Leading article: The dividing lines are clear – and there's no reason to fear the prospect of a hung parliament

With the manifesto launch by the Liberal Democrats, all three mainstream parties have now set out their electoral stalls. And tonight the three leaders will stand side by side on a stage in Manchester for the first of three televised election debates – an encounter without precedent in this country. Whether the content of the manifestos or the debate performance will make the greater impact – and it is hard to believe it will not be the debates – this is a campaign in which the third party has more direct access to the voting public, on a more equal basis, than ever before. There is a possibility here for a new dynamic, and one that would be thoroughly welcome.

The manifestos have their place, as the parties well understand. The appearance of the published document, the venue for the launch, and the style of the presentation all form part of the message the parties are seeking to sell. In the event, they tried almost too hard: their messages had so many layers. What is beyond dispute, though, is that there are now clear dividing lines; the voters cannot complain they have no choice.

Labour's manifesto cover breathes the optimism of the bright new day. Gordon Brown chose a new, as yet unopened, hospital in which to launch it, against a projected backdrop of sun lit fields, saying, in a pointed nod to the Conservatives, that Labour had not just built the roof while the sun was shining, but the whole hospital.

The Conservatives' restrained and classical manifesto design exudes establishment confidence and entitlement, even if the need-for-regeneration message conveyed by the Battersea Power Station launch could be read in several ways. David Cameron's call for localism and reliance on the good sense of individuals struck a fresh note and had the great merit of intellectual coherence, but it raises questions about the party's understanding of the public mood. It is not at all clear that parents' keenness to set up new schools for want of decent state provision on their doorsteps can be translated into a broader will to participate and volunteer.

The glaring gap in the proposals of both major parties was on the economy: not on what they positively wanted to do, but on where they would find the money at a time of overall austerity. On taxation, they were more eloquent about what they would not do in office, rather than what they would. The Conservatives might have won points with sections of the business community for promising not to implement Labour's planned increase in National Insurance contributions, but they also lost points with the same group of employers with their proposed cap on immigration. And even when spelt out, the "efficiency savings" they would harvest to pay for the non-rise in National Insurance lacked complete credibility.

The Liberal Democrats have carved out distinct territory

Indeed, this is where both parties have so far fallen down most egregiously. While essentially in accord that the economy is the priority and that either more money would have to be raised or more spending cut, or probably both, they were reluctant to give details of the bad news. Which is where the Liberal Democrats have been able, to a greater extent than in previous elections, to carve out their own distinct territory.

Thanks in part to the trust inspired by its Treasury spokesman, Vince Cable, through the financial crisis, the third party has felt confident enough to be comparatively precise about where the axe would fall to pay for its proposed spending. The choice of venue for its manifesto launch – the headquarters of Bloomberg in the City of London – seemed designed to capitalise on its association with fiscal responsibility. And its proposal to raise the personal tax-free allowance to £10,000 across the board is an elegant measure that simultaneously takes many low-earning individuals out of tax altogether and simplifies the application of the tax credit system.

The Liberal Democrats' tax and spending plans have a distinct bias against the top – but not higher-level – earners; hence, among other measures, the "mansion tax". They have also been definite about their intention to cancel ID cards – which they, and we, dislike not just on cost grounds – and the Trident nuclear programme. They have also shown exemplary clarity on banking reform, with their plans not only for a levy, but a break-up of the largest institutions to ensure that no bank will again be "too big to fail". The Liberal Democrats are also the only party to advance serious proposals for electoral and constitutional reform.

It could be observed that a third party has the luxury of spelling out unpopular policies, confident that it will not be called upon to implement them. But this would be unfair for two reasons. The first is that the Liberal Democrats offer some realistic and imaginative solutions that might yet find their way into the plans of one or other major party. Policy-poaching has precedents, as the Conservatives' George Osborne knows to his cost. The other relates to the level playing-field created by the debates – if not, sadly, by the electoral system – and the profound disillusionment with mainstream politics that can be detected among the voters at large.

The widespread feeling of "a plague on both their houses", attributable in part to the MPs' expenses scandal, helps explain why more voters favour the outcome of a hung parliament than a victory by either of the main parties. So might the increasingly confident performances put in by the Liberal Democrat leader, Nick Clegg. The pity is that this is one result we cannot vote for. And an attempt to vote tactically holds the risk of a producing a perverse outcome.

Coalitions can prove as stable as single-party governments

The prospect of a hung parliament is also met with trepidation in some quarters, where it is seen as synonymous with instability and indecision. But for all sorts of sound reasons this is a false assumption. In countries with voting by proportional representation, coalitions are routine and often prove as stable as single-party governments – with the added bonus that they are more representative of voters' opinion. At a time when unpalatable decisions will be hard to avoid and economic pain will have to be shared, a broader-based government would represent an opportunity rather than a catastrophe.

A hung parliament, and the awkwardness it would entail for the major parties, would have the further benefit of demonstrating beyond doubt that the present, first-past-the-post system has run its course. If it cannot produce a clear result, even when the odds are stacked in favour of the two main parties, the case for electoral reform would be proven. Of a hung parliament after 6 May, we say: "Bring it on!"