Online research in philosophy

The following Principle of Substitutivity holds for the former, but not for the latter sentence: (PS) The truth value of (the proposition expressed by) a sentence that contains an occurrence of t1 remains constant when t2 is substituted for t1, provided that t1 and t2 are codesignative singular terms. It is an undeniable fact that different sentences behave differently when it comes to which substitutions preserve their truth value. What is curious is that this fact has been presented by the philosophical tradition as a puzzle. To be more precise, what is supposed to be puzzling is the breakdown of PS in some sentences. Meanwhile, it is assumed that everything is as it should be, that nothing needs to be explained when we observe that the substitution of 'the number of planets' for 'nine' in 'nine is greater than seven' guarantees the preservation of truth value, in spite of the fact that the subject matter of the former sentence and the subject matter of 'the number of planets is greater than seven' are radically different. The former sentence expresses a claim about numbers and their relationships, whereas the latter sentence makes an assertion about our solar system.

The verification theory of meaning aims to characterise what it is for a sentence to be meaningful and also what kind of abstract object the meaning of a sentence is. A brief outline is given by Rudolph Carnap, one of the theory's most prominent defenders: If we knew what it would be for a given sentence to be found true then we would know what its meaning is. [...] thus the meaning of a sentence is in a certain sense identical with the way we determine its truth or falsehood; and a sentence has meaning only if such a determination is possible. [4: 420] In short, the verification theory of meaning claims that the meaning of a sentence is the method of its verification.

In uttering a sentence we are often taken to assert more than its literal meaning — though we sometimes assert less. Robyn Carston and others take this phenomenon to show that what is said or asserted by a speaker on an occasion of utterance is usually a contextuallyenriched version of the semantic content of the sentence. I shall argue that we can resist this conclusion if we recognize that what we think we are asserting, or take others to be asserting, involves selective attention to one of the ways a sentence could be true and neglects others. Most of the time people converge in their selective attention and so communication is not impaired. Though in the case of sentences involving predicates of taste, people’s attention to different aspect of the truth conditions leads to seemingly intractable disputes. I will propose a treatment of such cases on which speakers mean the same by a sentence, assert no more than its semantic content, hold conflicting opinions about its truth-value, and are both right.

If we try to evaluate the sentence on line 1 we ¯nd ourselves going in an unending cycle. For this reason alone we may conclude that the sentence is not true. Moreover we are driven to this conclusion by an elementary argument: If the sentence is true then what it asserts is true, but what it asserts is that the sentence on line 1 is not true. Consequently the sentence on line 1 is not true. But when we write this true conclusion on line 2 we ¯nd ourselves repeating the very same sentence. It seems that we are unable to deny the truth of the sentence on line 1 without asserting it at the same time.

Prosentential theorists claim that sentences such as “That’s true” are prosentences that function analogously to their better known cousins–pronouns. For example, just as we might use the pronoun ‘he’ in place of ‘James’ to transform “James went to the supermarket” into “He went to the supermarket,” so we might use the prosentenceforming operator ‘is true’ to transform “Snow is white” into “‘Snow is white’ is true.” According to the prosentential theory of truth, whenever a referring expression (for example, a definite description or a quote-name) is joined to the truth predicate, the resulting statement contains no more content than the sentence(s) picked out by the referring expression. To assert that a sentence is true is simply to assert or reassert that sentence; it is not to ascribe the property of truth to that sentence. The prosentential theory is one kind of deflationary theory of truth. Like all deflationary theories, it provides an alternative to explanations of truth that analyze truth in terms of reference, predicate satisfaction or a correspondence relation.

In his Paradoxes (1995: Cambridge University Press: 149) Mark Sainsbury presents the following pair of sentences: Line 1: The sentence written on Line 1 is nonsense. Line 2: The sentence written on Line 1 is nonsense. Sainsbury (1995: 149, 154) here makes three assertions: (1) The sentence in Line 1 is so viciously self-referential that it falls into the truth-value gap. The sentence is really nonsense. (2) The sentence in Line 2 is by contrast true. For it states precisely that the sentence in Line 1 is nonsense. (3) The two sentences in Lines 1 and 2 are an example of the principle that two sentence tokens of the same sentence-type can have different truth-values, although they have the same reference and state the same property of the object of reference. In this paper, I argue that Sainsbury’s assumptions are false in all three cases.

