The editors of Juncture call on the Labour party to 'recover the spirit of intellectual imagination and political openness, at a time when the challenges it faces are every bit as great as those it has faced in the past'.

As Juncture goes to press, the prime minister has just lost the authority of parliament for his foreign policy. The Syrian crisis has turned British politics on its head. Before the vote, Labour was becalmed, having spent the summer in one of its periodic bouts of public introspection. The Conservatives were ebullient, riding the wave of Labour's travails and the tentative upturn in the economy, albeit still lacking a strategic direction for modern conservatism - a fact brought sharply home by the death of Margaret Thatcher. Meanwhile, the Liberal Democrats continued to plough the deep trough of their dismal poll ratings, governing with maturity but not momentum. Even the insurgent outsiders of British politics - the SNP and Ukip - were starting to struggle as the public spotlight shines on their twin assaults on Britain's two unions.

Syria changes those calculations, at least for now. The stale air of an unusual mid-term year, brought on by the five-year fixed-term parliament, that had hung over British politics has been temporarily dispelled. But the underlying realities remain unchanged. Each party possesses strategic weaknesses. No political force commands the landscape or gives animating energy to the political scene. The big events of 2014 - European elections and the Scottish independence referendum - are awaited with caution and some trepidation, while all the time the horror unfolds in the Middle East. To many observers it looks like a re-run of the 1970s: political parties stuck in hand-to-hand combat, overshadowed by world events, with none yet able to break out into a new political paradigm.

As in the 1970s, the stasis points to hung parliaments and a messy pluralism in politics. But it also opens up the space for ideological revisionism, of the sort that characterised the emergent neoliberalism of the right-wing thinktanks and the influential Euro-communism of the left in that tumultuous decade. Each of these movements ranged well beyond day-to-day political tactics to embrace deeper renewal of foundational normative commitments, political alliances, cultural strategies and policy programmes. The 1980s were decisively shaped by what appeared at the time to be fringe movements.

What are their equivalents today? The right is in retread mode, as its modernisers jettison much of their recent agenda and the neoliberals drearily rehearse their libertarian nostrums as if the global financial crisis had never happened. They generate noise but none of the energy of the 1970s wave of rethinking. As Tim Bale argues on these pages, Tory modernisation has run into the sand, with no obvious future flag-bearer.

On the left, Ed Miliband has stated his conviction that Labour must reach for a transformative politics, to match the generational shifts that took place in 1945 or 1979, and it is striking how far he has personally led this ideological debate, with his influential, if sometimes terminologically derided agenda of 'responsible capitalism' and 'predistribution'. But he remains hemmed in by poor personal ratings, voters' alienation from politics, and a grim economic and fiscal environment. Labour's mid-term position is consequently weaker than it should be for a party on a clear path to victory, and by some margin - as John Curtice documents in his regular column.

Economic reform is also painstaking work. The chances of a breakthrough with the scale and longevity achieved by Attlee or Thatcher look slim. As Lane Kenworthy notes in the lead collection of essays for this edition, the 'predistribution' agenda faces some major challenges: for one, there is little prospect of a return of well-paid, unionised manufacturing jobs. Tax credits - writ large into a public wage or salary insurance programme - must take much of the strain, he insists.

For Roberto Mangabeira Unger, this is a narrow, unrewarding and timid politics. It traps the left in compensatory income transfers that do more to shackle and inhibit that they do to liberate. He insists that what he calls 'deep freedom' must be the left's goal, rather than a superficial equality of condition. 'Deep freedom,' he writes, 'combines a devotion to the empowerment of the ordinary person - a raising up of ordinary life to a higher plane of intensity, scope and capability - with a disposition to reshape the institutional arrangements of society in the service of such empowerment.' Pervasive, innovative and sustained institutional reforms of humankind's socioeconomic existence are the only worthy ambitions of a progressive project. European social democracy and what he has elsewhere called 'vulgar Keynesianism' have had their day. The state and market - indeed, humanity's very ways of life - must be sites of experimentation with new institutional and political forms. Ameliorating mankind's daily miseries cannot be the summit of the left's ambitions.

Unger's radicalism stands very deliberately and critically outside the social democratic tradition. By contrast, in his contribution Nick Pearce seeks the foundational renewal of social democracy itself, opening it up to new intellectual currents and political formations. In particular, he argues for embracing the insights of relational egalitarians, who reject the reduction of equality to the distribution of a single good or set of goods - whether income, wealth or capabilities - in favour of a social equality of status, standing and esteem; and for drawing more explicitly on recent civic republican and realist political theory, both to refound social democracy's normative commitments to liberty and self-government and to change the way it practises politics and makes policy. In this way, Pearce argues, social democrats can rescue equality from its reduction to abstract, ahistorical patterns and revitalise both their statecraft and political strategies, becoming more pluralist, democratic and expansive in the process.

The implication of Pearce's piece is that social democrats can only renew by embracing the intellectual and political resources of other political traditions, not simply by drawing on their own, as Blue Labour theorists argue. That means finding new ways of tapping into conservative sentiments and sensibilities, but also opening out to liberals, particularly those who draw on civic republican thinking. In this respect, it is noteworthy that, like Unger, Pearce stresses the importance of institutions - a major blind spot in contemporary liberalism, with its emphasis on individuals and their capabilities, and a faultline in conservative debates between Burkeans and market fundamentalists.

These are important foundational debates for the British left. The Labour party has never been a particularly intellectual party, a fact which allowed it to draw freely over the previous century on the work of great thinkers outside its ranks. But it is also true that in significant moments of revisionism - principally the 1950s and 1980s - it entertained fertile intellectual debates on its core values and animating political ambitions. It urgently needs to recover this spirit of intellectual imagination and political openness again today, at a time when the challenges it faces are every bit as great as those it has faced in the past.

- Guy Lodge, Will Paxton and Nick Pearce

This editorial appears in issue 20(2) of Juncture, IPPR's quarterly journal for rethinking the centre-left.