Why aren't aid organisations better learners?

Organizations responsible for international development assistance have long been perceived to be slow learners. One of the main problems pinpointed in Cassen’s 1986 study, Does Aid Work?, was that aid organizations do not seem to learn from their mistakes. The recent Swedish Foreign Ministry report (Organizational Learning in Development Cooperation: How Knowledge is Generated and Used, 1998) arrives at a similar, though more nuanced conclusion: that aid agencies learn, but "slowly and cautiously".