Well, I've given this piece the necessary cooling-off period. And now the recent attacks in London bring the salient issue right back to the surface...
What justifies the use of violence? There's a loaded question! Nothing? Self-Defense? Self-Interest? Those three options define the spectrum of possible justifications for violence. Unfortunately there is a small continent of gray area between and among the three.
There is room here for a lengthy philosophical debate, but I will leave that to someone more qualified than me. Think of these options as evolutionary strategies, perpetually repeating phenotypes of the fundamental "genetics" of our universe. Suggesting that "nothing" justifies violence is a fatal expression of our nature--it's like a baby born without an immune system. It will only survive (as a party capable of free expression) as long as it does not contact a party that has selected the "self-interest" justification of violence. Despite its ongoing spiritual attractiveness, and its potential educational value, non-violence as an implementable strategy is an (ongoing) evolutionary failure. 99.99% of humanity could be staunchly non-violent, but the reality is that violence will always emerge in part of the population. The larger the proportion of non-violent actors, the easier it will be for a few "self-interested" violent actors to create a truly nightmarish world.
This leaves us with the very fuzzy gray-area between "self-defense" and "self-interest". Self-defense is, after all, a self-interested action. Perhaps it is best to characterize these two options in terms of Hierarchy vs. Rhizome. A system accepting the justification of violence based on selfish interest will create a system of competing hierarchies, intensifying, competing over scarce resources and destroying and absorbing weaker systems. Assuming selfish interest extends temporally (e.g. "my interests are more important than those of my grandchildren"), then such a system is also fundamentally non-sustainable in any system governed by finite resources.
In the end, it is actually the logic of hierarchy, not its component logic of "self-interest" that defines such systems. This is important, because this distinction will help to eliminate the gray area between "self-defense" and "self-interest". Unfortunately, it is impossible to adequately separate "self-defense" from "self-interest" as long as we insist on using those terms. Let's throw out our remaining competitors entirely--"self-interest" and "self-defense"--and instead view the justification of violence through the lens of Hierarchy and Rhizome. If hierarchy produces a non-sustainable use of violence, then we are left with rhizome as a justification for violence. Violence within the context of rhizome does not seek to eliminate the competition, does not seek to dominate, does not seek to expand. Rhizome violence represents a negative feedback loop, it seeks to maintain itself, it seeks sustainability. It acts in "self-defense", but critically it does not act in self-defense of its selfish, hierarchal control over others, but only in defense of its own sustainability.
How does this guide us in the appropriate use of violence? Well, if by "us" you mean any given nation-state, then it doesn't. Nation-states are all fundamentally hierarchal, and therefore are fixed in their use of violence to defend their self-interest in an environment of peer-polity competition. Was a pre-emptive strike against Iraq "self-defense". The answer will help us better understand the gray area problem and the need to define the justification of violence in terms of Hierarchy vs. Rhizome: sure, the 2003+ Iraq war was "self-defense". It was the defense of the selfish interests of the American hierarchy, without which it would cease to exist. For Hierarchy, selfish interest IS fundamentally self-defense!
Without passing divine judgment on absolute "right" and "wrong", Hierarchy (and its necessary component of violence) is not sustainable, while Rhizome (and its necessary component of violence) is sustainable. So, at least through the lens of Kant's categorical imperative, Hierarchy is "wrong" and Rhizome is "right".
So back to Ward Churchill for a moment: IF one accepts that it is right (or wrong) to act in defense of one's hierarchal interests (as America is doing in Iraq), is it any less right (or wrong) to attack America in defense of one's hierarchal interests (as al-Qa'ida is doing)? Were Iraqi conscripts any less (or more) the "little Eichmans" of hierarchy than were the 'knowledge-workers' (critical to America's economic hierarchy) that died in the 9/11 attacks?
**On a side note, it's important to mention that al-Qa'ida violence, at times, comes quite close to the Rhizome model of violence. While "we" may not like it because white people, often Americans are dying, the violence of the afghan tribes to defend remote hamlets from the influence of an outside hierarchy is quite rhizomatic in nature. Al-Qa'ida may aspire to form an Islamic, hierarchal empire, but they also hope to achieve victory by acting as a doctrine center for decentralized operations against their hierarchal enemy. It is my opinion that this strategy is being handicapped by the ideal of hierarchal Islam. If they were to instead act as a doctrine center, a teacher of the open source warfare model to be used by people everywhere to check hierarchy, they would meet with much greater success. The primary motivation of their recruits, and of unrest in the Arab and third world in general, stems, in my opinion, from an anti-hierarchal sentiment, not from a true belief in one monotheistic, hierarchal ideology or another. If this kind of open-source warfare catches on, watch out!