true of an object x just in case x is gold, whereas our contemporaries on Twin Earth take Twin Lockes word gold to be true of an object x just in case (as we would say it) x is either gold or platinum. We conclude that Lockes utterance is false, and our contemporaries on Twin Earth conclude that Twin Lockes utterance is true. 7. A dilemma for the causal-historical theory of denotation Lets see if the causal-historical facts determine that our entrenched practical judgment that the denotation of the English word gold did not change since 1649. Suppose that in 1649 members of both linguistic communities affirmed the following "ostensive definition": (A) x is gold if and only if for most things y that I and other speakers in my linguistic community have on other occasions called gold, x is (a bit of) the same substance as y. The question is whether any such ostensive definition in 1649 actually determined that gold is true of x if and only if x is (a bit of) the element with atomic number 79. The answer is "no". To see why, note first that to explain our practical judgment that the denotation of the English word gold did not change since 1649 by appealing to (A), we must assume that (B) for all x and y, if x and y are gold, then x is (a bit of) the same substance as y is true in English and Twin English. But even if (B) is true in Twin English, it may be that for some x and y, x is (a bit of) the same substance as y is true in Twin English of the ordered pair (x, y(, but x does not have the same atomic number as y. One might try to rule this out by stipulating that (C) for all x and y, if x is (a bit of) the same substance as y, then x has the same atomic number as y is true in both in English and Twin English. One problem with this strategy is that in 1649 no one was in a position to formulate (C), since analytical chemistry had not yet been developed. The crucial problem, however, is that even if we stipulate that (C) is true in English and Twin English, (B) may be false in Twin English. One may "ostensively define gold by affirming (A) without thereby guaranteeing that (B) is true. The problem is that a Kripke-style ostensive definition of the denotation of a term can be part of a theory of what determines the denotation of the term, hence not just another entrenched belief that we express by using the term, only if we know that the ostensive definition could not turn out to be false. In fact, however, we trust our practical judgments of sameness of denotation across time more than we trust any particular theory of denotation, so we have no guarantee that we cannot revise a given ostensive definition without changing the subject. I conclude that affirmations of (A) in 1649 could not determine either the Earthlings or Twin Earthlings discoveries about what their word-form gold denotes, and therefore could not determine the truth or falsity of the practical judgments of sameness of denotation for gold in either linguistic community. 8. Dispositions Suppose that Locke and Twin Locke would have accepted that gold is (a bit of) the element with atomic number 79 if they had been presented with the evidence we now have for this conclusion. One might think that an affirmation of (A) in 1649 rules out the Twin Earthlings practical judgments of sameness of denotation for gold if it is supplemented with a counterfactual of this kind. The problem with this strategy is that whether or not an individual would accept or reject certain sentences may depend on the order in which he is presented with evidence that supports those sentences. It is plausible to suppose that Locke and Twin Locke would have affirmed the sentence x is gold if and only if x is (a bit of) the element with atomic number 79 if they had been presented with the same evidence that later English speakers encountered, in the same order in which they actually encountered it. But it is equally plausible to suppose that Locke and Twin Locke would have affirmed the sentence x is gold if and only if either x is the element with atomic number 79 or x is the element with atomic number 78 if they had been presented with the same evidence that later Twin English speakers encountered, in the same order in which they actually encountered it. We have no independent grounds for saying that one of these presentations of the evidence is correct and the other is incorrect, and so an appeal to dispositions cannot show that our community's practical judgments of sameness of denotation for gold are correct and theirs are incorrect. 9. Are our practical judgments of sameness of denotation subjective? As we saw earlier, the spelling-plus-ex-use conception of words commits us to (P2), according to which our practical judgments of sameness of denotation are factual, hence objective, all only if they are determined by uniquely specifiable facts about language ex-use. But the gold-platinum thought experiment shows that two of the most promising theories of what determines the denotations of our words--the causal-historical theory and the dispositional theoryfail to that determine true of our practical judgments of sameness of denotation across time for gold. In this brief lecture I cannot to discuss all of the possible responses to this failure, nor can I survey all the theories of what determines the denotations of our words. I will say only that in my view the gold-platinum thought experiment undermines all such theories. Given the spelling-plus-ex-use conception of words, we are therefore inevitably led to the conclusion that our