The argument for staying in Iraq is that "if we withdraw, the country will descend into chaos." This is probably true. However, if we stay, something far worse will happen.
When we invaded Iraq, Iraqi resistance was small and unorganized. There were few, if any, links with Al Qaida. Now, because of our presence, Iraq is the center of terrorist, anti-American activity. Fighters and dollars are pouring over the borders from a host of Muslim countries. Our presence is the best recruiting tool Muslim terrorists ever had.
Our presence in Iraq is GOOD for terrorists. The longer we stay, the more formidable their army becomes. As soon as we leave, they'll stop fighting us and start fighting each other.
We have to leave at some point--whether it's next week, next year, or next decade. Do we leave right now while the terrorists are still organizing, or do we wait until they're a hardened, organized, multi-national, anti-American Muslim army?