DM: It's probably worth clarifying what aid I'm critiquing in this book. I'm not talking about humanitarian aid. I agree that if there is a world emergency or a tragedy, whether it's a tsunami or a Katrina or Mozambican floods, we as human beings should intervene. Nor am I talking about charitable aid-the money that goes directly towards certain projects, like girls' education. That's relatively small scale. Although those types of aid have problems, certainly with respect to implementation, that's outside the scope of this book.

The book is really about a third type of aid, which is the large government-to-government flows or multilateral-to-government flows. What I am really focused on is delivering long-term sustainable growth that can meaningfully alter the number of people living in poverty in Africa. On that measure - delivering growth and reducing poverty - I would say aid has failed.

RD: The one that puzzles me, because I'm not an economist, is Ireland. I remember going to Ireland as a kid on holidays and seeing children without shoes. You know, it was really quite shockingly poor and, of course, Ireland was the butt of all the jokes. They were stupid, poor, drunken, useless and that was the Irish joke. Then, suddenly, they took off and they were the Celtic tiger. And they did it with European Union aid, which went to poor areas. So there it seems that you can do it. Nobody tells Irish jokes any more.

DM: I would consider the case of Ireland as very similar to the Marshall Plan, in the sense that the aid interventions were short, sharp and finite. The aid problem in Africa is that it's an open-ended commitment. There is no indication at all of when this is going to cease. Nobody says, "You've got five years of aid and then it is over, so figure out what you are going to do." To me, that is very different from what you had in Ireland. One of the critiques of aid that I discuss is the whole notion of disenfranchising the domestic citizenry. The problem in the African context is that the African governments become so beholden to the donors that actually there is no accountability to the domestic citizenry. That is certainly not the case with Ireland. So yes, we can pick one or two scenarios, but this is a continent of over 50 countries which has failed to maintain levels of economic growth or meaningfully reduce poverty after more than 60 years and a trillion dollars of aid.