Page 308 - Encyclopedia of Philosophy of Language

Language and Logic
could not have originated from any distinct cell D. Or
as Kripke puts it rhetorically, 'How could a person originating from different parents, from a totally different sperm and egg, be this very woman?.' (Kripke 1980:113). Subsequent work on this topic has shown that Kripke's intuition can be traced to principles about the acceptability of criteria for determining the identity of an object in a possible world, but whether these principles are correct is itself a matter of contro- versy (Forbes 1985).
4. The Source of Necessity
Quine has argued that the various kinds of necessity discussed here are creatures of darkness to the extent that they go beyond some explicit notion of formal validity which can be expressed in a predicate (Quine 1976: paper 15). But few have been persuaded by his skepticism, and thus the majority of philosophers incur the problem of the source of necessity.
On the conventionalist account, logical, math- ematical, and metaphysical necessity can be traced to conventions governing the use of language. But conventionalism has hardly been a success even in the easiest case of logical necessity (Quine 1976: paper 11), and it is hard to see how it could explain de re metaphysical necessities. That there is a convention, for each organism x and propagule y from which x originates, to treat any assertion to the effect that x originates from y as a necessary truth, seems an unpromising account of how such necessity arises (but see Sidelle 1989: Chap. 3).
Conventionalism is one flavor of the position that necessity must ultimately reduce to facts about mean- ing or concepts: the necessity of 'all bachelors are unmarried' is the paradigm, and all other necessities are to be somehow reduced to the case of straight- forwardly analytic truths. But the de re necessities mentioned above appear to constitute very great stum- bling blocks to such linguistic approaches to necessity.
At the opposite end of the spectrum of views about the source of necessity there is David Lewis's position (Lewis 1986b), which removes the source of necessity from language and thought as far as can be. According to Lewis, a necessary truth is one which holds in every
possible world, and a possible world is a complete way things could have been which exists in exactly the way the actual world exists: this world is to other worlds as this place is to other places. It seems that no further account of the source necessity could be given: the necessities are just those things which 'happen' to hold in all worlds.
An intermediate but still realist position is one which discerns the source of necessity in the structure of properties. Such a view appears to have a good chance of dovetailing with a plausible epistemology of modality, whose task is to explain how we know what is necessary and what is not. Both the source problem and the epistemological problem are impor- tant areas of future research (see Fine 1994).
See also: Essentialism; Modal Logic.
Bibliography
Field H 1989 Realism. Mathematics and Modality. Basil Blackwell, New York
Fine K 1994 Essence and modality. In: Tomberlin J (ed.) Philosophical Perspectives, vol. 8. Ridgeview, Atascadero, CA
Forbes G 1985 The Metaphysics of Modality. Clarendon Press, Oxford
Frege G 1986 The Foundations of Arithmetic. Basil Blackwell, Oxford
Kripke S A 1980 Naming and Necessity. Blackwell, Oxford Lewis D K 1986a Philosophical Papers, vol. II. Oxford Uni-
versity Press, New York
Lewis O K 1986b On The Plurality of Worlds. Basil
Blackwell, Oxford
Putnam H 1975 Mind, Language and Reality Philosophical
Papers, vol. 2. Cambridge University Press, Cambridge Quine W V O 1976 The Ways of Paradox. Harvard Uni-
versity Press, Cambridge, MA
Russell B 1919 Introduction to Mathematical Philosophy.
Allen and Unwin, London
Sidelle A 1989 Necessity, Essence and Individuation. Cornell
University Press, Ithaca, NY
Van Inwagen P 1983 An Essay on Free Will. Clarendon Press,
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Wiggins D 1980 Sameness and Substance. Blackwell, Oxford Wright C 1980 Wittgenstein on the Foundations of Math-
ematics.Duckworth, London
Y ablo S 1992 Cause and essence. Synthese 93: 403-49
Occasion Sentences and Eternal Sentences C. J. Hookway
The distinction between occasion sentences and eter- nal sentences is important in the philosophy of Quine. The truth value of a sentence such as "That bird is a
seagull' will vary with the context of utterance. 'I was angry with you yesterday' is similarly true on some occasions, false on others, depending upon the
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