塔斯基的真理定义与物理论

塔斯基（Tarski）于1933年发表了他著名的真理定义,并相信该定义能够为其物理论的哲学立场服务;但费尔德（Field）批评说,塔斯基实际上所给出的真理定义并没能成功地达成这个目标。不过,费尔德同时也认为,一个部分奠基在塔斯基真理定义之上、并且是物理论者可以接受的化约性真理理论并非不可能。费尔德对于塔斯基真理定义的这些批评,在哲学家中曾经引起了许多意见不一的反应。本文的目的是想回答在这些讨论当中曾经被提出过的三个问题。首先,塔斯基实际上所给出的真理定义是不是一个物理论者可以接受的化约性定义？其次,费尔德所设想的那种可被物理论者所接受的化约性真理理论是否可能成功？最后,如果塔斯基实际上所给出的定义并不能符合物理论的化约目标,那么,一个物理论者是否便应该据此去反对塔斯基的真理定义？本文的最终结论是：这三个问题的正确答案都是否定的。     

对塔斯基“真”理论的辩护——与陈晓平教授商榷

陈晓平教授对塔斯基的"真"理论提出四点批评,并给出了使用"T′模式"作为真之定义的建议。但"T′模式"并不具有"内容恰当性"和"形式正确性",其引入的对"p"的摹状词解释比塔斯基的方案更复杂,对"真"进行递归定义在现有逻辑学内是不可能的。陈晓平教授对塔斯基"真"理论的批评和建议的失误之处在于误解塔斯基的原意、引入形而上学词项、需要新建形式逻辑。总之,其作为真之定义的"T′模式"是"不能允许地冗长"。     

The Liar, the Strengthened Liar, and Bivalence

A view often expressed is that to classify the liar sentence as neither true nor false is satisfactory for the simple liar but not for the strengthened liar. I argue that in fact it is equally unsatisfactory for both liars. I go on to discuss whether, nevertheless, Kripke's theory of truth represents an advance on that of Tarski.     

Tarski ‐ a dilemma

Tarski's correspondence theory of truth (which he spells out in his semantic conception of truth) is open to two interpretations. This ambiguity in the theory has led philosophers to find support in it for metaphysical reali sm. In fact, Tarski's theory turns out to support a form of ontological relativism. In different passages Tarski himself gives support to each of these interpretations. The first interpretation leads to ontological relativism, while the second sacrifices the connection between language and the world. I clarify the dilemma that I see in having to choose between these two interpretations, explain how these interpretations have their source in different problems which occupied Tarski, and consider a possible solution to the dilemma. Finally, finding good reasons to claim that Tarski's theory is indeed a correspondence theory of truth, I argue in favour of the first interpretation with its relativistic implications.     

Propositions, semantic values, and rigidity

Jeffrey King has recently argued: (i) that the semantic value of a sentence at a context is (or determines) a function from possible worlds to truth values, and (ii) that this undermines Jason Stanley's argument against the rigidity thesis, the claim that no rigid term has the same content as a non-rigid term. I show that King's main argument for (i) fails, and that Stanley's argument is consistent with the claim that the semantic value of a sentence at a context is (or determines) a function from worlds to truth values.     

On the Matter of Essential Richness

Alfred Tarski (1944) wrote that “the condition of the ‘essential richness’ of the metalanguage proves to be, not only necessary, but also sufficient for the construction of a satisfactory definition of truth.” But it has remained unclear what Tarski meant by an ‘essentially richer’ metalanguage. Moreover, DeVidi and Solomon (1999) have argued in this Journal that there is nothing that Tarski could have meant by that phrase which would make his pronouncement true. We develop an answer to the historical question of what Tarski meant by ‘essentially richer’ and pinpoint the general result that stands behind his essential richness claim. In defense of Tarski, we then show that each of the several arguments of DeVidi and Solomon are either moot or mistaken. One of the fruits of our investigation is the reclamation of what Tarski took to be his central result on truth. This is a reclamation since: (i) if one does not understand ‘essential richness’, one does not know what that result is, and (ii) we must unearth a heretofore unrecognized change that occurs in Tarski's view – an alteration of his main thesis in light of a failing he discovered in it.     

