This FP column suggests that $40 billion a year would raise the incomes of the poorest up to $1.25/day in 2015. Allowing for poor targetting, that's maybe $100bn or 0.25% of rich country GDP. I responded to some of the comments on the piece here.
Charles Kenny
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Charles Kenny writes about global development — what’s working, what isn’t, and how the world can do better. An economist who spent fifteen years at the World Bank, he is now a senior fellow at the Center for Global Development in Washington, DC.
Charles Kenny 