There were times this past week when it seemed like the 19th-century Know-Nothing Party had returned to Washington. President Obama insisted he knew nothing about major decisions in the State Department, or the Justice Department, or the Internal Revenue Service. The heads of those agencies, in turn, insisted they knew nothing about major decisions by their subordinates. It was as if the government functioned by some hidden hand. The growing dominance of the federal government over the states has obscured more fundamental changes within the federal government itself: It is not just bigger, it is dangerously off kilter. Our carefully...