Must-Read: Paul Krugman: The Fall and Rise of Development Economics: "High development theorists were having a hard time expressing their ideas in the kind of tightly specified models...
...that were increasingly becoming the unique language of discourse of economic analysis. They were faced with the choice of either adopting that increasingly dominant intellectual style, or finding themselves pushed into the intellectual periphery. They didn't make the transition, and as a result high development theory was largely purged from economics, even development economics.
Hirschman's Strategy... said that both the theorist and the practical policy-maker could and should ignore the pressures to produce buttoned-down, mathematically consistent analyses, and adopt instead a sort of muscular pragmatism.... We can now see that high development theory made perfectly good sense after all. But in order to see that, we need to adopt exactly the intellectual attitude Hirschman rejected... produce controlled, silly models that illustrate key concepts...