After four general election defeats and nearly 15 years in opposition, the Labour party seems likely to form the next government. Despite doubling down on its misguided attack ads targeting Rishi Sunak, Labour is looking forwards. Buoyed up by a big poll lead, the leader of the opposition, Keir Starmer, has started setting out his policy agenda in the form of five “national missions” focusing on economic growth, clean energy, the NHS, expanding opportunity and tackling crime. The missions themselves are hard to disagree with, and relatively light on detail. But, while the rhetoric is conspicuously modest, there is reason for optimism that a Starmer government would represent a significant change of direction for the UK. The most clearly defined mission – to “make Britain a clean energy superpower” – is backed by pledges to establish a publicly funded Great British Energy company, increase public investment significantly and create a zero-carbon electricity system by 2030. And there are signs of a promising agenda beyond the climate emergency, including raising the minimum wage to the level of the living wage, a wide-ranging industrial strategy and abolishing the House of Lords. And yet Starmer has struggled to set out a vision that could bring these currently rather disparate policy ideas into a coherent whole. It’s easy to put this down to his personality, more technocrat than visionary, but it also reflects the dearth of systematic thinking about the philosophical foundations for progressive politics in recent decades. Does this really matter? The Labour party could probably win the next election without developing such a vision. But the challenge – and historic opportunity – of our present moment is not simply to win the next election; it is to define a governing ideology that can finally supplant neoliberalism. But whereas Margaret Thatcher drew on thinkers such as Friedrich Hayek and Milton Friedman, where could Starmer look for inspiration? For many on the left, the answers lie with Marx and the socialist tradition. There is much of value here, and over the past decade it has been self-described socialists who have been the primary source of creativity within progressive politics. Starmer’s willingness to alienate the left in order to make a clean break with Jeremy Corbyn is seriously shortsighted. Even so, today’s socialists often have a stronger sense of what they are against – inequality, poverty, capitalism – than what they are for. Indeed, while Corbyn’s 2019 manifesto included individually popular policies such as increasing taxes on high earners and nationalising the railways, it read more like a wishlist than a cohesive vision for a better society. But the ideas Labour needs are hiding in plain sight, in the work of the great liberal philosopher John Rawls. Rawls is the towering figure of 20th-century political philosophy – a thinker routinely compared to the likes of Plato, Hobbes, Kant and Mill (next to Rawls, Hayek and Friedman are intellectual minnows). His ideas represent an unparalleled resource for progressive intellectual renewal. At the heart of Rawls’s theory is a strikingly simple idea – that society should be fair. He argued that if we want to know what a fair society would look like, we should imagine how we would choose to organise it if we didn’t know what our position would be – rich or poor, black or white, gay or straight. His answer to this arresting thought experiment – the “original position” – took the form of two “principles of justice”, relating to freedom and equality respectively. First, if we really didn’t know who we would be, we would want to protect our “basic liberties”, including personal freedoms such as freedom of speech, religion and sexuality, but also the political freedoms we need to play a genuinely equal part in collective decision-making. Second, in addition to ensuring “fair equality of opportunity”, we would want to organise our economy so that the least well off are better off than under any alternative system (Rawls called this the “difference principle”). From this perspective, higher pay for some can be justified as an incentive to work, study or innovate, but only if this ultimately ends up benefiting those who have less – not just by a little, but as much as possible. We would also endorse a principle of sustainability – that we must maintain the physical and natural resources of society for future generations. Rawls’s vision is an antidote to the cynicism that pervades our political discourse today – a “realistic utopia” that provides the basis for a broad-based and genuinely transformative progressive politics. For a start, his ideas provide a unifying alternative to “identity politics”, which have seen the rights of disadvantaged groups pitted against one another. They also define a genuinely inclusive liberalism that can transcend the culture wars, where everyone is free to live according to their own personal beliefs, as long as others are free to do the same. Finally, they offer a way to overcome the divide between liberals and socialists that has been the achilles heel of progressive politics. Rawls’s principles also point towards a policy agenda that would match the scale of the challenges we face, in many cases building on the direction of travel emerging under Starmer. So, for example, to tackle the climate emergency, massive investment in clean energy should be combined with a comprehensive carbon tax. And while House of Lords reform is clearly essential, Rawls’s ideal of political equality would justify a more ambitious package, including proportional representation, a greater role for citizens’ assemblies and tough measures to get money out of politics – capping individual donations at a very low level and instead giving every citizen a “democracy voucher” of, say, £50, to donate to the party to their choice. His philosophy can also help move us beyond the “tax and transfer” paradigm that has long dominated progressive economic thinking. For Rawls, the problem with capitalism as we know it is not simply the unequal distribution of money, but the concentration of power in the hands of owners, and the way our society tramples on the dignity and self-respect of the least well off. True economic justice will require a more fundamental reshaping of our economy, tackling inequality at its source, replacing our harsh and punitive benefits system with something like an unconditional basic income, and instituting new models of democracy at work. It’s easy to be swept away by Rawls’s idealism. In reality, change depends on winning elections, and even though our present moment seems ripe for a truly transformative agenda, incremental change is usually better than no change at all. But Rawls’s ideas can help restore a sense of direction and ambition to progressive politics, reminding each of us that a better, fairer world is possible. Daniel Chandler is an economist and philosopher based at the London School of Economics, and the author of Free and Equal: What Would a Fair Society Look Like?, published on 20 April