America's Reputation, Commitments, and Syrian Chemical Weapons
I used to think war was simply stupid and useless. In an absolute sense, this is true: If everyone everywhere simply refused to participate in war, all of us would be better off, and armies would be unnecessary. But this is about as helpful as noting that we'd all be better off if everyone decided not to commit crimes, thus making police unnecessary. No one would argue the police should be abolished in order to stop crime. Similarly, one country deciding not to participate in wars would not prevent them.
But it's worse than all that because the police analogy is a poor one. In the world as a whole, there is no police force. There isn't one authortiy, subject to checks like judicial review, that enforces laws established through democratic processes. A better analogy might be the American frontier or wild west: a place where each person was responsible for his own safety and vigilante justice was the norm. In such a place, everyone had to be armed to defend himself.
The international system is anarchic like this. If a country gets into trouble, it can't call the police. The only thing it can do is call an alliance partner and hope that partner will be willing and able to help. As the most powerful country in the world, America is an alliance partner to many, like Japan, Australia, Taiwan, and South Korea in Asia-Pacific, or Saudi Arabia and Israel in the Middle East.
It is these alliances that have helped keep the world fairly quiet over the past 60-odd years: Japan could have nuclear weapons and a powerful military, but it does not, because it trusts its alliance with America to keep it safe, even as its next door neighbor China grows more powerful and belligerent each year. The same goes for all the other countries allied to America. American military might dwarfs the rest of the world in part because America is committed to protecting so much of the world and in part because so much of the world trusts American protection and therefore spends less than it otherwise might.
This is not a selfless act: America has much to gain from a world at peace, and much to lose from war, especially with the commitments it has. This stability survives on trust, however, which in return relies on America's reputation. If Japan stopped trusting America's ability or willingness to protect it, as a recent push to change its constitution to allow it to have a "real" military suggests it is already beginning to do, it might build up its military and issue deterrent threats of its own. It might even seek an atomic weapon as a guarantee. All of this would dangerously increase tensions with China and might make other neighbors nervous, too. Trust would begin to breakdown.
Likewise, if Saudi Arabia did not trust American security guarantees, it would likely likely beef up its own military power out of fear of Iran, encouraging others in the Middle East to follow suit out of fear of Saudi power. Lack of trust in America's ability and/or willingness to protect its allies would lead to destabilizing chain reactions.
This brings me to Syria. President Obama swore that the use of chemical weapons would not be tolerated. Had he said nothing, perhaps America could argue it had "no dog in this fight," but he made a very public promise, so America's reputation is at stake and with it, all the stability-enhancing alliances I mentioned above.
Few would doubt America's commitment to protecting itself if directly threatened, but its commitment to its allies is less certain. Obama has promised to prevent Iran from getting a bomb using whatever means necessary. The hope is that this threat alone will be enough to force Iran to back down. But the efficacy of that threat relies on America's reputation. If America is unwilling to attack Syria when it has made a highly public commitment to doing so, its claim to be able and willing to stop Iran from getting the bomb looks ridiculous.
Furthermore, once America is no longer seen as an important ally, its influence will shrink, reducing its ability to impact other world events in a way favorable to it, including drives for democracy and free trade. The result would be a less stable world with a diminished America lashed to the helm, steering an increasingly uncontrolled course. This is why limited action on Syria is needed. Not to end the war, topple the regime, or alleviate the humanitarian crisis there, but, believe it or not, for even bigger reasons that impact the entire world, rather than just one tragically war-torn part of it.