Security procedures at Frankfurt International Airport are much more stringent than those at any airport I've been to in the United States. Everyone going through the checkpoint gets a good, old-fashioned wanding, and the security questions are asked in a serious rather than pro forma manner. The process takes forever, but it does inspire confidence in those otherwise feckless, terrorist-appeasing Germans.

That said, U.S. Customs and Immigration are far more serious than their counterparts abroad. Upon returning to Pittsburgh, I was asked about my hat (featuring a Cal Berkeley Golden Bear), my job, and what exactly I had been up to abroad. I think the purpose was to determine whether I was, in fact, a real American, although it's unclear whether associating myself with the good communists at Berkeley helped or hurt my case.

I'm vaguely aware that there's a book about Vietnam by this title, but in this case I'm talking about a kind of informal theory that, according to my source, has gained credence among development experts with enough real-world experience to become somewhat cynical.

My source in this case is a wonderful and wonderfully garrulous British development specialist I met in Diwa, a bookstore in Zamalek catering to expats and upper-class Egyptians. (Yes, rather than spending my time in Khan el-Khalili market searching for precious trinkets to take home, I looked instead for books. What can I say? I'm a big nerd). Anyway, this gentleman had spent time in Tanzania and Gaza, among other places, and had recently been sent to Egypt as part of a project for the Finnish government. He saw me browsing the small development section of the bookstore, and, noting my interest, began to regale me with tales and insights from his world.

One point that stuck with me in particular was his notion of the Rational Peasant, because I had been walking around Cairo and seeing much behavior that struck me as bizarre. In Cairo, as opposed to places like Rio de Janeiro and Sao Paulo, it's nearly impossible to avoid being confronted with Egypt's endemic poverty. It's quite common to see fellahin walking with donkeys pulling carts loaded with vegetables, fruits, or bread from the rural areas south and north of the city--20 and 30 kilometers away from the point of sale (usually the side of the road). This, for instance, struck me as irrational in an era of highways, buses, and trains. Why couldn't these peasant farmers save themselves (and their donkeys) the trouble and simply sell their produce to a middleman, who would then transport the goods and sell to shops? Or band together with friends, borrow money, and purchase an old truck to share?

Obviously, many did so, or the streets would have been overrun with donkey carts. But what my new friend told me he had learned in his years of development work was that it was important not to assume that peasants hadn't considered these possibilities. Given their need to survive above all else, peasant farmers will seek to minimize their risks, even if doing so means forgoing the opportunity to build a better life. He told me a story of a time in Tanzania when his team arranged to purchase cows for a village that didn't have any. Didn't they know that cows could be used to plow their fields more easily?

Sadly, all of the cows died a few days after they arrived. The culprit? The dreaded tse-tse fly. Had the team simply asked the villagers why they didn't have any cows, they could have saved themselves the trouble.