The end of the “development expert” paradigm does not mean the end of hope for development. Development is already gradually ending poverty (global poverty rates have fallen by more than half in the past three decades) – not be- cause of development experts such as those who wrote the World Bank Growth Commission report – but thanks to more freedom for more of the 6.7bn individual development experts alive today.
This may or may not relate to the Caplan-Cowen debate over whether "People are basically all the same." Easterly says that there is no such thing as a special "development expert" who can benefit poor countries by telling them what to do. On the other hand, as he points out, knowing that there is no development expertise is in itself a form of special expertise, which he credits Hayek with having.
My take on the Caplan-Cowen debate is this. Imagine that we lined up everyone in the world according to how similar they are to, say, Bryan, and give them each a score. Person number 1 is close to an identical twin. Call this person's score 100. Person number 6.7 billion is about as different from Bryan as any human being can be. Call this person's score 0. In functional notation, f(1) = 100 and f(6.7 billion) = 0.
One way to describe the Caplan-Cowen debate is that Bryan thinks that the function f(i) degrades quickly, while Cowen thinks it degrades slowly. My guess is that it degrades more slowly than Caplan intuitively believes but perhaps more quickly than what Cowen intuitively believes. However, I am not sure what the similarity metric is. Cowen makes it sound like it measures moral tendencies, whereas Caplan makes it sound like intellectual compatibility. Perhaps they are talking past one another, and I am merely adding to the breeze.