The problem with this argument is that by attacking Syria, the US would actually be breaking international law, which forbids the sort of strike that Obama is contemplating. In essence, Obama wants to break international law in order to uphold it, a senseless proposition. Assuming the US does have a special obligation to the world, the best way to fulfill it would be to play by the rules. That means respecting both the Constitution and international law. A unilateral strike on Syria would violate both.
(For those who think the president has the power under the Constitution to launch an attack, I addressed that issue here and here. Both Thomas Jefferson and Candidate Obama said that the president did not have that power.)
Of course, it may be that Obama thinks our obligation to punish Assad is greater than our obligation to obey the law. But if we adopt that line of reasoning, then Russia, who is currently moving warships into the area, may very well adopt a similar line of reasoning toward us. We would, after all, be breaking the same sort of international agreement that Assad is supposedly breaking, and we would, therefore, be worthy of receiving the same sort of unilateral punishment at the hands of Russia.Would people complain if Russia attacked us? Of course. But anyone who thinks that Obama is justified in punishing Syria would have to agree that Russia would be equally justified in punishing us. As Obama said today, no one will take international laws seriously if no one enforces them. Just imagine those words coming from a Moscow official next week when Russia is sinking our warships. I wonder if Obama would see the irony.
Of course, all this can be avoided if Obama sits tight and convenes Congress for a vote. It would fail, but it would send an important message to the rest of the world, that world-leaders are bound by their own laws. That sounds much better to me than the reckless course of action currently being considered.