I should start with the usual disclaimers. I don't know much about foreign policy and I know even less about Syria. These are, however, the same disclaimers most of the pundits on TV should be making and aren't. So some broad observations informed by an appropriate dose of humility and the broad contours of history might actually be rather useful.
There are several big-picture things about this potential war that are easy to assume, but in fact should not be assumed. The first thing to realize is that in all likelihood nearly everyone is blowing this out of proportion. Whether we attack or don't, these events are likely to be a footnote in the history of the twenty-first century. To argue, as some in the administration have, that not acting will somehow "embolden our enemies" (I hate that stupid phrase) as far away as North Korea is absurd. On the other hand, assuming that lobbing some cruise missiles into Syria is going to lead to a giant conflagration is equally unlikely.
There is little reason to suppose that Syria would be another Iraq. That's just lazy extrapolation from whatever happened recently. One can come up with some sort of convoluted series of events where we end up with 160,000 troops in Syria as we had in Iraq, but the odds of that are infinitesimal. It's just fear-mongering to assume that the next war will look like the last one. The more important point is that Iraq, the sum of all our fears in this war-weary generation, was not a very big war and probably won't be a significant historical event. Our war in the Philippines a hundred years before Iraq killed a lot more people. What's that, you say? You haven't heard much about that? Exactly.
A few other assumptions that should not be made:
That we, the average citizens, have anything like an adequate amount of information to have an informed view.
That the President has adequate or completely truthful information.
That our government is being honest with us.
That Assad used chemical weapons.
That a failure to attack won't lead to more and deadlier use of chemical weapons.
That an attack won't lead to more and deadlier use of chemical weapons.
When you challenge these assumptions from both sides, it becomes very difficult to have a strong opinion one way or another on this. I am very equivocal because I don't bring strong a priori principles to the debate. I am terrified by perennial hawks like McCain and Graham, but on the other hand I can see the value in enforcing norms against chemical weapons, even if we helped Saddam use them back in the 1980s. My Christian faith does not at this point lead me to be a strict pacifist in international relations, though I'm inclined to think I should have better reasoned justifications for not being strictly pacifistic.
In the end, I suppose I come down against military force in this case because I think our entire foreign policy is so militarized that we face a constant parade of false either-or choices. Attack or not attack. Well, there are lots of other things that could be done in the long-term, but our actual engagement with other countries is dramatically misaligned with our stated values. With many foreign governments, the Pentagon has more pull than the State Department. That is an ongoing, quiet disaster that leaves us with a narrow range of options when crises flare up. We ought to reduce our military budget (and military foreign aid) while dramatically ramping up diplomatic and economic aid spending.
In any given crisis, there are nearly always good reasons to use military force. But in the bigger picture, we must face the fact that we have become an extremely militaristic nation whose behavior is exactly the opposite of its self-image as a peace loving people. War should truly be a last resort, but that's just a random cliché we use. It's not how we conduct foreign policy.