Economist Steven Levitt and Gladwell have a running dispute about whether the fall in New York City's crime rate can be attributed to the actions of the police department and "Fixing Broken Windows" (as claimed in "The Tipping Point"). In "Freakonomics", Levitt attributes the decrease in crime to two primary factors: 1) a drastic increase in the number of police officers trained and deployed on the streets and hiring Raymond W. Kelly as police commissioner (thanks to the efforts of former mayor David Dinkins) and 2) a decrease in the number of unwanted children made possible by "Roe v. Wade", causing crime to drop nationally in all major cities—"[e]ven in Los Angeles, a city notorious for bad policing". And although psychologist Steven Pinker argues the second factor relies on tenuous links, recent evidence seems to uphold the likelihood of a significant causal link.