Some on the left are against the strikes because they never want to use force. Some on the right are opposed simply because they don’t trust Obama. Some think the evidence needs to be better (and some even suspect the Syrian opposition might have used the chemical weapons to gin up support for their fight against President Bashar al-Assad). Some doubt the U.S. has a strategic goal since Obama has said altering the momentum of the war is not an objective. Some worry about the possible consequences in the Mideast of a strike.
Still, Obama plods on. There was even speculation that the strikes might have to be wider than originally intended because the delay to “consult Congress” allowed Syria to hide the possible missile targets in new locations. We might not even know where some of them are.
If we end up not striking Syria, the U.S. will lose whatever credibility it has left in the world. And no other world leader will ever know for sure again in Obama really speaks for this country. That’s the best reason some people can come up for going ahead with the strikes. It has come to this.