Hobsbawm: Here we are, paying our respects to Karl Marx. Jacques Attali's biography of him, which has sold like hot cakes in France, is being translated in Britain. I've only done the biography of Marx in The Dictionary of National Biography, in a more modest way. When you consider, it's really rather strange that we should be here to talk to an enormous audience about it. One can't say that he died a failure in 1883, because his writings had begun to have some impact in Russia and a political movement in Germany was already in being under the leadership of his disciples. And yet, how could he have been satisfied with his life's work? He'd written a few brilliant pamphlets and the torso of an uncompleted major work: Das Kapital. His major political effort since the failure of the 1848 revolution, the so-called First International of 1864-73, had foundered. He had established no place of significance in the politics of the intellectual life of Britain, where he had lived for over half his lifetime. And yet what an extraordinary posthumous political success.

There is no other case of a thinker who left such a tremendous mark on the 20th century. Yet, for more than 15 years after the end of the Soviet Union, Marx was in no man's land. Some journalist has even suggested that we are here tonight to try to rescue him from the dustbin of history. Marx today is incredibly influential. I don't think enough has been made of the BBC poll which named him the most famous of all philosophers. If you actually put "Marx" into Google you will find that there are several million entries - in fact, 39 million when I tried it last time. He is much the largest of the great international presences, exceeded only by Charles Darwin and Adam Smith.

How are we to explain this sudden re-emergence? First, I think, the end of the official Marxism of the USSR has liberated Marx from the public identification with Leninism in theory, and with the Leninist regimes in practice. People have begun to notice once again that there are things in Marx that are really quite interesting. And this, in a sense, takes me to the second and main reason: that the globalised capitalist world that emerged in the 1990s was in some ways uncannily like the world Marx predicted in 1848 in the Communist Manifesto. This became clear in the public reaction to the 150th anniversary of that manifesto - which, incidentally, was a year of quite dramatic economic upheaval in large parts of the world. Paradoxically, it was the capitalists who rediscovered Marx, more than others. The socialists had by that time had the courage knocked out of them, and they weren't particularly trying to celebrate the anniversary.

I recall my own amazement when I was approached at that time by the editor of the in-flight magazine of United Airlines - on which, I may take it, most passengers are people travelling on business. He thought that the readers would be interested in a debate on Marx, because after all it did seem relevant to the present situation. A year or two later, when I found myself having lunch with George Soros, I was equally amazed when he said: "What do you think of Marx?" Well now, knowing that our opinions on various things didn't agree, I gave a sort of ambiguous answer, saying: "Some people think he's good, some people think he's bad," to which Soros said: "Do you know, I've just been reading that man and there is an awful lot in what he says."

So here we are tonight. Jacques Attali, I need hardly remind you, has been highly active in both politics and intentional finance. He is not, and has never been, a Marxist, but he, too, comes to the conclusion that now is the time when Marx has something to say.

Attali: What he tried with the international socialist movement was an amazing attempt to think about the world in global terms. Marx is an amazingly modern thinker, because when you look at what he has written, it is not a theory of what an organised socialist country should be like, but how capitalism will be in the future. Contrary to the caricature of Marxism, he is first an admirer of capitalism. For him, it is a much better system than any other before it, because he considers the earlier systems to be obscurantist. Once or twice he had the idea that it was going to be the end, but he very rapidly decided that this was not the case, and that capitalism had a huge future.

What is very modern also in his view is that he considered that capitalism would end only when it was a global force, when the whole of the working class was part of it, when nations disappeared, when technology was able to transform the life of a country. He mentioned China and India as potential partners of capitalism, and said, for instance, that protectionism is a mistake, that free trade is a condition for progress.

For Marx, capitalism has to be worldwide before we think about socialism. Socialism for him is beyond capitalism and not instead of capitalism. He has much say on globalisation, what is happening to movement of companies, delocalisation and everything that is linked to the way we live today. In a sense, the Soviet Union was destroying or interrupting the validity of Marx's thinking and the fall of the Berlin Wall is giving back a raison d'etre to his work, because Marx was thinking of the world globally and the Soviet system was a nightmare that he did not forecast.

Hobsbawm: We now have the realisation of some of what Marx anticipated: a globalised economy. It has had a number of effects which, however, he would not have predicted. For instance, the Marxist prediction that a growing proletariat in the industrialised countries would overthrow capitalism didn't work, because the progress of capitalism eventually does without the working class, as it does without the peasantry. Up to 1914 the prediction was quite reasonable, and indeed, it created mass parties which still exist. In short, the basic conditions under which Marxism operates in the 21st century will be quite different from those of the 20th century. But one thing will remain: the necessity not only to criticise capitalism, but to demonstrate that the very process of globalisation in the capitalist way generates not only growth, but also tensions and crisis, and that the process of capitalism is incapable of coming to terms with these.

Attali: Marx predicted that capitalism will grow, that inequalities will grow with it, that the working class will be destroyed and that the workers will be poor. This is not true in the developed world, but if you look at things globally, it is true. Concentration of wealth is growing worldwide. The share of wealth which is owned by a small number is growing, and the number of rich people is narrowing. There are three billion people who live on less than $2 a day and out of nine billion human beings 40 years from now, 4.5 billion will be below the poverty line. This is Marx's nightmare. And you cannot say that they are not workers. Even if they are unemployed, they are workers. And people who work with only their head, or digital workers - they are still workers. The contradictions at the heart of the market economy, to use the modern term, are more true than they ever were when applied to capitalism, which had 19th-century connotations.

If you look at the history of mankind in the past two centuries, this is the fourth attempt at globalisation. The first came at the end of the 18th century, collapsing with the Napoleonic wars. The second came at the end of the 19th century and collapsed with the First World War. The globalisation of the 1920s collapsed with the Second World War. We are in the fourth attempt at globalisation in two centuries and the most probable outcome is that this attempt will go the same way as the previous, leading to isolationism and protectionism.

In 1849 Marx wrote about going back to protectionism and other kinds of barbarism. At the beginning of the 20th century it was impossible to imagine, and today is the same. We cannot imagine the barbarism that will happen, but it is obvious that it will. The only way to imagine a solution will be to organise, on a worldwide level, a compromise between the market and democracy.

These are edited highlights of a debate held on 2 March as part of Jewish Book Week. It was chaired by John Kampfner, NS editor