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I first came across the work of the development economist Michael Clemens when I began to investigate the aid industry almost a decade ago. It struck me as odd there was this hallowed international target for wealthy countries to hand over 0.7 per cent of national income to help poorer places. Then I stumbled on a paper he had written with a colleague in 2005 that laid bare the folly of this concept, explaining its unscientific origins and pointing out that updating the figures would mean an aid goal of just 0.01 per cent for rich nations. And that was 13 years ago, since when the world has become significantly wealthier.

Clemens, 45, is one of the most important and courageous global thinkers. That work on the aid target underlined his free-thinking approach, with rigorous reliance on data regardless of the conclusion. Colleagues at the Center for Global Development think tank in Washington – where he is a senior fellow – say he is remorseless in pushing them to always focus on evidence over ideology.

Two years later, I was working on a story in Ghana about the Millennium Villages. This daft idea was pushed by the pugnacious aid guru Jeffrey Sachs, who persuaded international donors, including Britain, to pour huge sums into his pet project. Clemens had, quite rightly, raised serious issues over imprecise evidence. I was struck by his tenacity in fighting his corner when the celebrated Colombia professor hit back. Although I suspect he is sceptical on much aid, Clemens won an award for a shared paper suggesting donations can assist growth despite wide variety of results and diminishing impact at higher levels.