Radical Interpretation and Logical Pluralism

I examine Quine’s and Davidson’s arguments to the effect that classical logic is the one and only correct logic. This conclusion is drawn from their views on radical translation and interpretation, respectively. I focus on the latter, but I first address, independently, Quine’s argument to the effect that the ‘deviant’ logician, who departs from classical logic, is merely changing the subject. Regarding logical pluralism, the question is whether there is more than one correct logic. I argue that bivalence may be subject matter dependent, but that distribution and the law of excluded middle can probably not be dropped whilst maintaining the standard meanings of the connectives. In discussing the ramifications of the indeterminacy of interpretation, I ask whether it forces Davidsonian interpreters to adopt Dummett’s epistemic conception of truth vis-à-vis their interpretations. And, if so, does this cohere with their attributing a nonepistemic notion of truth to their interpretees? This would be a form of logical pluralism. In addition, I discuss Davidson’s arguments against conceptual schemes. Schemes incommensurable with our own could be construed as wholesale deviant logics, or so I argue. And, if so, their possibility would yield, in turn, the possibility of a radical logical pluralism. I also address Davidson’s application of Tarski’s definition of truth.

     

The Trouble with Tarski

As a result of thinking ( pace Tarski, wrongly) that it is propositions, not sentences, that are true or false, it has been supposed (also wrongly) that propositions such as that 'Snow is white' is true if and only if snow is white are necessarily true. But changing the rules for the use of the words in a sentence has no effect on the truth of the proposition, only on what proposition it formulates. Many similar statements, e.g., that 'plus' does not mean plus, are only pragmatically contradictory: if this were true, it would be impossible to say so in these words. One should distinguish between sentences that express necessary truths, and sentences that necessarily express truths. It follows that many well known accounts of necessity are wrong, that the truth of an analytic proposition does not follow from the definitions of the words in the sentence that expresses it, that it is not helpful to define meaning in terms of truth, that truth is not relative to language, and that conventionalism is false. This paper is a move in the direction of establishing the eternity of truth.     

对塔斯基“真”理论的批评与重建

塔斯基首先提出关于真之定义的T模式即:"p"是真的,当且仅当,p。随后他又用X取代T模式中的"p",并且用"满足"来定义"真"。本文一方面根据"内容恰当性"要求,提出另一种模式T′即:"p"是真的,当且仅当,p是存在的;用以补充T模式,并完善塔斯基的语言层次论。另一方面根据"形式正确性"要求,指出塔斯基对T模式的这两项修改都是多余的。     

Two contextualist fallacies

I examine the radical contextualists’ two main arguments for the semantic underdeterminacy thesis, according to which all, or almost all, English sentences lack context-independent truth conditions. I show that both arguments are fallacious. The first argument, which I call the fallacy of the many understandings, mistakenly infers that a sentence S is semantically incomplete from the fact that S can be used to mean different things in different contexts. The second argument, which I call the open texture fallacy, wrongly concludes that a sentence S lacks context-independent truth conditions from the fact that there are circumstances in which the truth value of S would be indeterminate. I do however defend the claim that a certain class of sentences not containing any indexicals do lack context-independent truth conditions, and put forward an argument to that effect. But this argument, as I show, does not generalize to all sentences, and thus fails to support the semantic underdeterminacy thesis.     

Tarski on “essentially richer” metalanguages

It is well known that Tarski proved a result which can be stated roughly as: no sufficiently rich, consistent, classical language can contain its own truth definition. Tarski's way around this problem is to deal with two languages at a time, an object language for which we are defining truth and a metalanguage in which the definition occurs. An obvious question then is: under what conditions can we construct a definition of truth for a given object language. Tarski claims that it is necessary and sufficient that the metalanguage be essentially richer. Our contention, put bluntly, is that this claim deserves more scrutiny from philosophers than it usually gets and in fact is false unless essentially richer means nothing else than sufficient to contain a truth definition for the object language.     

Necessity and Language: In Defence of Conventionalism

Kalhat has forcefully criticised Wittgenstein's linguistic or conventionalist account of logical necessity, drawing partly on Waismann and Quine. I defend conventionalism against the charge that it cannot do justice to the truth of necessary propositions, renders them unacceptably arbitrary or reduces them to metalingustic statements. At the same time, I try to reconcile Wittgenstein's claim that necessary propositions are constitutive of meaning with the logical positivists’ claim that they are true by virtue of meaning. Explaining necessary propositions by reference to linguistic conventions does not reduce modal to non‐modal notions, but it avoids metaphysical accounts, which are incapable of explaining how we can have a priori knowledge of necessity.     

