The Non Aggression Principle does not require proportionality. Because disproportionate defensive or retaliatory force is not initiatory force, the NAP has nothing to say about it. The NAP is the lowest acceptable standard for human behavior, so the fact that something does not violate it doesn’t necessarily speak well of that thing. It is more horrendously frightening that any level of credence is given per se to things that do not violate the NAP, than it is meritorious that an action does not violate the NAP. Absolutely no response to initiatory force violates the NAP. Some responses to initiatory force can violate the “Don’t Be An Asshole Principle”, or even the “Don’t Be A Heinous Human Being Principle”, but the fact that they are disproportionate does not alone accomplish this.
Proportionality is an entirely irrational requirement. The second you add a moral requirement of proportionality you put an obligation on all victims to first of all accurately measure, and then accurately refrain from using any force that is not proportionate to the force that their aggressor used. So if you are currently being attacked, instead of responding in the way most likely to remove the threat to your safety, you have to stand there and think about the exact level of force that is being enacted upon you. Then you have to think of a way to enact that amount of force. Then you have to be a skillful enough fighter to enact the same level of force that it being enacted on you. And if you screw any of that up, you’ve either violated the NAP or at least are a bad person, depending on which standard you’re imposing. And if you think that disproportionate responses are NAP violations, then if you screw this up, or if you just decide to punch your attacker harder than he punched you because you’re mad, or because you’re, you know, trying to walk away from this, then the person who attacked you can now defend himself against you in the amount of any force you used that exceeded the amount of force he attacked you with. Any margin of error or measurement errors that occur are the fault of the aggressor because he is the one who caused the situation in the first place; there would be nothing to be measured if he had not violated the NAP. And any costs of such errors should lie with the person who caused them- the aggressor. I would even go so far as to say that the moral culpability of any “excessive” defensive force perpetrated due to nothing more than an emotional reaction to being attacked is more properly assigned to the attacker than the victim.
Proportionality does not straight out say that it is ok to commit small infractions or to attack people who are weaker than you, but it enables the idea. If someone walks into my office every day, steals one piece of paper, then runs away there’s not a damn thing I can do about it under proportionality. After about a year I can go to his house and take back a pack of paper. But only if I can get into his house without damaging it because he didn’t damage my door. (And that’s only if you believe in retaliatory force, because if you don’t I can only take back the piece of paper while he steals it.) Technically that does not mean that smaller NAP violations are ok, but it makes them unenforceable- I can’t end it on day 15 in a free society (or even threaten to end it, because an assault is more force than stealing one sheet of paper) and I can’t call the State in the current society. You can also physically attack people who are weaker than you with impunity, under proportionality. It would still be a NAP violation, but if your victim tried to stop you they would be either violating the NAP or at least a bad person. Because if your victim can only use the level of force you use, then if you punch them at 1000 psi, then that is all they can do to you. Of course, most people can’t do that according to Google, but that’s your victim’s problem because shooting you would be more force than you used. So would calling the largest most heavily armed gang in the history of the world aka the State.
If you hold that causing the same amount of damage, and not using the same amount of force, is proportional, then not only is attacking weaker people unenforceable, but all property violations are unenforceable. If a person who is significantly stronger than you (or several people depending on how strong/arrogant you are) decides that they would just like to kick your ass a little bit but not kill or wound you, then you can not morally do anything about it under proportionality. If you try to defend yourself by only injuring them to the extent they intend to injure you, you will not succeed in doing even that and you are most likely just going to piss them off. You also can not defend against any property violations. If someone trespasses on your land, destroys your door, and begins placing light valuable items you own into a bag he is carrying, not only can you not shoot or stab him, you can’t even hit his arm in some poor attempt to make him stop because damaging property that is infinitely scarce and has no substitute goods- a person’s own body- is not proportionate to damaging other property. Theft is still a NAP violation but you are effectively barred from using any level of defensive force against it. Then, after you are finished being robbed, you get to go sit as a defendant in front of an arbitrator, California-style http://www.cbsnews.com/news/burglar-sues-calif-homeowner-90-who-returned-fire/ because proportionality. (I was unable to find whether or not the POS won the lawsuit, but that has no bearing on the integrity level of the legal system, or more pertinently the morality of proportionality, because if this system had any integrity this lawsuit would have been immediately thrown out on a motion to dismiss for failure to state a claim on which relief can be granted, and the attorney would have faced sanctions for filing frivolous lawsuits.)
