How do we know what we know about economics?

A brilliant and honest essay by Russ Roberts — this is sort of the long form of Roberts’ charts I discussed back here.

I was asked the other day by a reporter if NAFTA had been a good thing or a bad thing for America. I said that both the proponents and opponents of NAFTA had no legitimate, unassailable or even suggestive, statistical evidence on their side. I said it was absurd to think that in a $14 trillion economy, you could tease out the impact of increased trade with Mexico and Canada and disentangle it from the thousands of other changes going on.

I suggested that anyone who provided an empirical case for or against the agreement was essentially being dishonest–using statistics selectively to make the case for a pre-existing world-view.

The reporter found this viewpoint unacceptable. Surely, he said, economics can help us answer the question of whether NAFTA has been good for America or bad. Or at least good or bad, for say Ohio.

I said no, there was no empirical evidence that would be decisive. It isn’t just that it’s hard to measure the net impact precisely. I argued that it can’t be measured.

Don’t miss the entire essay.