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. (shrink)

By a `denoting phrase' I mean a phrase such as any one of the following: a man, some man, any man, every man, all men, the present King of England, the present King of France, the center of mass of the solar system at the first instant of the twentieth century, the revolution of the earth round the sun, the revolution of the sun round the earth. Thus a phrase is denoting solely in virtue of its form. We may distinguish (...) three cases: (1) A phrase may be denoting, and yet not denote anything; e.g., `the present King of France'. (2) A phrase may denote one definite object; e.g., `the present King of England' denotes a certain man. (3) A phrase may denote ambiguously; e.g. `a man' denotes not many men, but an ambiguous man. The interpretation of such phrases is a matter of considerably difficulty; indeed, it is very hard to frame any theory not susceptible of formal refutation. All the difficulties with which I am acquainted are met, so far as I can discover, by the theory which I am about to explain. (shrink)

Føllesdal (1966 and 1969) claims that modal distinctions collapse, that is that p and Necessarily p are equivalent, in any system of modal logic that incorporates a standard theory of definite descriptions, like the one proposed by Carnap in M&N. I argue that his argument fails.

An appraisal of the current status of the modalities and of quine's arguments against them. The author accepts "quine's thesis," that one cannot quantify into referentially opaque contexts, And argues that nobody has succeeded in making sense of such quantification. However, It is shown that modal constructions, Being constructions on general terms and sentences, Can be referentially transparent and extensionally opaque and that consequently the collapse of modal distinctions warned against by quine in "word and object" can be avoided. This (...) combination of referential transparency and extensional opacity is just what quine means by essentialism, And the author therefore agrees with quine that quantified modal logic commits one to essentialism. (shrink)