Full Idea
It makes sense to think that one could recognise that something is a language without necessarily being able to translate it; cryptographers do this all the time.
Gist of Idea
Cryptographers can recognise that something is a language, without translating it
Source
Paul O'Grady (Relativism [2002], Ch.5)
Book Reference
O'Grady,Paul: 'Relativism' [Acumen 2002], p.169
A Reaction
Maybe, but cryptographers usually have a lot of context to work with. If we met extraterrestrials if might not be so clear. One can only spot patterns, and crystals have those.