The question of motivation is a tricky thing. Our own motivations are often not transparent to us. Another person’s motivations are often even harder to figure out, although just as often we have a clearer view of others than they do of themselves.

And then there’s the Bush administration — or to accept Billmon’s theory-laden phrase, the Cheney administration. Already, hundreds of thousands of words have been written on the question of how this president and/or the people around him make decisions. The difficulty of ascribing a motivation to any collective is compounded in this case by a serious lack of transparency, not to mention the unresolved question of Bush’s intellectual and emotional competence to be the “decider.”

A few recent publications have addressed the question of the motivation for taking the country into war in Iraq. Ron Suskind’s book The One Percent Doctrine looks like it’s full of the explosive, behind-the-scenes revelations that Suskind is known for. I was especially horrified by this comment he made in an online chat about how Bush makes decisions:

George Bush is a man who has never embraced the analytical traditions prized in America’s professional class. He has instead improvised models throughout his life, especially of late to embrace action driven by instinct. He trusts his instincts for better or for worse. But no doubt, his instincts have taken him pretty far in this world. His White House reflects him.

In a way, the vice president has been active in constructing a White House, an architecture around George Bush, where the president can be driven by these lights of impulse and improvisation and still be president, a president who still, after more than five years, is a unique blend of opacity and action.

Last week’s Frontline episode, “The Dark Side” (which you can watch online at the website) brought together loads of information that had already been reported about the extraordinary foreign-policy role of Dick Cheney. And an article in yesterday’s Washington Post revealed that CIA director George Tenet ignored warnings that the claim about mobile Iraqi germ-warfare labs was completely fabricated — demonstrating, as Yglesias puts it, “a near-perfect indifference to the truth.”

Let me try to lay out the three going explanations of what motivated the Bush administration to go to war in Iraq:

1. The administration genuinely believed there were weapons of mass destruction, invaded Iraq to eliminate them, and only then discovered that they weren’t there.

2. The administration didn’t know for sure whether there were WMDs, but it thought there might be and couldn’t allow that possibility. So it did invade for 9/11-related reasons, basically the “one-percent doctrine” that Suskind talks about — even a one percent chance that a terrorist attack might happen must be treated as a certainty.

3. The administration didn’t know for sure whether there were WMDs, and it didn’t really care. 9/11 provided a pretext for the invasion, which was envisioned well before 9/11 and motivated by a geopolitical strategy for controlling Middle East oil reserves.

Only the first of these implied that the administration acted out of good faith; it’s the line taken by the administration and its supporters (when they’re not playing up the obviously spurious “we invaded to spread democracy” line). This explanation is the one that involves talk of “intelligence failures” leading up to the invasion and occasions earnest brow-knitting and commission-empanelling on the topic of “How could we have been so mistaken?”

The other two imply misuse of intelligence rather than intelligence failure. They both imply a bad-faith “misleading into war” in John Kerry’s awkward and perhaps overly politic phrase.

The second option at least allows the administration to look like it cares about defending us from terrorism, and it’s the line that seems to be implicitly taken by several of the “tough-minded” former CIA officers who appeared on Frontline to diss Cheney, Rumsefeld, and Tenet.

But to my mind, the evidence for the third option is overwhelming. It includes: the obvious indifference to (even contempt for) WMD intelligence displayed by Cheney, the note that Rumsfeld jotted down on September 11, 2001 about going after Iraq, not just Osama bin Laden, and the plans hatched in the late ’90s by the Project for the New American Century. I’m most convinced by the meticulous case laid out by Kevin Phillips in American Theocracy that Iraq is part of a grand game being played for the remaining oil reserves in the peak-oil era — and, incidentally, to forestall moves to price oil in euros rather than dollars and thus collapse the U.S. currency that’s already looking weak due to our massive budget and current-accounts deficits.

Why does any of this matter? Isn’t it ancient history — we’re already in Iraq, so why bicker about why we went?

It’s because the reason we went to war determines how we can end the war — what victory would look like. If either of the first two reasons is the actual one, then victory looks like the elimination of WMDs (and that was easy, since there never were any), the elimination of Saddam Hussein’s regime and its desire to have WMDs (already done), and the establishment of a reasonably stable, non-WMD-seeking regime in Baghdad (difficult, but at least it’s a concrete goal).

However, if the third reason describes the Bush team’s real motivation, there is no end in sight. To make the petro-strategic power play in Iraq really work, you have to establish a permanent presence there — military bases that allow you to project power throughout the region and preserve the access of American oil companies to Iraqi oil reserves.

In this scenario, a continued low or moderate level of guerilla warfare in Iraq is actually not a bad thing, since it gives the United States an excuse to keep its forces in the country without making its strategic aims blatantly obvious. Which brings us to a final piece of evidence in favor of the third interpretation of the Bush administration’s motives in Iraq: They have carefully avoided saying that the U.S. is not and will not build permanent bases there. It looks like we’re in this for the long haul.