To be clear, I don't think I've made a very good argument in a positive sense. I think it's too complicated, and I don't think there's a good simple explanation for all of the trends. I have no confident explanation for the decline in crime rates after the mid-90s, for example. I just think Wil's assertions are unfounded.
It doesn't make sense to blame liberal policy for failures related to homicide rates if homicide rates (and most other crime rates) have been generally in decline.
It doesn't make sense to associate homicide rates to single-parent homes either, given that the trend lines are moving in opposite directions. Unless the argument is that an increase in single-parent homes is causing a decline in crime rates. Changes in family structure are part of a much larger cultural change since the 60s. The effects of those changes are pretty complicated.
It does make sense to think that there is a connection between the cycle of poverty and single-parent homes. The Stanford Center article discusses that. And certainly there is a connection between poverty and crime, albeit a very complicated one.
It doesn't make sense AFAICT to think that slashing welfare spending indiscriminately would reduce the number of single-parent homes, nor to think that it would reduce crime.
It does make sense that different kinds of anti-poverty programs could be more or less useful. Some of the
other articles from that same Stanford publication discuss that.
I don't think it can be argued that social policy since the 60s has been as successful as many hoped, although it's also true that Wil is wrong to think of all of that as an explicitly liberal project, or something where liberals have always gotten what they wanted. "Welfare reform" in the 90s was definitely not driven by liberal ideology, for example.