Guardian reporter Madeleine Bunting was in the audience for the talk and recorded some of Shah's comments.
But the subject that is probably closest to Shah's personal interests is food security. For seven years, he was director of programmes at the Bill and Melinda Gates Foundation on agriculture. And well before that, he remembers as a small boy visiting India for the first time with his parents from his home in suburban Detroit and experiencing with shock the slums of Mumbai and the acute human suffering he saw there. That childhood experience is what has driven his career.
"The 2008-09 food crisis pushed 100 million people back into poverty. We have been here before. In the late 60s, Paul Ehrlich was warning of a population bomb in which millions would starve, but that led to US agronomist, Norman Borlaug and his work on the green revolution – which has saved hundreds of millions of lives. We have learned a lot now about the environmental degradation it caused.
"But Africa was bypassed, and in 2006 the US was spending only $240m of its aid budget on agriculture, less than 3%. We have now increased that to $1.2bn in a programme, Feed the Future, which is working in 20 countries. The aim is to lift more than 18 million out of poverty and ensure that 7.1 million children are no longer malnourished."
Shah sees a big role for the private sector in this programme but also emphasises that the biggest impact on poverty will come from reaching small-scale women producers. USAid is working with co-operatives in countries such as Uganda.
"This is a structural challenge in global development: there are agrarian economies where large numbers of families devote 70% of their income to food, and that makes them highly susceptible to price shocks. A huge risk."
He believes that the right combination of technology and political will can have a huge impact in tackling this challenge, and points to the past as a reminder of what aid can achieve. "The Marshall plan for Europe after the second world war, the green revolution and oral rehydration are three examples of initiatives which have saved millions of lives. The last was the invention of USAid when diarrhoea was ravaging families in many developing countries and much of the effort was focused on extending healthcare services. But a simple rehydration solution given to mothers has empowered them to save their children's lives. It's one of the greatest success stories of aid. Not only does it save lives, it reduces the disease burden of stunted development."
On such subjects, Shah is a powerful advocate for aid, but question him on controversial aspects of US development policy, such as subsidies to US cotton farmers that hit west Africa so badly, and he becomes vague – an indication of how USAid can find its work undermined by other government department policies such as on trade or agriculture.