The authors identify three major approaches to dealing with world poverty, suggest that whatever their virtues and faults, there is a very piecemeal and pragmatic approach through which significant gains can be made without addressing the systemic obstacles identified by the three approaches. Their analysis is brilliant, focused, rooted in first-rate data sets, yet rich in social detail and anecdotal vignettes. I believe there are probably right, and their approach deserves to be widely studied an evaluated by policy makers in the advanced and developing countries.
The dominant school of thought is probably the supply-side theory, most visibly represented by Jeffrey Sachs (the authors call him a "supply wallah"). According to this theory, the poor are poor because they lack money and resources, and there is a "poverty trap" such that investment in productive technologies must be very large in order to have a positive and sustainable effect. Because poor individuals, and even poor countries, lack the capacity to finance such investments, they are trapped in a low-level economic equilibrium. For this reason, Sachs and the supply theorists advise that the rich countries transfer a large lump-sum amount of money to a poor country, so it can get over the poverty-trap hump.
A second salient school of thought is the demand-side theory, represented by William Easterly and many others. Demand-siders (the authors call them "demand wallahs") believes that the poor are poor because they do not want to undertake what would be necessary to move out of poverty and there is no poverty trap. Thus, if you throw money and resources to the poor, they consume it immediately rather than using it for long-term betterment.
The third school of thought is the corruption school, represented by Acemoglu and Robinson, as expounded in the book Why Nations Fail. According to this theory, countries remain poor because their governments are predatory, exploiting the citizenry by refusing to make investments in productive infrastructure, by direction all profits to cronies, and by permitting rampant corruption that renders creative entrepreneurship unprofitable. According to this school, to which I admit to being very favorable, the supply wallahs are wrong because the resources throw into the system will be appropriate by the rich and powerful, and the demand wallahs are wrong because the poor are actively maintained by the oligarchy in their position of servitude.
The authors are very insightful and balanced in presenting the views of these three schools and the evidence that supports these various positions. They also clearly explain their mutual critiques. For instance, the supply wallahs claim that states are predatory and corruption is rampant only because the country is so poor, and the demand wallahs claim that when the people want to move out of poverty, they will reform their governments. I find these defenses of supply and demand wallahs rather tendentious, leaving the corruptions school as the overall most plausible school.
I think it is fair to say that Banerjee and Duflo have little sympathy for demand and supply wallahs, but considerable respect for the corruption theory. Their own position is that there are virtually always ways to productively intervene to pull a significant fraction of people out of poverty. The authors, who have collected huge amounts of data and interviewed many poor people from around the world, make the following argument.
Most important, the poor in a poor country have about the same array of preferences and capacities as that of the human population as a whole, and humans are substantively rational in making decisions that affect their lives. However, the poor have a lot fewer resources than the well-off, they lack information and skills provided to the well-off, and lack access to such public goods as clean water and consumables subject to food and drug regulations.
The poor are therefore extremely heterogeneous. Microfinance organizations like the Grameen Bank therefore provide a general path to affluences, simply because only a fraction of the population has the will and ability to be successful entrepreneurs. On the other hand, entrepreneurs often fail several times before finally becoming successful, so the authors advise an expanded microfinance industry that is more tolerant of the sorts of behaviors that may involve short-term losses, but lead to long-run successes. The authors conclude that we must consider microfinance policies as extremely successful and worthy of following, even though it is not panacea for the abolition of poverty.
Because the poor lack access to social services freely available to the non-poor, the authors advocate such measures as providing clean water to poor villages and adding nutrients, such as iron, to staple foods. This, they argue, is not charity but simply the extension to poor of services already supplied to the rest of society.
Concerning education, the authors believe that poor parents are usually very eager to have their children educated, although they may lack the means of enrolling their children in schools or providing for their transportation to and from school. However, too often the content of schooling is determined by what is good for the more affluent classes, so poor children are led voluntarily to quit school. The authors advise that the content of education take into account the preferences and culture of the target population.
I cannot do justice to the beauty and intricacy of the argument developed in this book. The authors' main point is that we must look closely at the details of the lives of the poor in order to develop policies to help people to pull themselves out of poverty. This is neither demand or supply wallah-ism, and as they repeatedly stress, real progress can be made even in a society whose government provides a poor environment for economic development.