'Rouge equals red' : How is this a posteriori?

Question

[1.] Analytic a posteriori judgments cannot arise, since there is never any need to appeal to experience in support of a purely explicative assertion.

[2.] Analytic a posteriori claims are claims that are tautologically true, but can only be understood through empiricism. Walter Block has an excellent example of such a truth.

Although there is some question about this in philosophical circles, one way to characterize the elements in this set is in terms of the ways in which we come to learn language. For example, “We shall use language in such a way that ‘rouge’ in French will translate to ‘red’ in English.” We learn this through experience, but to say “[3.] Rouge equals red” is an analytic statement. For A, the analytic a posteriori, we can learn each of the words in this sentence through experience (in an a posteriori manner), and yet the meaning of it is tautological.[1] [This link was broken when I tried it on 2016/3/9.]

I agree, and so do not challenge here, that 3 is analytic; as the etymology of 'analytic' suggests, the meaning of the sentence must be 'loosened up' from the sentence that itself must be 'loosened up' by examining each word.

Hereafter, I use the (Proto-Indo-European root) reudh to mean the colour red itself (which transcends all languages) and to disambiguate it from the English noun 'red'.

But as 1 and 2 appear to contradict each other, I question whether 3 is a posteriori. Why need I any visual experience of reudh, or any colour, to understand 3? If, never having seen reudh, I am told that 'rouge' means the exact same thing as 'red', then I will have understood the equivalence of the nouns 'red' and 'rouge' (though I still will not know how reubh appears).

Answer 1

Concerning the given explanation:

For A, the analytic a posteriori, we can learn each of the words in this sentence through experience (in an a posteriori manner), and yet the meaning of it is tautological.

To learn in an a posteriori manner means to learn by induction i.e.  (1) To learn from examples, such that each positive example strengthens one's confidence in the result. (2) That there always remains the possibility of a negative example, a counter-example, of dis-proving the result.

Whether "red is rouge" is a posteriori depends in particular on (2). That is, is it conceivable that one will suddenly realize that red is not rouge? For Kant, who was the first to discuss these distinctions at length, it is not possible that red will turn out not to be rouge. But by other conceptions of meaning it may be possible. The example is controversial, and so is the very possibility of analytic a posteriori statements.