The Constitution was designed to do many things at once. Modern conservatives who say it set limits on the power of government are correct. Modern progressives who say it created a flexible framework to promote the general welfare are also correct. Those who say it established federal supremacy are as correct as those who say it safeguarded the sovereignty of the states.
The foremost thing it does, however, is embodied in its structure, rather than its text. It forces politicians to compromise, by creating competing power centers and depriving any of them of the power to impose its will on the others. The resulting system is often referred to as one of "checks and balances," but that phrase, as William Connelly, Jr., notes in his 2010 book James Madison Rules America, fails to do justice to both the intricacy and the dynamism of the constitutional order.
The Constitution forces compromise not merely between the branches, levels, and institutions of government but also within each of them, and within each of the parties that populate them. Members of the majority party in each chamber of Congress must negotiate with one another to garner votes, and members of the minority party must negotiate with one another about whether to cooperate with the majority or obstruct it. "Factions within each party constantly fight over whether they are part of the government or part of the opposition," writes Connelly. "The majority party in Congress is not the government, nor is the minority party merely the opposition, whether under conditions of divided government or even under conditions of so-called united party government. Neither Democrats nor Republicans govern; rather, the Constitution governs."He adds that although the Madisonian system will compel compromise, spoilers who oppose compromise can cause trouble along the way.
In particular, spoilers have three pernicious effects. First, they make it difficult for leaders to lead. If any deal that a leader brings back from negotiations is suspect precisely because it is a deal, and if any leader who brings back such a deal is likely to be accused of treason by a significant share of his base, then it will be hard for a leader either to accept or deliver on a compromise — exactly the kind of problem that has weakened House speaker John Boehner in recent years.
Second, the presence of a knot of spoilers on one side increases polarization by hardening opinion on the other side. Why compromise, after all, if you think the other side will put any concessions in its pocket and then ask for more without giving any ground? "We won't compromise because they won't" is not an unreasonable attitude. As opposing positions polarize and harden, the substantive ground for compromise shrinks, and the trust necessary to find it erodes. That, in turn, makes it harder, not easier, to make painful but important policy changes such as long-term budget restraints or entitlement reform.
Finally, either party's isolation from the political mainstream, and from the mainstream's acceptance of the give-and-take of transactional politics, is undesirable in its own right. At some point, when insurgent voices within a party become dominant (or at least disproportionately influential), that party will begin behaving less like a party and more like an interest group