I have often gotten into arguments with people over the justifications of violence...usually my stance is that violence is never justified, but lately have been trying to determine if that is actually true, and if not, determine when violence is actually justifiable. I am currently reading abridged version of Rising Up and Rising Down: Some Thoughts on Violence, Freedom, and Urgent Means by William T. Vollman, and it has given me pause. I thought I would bring some of the ideas to discussion here (there will be quite a few direct quotes from the text, which I will underline in order to distinguish them from my own words), in the hopes that some of you will offer your own points of view, that I might learn something, or at the very least, that there will be an amusing discussion.
An introduction to some of the problems inherent in the justification of violence, and ethics in general.
First off, ethics is not a circumstantially exact science, and if it ever became one, free will and cultural varibility might be compsomised. Our ethical decisions are always coloured by personal and cultural bias and context. Because this is the case, any system of morality will give rise to different judgments in the same circumstances, when applied by different people.
Benjamin Frankline used to divide a sheet of paper into two columns, one in favor of a decision, the other against. "And tho' the Weight of Reasons cannot be taken with the Precision of Algebraic Quantities,...I have found great Advantage from this kind of Equation, in what may be called Moral or Prudential Algebra." Much of this procedure indeed makes common sense, but its sums, variables and formulas necessarily or unnecessarily rests upon vaguely defined terms. Plato's moral calculus differs from Cortes's, not least because their definitions of piety are different. Moses's Ten Commandments leave Lenin cold, in part on disagreements over the defined range and domain of that variable called Man: Does it include or dominate Woman? May it be substituted for God? Do its characteristics alter with its productive class?
In many situations requiring moral judgment, there is no "correct" answer. One person's right answer might be wrong if given by another.
Which does one put first, defense of gender, which might repudiate female circumcision, or defense of culture, which might demand it? When does defense of race (one's own family) supersede defense of homeland? ...if you consider only one of those two categories of defense, your judgment will remain superficial, unfair, and therefore unrealistic. Can defense of gender meet defense of culture somewhere? I hope and believe so, provided that both sides respect each other by applying some approximation of the Golden Rule.
Most often when people are faced with finding moral answers to dillemas that affect more than one person, and more than one kind of moral consideration, there is some range of consensus that can lead to a solution or compromise that should satisfy all parties, and all moral considerations to some extent.
Yes, the divergence may at times widen far enough to allow for more than one specific "right" choice--for example, in the case of Caesar versus Pompey--for people and situations less frequently dazzle us with the pinpoint light of self-evident truth than with the diffuse glare of ambiguity. Still and all, the question of when violence is justified need not be left entirely unanswered.
There are some categories of justification of violence that does not, by definition, allow a consensus view, for example ethos of homeland, identity of race, place and animals, ecological threat, inalienable qualities of creed.
More traditional categories such as class inevitably provoke irreconcilable differences of opinion, but it remains possible to argue out those differences based on common presuppositions about fundamental human rights.
Fundamental human rights suppositions seem to be absent for such categories of ethos of homeland, etc. And there are questions that have not yet been answered well enough to create a consensus view.
What right do we grant an ancient redwood grove to remain as it is? Which alien ethos of creed, homeland or race can we tolerate; and when do customs which some people consider abhorrent, such as hunting, justify violent intervention? Does a white separatist have the same rights as a black separatist?
The best way to determine whether or not an act of violence is justified is to determine every possible justification, or reason why it might not be justified. For example, consider the case of a Palestinian suicide bomber. What justifications does he (or his enemies) have for their acts of violence? In order to determine that, we need to look justifications concerning homeland, creed, war aims, ground, honour and authority, as well as policies of deterrence, retaliation and punishment, as well as "the fate-invocation of inevitablity." Perhaps if we make a list of the pros and cons, we can begin to use Franklin's moral algebra.
When one commits violence, it is more likely that it will be unjustified than justified. Therefore, I would advise that if an act seems...to be classified as evil, it should be treted as suspect at best. On the other hand, if the act seems to obey all the rules for justification...it should be treated as--somewhat less suspect. At its most noble, an act which passes all the [moral] tests...can only be said to tend to be justified. Since [the] rules necessarily remain vague, and their interpretation open to opnion, no one test is sure...
We should do our best to follow a moral calculus, and follow it consistently, when making moral decisions, but we also need to retain some flexibility.
Calculus-lessness reliably produces amoral brutality; but, as Clausewitz reminds us, methodicism easily becomes stupidity. We must seek out the truth of each particular case.
That's all I'm going to write for now...just an introduction to the kinds of things I've been thinking about, and some of what Vollman has to say about it. I will be back later, though, with more.

Feel free to comment and discuss!