Leading article:It pays to listen to the Liberal Democrats

With a whimper, not a bang, the party conference season has begun. The logos even match the weather: lots of gloomy grey, with the occasional glimmer of damp gold. Paddy Ashdown's podium speech will make it on to the television news bulletins. But most of the media will view this week's Liberal Democrat conference as a practice run for the red and blue political extravaganzas to follow.

However, it would be a big mistake to ignore the debates in Brighton. True, Paddy Ashdown will not win the general election. Even in the event of a hung parliament the government is unlikely to march to a Liberal Democrat tune. Compromises will be made, deals done, and Liberal Democrats will temper their policy ambitions faced with the pragmatics of power.

However, it is exactly because the Liberal Democrats are not pursuing victory at the general election that they are so important today. Since they won't have to take responsibility for executing their policies, they can think the unthinkable. And because they don't have to build a majority coalition across the country, they can advocate the unpalatable. Not for them the anguish that convulses Labour and the Tories over unpopular policies which might lose them votes.

Liberal Democrat politicians form an elected national think-tank, bringing legitimacy to new ideas and drawing them into the political mainstream. Our democracy is much richer for them.

The party has an extremely useful, if slightly curious, double identity. On the one hand, Liberal Democrats are the moderates, tucked in between two warring coalitions, avoiding dogma and ideology and talking sense. On the other, they are the party of stroppy little guys, instinctive rebels and outsiders, who can't help themselves reacting against any big institution or broad consensus of ideas.

So the non-conformists among them back unconventional ideas and new approaches to the world. That activists at the Liberal Democrat conference last year wanted to examine the legalisation of drugs should come as no surprise. But their moderate side lends respectability and credibility to ideas that might otherwise be laughed out of sight.

Thus not only can they bounce the Conservatives and Labour into accepting new ideas, they can also persuade the public where the other two parties might fail. Cautious always about the votes they might lose in the run- up to a close election, neither main party is in a strong position to provide national leadership on difficult issues.

Consider petrol taxes. The Liberal Democrats were not the first group to propose higher taxes on pollution and car use. Nevertheless the Liberal Democrat talking heads who kept discussing green taxation on television before the last election did raise the issue in the public consciousness. So by the time the Conservative government started pushing up petrol taxes, no one believed they were giving in to the ravings of environmental extremists. The Tories were able to do something progressive, and still sound conservative.

Similarly, the Liberal Democrats have pushed the debate on constitutional reform. Their proposals are not revolutionary; the Queen still reigns in Ashdown's vision of the future. But they have argued for wider institutional change than the Labour Party - calling for proportional representation to elect the House of Commons, and endorsing regional government with more enthusiasm than Tony Blair has so far done.

On the most difficult political issue of all - taxation - the Liberal Democrat voice is now vital. While Conservative and Labour politicians wouldn't dream of calling for tax rises in the runup to the election, the Liberal Democrats are still advocating an extra 1p on income tax to spend on education. The fact is that the Liberal Democrats are the only national political party to challenge the prevalent popular view that all tax rises for all purposes are deeply undesirable (and even, as John Major implies, morally wrong). And thank goodness they are, because with the public finances so weak, and the demand for investment in education so high, the next government may well need to raise taxes.

But the Conservatives won't admit that tax increases can be constructive. And Labour can't. Having lost elections in the past on tax-and-spend, Labour can only follow the existing public consensus on taxation. It has not the authority or strength to build a popular consensus in favour of tax increases. So it falls to the Liberal Democrats to persuade voters that higher taxes need not be such a terrible thing.

Those who say that British politics isn't big enough for more than two major parties are wrong. There may not be much ideological space between new Labour and left-wing Conservatives, but the political space around them is immense. It is true that the moderate side of the Liberal Democrat identity, eschewing extremism and ideology, is now personified far more effectively in Tony Blair. But the creative, independent, truly liberal side of the Liberal Democrats would be sorely missed if Ashdown's party did not exist.

Ashdown might show a willingness to be aligned increasingly with Tony Blair. But even this is tempered by the increasing illiberal tendencies of some leading Labour figures. And British democracy would be poorer if the Liberal Democrats were submerged underneath a new, Labour-led centrist party. Whether it be providing local government leadership, healthy opposition to both Labour and the Tories at local level, or generating radical new policies for the nation, the Liberal Democrats have an important role to play. We should watch events at Brighton closely this week, not to see the policies of the next government, but because we may see the glimmer of policies for the next millennium.