Socially and culturally one... yes thats exactly what i meant. Thats the meaning of the phrase "Unity in Diversity" - Diversity in cultures. You are absolutely right when you say that we should learn a language if we have stayed at a place for a while. I feel this language learning exercise should be seen as an expansion of our knowledge-base and not as if we are forced to learn an alien language. At the end of the day a language is only a medium of communication. Therefore, no language can be characterised as universally great or lowly. Language like religion, marriage, personal habit patterns etc. is an extremely personal choice. If somebody finds Kannada interesting let him/her learn it... on the other hand if someone else adores German let him/her study that. One language is better than the other is just a personal inclination. As all the languages are invented (??) by humans so choose anything to speak (of course the other person should also know the same language:-)). Thats what I mean by freedom and tolerance towards one another. Why should it become a matter of debate?
