Leading article: India tears up the rule book

India's political traditions lie in ruins. They have been shattered by the country's have-nots and outsiders. They are unlikely to be put back together again. The only certainty is that the country is headed for an extended period of political instability. No party commands an overall majority after last week's inconclusive elections, the largest democratic ballot in history. Whatever government emerges will be a potentially unstable coalition with a very limited life expectancy. There may well be another election within months. That may deliver a very similar result, in which case India's politicians will have to learn new tricks, of ruling through a long-term coalition. Just as likely it may deliver an overall majority to the Hindu Bharatiya Janata Party.

Either way, the dominance of the Congress Party, which has ruled virtually without break for 50 years, is at an end. Its collapse in the polls, to a 30 per cent share of the vote, is the reflection of deeper, potentially darker forces at work in Indian politics. Congress government helped to hold the country together. Now it threatens to fragment along religious, caste and regional lines.

Congress ruled, through corruption, horse trading and cynicism. But the high caste intellectuals who created the party also formed a compact with their lower caste supporters. Alongside socialist economic policies it created a vast, leaky social welfare network for the poor, who repaid Congress by voting for it time and again in elections. More recently Congress has been reformist, ditching protectionist policies, welcoming foreign investment, floating the currency, simplifying the tax-system and allowing private banking. It reduced inflation and dramatically increased exports. Yet these economic achievements could not protect the party from the force of disenchanted caste, religious and regional politics.

The real winners in the election were a host of parties representing "low" and "backward" castes and populist regional movements. These 20 or so parties now account for about 40 per cent of the popular vote. This is in part because many lower caste Muslim groups fear that Congress is not being tough enough in response to the rise of the mainly middle and upper caste Hindu BJP. It is also a reaction against the heavy handed rule of Congress from the centre. Indira Gandhi, the great Congress ruler, distorted the Indian constitution's commitment to federalism by attempting to keep the states under firm central control. That is no longer possible: Congress's base in regional politics is increasingly weak. Whichever party rules in India will now confront a more fractious federalism.

The dangers in this situation are immense both for the social fabric of India and its relations with the outside world. The BJP's commitment to economic liberalisation and openness are untested. It wants to court a more moderate image. The party's most forward-looking leaders espouse market economics. The BJP and its more militant ally, the Shiv Sena, have been more or less friendly to foreign investment in Maharashtra state where they control the local government. So despite the wilder economic nationalism of some of its leaders and many of its supporters, it should not be taken for granted that a BJP-led government would be hostile to foreign investment per se.

So far it has said nothing about whether a BJP government would carry out its promise to build nuclear weapons, a policy that would bring it into confrontation with Washington and help further to destabilise the region. If the BJP is serious about wanting to become a responsible government it should make clear that, everything else being equal, it does not plan a nuclear future for India.

However, perhaps the greatest danger is that India will become increasingly ungovernable as the old political system based around Congress hegemony fragments. Religious violence could easily undermine the BJP's commitment to secularism. To govern, the BJP may have to cede powers to the provinces, which might feed regional separatism. If its own extremists are given their head they may well encourage extremism in reaction from populist Muslim parties. At the moment the political system is fragmenting; it may yet polarise.

It is far too early and it would be far too pessimistic to assume this will be the fate of a country that has a huge capacity to absorb change. Indeed, a more optimistic scenario may be just as likely. The fall of Congress may be vital to the health of Indian democracy, by providing choice and change. Its political leaders may yet be able to find a way of governing through a stable coalition if they all understand how little they have to gain from polarisation and conflict. The end of the Congress era may yet create the basis for a new political maturity. That would be a prize indeed.