The end justifies the means. That is how L. Paul Bremer, the smooth-talking but ultimately incompetent de facto U.S. civilian ruler of Iraq in 2003 and 2004, now justifies the U.S. invasion. Ever since the original legitimizing cause — the presumed presence of weapons of mass destruction — was disproven, official Washington has had a problem.

The United States, which had long restricted its friend/foe thinking to foreign affairs, is now transferring that mindset to the domestic political arena.

According to Mr. Bremer, the underlying rationale was that Islamic terrorism is rooted in the severe limitations to real political choice. In short, he believes the introduction of democracy and the development of a modern political system is the best antidote to terrorism.

That way, the former American proconsul of Iraq explains, cultures that have relied strictly on a black/white, good/bad model of politics would become accustomed to dealing with political nuance and shades of gray. This, he argues correctly, makes everybody involved understand the vital nature of compromise in the domestic political arena.

The latter undoubtedly is the key prerequisite to solving a nation's problems and avoiding a further radicalization of the political process. So far, so good.

However, what is truly amazing about Mr. Bremer's 2011 effort to explain — with the benefit of hindsight — the 2003 invasion of Iraq is that the horrifying, but very logical, consequence of this effort totally escapes him.

Never mind that, even charitably speaking, the effort to bring democracy to Iraq has so far yielded only mixed results. The key point he overlooks is that the United States is poorly suited to teach any nation to avoid thinking in black/white, good/bad, friend/foe terms.

Mr. Bremer makes his case without blushing. He doesn't even seem aware that U.S. democracy is now gripped by such an extreme degree of political animosity that everything is portrayed either as strictly black or strictly white. Amidst all this, the ability to see nuance, a prerequisite to reaching compromise, is vanishing rapidly. Perhaps even worse, a willingness to build bridges is not considered an asset, but a political liability.

Much as Montezuma exacted his revenge on the Spanish occupiers of Mexico in the 16th century, so too is Saddam striking back against the United States.

This reality was on full display to the entire world during last August’s debt ceiling drama. A U.S. political process that is vituperative and that turns all politics into a zero-sum game is definitely not what the world was expecting.

Much as Montezuma exacted his revenge on the Spanish occupiers of Mexico in the 16th century, so too is Saddam striking back against the United States. His posthumous revenge seems to take the form of transferring the dysfunctionality of the Iraqi political process onto the United States.

In Iraq, a country that historically has been quite adept at seeing in shades of gray, the stakes since 2003 have been “either/or” for the country’s Sunnis, Shiites and Kurds. Similarly, over the last two decades, the United States’ two political parties have become entrenched in a zero-sum mindset.

The only real-life effect of these zero-sum games is to hollow out both nations while enriching the political classes and their acolytes. It is as if, by force of its ill-advised and unnecessary invasion, the United States exposed itself to that same virus.

Strange and unlikely convergences emerge during war. Much as the United States’ warriors became like the medieval holy warriors they fought, so too have the U.S. and Iraqi political systems converged in terms of their polarization.

This is far more than a matter of historic curiosity. Sometimes, great civilizations stumble over very simple things. In the past, it often was the disappearance of sufficient water supplies that put an end to a culture that had dominated its region, or even considerable parts of the world.

The only real-life effect of these zero-sum games is to hollow out both nations while enriching the political classes and their acolytes.

In the contemporary case of the United States, it is something equally profound — its increasingly, and quite possibly irreparably, dysfunctional political process.

Nowhere does its obsession with strictly binary choices become more readily, and more painfully, apparent than in the U.S. debate about the budget. The real surprise in what by international comparison is an eminently fixable problem, is how many key participants insist on framing a false choice.

They either insist, ardently and with no abandon, on cutting spending. Or, to a lesser extent, they argue that salvation can be found only by raising revenues. Grover Norquist, the Republican operative enforcing anti-tax pledges from candidates for political office over the past quarter century, is perhaps the most grotesque enforcer of that binary choice rule.

What makes the present times in American democracy so treacherous is to see how a nation that had long restricted its friend/foe thinking to foreign affairs is now transferring that mindset to the domestic political arena. As it stands, Saddam is having the last laugh.