For a polity disfigured by scandal and rapidly losing its sense of proportion, what chance does a rather dry, 400-page report on social investment have of capturing the nation's attention, let alone its imagination? Our political culture may be judged by the answer. Like it or loathe it, the Social Justice Commission's report, issued yesterday, is what we should all be talking about.

The Labour-sponsored exercise has been hyped as a patriotic blueprint for a new Britain, a new Beveridge - and dismissed as a rambling manifesto from the tooth fairy. It is neither. Instead, it offers something valuable, an unsentimental alternative to Tory neo-liberalism. It is not a blueprint, for in the modern world governments are not able to reshape societies as once they could. But it is a breath of fresh air, a serious go at serious questions.

Very good. But does it soften, chip or bend the iron law of tax and spend?

Let us start with the political simplicities. The Tory appeal on welfare sounds increasingly retributive. Conservatives are no longer apologetic about unemployment or low pay. They celebrate the vigorous economic blast from Asia, extend means-testing, oppose the minimum wage. They wave a stick at the jobless and say to the rest of the country: 'Unemployment is partly self-inflicted, and we will not let idlers waste your hard-earned money.'

This is social justice, too - but it is a vision of justice that leans to the stocks and the whipping-post. The instincts are not so different from those of the Tory grassroots when it comes to ram-raiders. Brutal or robust, depending on your view, this retributive social justice has however been hugely popular in the years when Thatcherism celebrated the 'vigorous virtues'.

Against that appeal, Labour now says to the middle classes: 'It is the Government, through lack of investment and short-sightedness, that is to blame. If they say they will cut your taxes, you must ask yourselves first, do I believe them, and second, what is the price? Will those tax cuts have to be purchased at the expense of school and college fees, health insurance premiums, and the cost of rising crime? Nothing comes for nothing.'

The big question in British politics is whether Labour can persuade voters to listen. More specifically, can it so convince them about its own seriousness as to persuade them to forgo those tax cuts? In just two years, can it make the idea of government popular again? Can it refashion the disgust with politics, capture and shape the anger, dent the defeatism?

Putting it like that shows what a big task Tony Blair faces - though it also shows how the 'sleaze' stories contending for media space with the commission are connected to this same agenda: if people think politicians as a class are dishonest, they will be even less willing to vote for higher taxes. Sleaze is a weapon of great potential power; but it is an unpredictable weapon that has the capacity for blowing away a political class, and not just a government. Anyone who wonders why Mr Blair sounds a bit goody-two-shoes need think no further.

If Labour's gentler, non-retributive version of social justice is to matter, it will be because it helps to turn the national mood. Against that task, how does the commission shape up? Initial scepticism is in order. For 10 years I have sat gamely through countless well-orchestrated launches of plausible-sounding policy packages from Labour - hours of piped Brahms and pastel lighting in rented halls in central London, brave talk of new beginnings and fresh starts.

And none of it has meant a damn thing. Oh, it may have saved Labour from final destruction or closed the gap with the Conservatives a touch. But Labour never won and the policies were pulped almost as quickly as most first novels. In the end, voters did not trust the fine promises about their money.

This report, produced at arm's length from the party, is more detailed and more honest than those. It grasps some nettles - including proposing to tax child benefit; suggesting a new top rate of income tax and a lower minimum wage than the trade unions want; arguing that university students should repay much of their grants in later life; ditching the costly earnings-link for pensions; and accepting that the pension age for women should be equalised up, at 65. The tooth fairy would have balked at all those.

Second, it is up-to-date in its analysis. This is clearest in what could be called the feminisation of economics. In the old days 'economics' was what the Treasury and Bank of England, guided by the spirits of dead intellectuals, got up to. It was mostly macroeconomics - a boys' world of mighty abstractions and jargon posing as science. To be taken seriously, you had to read Euromoney, know that the Kondratieff cycle didn't need mudguards -and be the proud possessor of a shavable chin.

Then macroeconomic power whooshed away to the global markets, leaving the national economic debate focusing on the (literally) more homely matter of supply side economics - patterns of work, education standards, the role of the family. The vast growth of female workers, often mothers, mostly part-time, brought issues that were once patronised into obscurity right to the heart of political-economic argument.

Sir Gordon Borrie's report wickedly quotes Beveridge saying that over the next 30 years, 'housewives as mothers have vital work to do in ensuring the adequate continuance of the British race and of British ideals in the world'. Today, with the 'female' sectors of the economy outstripping manufacturing and construction, mothers' vital work includes ensuring the adequate continuance of the British economy, too. This gives the left a new opportunity: voters may trust the typical ex-City Tory minister to know more about macroeconomics, but they are less likely to accept his inbuilt superiority when it comes to child care and part-time working. It is hard to know quite how important this shift will be - but Borrie reflects the change.

On the minus side, there is an unhappy tendency to euphemism that will not survive political debate. Social justice, Labour-style, must involve helping the folk at the bottom by taking money from the wallets and bank accounts of the better off; it is idle to pretend otherwise, and no one will believe otherwise. These hard choices cannot be smoothed away with nice-speak about 'investment' or eroded with polysyllables. After this report they remain, untouched, for the party to confront.

Further, the more complex 'intelligent welfare state' favoured by the commission, if it is really to be able to focus on individual needs, will also need a larger, more expensive and more invasive bureaucracy than we have at present. This may be a price well worth paying. But it is a price.

In its more political asides, the commission makes an eloquent case for devolving power from the centre. But Labour is still light years away from a vision of welfare that is controlled locally, rather than by Whitehall.

Finally, while the report goes a long way to giving Labour a more convincing welfare agenda than the party had during the Foot, Kinnock or Smith years, it does not go nearly far enough to convince voters that there is an alternative and more efficient provision of services on offer from the left.

There is a huge job still to do in developing policy on schools, hospitals, the provision of training, and so on.

It is, however, a job worth doing. This has been a grim time for politics and for the country itself. If we laugh about the Ritz, and the Prince and the stench, there is a hard, unamused edge to our laughter. Against this petty, dirty background, the policy-wonk seriousness of the Social Justice people seems almost naive. For Tony Blair to sell their vision, to persuade people that a fresh political start is possible, would require plain speaking, clear choices and a tingle of patriotic optimism most of us haven't felt for ages. Whatever your politics, keep your fingers crossed for that.

'Social Justice: Strategies for National Renewal', Institute for Public Policy Research; Vintage pounds 6.99.