The method to the GOP's alleged debt-ceiling "madness"

For decades, the tug-of-war between left and right has kept government’s share of the economy nearly constant, around 19 percent of G.D.P. But in what you might call the revenge of Lyndon Johnson, the ballooning cost of Medicare is poised to tilt the debate decisively toward liberalism.

For now, tax increases and entitlement cuts are equally unpopular. But with every passing year, the constituency for letting Medicare grow as scheduled gets bigger and bigger, and the clout of working-age taxpayers diminishes. Already, even a relatively radical proposal like Paul Ryan’s budget seems compelled to exempt current retirees from its Medicare reforms. Imagine how the landscape will look in a decade.

These are the realities driving Republican intransigence. Past experience, present politics and future trends all suggest that conservatives should be aiming for the nearly perfect in the current negotiation, rather than the merely good.

But this logic also cuts both ways. Precisely because conservatives have a window of opportunity that they may not have again, there’s also a strong case to be made for striking the biggest possible deal — even if that deal requires concessions that a smaller deal does not.