The demonstration in London on 26 March was billed by the organisers, the TUC, as the "March for the Alternative". The march did, as the unions hoped, "give a voice" to those affected by the cuts and it showed that "people reject the argument that there is no alternative". What is still missing is a clear sense of what the alternative is, or might be.

The ambiguities created by the relationship between the labour movement and the Labour Party didn't help. The organisers decided not to give a platform to anyone from UK Uncut, for example, though that group has done more than anyone else to popularise an alternative to public-sector cuts. It has done this by using direct actions to focus attention on offshore finance and the large-scale tax avoidance and evasion it enables.

UK Uncut has recognised that an alternative to the cuts must be understood in terms of an alternative political economy, one in which the interests of large concentrations of capital do not trump considerations of the public good.

That this campaign group was absent from the schedule of speakers, while Ed Miliband was given a platform to present an "alternative" to the cuts that is itself a programme of cuts, highlights the problem organised labour now faces. In the past, the unions have sought to focus on issues of distribution within a capitalist economy and left the Labour Party to handle the politics – parliament was where the responsible and informed representatives of the working class would preside over a gradual, indeed sometimes imperceptible, move towards social transformation.

But once New Labour dropped even a rhetorical commitment to socialism, the trade unions' efforts to separate the political from the economic would come to seem increasingly irrational and self-destructive. One can only wonder what trade unionists thought when they heard a Labour prime minister boast in 2000 that Britain had "the most restrictive trade union laws in the western world". This is surely not what the unions had in mind when they set out on the long road to political power.

There is a choice

The Labour Party the unions created now believes that there is no alternative to a financialised economy run by privately owned, but publicly guaranteed, banks. Those who control credit must be given every encouragement and inducement and nothing can be proposed that might unnerve the financial markets.

That is the position of the leader of the opposition and his front bench. Union leaders can call on the support of the Parliamentary Labour Party as much as they like. They will not get it while the Labour Party, like the rest of the political class, remains overwhelmingly committed to the neoliberal settlement.

The vast majority of people in the country can see that there is something wrong with this settlement. They can see that Britain's industries have not flourished in the years since 1979. They can see that the public sector has not been improved by the introduction of market mechanisms.

The privatisations that were advertised as a way of introducing vigorous competition and innovation have instead created lazily piratical cartels in one sector after another. Above all, people can see that the financial sector has not used its control of credit to build viable businesses that deliver well-paid jobs to the working majority. Instead, it connived in a vast Ponzi scheme that combined the ethics of organised crime with some bewilderingly complicated mathematics, to devastating effect.

Those who belong to trade unions now have a choice. They can either remain committed to a defensive agenda, which leaves the question of political economy untouched. Or they can begin to ask what an alternative would actually look like.

The UK Uncut movement is a useful place to start. But as one begins to consider taxation, one soon becomes aware that the demand that large businesses pay more tax has profound political implications. Besides, as Ann Pettifor and others have pointed out, the debate must extend beyond taxation and expenditure to embrace the structure of the enterprise, the system of credit and the communications industry.

The British economy is in trouble. The cuts agenda will make things worse, certainly. But it isn't enough to resist them. The model of economic and social organisation adopted in 1979 has failed and will continue to fail.

Fiddling while Rome burns

As for the leaders of the trade unions, they too have a choice. They can remain committed to a narrowly wage-and-conditions agenda and pretend that they have no control over the political party that they bankroll. Or they can begin to re-create their institutions as venues for debate about the common good.

It is workers that create value – both marketable goods and the commonwealth of hospitals and schools and clean streets and safe drinking water. It is workers who must now meet and decide how best to reform matters. Parliament is not responding to the needs of the country. It is fiddling its expenses while putting on a serious expression and insisting that there is no alternative . . . and anyway, it is the other side's fault.

The trade unions have the infrastructure and the organisational ability to host this debate. It also offers them their best chance of survival. This will mean an intense period of discussion and conversation. The relationship with the Labour Party will have to be reconsidered. The role of the unions will need to be reconsidered, too.

The unions can grow and reassert themselves in the national life only if they are able to articulate an account of political economy that addresses both how we distribute private spoils and how we secure the common wealth. It must discover this account in the free conversations and deliberations of its members and it must create the institutional means to share it with the wider nation. The unions will have to go back into the publishing business and will have to stop leaving the politics to others.

If the unions accept, and attempt to negotiate with, the neoliberal settlement they will die. Because capital, aided and abetted by the Labour leadership, will kill them.

Dan Hind is the author of "The Return of the Public" (Verso, £14.99). He blogs here and is on Twitter here.