Harold Pollack is the Helen Ross Professor of Social Service Administration at the University of Chicago and a Special Correspondent for The Treatment. Megan McArdle and Ezra Klein (and friends) are duking it out over the potential impact of universal health insurance coverage on mortality. Jonathan Cohn has already weighed in, but I wanted to add my two cents. It’s useful to divide this controversy into two separate questions. First, does health insurance improve health, and if so, how, and by how much? Second, what else do we need to do? The first question occasions a very old argument.