We tend to imagine that organised attempts to make the world a better place are almost always successful, at least to some extent. However, this is simply not the case.

GiveWell surveyed the literature on the effects of social interventions, concluding:

We think that charities can easily fail to have impact, even when they're doing exactly what they say they are. In fact, our review of academic research has led us to believe that many of the problems charities aim to address are extremely difficult problems that foundations, governments and experts have struggled with for decades. Many well-funded, well-executed, logical programs simply haven't had the desired results.

David Anderson, assistant director of the Coalition for Evidence Based Policy estimates: