Can you think without language? Answer: Nope, at least not at the level humans are accustomed to. That's why deafness can have far more serious consequences than blindness, developmentally speaking.
R. Schank, and R. Abelson. Thinking: Readings in Cognitive Science, Proceedings of the Fourth International Joint Conference on Artificial Intelligence, page 151-157. Tbilisi, USSR, (1975)