The great cliche among the chin-stroking, eat-your-spinach types these days is that they've never seen Washington so partisan. What's funny is that there probably hasn't been a time in the last 20 years when the forces of David Broderdom haven't waxed dyspeptic about the "tone in Washington."

But at this time of year - when everybody talks about peace on Earth, goodwill toward men and all that jazz - the lament over partisanship takes on a particularly melancholy tone. If only we could be more like the citizens of Bedford Falls in "It's a Wonderful Life," where everybody comes together out of a common love of their fellow man. (I think the image of citizens joyously leaping at the opportunity to upend their purses and empty their wallets is particularly attractive to some in Washington.)

One of the greatest sources of political grief is the confusion of personal passions and preferences for political principles. In our own lives we all believe in comity and cooperation. In business we are encouraged to work as a team. The ideal in family life is mutual sacrifice and support. Most religions teach that we should treat our fellow man as a brother. We have a tendency to believe that these sorts of values should inform our politics as well. How many dictators have justified their rule on the grounds that the nation needs a strong father figure?

In the United States, the migration of social values to politics leads to the perennial question: "Why can't we all just get along?"

Politicians from both sides of the aisle take advantage of this natural human desire. Bill Clinton promised to get us past the "brain-dead politics of left and right." His wife has spoken and written many times of how we all need to get past our "partisan differences." George W. Bush was elected in part on his promise to "change the tone" in Washington and be a "uniter not a divider."

Of course, there's nothing wrong with people being more polite to one another. But the belief that a healthy liberal democracy is one in which partisanship has disappeared is not merely ignorant, it's dangerous. Liberal democracy ceases to exist when partisanship vanishes. Democracy is about disagreement before it is about agreement.

Now, obviously, some forms of partisanship are less admirable than others, and I'm sure we can all think of examples on our own. But out of deference to the spirit of the season, let's keep them to ourselves. Rather, let's look at this dispassionately.

If you were on trial for murder, would you want your lawyer to put aside his differences with the prosecution and, in the spirit of bipartisanship, strike a compromise? Sure, lawyers on both sides should be polite and obey the rules as officers of the court. But we understand that there are some things more important than the spirit of compromise in a system designed to be adversarial.

American politics is adversarial by design too. Partisanship and ambition are the vehicles by which important arguments are made. Continued...