Here's an argument inspired by Plantinga's argument from counterfactuals:
- The meaning of a word is wholly determined by the decisions of language users.
- The meaning of "bald" is not wholly determined by the decisions earthly language users.
- Therefore, there is a non-earthly language user whose decisions at least partly determine the meaning of "bald".
- In any hypothetical sequence to whose last member "bald" does not apply and to whose first it does, there is a transition point in the sequence, i.e., a member to whom "bald" applies but to whose successor it does not.
- The points in a hypothetical sequence at which "bald" does or does not apply are wholly determined by the meaning of "bald".
- There are hypothetical sequences where the decisions of earthly language users do not determine the transition point.
- So, (2) is true.
That leaves (4). But that's a matter of logic for any fixed sequence, as a standard argument for epistemicism points out. For suppose there is no transition point. Then:
- not ("bald" applies to xn and "bald" does not apply to xn+1)
And the best candidate for the non-earthly language user is God. For any finite language user, say an alien who gave us language, would be in the same boat: its decisions would be insufficient to determine all meaning.