What kind of society do we want? The most obvious answer is simple: we want people to be happy. We want our children to be as happy as possible, so why not everyone else? The goal should be a world where people enjoy their lives, and feel satisfied and fulfilled.

This noble idea was born in the 18th-century Enlightenment. It was probably the most important idea of the modern age. Yet somehow it is seldom talked of today in debates about our future. Some people say it is too ambitious; others say it is not ambitious enough. It is neither. We simply want to make people as happy as possible. And, especially, we want to reduce misery.

This should be the goal of every government and every one of us. More than 200 years ago, Thomas Jefferson wrote: “The care of human life and happiness … is the first and only legitimate object of good government.” Why else would we have a government than to give us a fairly distributed, better quality of life?

But what chance is there of politicians embracing this goal? Fortunately, it is in their interest to do so. The people’s life satisfaction is the best predictor of whether the governing party (or parties) gets re-elected. It is a better predictor than economic growth, unemployment or inflation. That is what evidence in national elections in Europe since the 1970s and in recent US presidential elections shows. It’s not “the economy, stupid”. It’s people’s wellbeing.

Keir Starmer gets this. He has promised: “With every pound spent on your behalf we would expect the Treasury to weigh not just its effect on national income but also its effect on wellbeing.”

This should lead to big changes in national spending priorities. The new science of wellbeing tells us a lot about how policies affect people’s wellbeing. We can then compare this benefit with a policy’s cost and choose those policies that give the highest bang for the buck – ie the most wellbeing for each pound spent. Mental health emerges as a high priority: The service provided by NHS talking therapies is a success because it saves more than it costs. But we desperately need a parallel service for adults with addiction or personality disorders, who get very little therapy. Similarly, mental health support in schools has been severely held back by lack of funding. It needs a better deal.

Altogether the government spends less than £2bn a year on psychological therapy. By contrast, roads and railways transport gets close to £62bn. Yet an extra pound spent on therapy makes much more positive difference to people’s lives than a pound spent on road or rail. Similarly, we shamelessly neglect the post-school education of people who do not go to university. They need guaranteed access to an apprenticeship, provided they are qualified. And so on.

We spend too much on things relative to what we spend on people. A major rethink is needed across the field of public spending.

The same is true for other organisations. They should be justified by how they contribute to human wellbeing. Schools should not be exam factories; they should be places where young people learn the skills of a life that satisfies and contributes to the wellbeing of others. There are excellent curriculums, such as Healthy Minds in secondary schools, that have proven impacts on wellbeing. Similarly, employers should give more weight to the wellbeing of their workers.

What matters most is our own personal goals. In the dominant culture today, the overarching goal is individual success, compared with other people (better grades, better jobs, better income). But this is a zero-sum game. For every winner there is a loser. So however hard people try, overall total wellbeing doesn’t change. But we can be happier if our individual aim is to make others happy and we derive much of our own happiness from doing that. We need that positive-sum goal and countries with high levels of social support and trust (such as the Nordic countries) are indeed happier.

It’s not enough for philosophers to say we have “reciprocal obligations” to each other. We must say what those obligations are – to help other people to be happy. That is the message of the Action for Happiness movement. Its members pledge to “create more happiness and less unhappiness in the world”. And it provides wonderful materials and meetings to help people live this way.

The UN International Day of Happiness takes place on 20 March, when many of us will celebrate at the World Happiness Summit in London. As the general election approaches, let’s ask every politician: “What is the goal your party is offering to the country?”

Above all, let each of us be, as best we can, a creator of happiness – as the Como Wellbeing Manifesto put it, let’s put wellbeing first.

• Richard Layard is co-author of Can We Be Happier? and Wellbeing: Science and Policy. The World Happiness Summit is on 19-20 March at the Queen Elizabeth Hall, South Bank, London SE1