Anthony Barnett, in the OurKingdom blog of openDemocracy can't find much evidence of new thinking on the left. Perhaps there is an echo here of Jimmy Porter (in Look Back in Anger, John Osborne's 1956 play): "There are no good, brave causes left".

In fact, the left has greater cause for confidence than for many years. It has struggled to find that confidence – after the deep psychological scars of the Margaret Thatcher years, followed during the Tony Blair ones by the divisions between a centre-left government and much liberal-left opinion over foreign policy and civil liberties. But we could be on the brink of a realigning moment. The centre-left has an opportunity to define a new centre-ground: one considerably different from that which it inherited. If we succeed in this, it will in turn set the terms of the inquest which Britain's right has still to seriously begin.

Whether this opportunity is taken, or whether the legacy of New Labour will prove as easily dismantled as that of Bill Clinton in the United States, will depend on the left's ability now to win the battle of ideas. Here, Anthony’s sense of urgency is appropriate.

To begin with, two caveats. First, there are many lefts. I would call mine the constructive left - a broad and plural left which is idealistic and ideological, but also interested in turning ideas into practical social change. Second, since it is not the mid-1990s anymore, new thinking should admit renewals of old ideas. Here are the five key areas which I believe go together, where progressives can win the arguments.

Equality

First, equality. This must be the defining mission of the left. Are we emerging from an era where it was a cause which dared not speak its name? But which equalities? How do we narrow the gaps? And how can the public argument be won?

A powerful core narrative is emerging. We should not inherit our life-chances at birth. But opportunities today depend far too strongly on where you are born and who your parents are. The central task of progressive politics is to reverse that, adopting a "life-chances litmus test" for all policy: does this improve outcomes for all, and narrow the gaps?' This cuts through the equal opportunity/outcome trenchlines: today's unequal outcomes shape tomorrow's unequal opportunities, and the inter-generational transmission of advantage and disadvantage should be of particular concern.

This approach means deepening the early-intervention agenda, now that the welfare state has discovered the under-5s, as with the Fabian Society's advocacy of tackling Inequalities at birth. And these arguments have led to policy changes - with child benefit being paid in pregnancy, and extra support for nutrition in pregnancy.

Closing the class-attainment gap in education is a related area. A difficult emerging issue here is what types of intervention in the family and home environment will be legitimate and effective. The new department fusing children and schools policy offers the right framework - but a punitive approach will fail - and alternatives to the "respect" agenda are needed.

Wealth inequalities must be addressed, which build on some symbolic steps to extend asset ownership, such as baby-bonds. We are on the brink of an inter-generational cascade of wealth inequality, which will divide us between the "have mores" and the "have nots". Could inheritance tax be made more legitimate by funding opportunities and assets for those with none?

Democracy

Second, democracy. It is a tribute to those who have campaigned for democratic reform over the last twenty years that the arguments are today much richer. Some reasonably fear that the left will see this as second-order. However, the equal-life-chances argument is fundamentally about autonomy - the importance of being authors of our own lives. This makes inequalities of power much more central, and could help to bridge a division between caring most about outcomes or processes. There is an appetite for more direct engagement to supplement representative democracy. The difficult issue is whether we can keep sight of what politics is about.

One reason democratic reform must engage a broader public is that the process needs to have an important educative function. Blogs can be brilliant - but don't they strengthen a cultural shift towards an insistent articulation of "what I want", with little emphasis on aggregating interests and seeking the compromises which are the stuff of democratic politics? Citizens' forums will be valuable where people engage with trade-offs - but this will need to challenge citizens not just leaders.

Citizenship

Third, citizenship. Gordon Brown's emphasis on Britishness is not to all tastes. It surprises me that so many people on the left do not understand that this is about collectivism. We should not get too hung up on the abstract language of multiculturalism, for and against (critics and advocates are talking about different things). But the most significant progressive critique comes not from on high but from second- and third- generation Britons for whom the assumptions and boxes are simply too narrow, as the New Generation Network manifesto demonstrates.

