These insightful comments raise several points that I neglected, and bring out the subtleties of the issues I wrestled with in my piece. Four questions, in particular, emerge throughout the responses.

Is Africa’s recent economic turnaround driven mainly by external factors? Nearly everyone agrees that understanding Africa’s place in the global economy is critical to decoding its economic performance, although they place different degrees of emphasis on commodity prices, aid, trade, and investment. Ken Banks disagrees. He argues that mobile technology has been revolutionizing African economies and societies from within, providing employment, boosting farm productivity, and energizing African entrepreneurs. While many of his points are reasonable, the single-minded focus on cell phones is unconvincing. The study Banks himself cites suggests that a tripling of mobile penetration from ten to thirty cell phones per hundred people would boost income per capita by scarcely one to two percent—hardly revolutionary. To assert that global economic conditions matter for Africa—as they do for other regions—is not to typecast Africans as “passive victims,” but rather to appreciate the real-world constraints within which African policymakers must operate.

Is African democratization a sham? Robert Bates articulates the clearest vision of where Africa is headed, and it’s not optimistic. Bates believes Africa’s current economic expansion is a blip, driven by temporarily high commodity export prices rather than deeper internal changes. He believes that for all the talk of African democracies, the nature of governing hasn’t changed much at all, a position shared by Jeremy Weinstein. Bates and Weinstein aren’t even sure we should call these new African multi-party regimes—where the art of rigging elections is perfected and oppositions rarely win—democracies. Weinstein believes Africa’s persistent ethnic rivalries and conflict will hinder further reform. Paul Collier tends to share this pessimism about African democratization, pointing to Zimbabwe’s relentless slide, even as he shares my cautious optimism about Africa’s economic future.

I understand Bates, Collier, and Weinstein’s disappointment with the limits of Africa’s political transformation. But their analyses fail to acknowledge that genuine progress has occurred. I have not presented decisive evidence on the economic payoffs to democracy, a puzzle that has wrong-footed social scientists for decades. But the political transitions in many countries—Kenya, South Africa, Ghana, and others—have been remarkable, if incomplete. If these political changes have not yet paid large economic dividends, there is hope they will in the not too distant future.

South Africa plays a giant role in this story; Bates rightly emphasizes its importance, which I largely neglected. South Africa has been a major force for investment and trade, and the leading migration destination for many of its neighbors. Moreover, its democratic opening has inspired the world. So much is riding on its steady (if slow) economic growth. Political instability in South Africa, say, in the aftermath of next year’s presidential polls, could have massive consequences for Africa’s overall economic development trajectory.

What role is foreign aid playing? Rachel Glennerster is optimistic about Africa’s future, and gives foreign aid donors a good share of the credit. In her view, foreign aid has largely been a force for sound policymaking in Africa since the end of the Cold War, during which, she observes, donor motives were far less altruistic. She focuses on cases in which donors were instrumental in solidifying the transition to multi-party competition, as in Kenya. Yet I think these cases are only a part of the story. In other situations Western support for human rights and democracy in Africa is more rhetoric than reality. In the 1990s large foreign aid donors (including the World Bank) lavished financial support on Uganda, a one-party regime that meddled militarily in its neighbors’ affairs, looting piles of diamonds from war-torn Congo along the way. The United States and France today are far more interested in securing a stable supply of petroleum from Nigeria and Gabon than in investigating credible claims about election rigging there. It is fair to say that Western support for African democracy remains uneven.

Should African policymakers focus resources on improving agricultural productivity? Olu Ajakaiye and Rosamond Naylor lay out sharply different views in the latest chapter of this classic development debate. While I’m highly sympathetic to Ajakaiye’s view that the best way to eliminate the massive risk facing African farmers is for more Africans to work in factories than on farms—following the trajectory of other now-rich countries—neither he nor I can articulate a clear set of policies that will generate industrial development. Import-substituting industrialization policies in the 1960s and ’70s proved disappointing, as have more recent laissez-faire approaches. Instead of trying to establish a new industrial development scheme, Naylor lays out a series of policy steps to address farming risk and low productivity, problems made ever more critical with climate change looming. The coherence and concreteness of her proposals make them highly attractive.

Yet the agricultural productivity gains that both Naylor and David Weil call for will be hard to achieve. As Weil admits, less corrupt and more capable African institutions are a prerequisite for essential investments in irrigation, agricultural technologies, and adequate crop insurance. He also argues that the challenge of high population growth, which leads to land shortages or fuels urban crime, will require better governance. But, as Smita Singh observes, the big question is how to make African state institutions more effective and accountable.

What is the way forward, then? Collier believes that the key issue for African countries trying to sustain current economic booms is to learn from the past and avoid the unsuccessful policies adopted during the commodity boom of the 1970s. He thinks many African leaders are ready to learn from these past failures, and that this new attitude will help to sustain more robust economic growth.

Collier doesn’t specify how we can learn what works best and ensure its implementation. Glennerster believes rigorous impact evaluations can play a key role in determining which policies are most effective at bolstering economic development and institutional performance, and I agree with her that they are a promising tool for African policymakers and donors alike.

Following more or less the same rigorous methodology as counterparts in the medical sciences, economists have in recent years started taking the lessons of randomized trials to heart. One place to witness this new approach in action is in Kenya’s Busia district. The economists working in Busia—led by Harvard economist Michael Kremer, and including myself—are at the forefront of a growing movement to obtain better evidence on what works in development. In collaboration with NGOs, academic researchers working in Busia used randomized program evaluations to show that providing anti-parasitic drugs for intestinal worms—a major scourge affecting over 90 percent of Busia’s children—can boost primary school attendance and may have longer-term effects on students’ health. Comparing deworming to other common interventions shows it to be arguably the most cost-effective way to achieve such gains in rural Africa. Just as medical researchers are confident that their new therapies are responsible for health improvements among their treatment group, we can be sure that anti-parasitic drugs are responsible for higher rates of school attendance.

While it’s natural to focus on such success stories, randomized evaluations don’t always produce positive results about program impacts. But information on failures is just as useful; it allows policymakers to shift funding from the projects that don’t work toward those that do. This is at the heart of the learning agenda that Collier, Glennerster, Singh, and I all believe is the key to Africa’s economic future. Democracies like those emerging in Africa are particularly good learning environments, settings where impact evaluations can be carried out, their fruits widely distributed, and governments held accountable for applying their lessons to policy. In nations with weaker governance, rigorous program evaluations can themselves serve as a form of political accountability, empowering decent government officials to push for reform.

With impact-evaluation results in hand, policymakers in poor countries will increasingly be able to rely on hard evidence when deciding how to use their scarce resources. We now know the benefits of anti-parasitic drugs in improving school attendance in Busia, and as a result the Kenyan national government has included mass school-based deworming in its official school health plan for the country. Word has spread, and other African countries have expanded their own school deworming plans. In Ghana, over four million children received anti-parasitic drugs at school in 2007.

Learning about deworming is a small step forward on its own. But it will be through many such small lessons—in areas as diverse as health, education, agriculture, governance, and foreign aid—that African countries might learn to sustain and possibly augment their recent economic growth, even after the inevitable fall in global commodity prices.  ©