2026-09-28
Agenda
Agenda
Unclear as it is, the traditional doctrine that the notion “meaning” possesses the extension/intension ambiguity has certain typical consequences. The doctrine that the meaning of a term is a concept carried the implication that meanings are mental entities. Frege, however, rebelled against this “psychologism.” Feeling that meanings are public property-that the same meaning can be “grasped” by more than one person and by persons at different times-he identified concepts (and hence “intensions” or meanings) with abstract entities rather than mental entities. (699–700)
“meaning” possesses the extension/intension ambiguity.
The doctrine that the meaning of a term is a concept carried the implication that meanings are mental entities.
Frege rebelled against this “psychologism.” Feeling that meanings are public property-that the same meaning can be “grasped” by more than one person and by persons at different times-he identified concepts (and hence “intensions” or meanings) with abstract entities rather than mental entities.
Feeling that meanings are public property-that the same meaning can be “grasped” by more than one person and by persons at different times-he identified concepts (and hence “intensions” or meanings) with abstract entities rather than mental entities. However, “grasping” these abstract entities was still an individual psychological act.
None of these philosophers doubted that understanding a word (knowing its intension) was just a matter of being in a certain psychological state (somewhat in the way in which knowing how to factor numbers in one’s head is just a matter of being in a certain very complex psychological state).
The timeworn example of the two terms ‘creature with a kidney’ and ‘creature with a heart’ does show that two terms can have the same extension and yet differ in intension.
But it was taken to be obvious that the reverse is impossible: two terms cannot differ in extension and have the same intension. Interestingly, no argument for this impossibility was ever offered.
For philosophers like Carnap, who accepted the verifiability theory of meaning, the concept corresponding to a term provided a criterion for belonging to the extension (not just in the sense of “necessary and sufficient condition,” but in the strong sense of way of recognizing whether a given thing falls into the extension or not).
So theory of meaning came to rest on two unchallenged assumptions:
- That knowing the meaning of a term is just a matter of being in a certain psychological state.
- That the meaning of a term determines its extension (in the sense that sameness of intension entails sameness of extension).
I shall argue that these two assumptions are not jointly satisfied by any notion, let alone any notion of meaning. The traditional concept of meaning is a concept which rests on a false theory.
Agenda
For the purpose of the following science-fiction examples, we shall suppose that somewhere there is a planet we shall call Twin Earth. Twin Earth is very much like Earth: in fact, people on Twin Earth even speak English. In fact, apart from the differences we shall specify in our science-fiction examples, the reader may suppose that Twin Earth is exactly like Earth. He may even suppose that he has a Doppelganger-an identical copy-on Twin Earth, if he wishes, although my stories will not depend on this.
One of the peculiarities of Twin Earth is that the liquid called “water” is not H20 but a different liquid whose chemical formula is very long and complicated. I shall abbreviate this chemical formula simply as XYZ. I shall suppose that XYZ is indistinguishable from water at normal temperatures and pressures. Also, I shall suppose that the oceans and lakes and seas of Twin Earth contain XYZ and not water, that it rains XYZ on Twin Earth and not water, etc.
If a space ship from Earth ever visits Twin Earth, then the supposition at first will be that ‘water’ has the same meaning on Earth and on Twin Earth. This supposition will be corrected when it is discovered that “water” on Twin Earth is XYZ, and the Earthian space ship will report somewhat as follows.
“On Twin Earth the word ‘water’ means XYZ.”
Symmetrically, if a space ship from Twin Earth ever visits Earth, then the supposition at first will be that the word ‘water’ has the same meaning on Twin Earth and on Earth. This supposition will be corrected when it is discovered that “water” on Earth is H2O, and the Twin Earthian space ship will report:
“On Earth the word ‘water’ means H2O.”
“On Twin Earth the word ‘water’ means XYZ.”
“On Earth the word ‘water’ means H2O.”
Now let us roll the time back to about 1750. The typical Earthian speaker of English did not know that water consisted of hydrogen and oxygen, and the typical Twin-Earthian speaker of English did not know that “water” consisted of XYZ.
Let Oscar1 be such a typical Earthian English speaker, and let Oscar2 be his counterpart on Twin Earth. You may suppose that there is no belief that Oscar, had about water that Oscar2 did not have about “water.” If you like, you may even suppose that Oscar1 and Oscar2 were exact duplicates in appearance, feelings, thoughts, interior monologue, etc.
Yet the extension of the term ‘water’ was just as much H2O on Earth in 1750 as in 1950; and the extension of the term ‘water’ was just as much XYZ on Twin Earth in 1750 as in 1950. Oscar1 and Oscar2 understood the term ‘water’ differently in 1750 although they were in the same psychological state, and although, given the state of science at the time, it would have taken their scientific communities about fifty years to discover that they understood the term ‘water’ differently.
Thus the extension of the term ‘water’ (and, in fact, its “meaning” in the intuitive preanalytical usage of that term) is not a function of the psychological state of the speaker by itself.
Argument
See p. 703
See p. 704
See the example of ‘gold’ on p. 704–5
Every linguistic community exemplifies the sort of division of linguistic labor just described; that is, it possesses at least some terms whose associated “criteria” are known only to a subset of the speakers who acquire the terms, and whose use by the other speakers depends upon a structured cooperation between them and the speakers in the relevant subsets. (706)
See p. 707