What does it take to use language? Linguists typically divide the knowledge into two categories: competence and performance, basically knowing the rules and speaking the language. This is pretty cut and dry, and linguistic anthropologists tend to think there is more to "knowing" a language than just knowing its rules. Because they are anthropologists, they like to have a list of things you need to know to "know" language: phonology, morphology, syntax, semantics, and pragmatics. We learn language primarily through interaction with others. It's generally accepted that language cannot be developed or learned in isolation, and that makes sense because language is used for communicating with others, right? Well, what about when we are communicating with ourselves?
We think in language. When we are thinking, most times we aren't thinking in abstract concepts; we are thinking in nouns, verbs, and adjectives. So, is it possible to have thought without language? This was the topic of a long discussion/debate in my linguistic anthropology class. During that class, I admit that I was a fence-sitter. I just didn't have a real opinion on the matter at the time. After sitting on the issue for two months, I think I'm ready to take a side and say that I believe that thought is possible without language. Think about it. If humans didn't have thought before they had language, how would the language have come about? The impetus for language was most likely to communicate thoughts that already existed to another member of the community.
Although I believe that thought can exist independently of language, I do think that the invention of language made thought a lot easier. Obviously, if the word for "need" does not exist in your language, you can still need things, only you wouldn't be able to express that. You might use the word "want" when you needed something. Similarly, people often start thinking about something in a discussion, and then will forget the word for the particular object or concept they are trying to talk about.
That's all I have to say on this topic for now, but I might revisit it later.