Leading article: A party dedicated to fairness and freedom

This week we have been trying to present the best case that can be made from the manifestos for voting for the main parties. Of the three, yesterday's from the Liberal Democrats is by far the most challenging, meaning that it would change Britain's political landscape most dramatically. But that observation is not an underhand reference to the electoral fact that the Liberal Democrats will not form the next government and so can afford to be bold while the serious contenders cower. They are radical not merely because it suits them: the Lib Dems put rare and special weight on the second of the great political ideas which make up their title, democracy.

Much of the case for voting for them rests on their faith in us, the citizenry. The Lib Dems are optimists. They believe we actively wish for a bigger stake in our government and would make use of the stronger democracy their manifesto proposes - proportional representation, a predominantly elected second chamber, new powers for local authorities, more referenda. That's its radicalism. None of those changes in the way of governing guarantee any changes in the policies themselves. The Lib Dems want to open the doors and windows at Westminster, renew political life in Cardiff and Edinburgh and - promising eventually a local income tax - inject new vitality into local government. How we might use this more powerful democracy is up to us.

Elsewhere, the manifesto groans with the Lib Dems' own suggestions for what they would do if they formed a majority government. Of course, given our electoral system and their standing in the polls, this is fantasy politics. But the days when the they could be fairly accused of administrative innocence are gone, thanks to their weight of numbers in local politics. Besides, a lot of effort has clearly gone into getting the fiscal arithmetic right, and it is all set out here (and in an accompanying document on costs) in black and white.

Putting a clear political tag on the Lib Dems is not easy; the manifesto bursts with ideas without betraying an ideology. There are echoes here of pristine Victorian liberalism, the creed of John Stuart Mill who believed in the educative nature of political participation, pavement upwards. The Liberal Democrats approach Europe in this way. They have no fear of federalism, provided we strive to make the institutions of the European Union more answerable. They would do this by making the European Parliament an active legislature, overseeing the work of the Council of Ministers and the European Commission.

But there are strong signals too of muscular collectivism. We could be made healthier by increasing taxes on tobacco, greener by altering the balance of taxes on petrol and public transport subsidy, better educated, by an extensive and expensive programme for the schools.

Locally, the Lib Dem state would be active, too. Councils would get involved in economic affairs, through development agencies. They would set prices for road use in congested areas, using the proceeds to improve public transport - and cycle ways. The Liberal Democrats believe strongly, too, in that branch of the Welfare State which is not always recognised as such - the town and country planning system. Their manifesto promises tough controls on development outside the urban envelope. Woe betide private house-builders who buy up green fields in the hope of extending suburbia.

Sometimes the recipe is for less government. In the only mainstream manifesto to mention gays and lesbians, the Lib Dems confirm their position as the most liberal of the national parties. They straightforwardly promise the repeal of that notorious clause in the 1988 Local Government Act forbidding "encouragement" of those nameless activities which so upset Mrs Thatcher and her Cabinet colleagues. Meanwhile they burnish their pink credentials by promising to crack down on homophobic attacks while - a coy phrase, but the meaning is clear - encouraging the police to become more representative of the communities they serve.

In economic life, Liberal Democratic government would balance freedom and restraint. Some markets are roundly denounced, among them those in British-made arms and in products made overseas by child, slave or forced labour. This is the only manifesto this week that dares talk about excessive concentration of media power, promising intervention to stop mergers or take-overs that damage diversity.

Rupert Murdoch is not mentioned by name, but as good as. For the Lib Dems are prepared to use words and phrases that were on the tips of Labour and Tory tongues but could not be uttered. Words such as local education authority, gay rights, Rupert Murdoch, council tax, European Parliament, public transport and fox hunting. It is not that they have a cut and dried policy for each. (Fox hunting and hare coursing are, they say, to be put to a free vote in the House of Commons.) But, on the evidence of this manifesto, the Liberal Democrats have no fear of the thought police who seem these days to be stalking the rest of British politics. This is a party easily patronised and laughed at by the big battalions. But for the rest of us, the best argument for the Liberal Democrats is to imagine politics without them - as a simple, stifling and self-censoring struggle between the Tories and New Labour. That would be, we think, intolerable.