By A C Grayling; Weidenfeld amp; Nicolson pound;18.99

For those who think big, difficult questions require big, difficult answers, A C Grayling’s eloquent book on the good life will come as some surprise. The best way to live turns out to be quite simple: “Try to be nice to people, avoid eating fat, read a good book every now and then, get some walking in and live together in peace and harmony with people of all creeds and nations.”

Those aren’t Grayling’s actual words, of course - they come from the end of Monty Python’s film The Meaning of Life. But, in essence, they are strikingly similar to Grayling’s summary of the ingredients of the good life: “Individual liberty, the pursuit of knowledge, the cultivation of pleasures that do not harm others, the satisfaction of art, personal relationships and a sense of belonging to the human community.” So why do we need a philosopher to tell us in more than 200 pages what five comedians can tell us in one sentence?

The question is not rhetorical, and Grayling’s answers are illuminating.

His subject is as much about the search for the best way to live as the best way to live itself. Grayling has constructed a polemical narrative that tells the history of moral thought as the gradual ascendancy of secular humanism over religion, the triumph of individual autonomy to choose values for ourselves over the heteronomy of the church.

The story is worth telling not just because it is more interesting to travel than to arrive, but because, to understand where we are, we need to understand where we have come from. We are constantly being told by religious conservatives that we have lost our “spiritual values” and live in a shallow, materialist world. Grayling challenges this received wisdom.

Far from living in a world without values, we inhabit a world that has rediscovered them. We have ceased to think of morality as mainly concerned with what people get up to in their bedrooms, and have turned our attention to issues such as human rights, poverty, exploitation and racism. By placing contemporary society in its proper historical context, Grayling is able to show that our modern, liberal society represents the triumph of the moral values of liberty, tolerance and the proper enjoyment of life.

Although far from perfect, modern liberal society has the great merit of having placed the good life within the reach of almost everybody. That explains how it is possible for us all to understand and see the value of the good life, and hence how even the Monty Python team can come up with a reasonable summary of what life is all about.

Grayling effectively demystifies a subject that is all too often discussed as though its secrets are accessible only to long-bearded gurus. He writes like a dream and with impressive but not overbearing erudition. If he has a weakness, it is that his disdain for religious belief is too strident to be effective against those he seeks to convert. Although I share his basic convictions, I do not see how you can persuasively speak to believers if you start from the premises that their doctrines are foolish and their religions almost entirely harmful.

Rather like Bertrand Russell, Grayling attacks the citadel of belief he abhors from far outside it. Only by getting inside the minds of believers and seeing what could credibly motivate religious belief can you become an effective critic of religion rather than a mere cheerleader for the infidels.

One minor irritant is that, as is their wont with popular philosophy titles, the publishers have made the jacket blurb suggest this is some kind of “how to” manual. But you will pore over these pages in vain for substantive practical advice on living. Grayling’s message is rather about the conditions that make living a good life possible. Once these are satisfied, it is up to us to go ahead and live life well or badly.

It is an empowering but also perhaps a frightening message, as it makes us free and therefore responsible for what we might prefer to have a God decide for us. But just as a child must grow up and learn to live apart from its parents, so humanity must grow up and see that the good life is in its own hands.

Julian Baggini (www.julianbaggini.com) is editor of the Philosophers’

Magazine (www.philosophers.co.uk) and author of Making Sense: philosophy behind the headlines and Atheism (both OUP)