For my own part, I would say that if we take the relevant unit of meaning to be the whole physical theory (a position I find compelling in principle, if unwieldy in practice), it follows that changing the physical theory does not preserve preexisting meanings. I would not say that the meaning of “momentum” changed, precisely, but that “momentum” acquired a new meaning in addition to its old one, and anyone talking about momentum in a relativistic context is using the new meaning, even though people talking about momentum in a non-relativistic context can go on using the old meaning. (I would also say that the intent of the first physicist to use the term is effectively irrelevant.)
This also implies that people who try to copy over assertions about momentum from non-relativistic contexts to relativistic ones are essentially confusing homophones… similar in principle to what happens if I try to copy over assertions about monarchs from lepidopterological contexts to governmental ones.
But, OK, I can understand how someone could sensibly argue that no, the meaning is preserved, because the meaning was always fuzzy in the first place, we just became aware of the fuzziness late in the game. (This seems to in turn depend on a strongly externalist account of meaning.)
OK, I think I follow.
For my own part, I would say that if we take the relevant unit of meaning to be the whole physical theory (a position I find compelling in principle, if unwieldy in practice), it follows that changing the physical theory does not preserve preexisting meanings. I would not say that the meaning of “momentum” changed, precisely, but that “momentum” acquired a new meaning in addition to its old one, and anyone talking about momentum in a relativistic context is using the new meaning, even though people talking about momentum in a non-relativistic context can go on using the old meaning. (I would also say that the intent of the first physicist to use the term is effectively irrelevant.)
This also implies that people who try to copy over assertions about momentum from non-relativistic contexts to relativistic ones are essentially confusing homophones… similar in principle to what happens if I try to copy over assertions about monarchs from lepidopterological contexts to governmental ones.
But, OK, I can understand how someone could sensibly argue that no, the meaning is preserved, because the meaning was always fuzzy in the first place, we just became aware of the fuzziness late in the game. (This seems to in turn depend on a strongly externalist account of meaning.)