WARRANTED ASSERTIBILITY AND THE NORMS OF ASSERTORIC PRACTICE: WHY TRUTH AND WARRANTED ASSERTIBILITY ARE NOT COINCIDENT NORMS

Crispin Wright has argued that truth and warranted assertibility are coincident but non‐co‐extensive norms of assertoric practice and that this fact inflates deflationary theories of truth. Wright's inflationary argument has generated much discussion in the literature. By contrast, relatively little has been said about the coincidence claim that is the focus of this paper. Wright's argument for the claim that truth and warranted assertibility are coincident norms is first presented. It is then suggested that the argument trades on an ambiguity in ‘justified’ and ‘warrantedly assertible’. Finally, it is argued that, once the ambiguity is removed, there is reason to reject the claim that truth and epistemic warrant are coincident norms of assertoric practice. One important result is that no epistemic theory of truth can satisfy what Wright takes to be a key platitude about assertion.     

Necessary Moral Truths and Theistic Metaethics

Theistic metaethics usually places one key restriction on the explanation of moral facts, namely: every moral fact must ultimately be explained by some fact about God. But the widely held belief that moral truths are necessary truths seems to undermine this claim. If a moral truth is necessary, then it seems like it neither needs nor has an explanation. Or so the objection typically goes. Recently, two proponents of theistic metaethics — William Lane Craig and Mark Murphy — have argued that this objection is flawed. They claim that even if a truth is necessary, it does not follow that it neither needs nor has an explanation. In this article, I challenge Craig and Murphy’s reasoning on three main grounds. First, I argue that the counterexamples they use to undermine the necessary truth objection to theistic metaethics are flawed. While they may provide some support for the notion that necessary truths can be explained, they do not provide support for the notion that necessary moral truths can be explained. Second, I argue that the principles of explanation that Murphy and Craig use to support theistic metaethics are either question-begging (in the case of Murphy) or improperly motivated (in the case of Craig). And third, I provide a general defence of the claim that necessary moral truths neither need nor have an explanation.     

Entailments are Cancellable

Several philosophers have recently claimed that if a proposition is cancellable from an uttered sentence then that proposition is not entailed by that uttered sentence. The claim should be a familiar one. It has become a standard device in the philosopher's tool‐kit. I argue that this claim is false. There is a kind of entailment—which I call “modal entailment”—that is context‐sensitive and, because of this, cancellable. So cancellability does not show that a proposition is not entailed by an uttered sentence. I close the paper by describing an implication this has for a disagreement between J. L. Austin and Grice concerning the relation between felicity and truth. 1     

The dynamic lexicon in a truth-conditional framework; or how to have Your cake and eat it

A fundamental principle of all truth-conditional approaches to semantics is that the meanings of sentences of natural language can be compositionally specified in terms of truth conditions, where the meanings of the sentences’ parts (words/lexical items) are specified in terms of the contribution they make to such conditions their host sentences possess. Thus, meanings of words fit the meanings of sentences at least to the extent that the stability of what a sentence might mean as specified in a theory is in accord with the stability of what a word might mean as similarly specified. In this paper, I shall be concerned with Ludlow’s (2014) idea that, in fact, there need be no such sympathy between words and sentences. He proposes that we can square what he calls a dynamic lexicon, where word meaning is not stable at all, with a traditional truth-conditional approach of the kind indicated, where sentence meaning is delivered via ‘absolute truth conditions’. I share Ludlow’s aspiration to accommodate dynamic features of word meaning with a truth conditional approach, but not his belief that the marriage is an easy deal. Thus, I shall present a problem for Ludlow’s position and show how resolving this problem leads to an alternative picture of how the meaning of a sentence may be truth-conditionally specified with all relevant dynamic features of the lexicon retained.     

Some Limitations to the Psychological Orientation in Semantic Theory

The psychological orientation treats semantics as a matter of idealized computation over symbolic structures, and semantic relations like denotation as relations between linguistic expressions and these structures. I argue that results similar to Gödel’s incompleteness theorems and Tarski’s theorem on truth create foundational difficulties for this view of semantics.     

Primary qualities, secondary qualities and the truth about intention

In this paper I will argue that Crispin Wright’s defence of the claim that the truth about intention is judgement-dependent is unstable because it can serve also to establish that the truth about shape is judgement-dependent, thereby violating his constraint that in developing the distinction between judgement-independent and judgement-dependent subject matters we have to be driven by the assumption that colour and shape will fall on different sides of the divide.