I am still not clear why we entered the war in Iraq.
Many opponents of the war say it was for oil, but destroying oil fields doesn't result in there being more oil anytime soon. Given that the price of oil has gone up (as have oil company profits), maybe it was a "war against oil", but surely had that been the oil companies Machiavellian aim, that could have been achieved much easier (just bomb the oil fields).
Proponents of the war argue it was because Iraq was thought to have possessed Weapons of Mass Destruction. However, if your enemy has dangerous weapons, isn't better not to encourage him to use them; that was our strategy during the Cold War. Had Hussein truly had WMDs in 2003 his logical move once actually attacked would have been to use them (he was in theory put into a use it or lose it situation) once his reign was threatened (as it is asserted was done during the Iran-Iraq war). If you believed there were really WMDs, why would you want to bring that on to our troops? That they were not almost immediately attacked after the US invaded should have been a good clue that WMDs were essentially non-existant.
It cannot be argued that the war was aimed at increasing stability in the Middle East, war does many things, stability is not one of that. While democracy is in general virtuous compared to dictatorship, it is not inherently more stable.
Arguing the war was for democracy seems weak. The war was not really aimed at making Iraq democratic – democractic institutions were clearly an afterthought in the war planning. While we cannot say that Democracy must arise internally to be stable (e.g. post-war Japan or Germany), there are many unstable democracies.
It is argued that we needed to strike first as a strategy of pre-emption, because they might use weapons they have or are planning to get. While it is better to attack before the enemy actually gets weapons than after, that kind of precedent seems foolish, and certainly something any other country in the world could use to justify attacking the United States. This argument was not used against Pakistan or India as they prepared to join the nuclear club, nor against North Korea or Iran now.
Others say that Saddam Hussein was an evil person and needed to be removed from power. Like most megalo-maniacal world leaders, he did not act on behalf of anyone beyond himself, his family, and cronies. That does not justify prioritizing an attack on him over any number of other dictators either on or off the axis of evil.
This leaves us with truly cynical reasons. Perhaps the war was to avenge Bush's father: George H.W. Bush, either for the first Gulf War's failure to remove Hussein (i.e. the finishing the job argument), or the for assassination attempt on April 13, 1993.
Or worse, the war was to bolster George W. Bush's re-election bid in 2004, with the notion the war would be a quick, simple victory. This seems a strange line of reasoning, wars in recent years have not done much to aid in re-election (witness Lyndon Johnson or George H.W. Bush).
At best there was miscalculation and faulty reasoning on the part of the administration as to what were in its own interests. My best guess is the administration was not thinking clearly when advocating, and then undertaking war.