The achievement of social justice requires first and foremost a successful economy. When politicians of whatever party talk about education these days, it is normally to point out - rightly - that higher standards of education are vital to our future economic prosperity.

But that is only the start. The evidence of the past 20 years suggests that economic growth does not in itself enhance social justice. “Trickle down”, the underpinning assumption of the Thatcher and Reagan years, is largely a myth. Income differentials between the rich and poor have widened dramatically in this country. What we have seen over two decades is that, in times of boom, the rich benefit most while, in recession, the poor get hit hardest.

As a society, we should be extremely worried about this state of affairs, for at least two reasons. The first is the now overwhelming evidence of the impact of inequality on health. Richard Wilkinson, in his relentless book, Unhealthy Societies, shows that, among developed societies, life expectancy is related not to average income per head, but to the extent of income inequality.

As he argues: “Countries in which the income differences between rich and poor are larger tend to have worse health than countries in which those differences are smaller”. Thus, life expectancy was higher in Sweden, Norway and Australia than in the United States or west Germany which, though richer, have much wider income differences between rich and poor. Japan is perhaps the most convincing example of all, with high life expectancy and relatively narrow income differentials.

It would appear that, if we want a more healthy society, we should begin to concern ourselves with income differentials. The second cause for concern flows from Wilkinson’s argument. One of the reasons that relative, as opposed to absolute, income has such an impact on health seems to be that the poor in a very unequal society feel excluded and powerless. The stress these feelings cause compounds the more obvious consequences of poverty on health.

Furthermore, contrary to the generally accepted notion that we have to choose between economic growth and greater social justice, the evidence suggests that, increasingly, the two are likely to go hand in hand, particularly as knowledge work replaces manual labour. And, in any case, gross inequality - such as that in this country - imposes huge costs on society, especially as people who are unemployed or on very low wages become, in economic terms, net burdens as opposed to net contributors.

We see, too, the rising cost of filling our prisons, and soon perhaps prison ships too. Each prisoner costs the state ten times what a secondary pupil costs. If the problem of social justice is relatively straightforward to identify, working out what to do about it is another matter.

Increasingly, we are part of a global market. Many of leading competitor countries, especially in the Pacific Rim, have much lower levels of public expenditure and, therefore, of taxation. Huge rises in income tax would be bad economics as well as bad politics, while marginal rises would make little difference.

There are three steps, however, that would make a difference. The first would be to reduce unemployment. This requires targeted programmes, training and the creation and maintenance of the conditions for economic growth. The second is a minimum wage. There are some scandalously low wages being paid in some sectors of the economy.

Those who oppose the minimum wage on the grounds that it is interfering with the market are failing to see the big picture. The only reason that employers can pay such offensively low wages is that the government effectively subsidises them through the benefits system (income support and the like). Those who oppose a minimum wage on free market grounds are - ironically - defending state subsidies.

Both these steps would help in the short and medium terms. But over the long term (10 or 20 years), education holds the key. If the next government (whoever it consists of) can work effectively with teachers to raise standards, especially of literacy and numeracy, the consequences for social justice in the long term will be profound.

The impact on potential lifetime earnings of a good education is substantial. The long-run impact on social justice of raising standards, particularly in disadvantaged areas, could be huge. All too often in the past, urban regeneration has been about concrete and tarmac rather than people. This, however, is only to deal with the hard economics of it.

Better educated people are more likely to live life to the full, to enjoy the benefits of civilisation and to resolve their differences with others peacefully and respectfully. In short, education, in addition to promoting economic growth, also helps to put in place the values and attitudes on which democracy is based. Anyone who doubts that should consider for a moment the important contribution the education service has made in promoting gender equality and racial harmony. Not perfect in either case but highly constructive in both.

When Tony Blair says his three priorities for domestic policy are education, education and education, and when John Major says his are the same but perhaps in a different order, they are both right. The Liberal Democrats, too, have identified the same priorities and advocated them consistently. Let’s hope that whoever wins - and whatever the opinion polls say, I haven’t made a prediction since Chesterfield reached the FA cup semi-final - they deliver on this shared priority, not in a narrow party-political sense, but in terms of promoting greater social justice in the next generation than we have enjoyed in this one.

Unhealthy Societies: The Afflictions of Inequality by Richard G. Wilkinson, Routledge 1996.