By all means, let's ban discrimination on the basis of medical history—but we also have to keep healthy people in the risk pool, which means requiring that people purchase insurance. This, in turn, requires substantial aid to lower-income Americans so that they can afford coverage.
And this, Krugman goes on to explain, looks "very much like the health reform bills that
have already passed both the House and the Senate." In two sentences, I think, he succinctly gets at the heart of what health-care reform does, particularly in explaining why banning discrimination against preexisting conditions (a pretty popular position) begets an individual mandate begets subsidies (less popular positions). Point to the Nobel Prize winner on this one.