Tyler Cowen writes:
Texas has begun to enforce [a law regarding parallel parking] only recently . . . Up until now, of course, there has been strong net mobility into the state of Texas, so was the previous lack of enforcement so bad?
I care not at all about the direction in which people park their cars and I have no opinion on this law, but I have to raise an alarm at Cowen’s argument here.
Let me strip it down to its basic form:
1. Until recently, state X had policy A.
2. Up until now, there has been strong net mobility into state X
3. Therefore, the presumption is that policy A is ok.
In this particular case, I think we can safely assume that parallel parking regulations have had close to zero impact on the population flows into and out of Texas. More generally, I think logicians could poke some holes into the argument that 1 and 2 above imply 3. For one thing, you could apply this argument to any policy in any state that’s had positive net migration.
Hair styling licensing in Florida, anyone?
P.S. I’m not trying to pick on Cowen here. Everybody makes mistakes. The most interesting logical errors are the ones that people make by accident, without reflection. So I thought it could be helpful to point this one out.
P.P.S. Commenters suggest Cowen was joking. In which case I applaud him for drawing attention to this common error in reasoning,