Or perhaps Steve Levitt is right that the drop in crime was due to the legalization of abortion (as laid out in the book Freakanomics). I personally don't like

Or perhaps Steve Levitt is right that the drop in crime was due to the legalization of abortion (as laid out in the book Freakanomics). I personally don't like either explanation, but it just goes to point out the challenges in getting from correlation to causation.