practical judgments of sameness of denotation are not factual, but subjective in some sense. The best known theory of denotation according to which our practical judgments of sameness of denotation are subjective is that of W. V. Quine. According to Quines theory, our practical judgments of sameness of denotation are indeterminate, in the sense that the facts about the linguistic behavior do not uniquely determine which of several different ways of translating other speakers' words is correct. Our practical judgments of sameness of denotation simply reflect our unthinking psychological preference for taking words that are spelled or pronounced in the same way to be the same. In fact, however, we could make different choices that would be equally correct according, to Quine. Quines theory is not incoherent, as some philosophers have argued. But it fails to fit with our practical identifications of agreements, disagreements, and discoveries. When we take ourselves to disagree with another investigator, for instance, we take for granted that we disagree about an objective matter of truth and falsity. In Quine's view, however, whether or not we disagree with someone else will depend on how we choose to translate her words into our own, and that choice is subjective, even if it is partly constrained by the facts about linguistic behavior. The same goes for our practical identifications of discoveries, which depend on our practical judgments of sameness of denotation across time. Thus Quines view implies that we have no reason to think that our agreements, disagreements, and discoveries are relevant to truth at all, because they are based in subjective, non-factual choices about how to translate each other's words. This undermines our practical point of view on inquiry, according to which our practical judgments of sameness of denotation constitute a framework within which we take our agreements, disagreements, and discoveries to be objective, and therefore relevant to our pursuit of truth. 10. A way out of the dilemma? Neither horn of the dilemma is acceptable. I propose that we reject the spelling-plus-ex-use conception of words, and take our practical judgments of sameness of denotation to be our best guide to sameness of denotation. Recall that to apply Tarskis method of defining truth to ones own words, one must be able to distinguish between words of ones own current idiolect orthographically. When we combine such disquotational definitions with our practice of taking at face value words of another speaker's idiolect, or words of our own idiolect at some other time, we make practical judgments of sameness of denotation. When we make such judgments, we directly use our own words, in the performative sense of use that contrasts with mentioning them. We do not assert that another speaker's word, or one of our words at some other time, has the same denotation as the word of our current idiolect that is spelled in the same way. Instead, we regard them as one and the same word. Practical judgments of sameness of denotation thereby express our practical understanding of the same-word relation. We are each in a position to construct a disquotational account of denotation for words of our own idiolect, and combine it with our practice of taking each other's words at face value to incorporate practical judgments of sameness of denotation. When we revise these judgments, we do so by relying on other practical judgments of sameness of denotation. Our revisions of our practical judgments of sameness of denotation therefore do not show that we have any understanding of how denotations are determined by facts about language use understood completely independently of our practice of taking each other's words at face value. This practice is fundamental to our understanding of the same-word relation, contrary to the spelling-plus-ex-use conception of words and the corresponding metaphysical principles (P1) and (P2). As I see it, our primary grip on denotation is disquotational. To specify the denotations of our words disquotationally we must use our words, in the performative sense that goes hand in hand with our practical judgments of sameness of denotation, which constitute our best grip on the same-word relation. In this way, our performative use of language is integral to our understanding of the same-word relation and the denotations of our words. In lecture 3, I will explain this alternative conception of the same-word relation in more detail, and show how it enables us to dissolve the apparent the puzzle raised by the gold-platinum thought experiment. PAGE  PAGE 18 This is not to say that it is a fact that snow is white because we accept the sentence snow is white, just that it is a fact that snow is white if and only if snow is white. W. V. Quine, Reply to Chomsky, in D. Davidson and J. Hintikka, eds., Words and Objections. I get the term orthographic from David Kaplan, Words, in Proceedings of the Aristotelian Society, Supplementary Vol. 64 (1990) : 93-119. I cannot list all the philosophers of language who implicitly or explicitly endorse the spelling-plus-ex-use conception of words. The conception is widespread, however, and is shared even by those, such as Paul Horwich, who reject so-called inflationary theories of truth. For instance, in Meaning, Use, and Truth, in Mind 104 (1995) Horwich endorses what he calls a use-theory of meaning, according to which: (i) there are meaning-properties, which are properties of tokens of words, considered as strings of letters; (ii) each