Full Idea
Stimulus synonymy of the occasion sentences 'Gavagai' and 'Rabbit' does not even guarantee that 'gavagai' and 'rabbit' are coextensive terms, terms true of the same things.
Clarification
'Gavagai' is an imagined native word which somehow refers to a passing rabbit
Gist of Idea
Stimulus synonymy of 'Gavagai' and 'Rabbit' does not even guarantee they are coextensive
Source
Willard Quine (Word and Object [1960], §12)
Book Reference
Quine,Willard: 'Word and Object' [MIT 1969], p.51
A Reaction
Since this scepticism eventually seems to result in the reader no longer knowing what they mean themselves by the word 'rabbit', I doubt Quine's claim. Problems after hearing one word of a foreign language disappear after years of residence.