It is often thought that questions of reference are crucial in assessing scientific realism, construed as the view that successful theories are at least approximately true descriptions of the unobservable; realism is justified only if terms in empirically successful theories generally refer to genuinely existing entities or properties. In this paper this view is questioned. First, it is argued that there are good reasons to think that questions of realism are largely decided by convention and carry no epistemic significance. An alternative conception of realism is then proposed, which focuses on the Ramsey sentences of scientific theories, constructed in the manner of David Lewis's 'How to define theoretical terms'. It is argued that because the Ramsey sentence of a theory preserves the epistemically significant part of the theory's content without generating commitments to any particular conclusions about reference, the realism issue is better addressed by asking whether Ramsey sentences of theories, rather than the theories themselves, are approximately true.

This paper argues that if a person's beliefs are idealized as a set of sentences (theoretical, observational, and mixed) then the device of Ramsey sentences provides a treatment, of the mind-brain problem, that has at least four noteworthy characteristics. First, sentences asserting correlations between one's own brain state and one's own "private" experiences are, on such treatment, reconstrued as neither causal, coreferential, nor as meaning postulates, but as clauses in an overall hypothesis (Ramsey sentence) whose only nonlogical constants have "private" meanings. Second, sentences asserting psycho-physical correlations in general, or in other individuals, remain theoretical and susceptible to scientific reduction, though not prejudged to be so. Third, communication between persons having mutually exclusive, "private," observational vocabularies can be made intelligible. Fourth, it becomes possible in principle (though not necessary) that the world could ultimately be given a total description in a scientific language, $L_{\varnothing}$ , without mental primitives. However, such a language would be susceptible to interpretation by a given individual using a metalanguage whose primitives (not among those of $L_{\varnothing}$ ) were privately observational to that individual. His procedure in accomplishing such an interpretation would be to construct a Tarskian truth definition in a metalanguage $ML_{\varnothing}$ and then to incorporate it, by Ramsifying its descriptive terms, in his own overall Ramsey sentence. The physical language, $L_{\varnothing}$ , while not containing a person's primitives, would, of course, be able to define their physical correlates, thus providing a certain sort of mutual mirroring, and a certain sort of relativity.

This paper argues that if a person's beliefs are idealized as a set of sentences (theoretical, observational, and mixed) then the device of Ramsey sentences provides a treatment, of the mind-brain problem, that has at least four noteworthy characteristics. First, sentences asserting correlations between one's own brain state and one's own "private" experiences are, on such treatment, reconstrued as neither causal, coreferential, nor as meaning postulates, but as clauses in an overall hypothesis (Ramsey sentence) whose only nonlogical constants have "private" meanings. Second, sentences asserting psycho-physical correlations in general, or in other individuals, remain theoretical and susceptible to scientific reduction, though not prejudged to be so. Third, communication between persons having mutually exclusive, "private," observational vocabularies can be made intelligible. Fourth, it becomes possible in principle (though not necessary) that the world could ultimately be given a total description in a scientific language, $L_{\varnothing}$ , without mental primitives. However, such a language would be susceptible to interpretation by a given individual using a metalanguage whose primitives (not among those of $L_{\varnothing}$ ) were privately observational to that individual. His procedure in accomplishing such an interpretation would be to construct a Tarskian truth definition in a metalanguage $ML_{\varnothing}$ and then to incorporate it, by Ramsifying its descriptive terms, in his own overall Ramsey sentence. The physical language, $L_{\varnothing}$ , while not containing a person's primitives, would, of course, be able to define their physical correlates, thus providing a certain sort of mutual mirroring, and a certain sort of relativity.

The method of Ramsey sentences has been proposed for handling theoretical constructs within a scientific system. Essentially it consists of constructing a certain "monolithic" sentence for an entire theory. In this present paper several improvements are suggested which help to overcome some of the awkward features of the method. In particular we have here many Ramsey sentences rather than just one, each erstwhile primitive theoretical term giving rise to a Ramsey sentence. Such a sentence in effect defines what we call a Ramsey constant. Using Ramsey constants, we attempt to improve the method in important logical and semantical respects. It is suggested also that such constants are of interest for the philosophy of mathematics.