FOOTBALL IS BLOCKING AND TACKLING.

Policy analysis is about elasticities. The economist who grasps these things better will write better and teach better.  Marginal Revolution's Tyler Cowen, "Consistency about elasticities," provides the useful teaching points.

What are your assumptions about elasticities?  And are those even the assumptions that actually matter to you?

How many economists do you know who start with beliefs about elasticities and then apply them consistently, before considering the politics of the conclusions?

How many of you actually think you are consistent across all of these views about elasticities? How many of you think you actually have a jerry-rigged model (“increasing returns for me but not for thee?”) that holds it all together?

Even the brightest among you will benefit from a modicum of repetition. Go, read, understand.