Lost in translation. Is that a 'rabbit' I see before me or is it a 'gavagai'

The indeterminacy of translation is a thesis propounded by 20th century analytic philosopher W. V. Quine. The classic statement of this thesis can be found in his 1960 book Word and Object, which gathered together and refined much of Quine's previous work on subjects other than formal logic and set theory. The indeterminacy of translation is also discussed at length in his Ontological Relativity (1968).

In these books, Quine considers the methods available to a field linguist attempting to translate a hitherto unknown language. He notes that there are always different ways one might break a sentence into words, and different ways to distribute functions among words. Any hypothesis of  translation could be defended only by appeal to context, by determining what other sentences a native would utter. But the same indeterminacy will appear there: any hypothesis can be defended if one adopts enough compensatory hypotheses about other parts of the language.

Consider Quine's example of the word "gavagai" uttered by a native upon seeing a rabbit. The linguist could do what seems natural and translate this as "Lo, a rabbit." But other translations would be compatible with all the evidence he has: "Lo, food"; "Let's go hunting"; "There will be a storm tonight" (these natives may be superstitious); "Lo, a momentary rabbit-stage"; "Lo, an undetached rabbit-part." Some of these might become less likely – that is, become more unwieldy hypotheses – in the light of subsequent observation. Others can only be ruled out by querying the natives: An affirmative answer to "Is this the same gavagai as that earlier one?" will rule out "momentary rabbit stage," and so forth. But these questions can only be asked once the linguist has mastered much of the natives' grammar and abstract vocabulary; that in turn can only be done on the basis of hypotheses derived from simpler, observation-connected bits of language; and those sentences, on their own, admit of multiple interpretations, as we have seen.

Indeterminacy of translation also applies to the interpretation of speakers of one's own language, and even to one's past utterances.  So now all those “I just don’t understand what you are trying to say” I have received for most of my adult life becomes clearer to me. And in future I won’t be saying, “...well, let me just put it another way.”