Some supporters of the proposed intervention in Syria call it a genuine case of humanitarian intervention (see here and here).  In reply, critics may:

A) Deny the validity of the doctrine itself (if you fall into this category, you can safely stop reading), or

B) Accept the doctrine but deny that it can justify the intervention in Syria.

I have long defended the doctrine of humanitarian intervention, and have argued that a number of past actions may have been justified under the doctrine (see here). I would like to explain, therefore, why my position on Syria falls under B) above: the military action proposed by the Obama administration (limited aerial bombings) would not be justified under the doctrine. In contrast, a full-fledged intervention that would overthrow Al-Assad while neutralizing Al-Qaeda could be justified under the doctrine if it complied with the principle of proportionality. Given the predictable dire consequences of a full invasion for the region and the world, such action is unlikely to be proportionate, and therefore the United States should stay out.

(One word of caution. The legal humanitarian intervention doctrine differs from its moral counterpart. Most international lawyers require United Nations Security Council authorization as a condition for the lawfulness of action (not Congressional authorization, which is irrelevant to international law.)  I disagree, but mine is concededly a minority view among international law scholars. I do not think the UNSC will authorize the intervention in Syria, but, be that as it may, I will focus here on the moral version of the doctrine, just because I do not believe the authorization vel non changes the moral position.)

Any act of war, and therefore any armed humanitarian action, must have a just cause. The only available just cause is rescuing large numbers of persons from deadly attacks (by their government or others). A war to make a point, or save the nation’s prestige, or advance the national interest, or even punish a war criminal, is never justified. Killing for symbolic reasons is impermissible.

Does the United States have a just cause for a military intervention in Syria? Since only rescuing victims of massive attacks counts as a just cause, there are only two possibilities in the present Syrian conflict:

1) Broad Just Cause: The intervention is justified because The United States would join the right side in a civil war; that is, it would help secure the victory of the revolutionaries who are rising against Al-Assad’s tyranny. Some (myself included) thought that the 2003 intervention in Iraq and the 2011 intervention in Libya could be justified in this way. But in Syria we have reliable information that the rebels are not pro-freedom revolutionaries but groups intent on establishing an even worse tyranny. In the Syrian conflict, none of the opposing sides has a just cause. Surely, then, this rationale does not work: an intervention in a civil war to secure the victory of would-be tyrants cannot be justified as humanitarian intervention, even if it helps overthrow the incumbent tyrant. A humanitarian intervention aims at ending tyranny.

This kind of action can only be justified if the United States joins the rebels, deposes Al-Assad, neutralizes in some way the influence of the extremists in the rebel movement, and helps democratic Syrians organize free elections and enact a liberal constitution. But, even leaving aside the fact that this method does not seemed to have worked well in Iraq (at least so far), this broad humanitarian action can only be implemented, as I indicated, with a full-fledged invasion, not with limited bombings.

2) Narrow Just Cause: The intervention is justified because it would destroy chemical weapons, deter their use, or otherwise rescue innocent victims. Using chemical weapons against combatants is a war crime; against civilians, a crime against humanity. So if the military intervention destroys those weapons, or if it deters the regime from using them again, or if it rescues vulnerable civilians, then perhaps (depending on the cost, that is, on the satisfaction of the proportionality principle) could be justified under the humanitarian intervention doctrine. This rationale is unrelated to the tyrannical nature of the Syrian regime; rather, the intervention has the limited purpose of preventing the use of prohibited weapons.

This is the rationale chosen by the U.S. Government. The draft  that President Obama will submit to the Congress reads:

(a) Authorization. — The President is authorized to use the Armed Forces of the United States as he determines to be necessary and appropriate in connection with the use of chemical weapons or other weapons of mass destruction in the conflict in Syria in order to

(1) prevent or deter the use or proliferation (including the transfer to terrorist groups or other state or non-state actors), within, to or from Syria, of any weapons of mass destruction, including chemical or biological weapons or components of or materials used in such weapons; or

(2) protect the United States and its allies and partners against the threat posed by such weapons.

