Daniel Trombly revisits an old argument in response to calls for an attack on Syria:

NATO intervention failed to deter non-Libyan tyrants and an intervention in Syria will not deter non-Syrian tyrants. There is no reason to think, knowing that our intervention in Libya was followed by increases in the degree of Syria’s repressive brutality, that other countries would follow suit. Precedent is only a deterrent if the power and will of a country to enforce that precedent at all places and times remains constant [bold mine-DL]. Given that everybody knows the resources and willpower of countries supporting R2P are finite, countries will generally (and correctly) bet that repressing a local effort at regime change is a more reasonable policy than succumbing to a revolution for fear of being deposed.

This is well stated, and obviously I agree with this argument since I have made some version of it more than once. As I said back in March 2011:

Jumping into a Libyan war for the sake of deterring other authoritarian governments won’t work, because the U.S. isn’t going to commit itself to a global policy of taking military action in support of rebel movements everywhere.

There are a few things to add to this. Advocates for intervention in Libya dismissed objections about inconsistency when critics made them on the grounds of “where we can, we must.” Now the argument for a Syrian intervention is “we should because we must.” Libyan war supporters acknowledged that the conditions that made the Libyan intervention possible were unlikely to be repeated very often, which was an attempt to persuade skeptics that Libya was not going to be the start of a series of wars. As it happened, they were right that the international conditions last spring were exceptional. However, Libyan war supporters don’t like to acknowledge that the Libyan war burned up a lot of international goodwill in the process.

Whatever international consensus or acquiescence to a humanitarian intervention existed last year is long gone because of the Libyan intervention. That doesn’t mean that there would have been a consensus for intervening in Syria had the Libyan war not happened (Russia would have been opposed regardless), but it does mean that the Libyan war has had the effect of making skeptical governments even more hostile to any meaningful international condemnation of Syria than they would have been otherwise. Interventionists often used the deterring-dictators argument in the same breath that they were saying that it was not possible (or even desirable) to intervene everywhere, and it never seemed to occur to them that these positions contradicted one another.

One of the flaws in the deterring-dictators argument is that it sets an impossibly high goal for the kind of behavior interventionists hope to prevent, and consequently dramatically lowers the bar for the kind of behavior that should trigger international intervention. The result is that interventionists feel compelled to call for military action in response to virtually any use of force by a regime against its population, which creates more obligations to intervene than any government can possibly fulfill. Many regimes are both capable and willing to use force against their populations to the same degree that Gaddafi did and Assad still does, and no government, Western or otherwise, is prepared for or interested in policing all of those states.

If R2P has any validity, the overeager application of the principle undermines it. The readiness to invoke R2P in response to low-level conflicts discredits it in the eyes of many governments around the world whose support it will need if it is ever going to become a widely-respected norm. As things stand now, Trombly is right that R2P as promoted by Hamid, Slaughter, et al. requires that “each commitment can only be secured through taking up more and greater commitments.” Meanwhile, a Western-led attack on Syria would represent a major threat to international peace and security, whose preservation is the first and most important role of the U.N. and the Security Council.