such property has an underlying nature, (iii) the underlying natures of meaning-properties are non-intentional, and (iv) the non-intentional underlying natures of meaning-properties are basic regularities of use, explanatorily fundamental generalizations about the circumstances in which words occur. According to this theory, the ex-use of a word is its meaning-property. I also use this thought experiment in my paper The Very Idea of Sameness of Extension Across Time. Maurice. P. Crosland, Historical Studies in the Language of Chemistry (London: Heinemann Educational Books Ltd., 1962), page 97. See the entries for 'gold' and 'platinum' in the New Columbia Encyclopedia (New York: Columbia University Press, 1975). Crosland reports that in 1752, a Swedish chemist named Scheffer concluded that the close similarity of (what we now call) platinum to gold justifies the claim that (what we now call) platinum is white gold. (p. 97) Crosland also points out that "the distinct nature of new substances was not always easy to demonstrate by elementary analytical methods and the skeptics could always maintain that any apparent discovery was really a substance previously known. . ." Maurice. P. Crosland, Historical Studies in the Language of Chemistry (London: Heinemann Educational Books Ltd., 1962), page 98. This thought experiment is similar in structure to the Druid thought experiment that Mark Wilson presents in his paper "Predicate Meets Property" (The Philosophical Review, XCI, No. 4:549-589): "A B-52 full of regular American types landed on their uncharted Island and the Druids exclaimed, 'Lo, a great silver bird falleth from the sky.' . . . [After this event]. . . the extension of the predicate 'is a bird' for the cosmopolitan Druidese is something like the set of flying devices (including animal varieties).... [But] . . . If the hapless aviators had crashed in the jungle unseen and were discovered by the Druids six months later as they camped discontentedly around the bomber's hulk, their Druid rescuers would have proclaimed, 'Lo, a great silver house lieth in the jungle.' . . . [In this alternative linguistic community] airplanes are no longer [read: are not] held to be 'birds'. . . .Which extension should be assigned to 'bird' in cosmopolitan Druidese thus depends upon the history of the introduction of B-52's to the island " (p. 549-550) A similar thought experiment is briefly sketched by Daniel Dennett on page 312 of "Evolution, Error, and Intentionality," in Daniel Dennett, The Intentional Stance (Cambridge, MA: MIT Press, 1987). This way of illustrating the odd consequences of the first thought experiment is adapted from a similar thought experiment presented by Keith Donnellan in his paper "Kripke and Putnam on Natural Kind Terms," in C. Ginet and S. Shoemaker, ed., Knowledge and Mind (Oxford: Oxford University Press, 1983), 84-104; p. 103. Similarly, we have no guarantee that a "recognitional capacity" that we associate with a given term determines the denotation of the term, in this sense proposed by Jessica Brown in her paper, "Natural Kind Terms and Recognitional Capacities" Mind 107 (April 1998):275-303. On any non-semantic account of a "recognitional capacity," the members of the Earth and Twin-Earth linguistic communities in my thought experiment associate the same "recognitional capacity" with the term gold in 1650. Yet they later characterize the denotation of gold differently, and revise the "recognitional capacities" they respectively associate with the word-form gold, without taking themselves to be changing the subject. If we take our practical judgments of sameness of denotation across time as our best guide to when we have changed the subject and when we haven't, then my thought experiment undermines Browns theory of what determines the denotation of natural kind terms. Hilary Putnam sometimes seems tempted by this idea. See, for example, "The Meaning of 'Meaning'," (reprinted in Hilary Putnam, Mind and Language, Cambridge: Cambridge University Press, 1975), pp. 237-238; and Representation and Reality (Cambridge, Mass.: MIT Press, 1988), pp. 30-37. This formulation of the challenge my thought experiment poses for dispositional theories is due to Bill Robinson. The point was already implicit in Mark Wilsons druid thought experiment (see footnote 18). The observations in this section suggest an argument against Paul Horwichs use theory of meaning. According to that theory, the meaning of a term is constituted by its possession of a certain "acceptance property" that can be specified independently of its meaning or denotation. Candidates for such properties are facts about a speakers linguistic behavior, in particular, facts about which sentences the speaker is disposed to accept under various circumstances. For instance, according to Horwich, "the acceptance property that governs the speakers overall use of "and" is (roughly) his tendency to accept p and q if and only if accepts both p and q. (Meaning, 45) Moreover, according to Horwich, two words express the same concept if they have the same basic acceptance property (46), and any two words that express the same concept must have the same denotation (69). Since Horwich can only appeal to linguistic dispositions, described in nonsemantic terms, he is apparently committed to saying that the term gold expresses the same concept, and therefore has the same denotation, in 1650 in both of the linguistic communities of my thought experiment. 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