pairs private donations with “matched funds” from development banks. Once a donor’s school is built and staffed, some of the more vulnerable students are then supported by conditional cash transfer of ten dollars per month, an attendance-contingent “bribe” meant to encourage parents to keep their children in school. This is a popular aid model based on Oportunidades, a successful social assistance program first run in Mexico.

Thirteen-year-old Kun Sokkea was an early beneficiary of the Rural Schools Project. She became the first in her family to complete elementary school and had been making the long commute to junior high on a bicycle that her American sponsors had bought for her. Then, an “older woman” neighbor borrowed and sold the bicycle “and kept the money she received for it.” Kun Sokkea’s school attendance and grades began to fall. The donors were outraged when they learned about the theft, but they “decided they couldn’t just buy Kun Sokkea another bicycle.” By the time Kristof and WuDunn followed up with her in 2009, she had dropped out of school entirely.

Sometimes, international aid succeeds in making progress on average but fails on a more personal level. Development economists can use randomized controlled trials to scientifically test the treatment effects of building a school in a rural area or incentivizing attendance, but they cannot evaluate the impact of buying a single student a bicycle. Kun Sokkea may have stayed enrolled if she had been given another bicycle, or she may have been more willing to make the walk if she had never been given a bicycle at all, or maybe the bicycle had nothing to do with dropping out. There are too many variables to derive real data from an anecdote.

When Kristof’s desire to make an impact leads him to buy the freedom of two trafficked girls, he learns that freedom cannot really be bought. “Helping people is difficult and unpredictable,” he writes, “and our interventions don’t always work, but successes are possible, and . . . victories are incredibly important.”

There are few places in the modern world where the concept of sexual honor endures in the archaic sense: that is, as the belief that a woman’s virginity is more precious than her life. According to Kristof and WuDunn, one such place is the Middle East, where an unsanctioned relationship can inspire intrafamily violence intended to reduce the shame caused by a female relative’s “immodesty.”

The authors recall the widely-broadcast honor killing of Du’a Aswad, a Kurdish teenager who was punished for staying out overnight with a boy she loved. Du’a died slowly after being stripped, kicked, and stoned with blocks of concrete by a group of more than one thousand men. Afterward, some of the men covered her naked body, “as if the obscenity were a teenage girl’s bare flesh rather than her bleeding corpse.”

Kristof and WuDunn court controversy with their focus on religious fanaticism only as it applies to the Middle East and Muslim world, and their examples of Christianity’s obsession with virginity and virtue appear benign in comparison. An “American-sponsored abstinence-only” sex education lesson vividly illustrates the belief that women’s bodies are made repulsive by the loss of purity. After receiving a lollipop from the program coordinator, girls are instructed to suck on it as they imagine that their body is a lollipop being “unwrapped” and consumed by a sexual partner. Once “he’s done with you,” they’re told, “all you have left for your next partner is a poorly wrapped, saliva-fouled sucker.”

It is because of this “cult of virginity” that rape has become such an effective “tool of war.” In Darfur, the Janjaweed not only gang-raped women: they also cut off women’s ears in order to “mark them forever as rape victims.” In rural Pakistan, Mukhtar Mai was gang-raped by a village council who assumed she would commit suicide afterward because her life’s value had already been lost. In Karachi, gynecologist Shershah Syed cautions rape victims not to report the crime to police, because “if a girl goes to the police, the police will rape her.” In too many places, without the most critical component of a woman’s humanity—her chastity—she is no longer entitled to human rights.