This statistic says that 56% of Indian's don't speak Hindi, and this statistic says that only 10% speaks English but still English and Hindi are recognized by the government as official languages. Generally speaking, across different countries, what are the basis for such a choice of National language when the country has states which speak different languages?
It has been said that Language is a dialect with an army and a navy. Although no general rules exist for how official languages are chosen for a country, there are several obvious considerations:
- The languages that facilitate communication - that is most people in the country know the language. This may seem obvious in the US, but less obvious in Germany or Italy a century ago, where a different dialect was spoken in every region, sometimes not quite understandable to the rest. Even more extreme case is the use of English in India or French in some African countries - although a language of colonizers, it is often the only option for successful communication between peoples speaking distinct languages.
- Underscoring national identity - language can be given a special status to underscore its historical and political meaning, as compared to other languages widely spoken in the country. Thus, in the post-Soviet space many countries degraded the status of Russian, despite the large fraction of their population speaking it as their mother tongue, and most of their population being highly proficient in it. One could specifically mention the Baltic countries and Ukraine. BCS (Bosnian, Croatian and Serb) is another example - formerly considered as a single language, these are now three different official languages in three different countries.
- Upholding the rights of national groups - Switzerland is the most striking example of a country that opted for using multiple languages, representing the major population groups constituting the country. It has four official languages: Standard German (somewhat different from the dialect spoken by the native Swiss), French, Italian, and (more recently) Rätoromanisch. Until recently Arabic in Israel was also an official language, as the one of the significant minority, but its status had been now downgraded.
Remark Beside the official language(s), a country might have some other designations, giving limited importance to other languages, e.g., those spoken by significant minorities, neighbours, etc. Thus, some languages may have official status in specific regions, be taught in schools or can be used for tests — e.g., in New Jersey the driving license exam is available in a dozen of languages (for others an official translator is required).