# Bridging syntax and semantics with Quine's Gavagai

Quine [has an argument](https://en.wikipedia.org/wiki/Indeterminacy_of_translation) showing that you can never be sure what words mean in a foreign language:

>Quine uses the example of the word "**gavagai**" uttered by a native speaker of the unknown language Arunta upon seeing a rabbit. A speaker of English 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.

What does this mean from the perspective of [empirically bridging syntax and semantics](https://www.lesswrong.com/posts/EEPdbtvW8ei9Yi2e8/bridging-syntax-and-semantics-empirically)?

Well, there is no real problem with "gavagai" from the empirical perspective; the fact that there seems to be one is, in my view, due to the fact that the syntax-semantic discussion has focused too heavily on the linguistic aspects of the problem.

Let $G$ be the symbol in the Arunta speaker's brain that activates when they say "gavagai". As Quine said towards the end of his quote, "some of these might become less likely – that is, become more unwieldy hypotheses – in the light of subsequent observation." Relatedly, Nick Bostrom [argues](https://nickbostrom.com/old/quine.html) that indeterminancy is a "matter of degree".

In practice, this means is that if, for instance, r="A rabbit is there" and s="A storm is coming tonight", then, if we accumulate enough observations, the $G$ is going to be predictive of $r$ better than it is of $s$, or vice versa. Thus there is an empirical test for whether $G$ corresponds to some of these hypotheses.

But what about u="An undetached rabbit-part is there"? It may be very difficult to find a situation that distinguishes between u and r in practice - so does $G$ stand for "rabbit", or  "undetached rabbit-part"?

Similarly to the example of the neural net in the [previous post](https://www.lesswrong.com/posts/EEPdbtvW8ei9Yi2e8/bridging-syntax-and-semantics-empirically), $G$ is a symbol for *both* r and u. If no experiment can distinguish between the two - or, at least, if no experiment can distinguish between the two in any typical environment that any Arunta speaker would ever experience - then they are synonymous (or, equivalently, they are strongly within each other's [web of connotations](https://www.lesswrong.com/posts/ix3KdfJxjo9GQFkCo/web-of-connotations-bleggs-rubes-thermostats-and-beliefs)).

If we presented the speaker with a situation far outside their typical environment, then we might be able to distinguish r from u - but we'd be uncertain if $G$ 'meant that all along', or if the speaker was extending the definition to a new situation.

## Back to linguistics

There *are* some ways we might be able to distinguish whether "gavagai" means "rabbit" or  "undetached rabbit-part", even if u and r cannot be distinguished in practice. It's plausible that there might be an *internal* variable $P$ in the speaker that corresponds to "part of an animal", and an internal $U$ that correponds to "undetached" (versus detached).

Then, when $G$ is activated, we might ask whether $P$ and $U$ are also activated, or not. You can see this as the *internal* web of connotations amongst the variables in the human brain. It seems people with different languages have different internal webs, [different ways of connecting words and concepts](http://www.lognostics.co.uk/vlibrary/meara1983.pdf) together.

This does not, however, affect the connection between $G$ and external variables.