Away from the Brexit and Trump headlines, the revival of socialism in the UK and US remains striking. Can Jeremy Corbyn and Bernie Sanders help to take it further?

The world is burning. The water is rising. A figure of exceptional cruelty sits in the White House, an inspiration to reactionaries everywhere. The wise men and women of the political centre are bewildered. (The norms are shredded, the civility is gone, fact-checking doesn’t appear to have its intended effect.) Disoriented by their loss of legitimacy, they dream of gluing their broken politics back together. They prefer not to reflect on why their politics broke in the first place.

Meanwhile, the long crisis of working-class life continues. Almost 80% of Americans live paycheck to paycheck. Nearly half wouldn’t be able to cover an unexpected $400 expense. Decades of stagnant wages, paired in the US with the soaring cost of housing, healthcare and education, have conspired to make living with dignity a luxury good. This doesn’t quite capture the depth of the crisis, however. It’s not just a decent standard of living but living itself that is increasingly at stake. Life expectancy in the US and the UK is falling. Climate change is killing people in California and Puerto Rico. Austerity is killing them in Liverpool and Flint, Michigan.

If all of this sounds pretty grim, it should. We are hurtling towards a bad future. Yet that future isn’t inevitable – and, in recent years, a growing number of people have been working hard to make it less likely. This is the bright spot in our mostly bleak moment: a rising wave of militancy and mobilisation on the left, particularly the socialist left, in the US and the UK, two countries where the left in general and socialism in particular have been in retreat since the late 1970s.

American and British socialists are no longer constantly losing. They are occasionally even winning. They are building institutions, running for office, organising workplaces, engaging in direct action and mutual aid. Against the nihilism of the right and the timidity of the centre, they are advancing a vision of a habitable future, one where the working class in all of its variety – young, migrant, queer – can live.

Corbyn and Sanders have pushed fringe ideas into the mainstream – they may soon have the power to put them into practice

The movements in the UK and US are not monolithic. They are composed of distinct currents, and contoured by countless debates. Socialism is a complex and contested tradition, no less so in 2018 than in 1968 or 1918. Still, two figures loom large: Jeremy Corbyn and Bernie Sanders. For all their differences, both belong to the socialist tradition – Corbyn hailing from the Bennite Labour left, Sanders from the Young People’s Socialist League. Both are “survivors” in Peter Frase’s term: they form a living link between the present and socialism’s last period of strength in the 1960s and 70s, having kept the faith through the long night of Thatcherism, Reaganism, Blairism and Clintonism. And both are central to the socialist resurgence in their respective countries. While the socialist moment certainly exceeds them – and indeed includes elements that are indifferent or hostile to them – they remain critically important to its prospects.

Two new books offer insights into their respective projects. Economics for the Many (Verso), a collection of essays edited by Corbyn’s shadow chancellor John McDonnell, is an overview of the new economic thinking around Corbynism, and a sketch of policies that a future Labour government might pursue. Sanders’ Where We Go from Here: Two Years in the Resistance (Biteback) is a memoir of political struggle since 2016, and a roadmap of sorts for progressive advance under Trump.

Whatever your thoughts on Corbyn and Sanders, the forces they have channelled and inspired are at an interesting stage of development: no longer in their insurgent phase, they have succeeded in pushing formerly fringe ideas into the mainstream, but don’t yet wield power on the scale required to put those ideas into practice. They may soon.

Even if it were to disappear tomorrow, Corbynism is an impressive achievement. When Corbyn won the leadership of the Labour party in 2015, the official consensus was that he wouldn’t last long. Memorably, Tony Blair warned of Labour’s “annihilation”. Three years later, Corbyn remains at the helm and Labour is in good health. Far from annihilating the party, Corbyn has invigorated it. Membership has soared: buoyed by an influx of some 350,000 new members, the party has nearly tripled in size. The general election in 2017 saw Labour’s largest increase in vote share since 1945 on the strength of its most radical manifesto in decades.

