Most people are baffled and cowed at the thought of discussing philosophy, while others just don't see the point. But you might remember Bryan Magee from his popular TV series a decade ago, The Great Philosophers, with his friendly egghead style and soft, reassuring Attenborough-ish tones, which opened up the subject of Greek philosophy like an advanced episode of The Magic Roundabout.

Now he's back with The Story of IT]Philosophy, a big bumper comic-book annual of a tome, full of colouredy pictures, which glides rapidly through the grand sweep of Western philosophy: from the Greeks through Christianity; from the stirrings of modern science and the great rationalists, Descartes and Liebnitz, through the Empiricists Locke, Berkeley and Hume to the French Revolutionary thinkers and the "golden age" of 19th-century German philosophy, wrapping up the 20th century in its final 36 pages.

A former Oxford don and Fellow of Philosophy at Yale, and now visiting professor at London University, the 68-year-old Magee has written popular books on Popper (whom he knew well until the latter's death four years ago), Schopenhauer, and British philosophy. He also spent many years working in television. In the early 1960s he was a reporter for This Week, the main current affairs programme on ITV, working in "the Middle East, North Africa and black Africa. When there was a revolution in Zanzibar" - in 1964, before the island joined Tanzania -"the island was sealed off. I got myself in illegally. I was the only reporter there."

He was also a Member of Parliament from 1974 to 1983. "It's difficult to tell my biography crisply; I pursued different paths, often like riding four horses at once in a circus. But yes, I was one of those Labour MPs who left the party and joined the Social Democrats, and for that reason lost my safe Labour seat, in Leighton in east London."

He joined Labour in the early 1950s, and first stood as a candidate in 1959, although he wasn't elected to parliament until 1974 under Harold Wilson. However, by 1981, then on the opposition benches, he found the party "had gone very far to the left and I couldn't go along with those votes, so I resigned from the party in 1981. And of course in the general election of 1983, I lost the seat to the Labour candidate.

"All my life I had left-of-centre views - I was a passionate schoolboy socialist, very extreme left although I wasn't a communist - and as I got older and saw more of the world, my views moved to the right, and I became a very firmly committed liberal with a small `l', and a democrat with a small `d'.

Born in the East End of London, he was - like many children of his generation - evacuated during the second World War. "I was very interested even then in what I only later realised was called philosophy. I used to lie awake at night puzzling about whether time had a beginning. I didn't put it to myself in that abstract way, but I'd think, before yesterday, there was another day, and before that and before that, and I always wondered could you go back forever." After boarding at a public school outside London, he had lost his cockney accent by the time he won a scholarship to Oxford. But before "going up to" Oxford, he did his military service at the Yugoslav frontier in 1948, after being sent to the Military Intelligence school in Sussex. "The communist regime under Tito was sending agents across that frontier into the West in really quite large numbers. I was at the very, very bottom level of juniority, but I happened to become quite good, and was eventually entrusted with my own interrogations.

"We were very gentlemanly. We never used illegal methods - at least, I never saw anything like that. But if an agent fell into our hands and was then returned to Yugoslavia, the authorities would be very concerned they might be double agents, and as it was an absolutely ruthless regime, they rarely took any chances. So the worst threat we could make, was to hand an agent back. So when we asked them to answer all our questions, it was an offer they couldn't refuse. "Most of these people were perfectly bona fide refugees, as in most communist regimes, fleeing from the country in colossal numbers, while the regime was placing its own agents in amongst them. We caught a lot but again, how many got through we don't know." Back to the book. Much of it seems historically graven in stone, and while he doesn't even mention E. M. Cioran and Theodor Adorno, he gives Michel Foucault and the French post-structuralists only half a page. "I mention them because they're part of the present scene and they get a lot of publicity, but my personal opinion is that they are largely rhetoricians, talking in very impressive-sounding words, but when you subject them to analysis, they're not really saying very much."

So, after absorbing his book, where would he recommend someone start reading into philosophy? "If I were to give someone a reading list, I would ask them to start with Hume, then Kant, and then Schopenhauer, they're good honest thinkers. They wouldn't be as difficult as Heidegger's Sein und Zeit, which is the most difficult book - that's worth reading - that I've ever read. So I've tried to give an interesting and worthwhile idea of it, which a non-specialist can understand without having to read it."

I mention that Nietzsche gets a nice eight-page slice of the book. "Yes, Nietzsche proposes the most fundamental challenge to people who are not religious. His view was that we have derived our morality from Judeo-Christianity, but these were completely different societies, with their Ten Commandments. Nietzsche said that if you no longer believe in religion, you can't go on with the old value system. Either you provide new foundations for morality which you genuinely believe in, or you go back to square one and think the whole thing through again."

So where does he stand himself on that issue? "I'm a genuine agnostic. I once started a TV discussion programme with the head of the Catholic church in Britain, Cardinal Heenan, sitting beside me in his full robes, and I said to him `I don't know whether God exists or not, and what's more I don't think you do either'. And I could have said the corresponding thing to an atheist. An atheist is someone who thinks he knows, and that's foolishness. . . "There is a clear difference between religion and philosophy, and major philosophers like Thomas Aquinas, who have been religious, have themselves obeyed the distinctions. If you are religious, reason and argument and rationality and discussion are of course important, but they're not everything. Faith is very important and in most religions so is obedience and authority. In philosophy, faith doesn't play any role; the whole point of it is try to understand things through reason."

ER, hang on. What exactly did you mean, then, by God? "I don't want to go into definitions of God, because that becomes an escape hatch. By any definition of God that reasonable people would accept, I think none of us know whether there is a God or not. I think we have to face up to the fact that we don't know and live our lives in the light of that fact."

Do you mean, morally, just in case there's a God? "Yes. If you believe that this world is all there is, then the boundaries of this world are the only boundaries that there are, and this leads to a very different set of values. But if you believe there is a reality outside this world, you might believe you have to be answerable for what you do. But, I gasp, that's hardly an escape from religion at all! "I'll give you a clear example. A couple of days ago I saw an exhibition of drawings by Beardsley, and among other things, he produced a number of erotic and, in some cases, obscene drawings.

Now before he died he converted to Catholicism, and on his deathbed, he was so racked with guilt at these filthy pictures, as he called them, he wrote a letter begging people to destroy them. . ." So what kind of God are we talking about here? "I'll engage in any type of verbal hair-splitting you like, but once you start talking about definitions, you're ceasing to talk about matters of substance. You don't hear physicists having debates about what they mean by energy, force and light; they leave these terms undiscussed and they just get on with doing more science. It just isn't the case that in order to make advances in understanding and knowledge you have to define your terms - that's a superstition." Ah, come on. "If you challenge me to define a term I use, then I have to introduce at least one new term, otherwise the definition would be circular. And once I introduce a new term, you can challenge me to define that, and soon we're in infinite regress, because we can't ever get to the situation where we've defined all our terms. It's logically impossible.

"There's almost certainly a great deal more to reality than we apprehend. We have our physical apparatus, the brain and central nervous system, and they're not abstract things, they're lots of stuff, of matter, that a surgeon can hold in his hand. Now, whatever our senses and brain can cope with, we have a chance of understanding - but beyond that, we can't know other dimensions of reality, just as a camera can't photograph a smell. To me, it could be a coincidence of completely flabbergasting proportions, if the totality of what is coincided with the totality of what we, as humans, can apprehend. It's like saying a hurricane could blow through a junkyard and leave behind it a Boeing 707. It's unbelievable . . . "

The Story of Philosophy, by Bryan Magee, is published by Dorling Kindersley at £19.99 in UK