One of the virtues of Britishness is that, as a civic identity for a multinational state, it has always been an inherently plural identity. But we may know too little of our own history to recognise this. At least we are moving away from the notion that to define our citizenship or identity is somehow un-British.

The difficult issue: what should a concrete and progressive citizenship agenda involve? Should we combine an objective audit of social equality - how far are we from equal opportunities and life-chances - with a more subjective account of the extent to which we experience ourselves as a political community? This second test would find out how far individuals and groups feel that they are indeed "integral" to a shared society, and would identify and address the barriers to this too.

The left will struggle to build coalitions for equality without addressing identity and the dangers of competing grievances among disadvantaged groups. But we should win an argument with the right that there will be no successful integration without greater equality.

Environment

Fourth, environment. The fusion of a "red" and "green" social democracy has barely begun. But one impact of climate change is that the era of minimal government is over - diehard Thatcherties need to be climate- change deniers to sustain their political project. A centre-right environmentalism needs to develop an adequate account of the essential role of the state and of multilateral governance. For the centre-left the challenge is around markets. A credible response will depend on defining more clearly the type of sustainable, social-market economy we want to advocate.

In the environmental settlement of this century, as in the welfare settlement of the last, social democracy's task will be to reform and save capitalism, not to eradicate it. A particularly radical idea - personal carbon-trading - was floated from within the cabinet by David Miliband. That highlights how the terrain is shifting rapidly. The Liberal Democrats' conference showed how more radical ideas are entering the mainstream. There are a wealth of ideas around how to engender pro-social behaviour, and how to break the link between carbon consumption and economic growth. The most difficult issue is how to get the international deal we need in time - the complexity and depth of the changes required make this like no other multilateral negotiation - and half a loaf will not be good enough.

International policy

Fifth, foreign policy. If we want no more Iraqs, but no more Rwandas or Bosnias either, then we need a new left internationalism for the world after George W Bush. We can not count on a swing back to multilateral "normality". Traditional realists and the George Galloway/John Pilger left will feel vindicated by events - these two camps of left and right are ever ready to explain why every policy will turn out worse than doing nothing. We need an effective multilateralism, and a European Union capable of leading on it. The new European Council for Foreign Relations, about to be launched, should help generate credible new ideas, and a British-French rapprochement is essential. But foreign policy can't be left to governments and diplomats. A big idea should be democratic preference among governments (including democratic thresholds in the multilateral system: why should Burma's junta have a vote at the United Nations while imprisoning the country's democratically elected leader?), as well as democratic pressure and solidarity from below, as pioneered by Avaaz.

We need to remain true to human-rights principles - but pursue these more humbly - what Ulrich Beck calls a “contextual universalism”. But what do those who we wish to show solidarity with, think we should do? An answer to this question - for solidarity is the foundation of left internationalism - would make us better prepared for what could be the last crisis of the Bush years: Iran. One of the questions the Fabian Society will be asking on 26 September, on the fringe of the Labour Party conference at Bournemouth, is: "what do Iran's democrats want from us?"

It is suitable to end a very brief overview on this question. There is evidence of a growing desire in parts of the Bush administration to attack Iran, while for its part, the regime in Tehran seeks strength from extremism. A planned war may be unlikely but the chance of one being precipitated is growing. We know all too well that, whatever the British government does, the polarisation which will then follow will freeze thinking, divide progressives, and strengthen the right. It is all the more important therefore not just to push forward with ideas and new thinking, but to bring them together into a coherent sense of direction as I have attempted to do, so that they can withstand the all-too-likely disasters of the aftermath of the war in Iraq.

Editor's note: Sunder's article is a response in OurKingdom which is an openDemocracy project reporting, analysing and debating the future of the United Kingdom. For more on what it does and up to the minute coverage see its group blog here.