There's a big debate about whether you have thought and then you communicate through language, or whether you have communication and that gives you thought. Now I don't think there is a strict opposition and I agree that symbolising, of which language is the most impressive manifestation, is indeed part and parcel of thinking. Symbols, once you understand how they work and how to use them, can crystallise thoughts so you can do mental things that you couldn't otherwise do. Which to a large extent - and of course you can have other symbolic systems such as gesture - is what makes thought what it is. A lot of the way we think depends upon language - not language as a separate thing, but language as it emerges out of communication. So language itself is not only something separate that just adds on, but something that crystallises a potential in interpersonal exchanges.

The argument goes like this: the first thing is communication, then language crystallises something in it, then it feeds back to give the detailed properties of thought. Language emerges as a system, and that leads to new thoughts emerging from language. I think what I disagree with is those who, like Chomsky and Pinker, want to separate out the meanings in language from the syntax in some important way. On balance what language is is a system of symbols to do things in relation to other people, to communicate. And much of the structure of language is implicit in non-verbal communication.

Peter Hobson in newscientist.com