The intervention is humanitarian in this narrow sense because preventing the gassing of civilians is a humanitarian objective: it saves those persons from terrible harm.

But what are the chances that the proposed bombings will do that?  Slim. For starters, the proposed action is caught in a dilemma. Either the bombings will weaken the regime or they will not. If they do, they will help Al Qaeda win. The (putative) humanitarian action will predictably open the door for something much worse for the Syrians and the world.  If instead the bombings do not weaken the regime, they would have served no purpose and would have been therefore impermissible under the humanitarian intervention doctrine, especially given the fact that the bombings would have killed innocent persons for no reason.

But maybe this is too quick. Let us examine this rationale more closely. Someone can retort as follows: “The action will do just enough damage, or show just enough military might, to deter Al-Assad from using the weapons again, but without weakening him to the point of allowing Al Qaeda’s victory. Regrettably, there will be some innocent casualties, but they will be justified under the proportionality principle.”  This reasoning is problematic. Suppose the bombings deter the regime from further using chemical weapons.  The bombings will still kill innocent persons. Can we kill some innocent persons in order to prevent the gas poisoning of other persons? And how should we factor the disagreeable fact that some of the persons hit by the chemical weapons were not innocent civilians, but rather villains intent on establishing a brutal tyranny? Needless to say, using chemical weapons is never justified, even against villains, but does their use automatically create a casus belli? For consider: using chemical weapons is a violation of the laws of war. Why don’t other violations of the laws of war justify military action? Surely both sides in the conflict have murdered POWs. Does that fact alone authorize a third party to bomb the violators?

I have no easy answers, but my point is that becoming a victim of a ius in bello violation does not automatically give the victim a just cause. If it did, third parties in World War II (say, Switzerland and Sweden) would have had a right to bomb Britain following Churchill’s devastation of Dresden. The Soviet Army committed terrible atrocities against German prisoners. Did that give outsiders a right to intervene in defense of Nazi Germany? Hardly: a warrior with an unjust cause does not acquire a just cause merely by enduring violations of ius in bello by his enemies.

In Syria, the Al Qaeda members who were gassed by Al-Assad’s criminal regime do not thereby become just warriors. Just warriors may commit war crimes and unjust warriors may respect the laws of war. In Syria both sides are unjust warriors. If we take the position that a violation of ius in bello like the use of chemical weapons warrants intervention on behalf of the victims regardless of the cause embraced by those victims, we end up with the curious result that intervention is permitted on behalf of tyranny (which is what an Al Qaeda rule will be).

The narrow humanitarian intervention rationale only works, then, for innocent victims of the use of prohibited weapons, even though it is true that any use of those weapons makes the user a war criminal. Hence the bombings proposed by the President are justified under the doctrine of humanitarian intervention only if:

1) They surgically (i.e., at no cost) destroy the prohibited weapons, or

2) They deter further use of chemical weapons against innocent persons and they are proportionate, that is, they (regrettably) bring about the deaths of a limited number of innocent bystanders in accordance with just-war guidelines as formulated by the doctrine of double effect and the Geneva Conventions (I am conceding here the permissibility of collateral deaths in the pursuit of a just cause; many people deny this, in which case the bombings have no justification even if they achieve their humanitarian purpose.)

What are the chances that the bombings will do that? Alternative (1) is logistically impossible, because the weapons cannot be surgically destroyed from afar: only a full-blown invasion can do that. Alternative (2) is highly improbable. Either Al-Assad will not be deterred, as suggested by his tenacity in holding to power; or the bombings will likely kill an impermissibly high number of innocent persons; or, conversely, they will be so effective that they will help Al Qaeda win the civil war.

All in all, the moral and epistemic uncertainties are daunting. A full invasion to end tyranny in Syria could be justified in principle but it is almost certain to have disastrous consequences. Likewise, a limited bombing could be justified in principle but it is unlikely to achieve its humanitarian aim. The United States should stay out.