Jamie Holmes has a very interesting piece in TNR about psychological and economic research into the interplay of poverty and self-control. Basically there’s a fair amount of research indicating that that mental self-control is a kind of finite resource. Resisting temptation is mentally exhausting. And it even appears that making any kind of tough decisions about trade-offs has the same effect. Since poor people face more intense tradeoffs, this means that simply making the decisions of ordinary daily life is exhausting and leaves behind less mental energy for other things.
In Poor Economics, Abhijit Banerjee and Esther Duflo make the point that poor people face certain kinds of choices that people in rich countries simply don’t make. You can’t rent an apartment in the United States that doesn’t have running water, and the safety of the municipal water supply is a public responsibility. Poor people in poor countries, by contrast, need to make active decisions about acquiring and purifying water. This isn’t just inconvenient in the sense that getting the right purification tablets might be expensive or boiling it might take time, it requires mental energy. You have to remember to do it, decide to do it, and follow through. And it’s like that over and over and over again—basically nothing can be taken for granted when you’re living near the margins of subsistence. And that, in turn, makes it extremely difficult to consistently make the good decision that you’d need to make to get away from subsisitence.