That's the easy part - the almost euphoric initial phase of a new movement. I remember the same exhilaration at the first conferences of the women's liberation movement. Then comes the difficult bit. The second ESF in Paris must provide a launch pad from which this new Europe-wide social justice movement (hugely reinforced by the 15 February protests against the war) can transform itself into a material force for resistance and change.
There's a need for strategic thinking to exploit the present contradictory moment. On the one hand, as anyone in Cancun will bear witness, EU institutions are pursuing neo-liberal economics to globally Dickensian conclusions. On the other, in Italy and the UK - the homelands of the European right in all its dubious forms - a popular awakening to the damaging consequences of neo-liberalism has already begun.
We must clear the ground by challenging the beguiling rhetoric, attractive to most Europeans, that a united Europe will counter the US. Equally plausible is a future of European multinationals competing with US rivals for cheap labour and plentiful markets in the South, or for any public sector deals that the US and EU connive to "free up". There could be a military build up in a "Fortress Europe", and a strengthening of European monetary policy not only against the dollar but also against the pressures of democratic accountability.
What is needed is an anti-imperialist, anti-neo-liberal alternative to US dominance. Rigorous policy proposals should be high on the list of what the next ESF stimulates. We need policies that bring us towards egalitarian economic relations with the South, towards a non-military security policy, towards democratic control over financial institutions, towards a just peace in the Middle East.
But policies are not enough on their own. We know that from the non-deeds of governments whose radical policies are subverted by the vested interests they supposedly set out to challenge.
We need to build new kinds of democratic power to reinforce the vote. We need workers" power that reaches out to citizens to improve public services and resist the global pressures to privatise. We need the power of an international peace movement backed by radical municipalities and able to open up inter-governmental contradictions. We need the strength of a movement for the free passage, and dignity, of people - built through solidarity between refugees and the labour and community movements.
To build these new kinds of power requires ways of organising that will be new in two respects. First, we will have to move beyond traditional electoral power. And second, we must make sure that whatever centralised power we put in place is accountable. We do not yet know the appropriate forms of political organisation for creating democratic and socially just alternatives at all levels - local and global. But most of us are involved in practical experiments and know of hundreds and thousands of organisations, networks and campaigns that share our values and goals. It makes sense to come together and exchange experiences. Together we can see more precisely where we want to go. And that is the point of the social forum.
The overriding concern must be to open up for all those resisting injustice a space conducive to the full exchange and thoughtful cross-fertilisation of ideas and action. Each organisation must come away from the ESF and similar forums strengthened in its capacity to resist and achieve positive change. This is especially important given the likelihood that next year's ESF will be in London.
What is needed is a real shift in culture throughout the left, so that we can engage wholeheartedly in building an infrastructure for supporting and connecting a diverse array of organisations and movements whose independence is integral to their strength. We need to labour in a process of social change that will be led in ways we cannot predict or control.
Hilary Wainwright is a member of Red Pepper's editorial collective and a fellow of the Transnational Institute.