The editorial for edition 22.1 of Juncture takes stock of the UK following May's general election, what it means for the parties of social democracy and liberalism, and how the new lands of national and regional geopolitics lie.

The election result has transformed the UK's political landscape. For the progressive centre-left, it marked a catastrophic defeat of both the liberal and social democratic traditions in this country. For the Conservative victors, it was a victory made sweeter by the fact that few saw it coming. But the new political terrain over which they now preside is littered with many potential pitfalls. The UK's constitutional settlement is buckling and in urgent need of democratic renovation, our relationship with Europe will be tested and potentially remade, and challenging questions of identity, security and place run through our politics. If the country is to navigate its way through intact, it will need to better understand itself and the social, economic and cultural trends that are reshaping our politics and political identities. To that end, this edition of Juncture presents an anatomical examination of the UK today, tracing its vital nerves and arteries, testing its creaky joints.

As Mike Kenny and Nick Pearce set out in the lead essay, faced with a dominant SNP in Scotland and a more self-conscious and sensitive national identity among the English, understanding and better articulating the national 'project' of the centre-left will be central to the renewal of social democracy, and of its political cousin, progressive liberalism. As the traditions, values and institutions that have undergirded the UK are challenged, and as the country goes adrift internationally, relocating a sense of national purpose and orientation is integral to the revival of progressive fortunes.

John Curtice, rightly regarded as the UK's leading psephologist and someone whom Juncture is proud to have worked with over the years, offers his first comprehensive account of Labour's election loss. Critically, his analysis confirms there is no single, straightforward explanation for its performance, either in Scotland or in Britain as a whole. Yet in England and Wales at least, he says, 'rather than a failure to win over the support of relatively affluent, more "aspirational" middle-class voters, the Achilles' heel of Labour's campaign appears to have been a failure to convince those who were sceptical about the Conservatives' economic record that Labour offered an attractive alternative'. In particular, Labour lost catastrophically among the over-65s and failed to win back the working-class voters who deserted it in 2010.

Restoring the party's reputation for economic competence is therefore critical to Labour's revival. Yet how it does that – offering to foster not just a well-run economy but a more attractive and equal one – remains the challenge. The recommendations for economic reform set out in this edition by the renowned economist Tony Atkinson suggest one potential avenue. His lucid essay underscores how inequality is not beyond the power of our institutions and government to challenge.

If Labour faces a crisis, liberalism too is under threat, its enemies triumphant and its main parliamentary standard-bearer, the Liberal Democrats, decimated. To confront that challenge, David Hall-Matthews argues that liberals of all parties must rediscover their core values of pluralism, decentralisation and resistance to arbitrary power. If, as seems likely, the coming parliament presents opportunities for cooperation across party lines in defence of liberalism, then that chance should be seized.

For the broader left, meanwhile, Eliane Glaser urges fierce debate. The hegemony of neoliberalism, she argues, will not be disturbed while the left remains at a crossroads intellectually and organisationally; it needs to embrace argument if it is to get its bearings and choose its path wisely. Tackling questions of democratic capture, a new political vocabulary, the pitfalls of populism, and the need for leadership and authority, Glaser asks how those bearings might be taken and how the new energy of the left can be converted into advances.

In his essay on how digital technology is transforming politics, David Runciman echoes Glaser in arguing that the IT revolution has some strikingly regressive features. New technologies are changing how people engage with politics and make voting choices – but, far more fundamentally, they are changing the way people live and work. As a result, while political parties can be as technologically savvy as they like, they have yet to rise to the central challenge Runciman poses here: to articulate a vision and a political economy for the digital age – an age of increasing automation – that ensures change works in the interests of more people than it does at present.

Certainly the SNP's triumph – almost unparalleled in British general election history – was built on more that just digital savviness. Nevertheless, James Stafford argues, the party's near-monopoly of Scottish representation in Westminster may end up giving it more status than actual influence. In Scotland, however, the SNP's social democratic positioning and their gradualist (for now) pursuit of independence will likely consolidate their position as the 'natural party of government'. If the 'Yellow Clyde' is to run red again, Stafford concludes, it will require a Labour party that can match political patience with bold constitutional and economic reform.

If arguments over devolution have been dominated by debates over Scotland's future, Arianna Giovannini and Ed Cox's survey of the new regionalist parties emerging in the north of England suggests a growing appetite for greater decentralisation to English regions and cities as well. They argue that the time is ripe for building democratic momentum across the UK behind a bold and positive vision of devolution. In his essay on the design and remit of a constitutional convention, Stuart White elegantly sets out an example of such as citizen-led approach to our constitutional moment. He rightly argues that the UK's constitutional order – how we organise the exercise of state power – is in a profound mess. Resolving it in a legitimate and long-lasting manner will require the peoples of the UK to democratically shape the solution.

This article appears in edition 22.1 of Juncture, IPPR's quarterly journal of politics and ideas, published by Wiley.