Proportionality is unconscionably vague. It says that things are NAP violations, but then refuses to define those things, and from all I can tell bases its standards entirely on feels. How many slaps are equal to a kick? How many car dents are equal to a push? Demanding exact adherence to these exchange rates is wholly unreasonable. I’m fairly certain that most people were making assumptions about what type of property the thief in the above paragraph was taking, the importance of it, and the relative value of the property compared to the thief’s safety. I think that, if enforced -and you can enforce NAP violations- that it is contrary to market based prices and somewhat reeks of central planning. At best it is an arbitrary value judgment about someone else’s property based on unknown information. While I would not physically overpower a person, restrain them, and lock them in a cage for six months for stealing a few ink pens http://www.nola.com/crime/index.ssf/2012/11/mississippi_man_arrested_for_s.html http://legis.la.gov/Legis/Law.aspx?d=78605 that is because I am assigning a value to a few ink pens. The fact that I think St Tammany Parish Officers acted egregiously (even ignoring the fact that these particular pens were ownerless and therefore could not be stolen) is because I know enough about St Tammany to know that losing these pens did not hurt them, and I am assuming that this was an isolated incident with absolutely no threat of prolonged escalation. But since when do we get to enforce our valuations of other people’s property?
The victim is in the best position to, and has to best moral claim to, assign a value to his own property. An outside observer can never really be sure of what level of damage is being defended against, even if a market value is known. All victims are not defending against the same threat when they defend against, for example, their computer being stolen. In all cases, a person has a right to use force to defend their ownership of their computer. But the value of continued immediate possession of a Mac Book Pro with several thousand dollars worth of Adobe software on it is not the same for all owners, and that is the implication when people compare the value of property to the level of force used to defend it. One theft victim might make 500k a year and use the computer to make memes. If you died stealing it you shouldn’t have been stealing, but the victim’s injury exposure wasn’t as high as other victims might be. Is it excessive for him to kill his aggressor? I don’t care. But I also don’t know what he thought was going to happen if he allowed it to continue and what his perceived level of danger was, so I can’t possibly make that determination. Another victim might have just turned “18,” started doing graphic design for a living, not have funds for new equipment, and lives in an area where getting a new job can take a significant amount of time. That is an attempted murder, whether the aggressor knows it or not, and deadly force is entirely appropriate. There is no possible justification for treating attempting to kill somebody with a gun or a knife differently that trying to kill somebody by depriving them of their resources. The level of force an aggressor utilizes to get to the same result is morally irrelevant. The victim of an aggression is morally able to care more about the effect the NAP violation had on them than the amount of force, methods, and potential benefits of the aggressor. In order to even begin to determine whether a victim “excessively” defended himself I would have to know what he thought the threat was, how harmed he would be by the aggression, and how likely he thought it was to escalate through multiple occurrences- and none of that is any of my fucking business.
Proportionality turns aggression into a good bet and removes deterrents. If you can only be met with the level of force that you are initiating then the aggressor controls what type of conflict will occur- if it is to his advantage for the conflict not to escalate, then the conflict can not escalate. If arbitrators can only award damages equal to stolen property and possibly time-value of money, then theft is a good bet because if you get away with it then you got extra property and if you get caught then you are back where you started. Arbitrators ought to be allowed to award punitive damages in order to deter aggression. An aggressor will also know ahead of time what the potential costs to a NAP violation will be, and will therefore will more effectively be able to plan them. Under proportionality an aggressor might not win, but he can’t lose.
There are certain levels of response to some aggressions that make a person a heinous immoral human being. However, proportionality is unworkable, unduly intrusive to victims, shifts responsibility for side effects of NAP violations from the aggressors to their victims, and makes aggression more profitable.