In September, Congress was very, very busy not passing appropriations bills. It managed to pass only two fiscal 2007 appropriations bills on time. This was partly because it was busy passing a ban on online gambling—a pre-election gift to the casino industry and Christian populists, one of Washington's least endearing coalitions. (Jack Abramoff, call your office.) It was also busy passing the Student and Teacher Safety Act of 2006, which requires schools throughout the country to allow random searches of students for weapons and narcotics, on pain of losing federal dollars.

Not content with trashing freedom and federalism in separate bills, the House efficiently trashed both together by voting to make it a federal crime to slaughter horses for human consumption. The American Horse

Slaughter Prevention Act would effectively shut down three slaughterhouses. It was reportedly brought to the floor as a favor to Rep. John Sweeney, R-N.Y., whose district, according to National Journal's CongressDaily, "includes the Saratoga racetrack and a strong horse community."

Democrats, who these days style themselves as the competent party, denounced the measure as a waste of precious time when so many 9/11 commission recommendations remain neglected. Then four-fifths of them voted for it. What not long ago was the party of reinventing government is today the party of random government.

Republicans, on the other hand, split on the horse-meat ban. Apparently the principle that Washington should resist the temptation to micromanage every aspect of American life, which once united the party, now divides it.

There's nothing new about election-season silliness. Still, the Republican Congress's September convulsions were also something serious: symptoms of the degenerative disease that one-party rule has inflicted on Washington.

Back in the 1980s and early 1990s, a lot of people worried that divided control (one party controls the White House, the other all or part of Congress) caused "gridlock." Unified command, these people speculated, would deliver something more like parliamentary government. The president would have political leeway to grasp the nettle of necessary but controversial reforms, and a Congress of the same party would have political leeway to pass them. The hypothesis was plausible on paper. But after four years of Republican rule, it is horse meat.

In today's America, neither party commands a majority and neither enjoys a decisive advantage; self-identified Democrats are more numerous, but Republicans are more likely to vote. The result has been that in the period since the South's Republican realignment ended the New Deal era's Democratic dominance, one-party rule has been rare: just 10 years of it since 1969.

Excluding a few all-Republican months at the start of President Bush's first term, the prior two stretches of one-party rule were 1977-1980 and 1993-1994. Although the former period produced a landmark deregulation of the transportation industry and the latter an important deficit-reduction measure, neither compiled a particularly distinguished record, and both were followed by popular backlash against the governing party.

In the 1970s, the Democratic Party still included many Southern conservatives, and the GOP some Northern liberals. Today, by contrast, more or less every Republican in Washington is to the right of more or less every Democrat. The average member of Congress today votes with the majority of his or her party 90 percent of the time. The 2003-2006 Republican era is not the first four-year run of one-party control, but it is the first to have taken place when neither party speaks for—or even to—the political center.

Ideological purity, party loyalty, and Republican control have thus produced an experiment in which a fiercely partisan and ideologically compact minority runs the entire government, locking out Democrats and alienating many independents. Like a one-armed canoeist, this lopsided rule has delivered neither efficiency nor effectiveness.

In September, with the session almost over, The Washington Post noted that the House was "on pace to shatter all records for inactivity." The current House, wrote The Post's Dana Milbank, had passed barely 400 measures. "The 'Do-Nothing' House of 1948 was positively frenetic by comparison, passing 1,191 measures."

If the portions were small, at least the food was bad. Unless you count a temporary cut in dividend tax rates, the creation of a national intelligence directorate, or some patching of the federal pension guarantee program, the Republicans have managed only one major program reform, the Medicare prescription drug benefit, and that was an exercise in irresponsibility, making the government's main domestic problem—long-term fiscal insolvency—much worse. Laws creating a legal framework for terrorism war detainees were important but flawed and overdue. Other than that? Social Security reform, no. Tax reform, no. Immigration reform, no. Fiscal probity, no.

Disaster response after Hurricane Katrina was abysmal. The preparation for and conduct of the Iraq occupation was little better. Abroad, world trade talks are stalled. North Korea is expanding and testing its nuclear arsenal. Iran is marching toward nuclear status. American prestige is at a low ebb.

Those are unarguable facts. Obviously, they are not all the fault of Republicans, President Bush, one-party rule, Washington, or, for that matter, America. But a search for policies enacted since 2003 that have enjoyed either substantive success or broad public support yields results that can only be called dispiriting. No other four-year period in memory looks as bleak.

In a complicated world, good policy is usually bound to be eclectic; in an unpredictable world, successful policy-making depends on correcting errors. Eclecticism comes from compromise, error-correction from coherent criticism. One-party rule seems to short-circuit both mechanisms.

Politicians compromise because they have to, not because they like to. Divided government forces them to compromise as a fact of daily life. Although compromise does not guarantee sound or successful policy-making, it does draw both parties toward the center and produce bipartisan buy-in. It's no coincidence that divided government produced the 1986 tax reform and the 1996 welfare reform, the great reforms of their respective eras.

Two-party rule also helps to marginalize partisan extremists and curb ideological excess. The Democratic Congress moderated President Reagan's unsustainable tax cuts and defense buildup, safeguarding his legacy. In the Clinton era, divided government produced a miraculously frugal fiscal detente. Ronald Reagan and Bill Clinton both succeeded not in spite of divided government but because of it.

One-party rule, by contrast, impelled the Republicans to govern from the center of their party, instead of the center of the country. It made them dependent on their base, magnifying the power of partisans and extremists. On Capitol Hill, meanwhile, governing with a narrow majority has required the Republicans to protect every GOP incumbent and scrounge every GOP vote, forcing them to pander every which way (see: horse meat). The result is the dysfunctional mixture of partisan extremism and philosophical incoherence that has characterized the party for the last four years. The Republicans lost their way because they won control.

Coherent criticism comes from a coherent opposition, and one-party rule undermined that, too. Without any institutional stake in the government's policies, Democrats have been free to surf the wave of Republican unpopularity, offering little—too little, in any case—by way of ideas and agenda. Control of part of the government would have forced them into the game, where they would have had to call some plays and keep their governing muscles in shape. Instead, they have atrophied.

Republicans, then, are unable to keep themselves from drifting into extremism and incoherence, and Democrats are neither willing nor able to stop them. Unified government turns out to be worse than "gridlock" (stasis). It is a negative-sum game, causing the institutional degeneration of both parties.

True, the horse-meat bill might have found its way through a Democratic House. True, bipartisan negotiations might have made some laws (the prescription drug benefit?) worse instead of better. Divided government is no panacea. Unified rule, however, has produced an unhappy electorate and two flailing, failing political parties, one with no governing philosophy and the other with too many.

In an October Harris poll, a large plurality of Americans said they would prefer divided government. In fact, so did a modest plurality of Republicans. The record is in, and the public is right.