The four-day week – without a reduction in pay – would drastically improve our economy and our society. That alone is enough for some. However, the four-day week is more than just an innovative business idea bequeathed to us by progressive bosses. It should be seen as a fundamental aim of our economy, one that would directly address a range social justice issues including persistent economic and gender inequality.

A recent survey found that Britons are the most enthusiastic in Europe about the proposal, with 71% believing it will make them happier. Businesses are moving to shorter hours at an increasing rate as they recognise the benefits to wellbeing and productivity. The Green party promised a four-day week in its general election manifesto, the SNP made the debate a central part of its annual conference this year, and Labour has formally announced a review led by Lord Robert Skidelsky into how policy might be used to shorten the working week. Trade unions including the CWU, Unite and the TUC have all lined up behind the issue.

It is hugely encouraging to see the re-emergence of working time as a matter of public discussion, recognising that the length of the working day is not natural or inevitable, but a social construct we can collectively change. However, public debate on the issue has tended to focus on the “business case”, which emphasises the productivity gains of happier workers. Though the mounting evidence to support the business case is useful, if the past 40 years of neoliberalism has taught us anything, it’s that we are likely to be bitterly disappointed if we leave important things to the whims of business and the free market.

A reduction in working time can be used to address increasing levels of economic inequality. Since 1979, Thatcherite economic policy has stripped away the rights of workers and trade unions, and eroded the power of organised labour – which previously ensured that the gains of the economy were more fairly distributed to workers and not just business owners. Over time, the huge amount of wealth generated in our economy has gone to an ever-smaller percentage of the population. The richest 1% of the population now owns more than 20 times more wealth than the poorest 20% (13 million people). This shift has paved the way for many of the social, economic and constitutional crises we currently face: deindustrialisation and lack of investment have devastated the former industrial and mining towns of Wales, Scotland, the Midlands and the north of England, while financial services, owners of capital and property owners in London and the south-east have benefited enormously.

Since 1979, economic productivity has doubled, while GDP per capita has increased fivefold. Beginning a steady and managed transition to a four-day working week without a reduction in pay would result in an hourly increase in wages of 20%. On a structural level this would lead to a significant reduction in economic inequality; time itself can be used as a way of ensuring that the gains of the economy are shared fairly with workers and communities. As hours are reduced, some of the profits of businesses can be effectively transferred to workers.

Owners of capital may lose out in this relationship if output does not increase across the board (it is unlikely to in social care for example) – and more people may have to be hired. But we shouldn’t see this as a bad thing. There is more than enough wealth in our economy to begin the transition to a four-day week immediately, and if that means some degree of redistribution of wealth (in the form of working time), then that is a choice we can collectively make – and it will require some policy change to ensure its success. The New Economics Foundation has called for the four-day week to be negotiated and institutionalised in rights gradually, in a way that is responsive to economic and industrial change.

Shorter working time can also be used to address gender inequality. The model of working time we use has barely changed since the days of the male breadwinner factory worker of the 1950s. The five-day week model of full-time work means women are far more likely to give up work to take up caring responsibilities, while women do an average of 60% more unpaid work than men.

The unequal distribution of unpaid work is not only unjust, it also hampers women’s career progression and facilitates gender disparities in the workplace. Women’s careers suffer as a result of the unequal distribution of care work: 41% of women in employment work part time compared with 13% of men. Part-time work is more insecure, lower paid and offers fewer opportunities for advancement than full-time work. It also means that it is much harder for men to do their fair share of unpaid labour. A four-day week would help to redistribute both paid and unpaid work between genders and help to address these injustices.

After winning the weekend and the eight-hour day, the four-day working week is the next logical stage in our economic development and would address a range of inequalities and injustices. But if history has shown us anything, it’s that we can’t wait for something so important to be bestowed to us – we will have to change the rules of our economy to ensure a shorter working week is available for all.

• Aidan Harper is a researcher at the New Economics Foundation