causality, voting, and recidivism

Jeremy Freese regularly offers insightful comments about social science research in his blog. Today he had an interesting post about "causal-sounding insinuations of relationships" between felon re-enfranchisement and recidivism, based on this statement from the Iowa governor:

Gov. Tom Vilsack of Iowa announced yesterday that he would restore voting rights for all felons who have completed their sentences, ending what advocates for voting rights had called one of the most restrictive disenfranchisement laws in the country. Mr. Vilsack, a Democrat who has been called a dark-horse presidential candidate for the 2008 election, pointed to research showing that ex-prisoners who vote are less likely to end up back in prison.

I'm not sure that's a statement of causality, but I guess that's not really the point. I confess that sometimes I slip into causal thinking even when I am careful to avoid making explicit causal inferences in my writing. I offered a (way too) long comment based on a recent law review piece with Jeff Manza.