Daniel Johnson: Here we are in the institute of Economic Affairs, this shrine of the free market, which is now under fire in a way that it perhaps hasn't been for a generation or more. Once again people are questioning the morality of capitalism, and they are even invoking the name of Marx, and those who are doing the invoking even include people like the Archbishop of Canterbury. Is this a good thing, or is this a bad reversion to old habits?

Samuel Brittan: I think that Marx is, to make a bad pun, a red herring. It's just become a shock-horror name to invoke, and I'm not shocked, but not that interested either. I've often wondered what Keynes would be saying now, I've never wondered what Marx would be saying. "Marxian socialism must always remain a portent to the historians of opinion - how a doctrine so illogical and so dull can have exercised so powerful and enduring an influence over the minds of men, and through them, the events of history." That's Keynes on Marx.

Edward Hadas: I think, as Sir Samuel says, quoting Marx is more of a cultural statement - like wearing a Che Guevara T-shirt - than an intellectual statement. There's a certain kind of perverse contradiction of reality. This very successful economy is identified as a failure again and again. Rowan Williams is just one of many people who look at what has to be considered, by pretty much any objective standard, a hugely successful economic experiment in modern times, and says, "No, no, it's a failure." When Marx made the claim, or, say, when Malthus made the claim that we were all about to be starving to death, at least a reader could reasonably say, "We haven't tried it out yet but look at the terrible squalor of industrial cities and the rapidly-growing population - yes, the system is working terribly and it's doomed to failure." There was a prediction, and there was a case - it may not have been a very logical one - but it has been firmly, thoroughly, completely disproved. And as for Marx's own version of the modern industrial economy that he planned out, we've given it a fair shot, I think. It's also been a failure.

DJ: Despite the unquestionable success of the market economy, doubts do still remain about its morality, and the present crisis has brought these doubts to a head. I'm not just thinking of this as an epiphenomenon of the crisis - it's having a direct impact on the course of events. So, for example, American members of Congress worry that their constituents are so angry with bankers that they will vote them out of office if they bail out the bankers. So they won't bail out the bankers, and this has an immediate impact on the stock markets. A moral view about the system or the individuals that work the system is directly relevant. It's having an impact every day.