Corbynism has shown the political viability of an unambiguously leftwing programme, one that directly attacks the logic of austerity and the supremacy of finance capital. I write this in the week of the Brexit non-vote and the challenge to Theresa May’s leadership; the immediate future is unclear. But if Labour were to win the next election, what would Corbyn in power look like?

Economics for the Many offers materials towards an answer. Its 16 essays cover a wide range of subjects, from trade to taxes to tech. They set forth different ways to think about the economy and provide a number of proposals for restructuring it. Broadly, the common thread is what Martin O’Neill and Joe Guinan have called Labour’s “institutional turn”: the ambition to move beyond tweaking existing institutional arrangements and begin generating new ones. Corbynism aspires to transform the British political economy as thoroughly as Thatcherism did.

What might this transformation look like? Judging from Economics for the Many, the desired outcome is a high-wage, high-productivity economy oriented away from finance and towards productive sectors. It’s one in which public banks, public investment and public ownership play a significant role, along with a large network of co-operatives. An active industrial policy shepherds the transition to a post-carbon society through a “Green New Deal”, while increased spending on healthcare, childcare and education sustains a robust system of social provision.

Facebook Twitter Pinterest Looming large … Jeremy Corbyn and Bernie Sanders. Composite: Rex/PA

This arrangement is still recognisably capitalist, but rebalanced on the basis of a new social-democratic settlement that pulls British society in a more humane and egalitarian direction. It’s also an arrangement that capital will fight tooth and nail to prevent. Even if Corbynism doesn’t break with capitalism, its agenda entails substantial social control over the accumulation process. If history is any guide, capital will try, or at least threaten, to sabotage this agenda by blowing up the economy: refusing to lend, refusing to invest, or pulling its money out of the country.

McDonnell is aware of this danger, which is why he has been “war-gaming” different scenarios. Many of the book’s contributors seem aware of it too: in one essay, Simon Wren-Lewis explains Labour’s “fiscal credibility rule”, designed to soothe financial markets by promising not to overspend. Other manoeuvres suggest themselves: playing small capital off against big capital, playing productive capital off against financial capital.

But these are, at best, short-term tactical moves to create a bit of breathing room while deeper developments are under way. The only force capable of securing a new social-democratic settlement is the same force that secured the last one: large-scale mobilisation from below. The welfare states of the postwar period were possible because millions of people expected and demanded change. The long postwar boom also meant, crucially, that those concessions could be funded out of growth, not redistribution.

Today, there is relatively little growth. As a result, an even greater mobilisation will be required. Contemporary social democracy will have to cut into capital’s slice rather than count on a bigger pie. This makes the question of class struggle centrally important – a question that is curiously absent from Economics for the Many. It’s a testament to the intellectual richness of Corbynism that there are enough ideas swirling around it to fill a very interesting book. Ideas aren’t the only thing, however, and may not even be the most important thing. One suspects that Corbynism’s fortunes will have more to do with how many people are willing to engage in disruptive action in their communities and workplaces to defend its project, and to develop it in new directions from below. Winning an election is only the first step. “The really important question,” Ralph Miliband once wrote, “is what happens then.”

On the other side of the Atlantic, the balance of forces is somewhat less favourable. Nobody is war‑gaming capital flight. The American left is more confident and combative than it has been in decades, but its enemies are stronger. In Where We Go from Here, Sanders describes the anger he felt on the day of Trump’s inauguration. He wanted to work on “enormous problems” like healthcare, inequality and climate change. Under Trump, however, he knew he would be pushed into a different posture: operating “in a defensive mode, preventing bad situations from becoming worse”.

In the age of Trump, the left is necessarily playing defence. But it’s important to play the right kind. Since the 2016 election, two schools of anti-Trumpism have emerged. The first wants to turn back the clock and restore the status quo ante. It places its faith in norms, bipartisanship and constitutionalism. This is the position of the liberal centre and the Democratic party leadership. It was well articulated by Nancy Pelosi in her victory speech after the Democrats regained the House of Representatives in the recent midterms, when she vowed to restore “the Constitution’s checks and balances to the Trump administration”.

