The great themes of Thailand in the 1990s were reform, openness and participation. Political institutions were overhauled by the most dramatic constitutional reform since 1932.

The press was celebrated as among the most free and feisty in Asia. Even electronic media began to ease free of state control. The bureaucracy was at last obliged to distribute power to elective local government. Civil society expanded in an upsurge of organisation, protest and debate. Economic planning was reoriented from growth to social goals. Reforms in education and healthcare were plotted by private initiative and forced upon a reluctant officialdom.

The great themes of the 2000s have been authoritarianism, suppression and exclusion. Thaksin Shinawatra used power won at the ballot box to suppress debate, emasculate institutions, favour cronies and move towards a one-party, one-man state. Electronic media were brought back under close control, print media intimidated and wars waged against community radio and websites. Thaksin was overthrown by an old-fashioned tank-trundling coup - a manoeuvre that had last succeeded half a century earlier. Politics are again dominated by individuals and types previously seen under dictatorship. Political activity is tightly controlled. Media are stifled by intimidation and self-censorship. In a throwback to the old era, rumour has again become a key part of day-to-day politics. The junta hand-picked people to re-draft a constitution that reduces the significance of elections and places great powers in the hands of a small number of people.

What happened? Why have the dominant trends of these two decades been so contrasting?

Some blame it all on Thaksin for aiming at such a monopoly of power and profit that it provoked such a primitive reaction. Some blame the drafters of the 1997 constitution for trying to create stronger and more stable governments without imagining how this design could be perverted by massive wealth. Some blame the 1997 economic crisis for undermining the old political order and shocking Thaksin and his business cronies into making their grab for power.

But stand back a bit and take a broader, longer perspective.

Thailand is grappling with the consequences of the great boom and the great bust. In the great boom, average incomes tripled in a little over a single decade. Across the spectrum of society, people had more wealth, more assets to protect and more interests to promote. At the top, new fortunes were created at a speed and on a scale never previously experienced. In short, the social order changed irrevocably.

Then the great bust delivered a staggering shock. An economy that had grown unfailingly for four decades suddenly shrank more than anyone thought possible. Businesses were bankrupted, millions unemployed, thousands forced back below the poverty line. The great bust impelled more people into politics, often to defend what they had gained over the great boom. They flocked to street demonstrations, supported new parties and participated in intense debate over Thailand's future.

Politics will only become stable when the political system reflects and accommodates the new social order, economic interests and political aspirations that have been created in these extraordinary two decades.

But the leadership since the late 1990s has totally failed to confront this challenge.

The Democrats who came to power in 1997 refused to accept the new order. They would not listen to the new businessmen who complained the government sided too compliantly with the IMF. They looked the other way when farmers took to the streets to complain they were left to bear the brunt of the crisis. As a result, the party was annihilated in the 2001 elections.

Thaksin emerged as the leader of exactly those political forces that the Democrats ignored. He articulated the ambitions of the new generation of businessmen made wealthy by the great boom. Perhaps despite himself, he turned into a populist and built a bridge between the new mass politics and the parliamentary system. But he failed to acknowledge that the old order still had interests to protect, and influence to do so. He provoked the elite. He stirred up the army. He antagonised the bureaucrats. He made the urban middle class fear that they would become politically irrelevant, and would pay the bill for enriching Thaksin's clique and allowing the clique to buy mass support.

The junta has taken this politics of exclusion to another extreme by banning all political activity and bringing back old-fashioned government by bureaucrats. Policy-making is not responsive to the major interests in the country, but to minority lobbies of economic nationalists, cultural atavists and moral crusaders who have access to these dinosaurs.

For the longer term, the junta hopes to impose a constitution that excludes the social and political forces they don't know how to control. The draft charter is an attempt to limit the importance of elections in determining who has power, while institutionalising a cosy little elite from the celestial ranks of the military, bureaucracy and judiciary.

This won't work. A political system is a set of rules and institutions for managing the various and conflicting demands on the state. Such systems work well when enough of the important interests accept that this set of rules is fair and workable. Otherwise there are powerful groups that feel forced to play outside the rules, and which tear up the rule book at the slightest opportunity.

The process for drawing up such a set of rules has to be inclusive. A hand-picked group of old school friends working within a deliberately restrictive framework cannot possibly succeed. Probably it will be best if this constitution-making process fails, either in the Drafting Assembly or the referendum.

That will create the opportunity to begin a more inclusive process that has some chance of creating a workable set of rules. But an acceptable constitution is only part of the problem. Key political forces have to be persuaded to work within a set of rules, however uncomfortable, rather than resorting to force and high-handedness. The dismal failure of this coup-installed government should serve as education. Or is that too hopeful?