The question of whether the rise of Internet pornography has reduced incidents of rape is nothing new, and something we've covered before. Back in 2006, Levitt expressed skepticism over research done by one of his former students that suggests a link, writing at the time:
The kind of variation in the data that gives the result is that states that are quicker to adopt the internet saw bigger declines in rape. He then does a nice thing in the paper, going beyond just this one prediction to test other hypotheses, like do crimes other than rape fall with the internet (he says no) and does other sexual behavior change with the internet (he says yes). The concern is always, with this kind of approach, that there are other factors that might be driving both the adoption of the internet and the decline in rape. The challenge to those who want to refute Todd Kendall’s argument is to identify those variables. The challenge for Todd is to find other kinds of “natural experiments” that support his hypothesis.
Now comes an article in the current issue of Scientific American Mind, which posits that for "most people, pornography has no negative effects—and it may even deter sexual violence." The article, titled "The Sunny Side of Smut," is by Melinda Wenner Moyer, a science writer. Here's a full version of the piece, via Moyer's website. Though an interesting read, the article adds no new empirical evidence to the subject, and relies heavily on the data showing that rape decreased faster in states that got the Internet quicker. As Levitt pointed out, that's not enough to go on.