I find myself more and more disturbed by the moral implications of President’s Obama’s approach to Syria. He speaks of “sending a message” and firing a “shot across the bow.” This is a dangerous way of thinking about war.

There are times when military force can and should be used. The use of chemical weapons by the Syrian regime may well be one of those times. But a just occasion does not automatically make a war just. One of the principles of just war teaching is probability of success. Another principle is proportionate use of force. Both principles require clarity about what goal we seek when going to war. Probability of success in achieving what? Proportional use of force to achieve what?

Here the Obama administration comes up short, for it has offered no cogent, realistic plan to achieve a just goal. Claims that military action is necessary to deter future uses of chemical weapons are empty. This goal—and indeed any just outcome in Syria at this juncture—requires decisively defeating the Assad regime. Yet the Obama administration seems unwilling to say it’s committed to achieving this goal. In fact, the administration seems unwilling to commit itself to any substantive, on-the-ground goal in Syria. Without a substantive goal, killing people there would be unjust, because purposeless. We would be killing them so that . . . . Try to complete that sentence. The best I can come up with is this: So that the world will know that the United States is serious about the fact that using chemical weapons is a bad thing.

Put simply: Just war-making requires clearly articulated and substantive goals. Launching cruise missiles or air strikes simply to “show resolve” or “send a message” cannot be justified. At the end of the day, these rationales authorize symbolic killing, which is fundamentally immoral.

There is something about American liberalism that makes it think irresponsibly about war. Perhaps that stems from its optimism about humanity. Unable to see sin for what it is, liberals don’t discipline themselves to think through the hard truths about fighting and deterring evil. Then, as events force them to resort to lethal force, they are so confident in their good intentions that they neglect careful moral analysis of their actions. Or perhaps it’s the utilitarian mentality that provides the functional morality of American liberalism, as if killing a few hundred people in Syria for symbolic purposes is by definition more just than substantive military action toward a clearly articulated goal that is sure to cause thousands of fatalities.