Your book, How Much Is Enough?, asks the ancient question of what constitutes a "good life". It examines in particular John Maynard Keynes's belief that in this century the spread of wealth would create a greater spread of leisure, and a great flowering of human potential. Wasn't that always a utopian idea?

I think the book is utopian in the light of what is going on at the moment. But I think it is also based on pretty hard economic reasoning. The calculation that Keynes made was that, if we got more money for less work, then we would want to work less. It was based on a notion of the satiability of human wants, which he got wrong of course to some degree.

Did aristocratic elites always use their leisure well?

No; of course a lot of them drank and squandered their money. But a lot, too, were very active in agriculture and the arts and building and so on. And in living good lives, surrounding themselves with beauty. The thought behind the book was: why shouldn't more people aspire to do that?

Keynes's friend Virginia Woolf came up with a figure of £500 a year that would enable you to live a good life, have a room of your own and all that, in 1930. In today's terms that would be £27,000 or so. To buy an average house in this country in 1930 cost just above £500. It is now £240,000. How do you square those figures?

Those figures are not inherent. It is just how we have chosen to organise things. Someone like Keynes never owned a house in his life – neither for that matter did Virginia Woolf.

How do you imagine an ideal day of the good life might unfold?

We imagine that society would be organised so the average person only has to work for a living three hours a day. For one thing, it is possible that person might enjoy his work so much he would want to work longer at it without more pay. There would I think be a huge proliferation of hobbies and adult education. A big expansion in travel. These things would fill many of the hours. And then: feasting. Music. The essence would be that people would do more things because they wanted to do them.

Such a shift could be brought about by policy interventions?

I think a change of philosophy would have to come first. It is only recently we have been bombarded with advertising 24 hours a day, for example, telling us to buy things. That could be limited to a certain number of hours a week. Another idea is a citzens' income. I think Gordon Brown had something of that in mind with his baby bond. Giving everyone a little bit of a pot at 18 or 21. That idea could be extended.

Inequality of income has been greatly exaggerated in the past 25 years. Is it going to take a huge political change to shift that back?

Isn't that what the Labour party is for?

It would also presumably require an exit from global competition, closed borders, protectionism…

It would require some restriction, I suppose. But otherwise we let economics bulldoze every other value we can think of. I have always regarded the metaphor of being in a race as a nonsense – "We must keep in the race, or the Chinese will overtake us." I mean, races must come to an end; they don't go on for ever.

Ethical checks and balances on capitalism used to come in large part from religion; it is hard to imagine religion re-establishing itself in that role in this country.

The question is, in the absence of religion, have we condemned ourselves to a love of money above all else? I think you can develop a secular ethics, but it is easier to do it from a religious standpoint. My own personal position is that I am not religious, but would like to be. I have long been impressed, for example, by the wisdom of the papal encyclicals, not all of the attitudes, but their general view of the place of human beings in the world.

You wrote this book with your son Edward, who teaches philosophy. Were you of one mind?

I don't think there was a lot of debate between us. The point of departure came from me, but a lot of the content was Edward's: the idea of happiness as a false god, and the ethical underpinnings of it all.

What's wrong with happiness?

Well, if you ask someone, "What is their aim in life?" and they say, "To be happy", then you have to try to define happiness, which doesn't get you very far.

What is your aim in life?

Very important to me has been intellectual work of one kind and another. Friendship has been very important to me. I have loved playing sport. Nature hasn't been the emotional force for me that it is for some people. Music has. I am very affected by beauty, I think.

But aren't you then presenting a patrician view of the good life, which is derived from your own experience of it?

I think the readers of the book who suggest we are simply proposing a version of the aristocratic lifestyle, or the Bloomsbury lifestyle, are selling the human race short. They are more or less saying, we might aspire to that, but most people wouldn't want to. I think the onus is on those people to demonstrate that the human race as a whole is incapable of rising to patrician levels. That was always the old socialistic dream of course – that once the economic necessities of life were catered to then you would get a huge expansion of human curiosity.

What went wrong?

The Thatcher years created a great regression in that belief, I think. We were getting there and then it was reversed. Though it was wicked and unrealisable, the failure of communism had a profound effect. There suddenly seemed no alternative to money as a way of organising society.

If you were writing an essay for your own grandchildren, as Keynes did, do you think they will be closer to his good society?

Well, we are not going the direction of his prophecy. For one thing he wasn't prepared at all for the shift back to inequality. It seemed to be on the wane in his lifetime. In a way our book is an attempt to get back on track.