Before America invaded Iraq, George Packer wrote an article for The New York Times Magazine on the liberal hawks that sought to categorize the pro- and anti-war arguments. Given that you often hear war supporters say that the doves opposed this war for the wrong reasons, it's interesting to see what Packer considered the arguments of the two sides:
For War
1. Saddam is cruel and dangerous.
2. Saddam has used weapons of mass destruction and has never stopped trying to develop them.
3. Iraqis are suffering under tyranny and sanctions.
4. Democracy would benefit Iraqis.
5. A democratic Iraq could drain influence from repressive Saudi Arabia.
6. A democratic Iraq could unlock the Israeli-Palestinian stalemate.
7. A democratic Iraq could begin to liberalize the Arab world.
8. Al Qaeda will be at war with us regardless of what we do in Iraq.
Against War
1. Containment has worked for 10 years, and inspections could still work.
2. We shouldn't start wars without immediate provocation and international support.
3. We could inflict terrible casualties, and so could Saddam.
4. A regional war could break out, and anti-Americanism could build to a more dangerous level.
5. Democracy can't be imposed on a country like Iraq.
6. Bush's political aims are unknown, and his record is not reassuring.
7. America's will and capacity for nation building are too limited.
8. War in Iraq will distract from the war on terrorism and swell Al Qaeda's ranks.
So far as I can tell, 2, 4, 5, 6, 7, and 8 on the pro-war case proved to be entirely wrong. The remaining rationales were that Saddam is a tyrant -- true, but not nearly reason enough to go to war -- and that Iraqis were suffering under sanctions. Our sanctions.
Meanwhile, literally every element of the anti-war case has been proven correct, save for four, which has proven accurate in a low-grade way as Iran has sought to increase its control over its destabilized neighbor.
These were the two cases. They existed -- both of them -- before the conflict. They had, as Packer details, high profile adherents. The anti-war case was internally coherent, rigorous, and in the final analysis, utterly correct. Not accidentally correct, but accurate in its particulars and predictions. No wonder those who got it wrong are so anxious to argue that nobody truly got it right.