Exactly 90 years ago, in March 1919, faced with another economic crisis, Vladimir Lenin discussed the dire straits of contemporary capitalism. He was, however, unwilling to write an epitaph: "To believe that there is no way out of the present crisis for capitalism is an error." That particular expectation of Lenin's, unlike some he held, proved to be correct enough. Even though American and European markets got into further problems in the 1920s, followed by the Great Depression of the 1930s, in the long haul after the end of the second world war, the market economy has been exceptionally dynamic, generating unprecedented expansion of the global economy over the past 60 years. Not any more, at least not right now. The global economic crisis began suddenly in the American autumn and is gathering speed at a frightening rate, and government attempts to stop it have had very little success despite unprecedented commitments of public funds.

The question that arises most forcefully now is not so much about the end of capitalism as about the nature of capitalism and the need for change. The invoking of old and new capitalism played an energising part in the animated discussions that took place in the symposium on "New World, New Capitalism" led by Nicolas Sarkozy, the French president, Tony Blair, the former British prime minister, and Angela Merkel, the German chancellor, in January in Paris.

The crisis, no matter how unbeatable it looks today, will eventually pass, but questions about future economic systems will remain. Do we really need a "new capitalism", carrying, in some significant way, the capitalist banner, rather than a non-monolithic economic system that draws on a variety of institutions chosen pragmatically and values that we can defend with reason? Should we search for a new capitalism or for a "new world" - to use the other term on offer at the Paris meeting - that need not take a specialised capitalist form? This is not only the question we face today, but I would argue it is also the question that the founder of modern economics, Adam Smith, in effect asked in the 18th century, even as he presented his pioneering analysis of the working of the market economy.