Gary Ebbs

Truth and words

Introduction 1. Regimentation 2. The Tarski-Quine thesis 3. The intersubjectivity constraint 4. How to think about words 5. Learning from others, interpretation, and charity 6. A puzzle about sameness of satisfaction across time 7. Sense and partial extension 8. The puzzle diagnosed and dissolved 9. Applications and consequences

Learning from Others

I once believed that there are several naturally occurring isotopes of gold. When asked, “Are there several naturally occurring isotopes of gold?” either I would simply say, “Yes,” or, if I was in the mood to be more explicit, I would say, “There are several naturally occurring isotopes of gold.” But four years ago, while browsing through the Encyclopedia Britannica article titled “Gold”, I read the sentence “The element’s only naturally occurring isotope is gold-197.” I took the author’s words at face value—I took him to have asserted that the element’s only naturally occurring isotope is gold-197—and I accepted that the element’s only naturally occurring isotope is gold-197 solely because I trusted him. I thereby took myself to have learned from him that the element’s only naturally occurring isotope is gold-197. It ordinarily goes without saying that we can learn from others in this way—by taking their words at face value and accepting what they write or say solely because we trust them. C. A. J. Coady has recently argued that we can justify our trust in what others write or say by appealing to Donald Davidson’s principle of charity, which exhorts us to interpret another speaker’s words in such a way that under the assigned interpretation, what the speaker asserts is true by our own lights. Against this, I will argue that if Davidson’s principle of charity is a constraint on correctly interpreting what others write or say, then our ordinary impression that we can learn from others by taking their words at face value and accepting what they write or say is an illusion created by habitual but unjustified misinterpretations of their utterances. The reason is that in a large number of cases in which we take ourselves to be learning from others by accepting what they write or say, what we take them to write or say, given ~what Davidson sees as! our tacit interpretations of what we read or hear, is not true by NOUS 36:4 ~2002! 525–549

Vagueness, Sharp Boundaries, and Supervenience Conditions

In his impressive book Vagueness, Timothy Williamson critically surveys the entire literature on vagueness and presents a brilliant new version of the theory that our vague concepts have unknown sharp boundaries.1 His probing criticisms of previous views of vagueness are unified by a deep commitment to realism and a correspondingly thorough rejection of definitional theories of meaning and consensus theories of truth. I share Williamson’s commitment to realism, and I find many of his arguments persuasive. As I see it, however, Williamson’s proposed explanation of our ignorance of borderline vague truths faces a dilemma: either we have no grounds for accepting it, or it is no more than an elaborate restatement of what it is supposed to explain – our starting observation that we do not know borderline vague truths. This dilemma discredits Williamson’s underlying methodological assumption that we can distinguish between “conceptual” and “empirical” sources of our ignorance of borderline vague truths. To show why, I will focus on an intuitively plausible assumption that many philosophers simply take for granted. The assumption is best seen as a generalization from intuitions about the conditions for applying particular vague concepts. For instance, consider the intuition that if any two individuals x and y have the same number of hairs on their heads, then x is bald if and only if y is bald. If we take this for granted, then if we know, for example, that Albert is bald and Bob is not bald, we will infer that Albert and Bob do not have the same number of hairs on their heads. If we also know that Albert has 10 hairs on his head, we will infer that every individual with 10 hairs on his head is bald. More generally, the intuition about baldness implies that an individual with n hairs on his head is bald only if every individual with n hairs on his head is bald. Both the intuition that if any two individuals x and y have the same number of hairs on their heads, then x is bald if and only if y is bald, and the consequence that an individual with n hairs on his head is bald only if every individual with n hairs on his head is bald are what I call substantive supervenience conditions for being bald. I call them “substantive” because they generalize

IS SKEPTICISM ABOUT SELF-KNOWLEDGE COHERENT?

In previous work I argued that skepticism about the compatibility ofanti-individualism with self-knowledge is incoherent. Anthony Brueckner isnot convinced by my argument, for reasons he has recently explained inprint. One premise in Brueckners reasoning is that a personsself-knowledge is confined to what she can derive solely from herfirst-person experiences of using her sentences. I argue that Bruecknersacceptance of this premise undermines another part of his reasoning – hisattempt to justify his claims about what thoughts our sincere utterances ofcertain sentences would express in various possible worlds. I describe aweird possible world in which a person who uses Brueckners reasoning endsup with false beliefs about what thoughts her sincere utterances of certainsentences would express in various possible worlds. I recommend that wereject Brueckners problematic conception of self-knowledge, and adopt onethat better fits the way we actually ascribe self-knowledge.

Satisfying Predicates: Kleene's Proof of the Hilbert–Bernays Theorem

The Hilbert–Bernays Theorem establishes that for any satisfiable first-order quantificational schema S, one can write out linguistic expressions that are guaranteed to yield a true sentence of elementary arithmetic when they are substituted for the predicate letters in S. The theorem implies that if L is a consistent, fully interpreted language rich enough to express elementary arithmetic, then a schema S is valid if and only if every sentence of L that can be obtained by substituting predicates of L for predicate letters in S is true. The theorem therefore licenses us to define validity substitutionally in languages rich enough to express arithmetic. The heart of the theorem is an arithmetization of Gödels completeness proof for first-order predicate logic. Hilbert and Bernays were the first to prove that there is such an arithmetization. Kleene established a strengthened version of it, and Kreisel, Mostowski, and Putnam refined Kleenes result. Despite the later refinements, Kleenes presentation of the arithmetization is still regarded as the standard one. It is highly compressed, however, and very difficult to read. My goals in this paper are expository: to present the basics of Kleenes arithmetization in a less compressed, more easily readable form, in a setting that highlights its relevance to issues in the philosophy of logic, especially to Quines substitutional definition of logical truth, and to formulate the Hilbert–Bernays Theorem in a way that incorporates Kreisels, Mostowskis, and Putnams refinements of Kleenes result.

Carnap, Tarski, and Quine at Harvard: Conversations on Logic, Mathematics, and Science

In the early 2000s, Greg Frost-Arnold and Paulo Mancosu each independently discovered Rudolf Carnaps shorthand notes of conversations that Carnap had with Alfred Tarski and W. V. Quine during the ...

Can First-Order Logical Truth be Defined in Purely Extensional Terms?

W. V. Quine thinks logical truth can be defined in purely extensional terms, as follows: a logical truth is a true sentence that exemplifies a logical form all of whose instances are true. P. F. Strawson objects that one cannot say what it is for a particular use of a sentence to exemplify a logical form without appealing to intensional notions, and hence that Quines efforts to define logical truth in purely extensional terms cannot succeed. Quines reply to this criticism is confused in ways that have not yet been noticed in the literature. This may seem to favour Strawsons side of the debate. In fact, however, a proper analysis of the difficulties that Quines reply faces suggests a new way to clarify and defend the view that logical truth can be defined in purely extensional terms.