The American left is more confident and combative than it has been in decades, but its enemies are stronger

The other anti-Trumpism, by contrast, emphasises politics over proceduralism. It wants to build a new progressive majority that both dismantles Trumpism and departs sharply from the business-friendly centrism that has long dominated the Democratic party. Sanders is the chief proponent of this vision, and Where We Go from Here shows him working tirelessly towards it. In a series of short chapters, we see him running all over the country, holding rallies in town halls.

There are certain prominent figures within the Democratic party who seem discombobulated by our political moment to the point of psychic disintegration. Creatures of consensus, they crave compromise. They need to believe in the existence of anti-Trump Republicans, despite the fact that virtually none exist. They keep trying to find and hold the centre while the right runs circles around them.

Sanders is not one of those figures. His approach to politics is rooted in conflict rather than consensus, which makes him better suited to the present situation than most of his Democratic colleagues. In fact, conflict is the theme of his book – not conflict between the parties, exactly, but conflict between the classes. Where We Go From Here is dripping in class struggle. On the very first page, Sanders takes aim at “the billionaire class and the politicians they own”, and it’s a theme he returns to repeatedly. This shouldn’t come as a surprise to anyone who has ever heard him speak, but it’s still a little astonishing to see a leading American politician – one of the most popular in the country – talk this way. It is perhaps the most distinctively socialist thing about him. There aren’t just rich people and poor people, he reminds us: the rich are rich because the poor are poor. The rich are pushing down wages, jacking up healthcare costs, making a killing from endless war, stripping Puerto Rico for parts.

The solution, Sanders says, is to launch a “political revolution” against them. By this he means pulling in the masses of people typically excluded from electoral politics – in particular the young, people of colour and the working class – and composing them into a grassroots movement that demands less plutocracy and more democracy. His vision is a majoritarian one. “Today, what the American people want is not what they are getting,” he writes, citing broad support for social-democratic policies such as Medicare for All.

When Sanders proposed such policies during his 2016 primary run, they were labelled “extreme” and “unrealistic”, he recalls. Now they are mainstream, and many more elected Democrats support them. Two years ago, he notes, he introduced legislation to raise the minimum wage. It had five co-sponsors. When he did so again in April 2017, 22 senators came onboard, including most of the Democratic leadership.

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Clearly, Sanders is winning some battles. But many others remain. He has succeeded in pushing the Democratic party leftwards in some respects, and has helped inspire a new generation of challengers such as Alexandria Ocasio-Cortez. The struggle is far from over, however. The party is still ruled by the centre, which enjoys structural advantages that may be difficult or impossible to dislodge. The Democratic party is extremely adept at co-opting and demobilising social movements, and has successfully resisted any number of attempts to restructure it into a true party of the left.

Beyond this obstacle lies another: the Republicans. Sanders is right to say that Trump’s party does not reflect the views of most Americans. In fact, the Republicans themselves seem to understand this: their power rests on voter suppression, gerrymandering and the outrageously anti-majoritarian architecture of the American political system. But if the Republicans are a minority party, the minority they represent isn’t tiny. About 47 million people voted for Republican candidates in the midterms, and Republican voters love Trump – his approval rating among them hovers around 90%. Even if progressives succeed in expanding voting rights and making representative institutions genuinely representative, this Trumpist bloc will remain, and may metastasise into something even more sinister.

It’s easy to feed the pessimism of the intellect, but it’s important to find sources of hope to keep fuelling the optimism of the will. And the best basis for optimism might ultimately be the strangeness of the situation we find ourselves in – a situation strange enough to make two old socialists central players in British and US politics. There are junctures in history when the elements come unstuck and rearrange themselves into new and surprising patterns. The course of events becomes impossible to predict. Time moves raggedly, in leaps and ruptures. Another world becomes possible, although there are no guarantees.

• To order a copy of Economics for the Many by John Mcdonnell (Verso, £12.99) for £11.43, go to guardianbookshop.com or call 0330 333 6846. Where We Go from Here: Two Years in the Resistance by Bernie Sanders (Biteback, £20). To order a copy for £17.60, go to guardianbookshop.com. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.