Over the past week, I took one flight in to Bengaluru and one flight out. The flight in was from Heathrow, British Airways non-stop from London to Karnataka's capital. It had announcements in Kannada, besides English. The flight out was to Goa, on IndiGo. It had announcements in Hindi, besides English. If you think there is nothing odd and infuriating about this, then you must be from the Hindi belt. The young man next to me on the IndiGo flight, travelling from a Kannada-speaking state to a Konkani - and Portuguese-speaking state, had no idea what the announcements were saying. He didn't turn off his phone, for example, because he wasn't told he should. To top it all, the member of the cabin crew who came over to tell him to do so told him in Hindi (and rather brusquely). This systematic corporate idiocy would have been comic if not for the fact that the nice young man was embarrassed, upset and, I think, angered in consequence.To be from a non-Hindi state in today's India is to deal with a hundred little humiliations. Tweet from Bengaluru, as I did last week, and your location attached to the tweet will come up not in English or Kannada but in Hindi. That is Twitter India's demented conception of friendly and sensitive language policy, apparently. (A request for clarification on whether Twitter India would change this insane policy is still unheeded as I write this. Perhaps because I asked on Twitter, and who really feels like checking Twitter these days, not even Twitter itself.)That is the broader cultural and social context in which we must situate what appears to be a very technocratic dispute that has recently cropped up involving the southern states of the Union. MK Stalin, the leader of Tamil Nadu's opposition, has written a letter questioning the terms of reference of the Fifteenth Finance Commission - an issue that may seem unimportant but in fact is pivotal for India's future as a united and harmonious country. Stalin joins other state leaders - including Karnataka Chief Minister Siddaramaiah, and Pawan Kalyan, the film star-turned-politician in Andhra Pradesh - in drawing attention to this apparently unimportant disagreement.What, you ask, could be at stake here? How could it be political enough to draw in three state leaders, and momentous enough to affect our destiny as a country? Well, Finance Commissions are a vitally important feature of our constitutional set-up. Every five years, the commission decides how tax revenue will be divided between various states (this is, of course, an even more important formula in the post-GST era). The more the commission's formula favours a particular state or set of states, the more money the state government gets from the national kitty to spend.One of the criteria used in this division is the state's share of the national population. This is natural, and as it should be. But the population shares used for this calculation have traditionally been frozen at the level determined by the 1971 census. The next finance commission, however, has been told by the Modi government to use the population shares of the 2011 census. And that's where the controversy comes in. Because in the decades between the 1971 and 2011 censuses, the share of the south (and of several other states) in India's population has declined. In other words, the Hindi heartland will, thanks to its abysmal failure to undertake family planning, get a larger share of taxes, thanks entirely to this one decision by the Modi government.It should thus be clear why this decision has the possibility of blowing up into becoming a major issue. Nor is it irrelevant that this decision has been taken by a government of the Bharatiya Janata Party, which is almost entirely a party of the North and West - and, even more importantly, is seen as such in most of the rest of the country. North-South relations in India have been kept from boiling over for decades mainly thanks to careful compromises which are rarely talked about politically. One such is the decision to freeze the number of Lok Sabha seats given to each state for decades. This decision, taken in 2002, postpones redistributing constituencies across states till the 2030s. As a consequence, the southern states have more seats now than their population share would really suggest they should have. This careful compromise was a product of the coalition era, in which neither the Congress, then a truly pan-India party, nor the Vajpayee-era BJP and the various regional parties that depended on each other for power in New Delhi, felt it was useful or wise to politicise the consequences of divergent population growth. Today's politics is different. The BJP is now dominant in Hindi-speaking India; it seeks to expand into the regions dominated by its erstwhile partners. The incentives of all political players have thus changed. The BJP is happy to increase the domination of its political heartland. And the regional players will be happy to corner the BJP by pointing out its Hindi-Hindu-Hindustan character.Political bargaining is not always about fairness. But is there a question of fairness here as well? There are two competing arguments. Here is the first: we are all Indians, we should not be valued differently. A vote in UP should count for as much as a vote in Tamil Nadu. A poor person in Bihar is as deserving of government support as a poor person in Andhra Pradesh; her government should not be given less money for her welfare. That would be the consequence of ignoring the changes in population shares since 1971. Such injustice would tear the country apart.Here is the second: states and societies that have struggled and succeeded should be rewarded. As late as the 1950s, Kerala was a basket case. As late as the early 1990s, many of Andhra Pradesh's development indicators looked like Uttar Pradesh's. These states and their governments have worked hard to turn themselves around. Most importantly, they - along with others, like West Bengal - have invested in women's empowerment, and as a result they have declining total fertility. In other words, empowered women, like everywhere else in the world, are having fewer babies in these states. States like UP and Bihar have not done the hard work needed to improve development indicators, including empowering their women; thus they have a still-exploding population, even as the South and East see their populations decline. Rewarding states for failing is fundamentally unfair to those who have made sacrifices in the past. Such injustice would tear the country apart.The fundamental social and economic disconnect between the North/West and South/East will continue to grow. Soon, it will be expressed in moral terms, and take on greater political weight. When combined with the easy Hindi supremacism that comes so easily to companies, politicians, and intellectuals from the North, it will become explosive. There are few easy solutions to this; but whatever solution exists will emerge from reasonable discussion and compromise. Nobody in the North should dismiss Stalin's letter Pawan Kalyan's tweet or Siddaramaiah's Facebook post as irrelevant, or stupid, or separatist, or as "petty politics". The danger lies in thinking that the unity of the Republic of India is not something that has to constantly be fought for.

(Mihir Swarup Sharma is a fellow at the Observer Research Foundation.)