The recent slowdown in health-care costs is one of those facts, like climate change or the rapid growth after Bill Clinton raised taxes, that flummoxes American conservatism. The slowdown of health-care costs is one of the most important developments in American politics. The long-term deficit crisis — those scary charts Paul Ryan likes to hold up, with federal spending soaring to absurd levels in a grim socialist dystopian future — all assume the cost of health care will continue to rise faster than the cost of other things. If that changes, the entire premise of the American debate changes. And there’s a lot of evidence to suggest it is changing — health-care costs have slowed dramatically, and experts believe it’s happening for non-temporary reasons.