This is interesting. Nevermind all the other disagreements we have... arguing that we're defending others' property when we stop them from doing something unknowingly against their interests might be a valid concept.
I guess a lot of this stems from assumptions about property.
You do realize, K, that many (if not most) anarchists of the past vehimently disagree with your view of property, right?
I could post a bunch of sources (not sure you're interested in those), but I really, really don't understand how you can be so sure that your definition of valid property is so correct, when there are VASTLY differing opinions on this (usually regarding land, animals, and the means of production) even within those who advocate the NAP.
- what's the legal consensual age for sex or contract?
- do animals have any "defensible" moral value?
- is all pollution aggression?
- are behaviors that are risky to the well-being of others aggression?
- what if someone is trying to commit suicide, and knows what they are doing... do I stop them?
If we can come to terms with the fact that people have VASTLY different views on what constitute legitimate property rights (even anarchists do), and that a violation of property is defensible with force (and doesn't require "cooperation"), then I don't see how you can be so confident about how we can "defend property" so flippantly. Maybe property is just a social construct (similar to government) to allow some people to control others.
Here's a good summary of the debate, if you'll read it.
A few quotes I liked:
But if “Trespassers Will Be Shot On Sight”? is a valid assertion of property rights by the owner, then it is clear that self-ownership has become alienable and inferior to property rights. Yes, of course, I might shoot someone because they are a credible threat to my life, but this is true whether they’ve threatened me in the home I own, the apartment I rent, the hotel where I’m staying, or the restaurant where I’m eating: it has nothing to do with my being the owner of the property.
Furthermore, even to the extent property rights are legitimate, dispute resolution over property cannot be territorially based, because that means begging the very question. You can’t do that on my property! Who says? The judge says! Which judge? The judge I selected for all disputes involving my property! Who says it is your property? The judge! Which judge? The judge I selected for all disputes involving my property! I want a different judge! You have no choice, since you’re on my property! According to who? The judge! Which judge? The judge I selected for all disputes involving my property!
Based on their great longevity, I think experiments in anarcho-capitalism have proven more successful than those under anarcho-communism. But I think the anarcho-communists have the answer to why the former still eventually failed: concentrations of power are dangerous even when they result from voluntary behavior. In both Iceland and Ireland, voluntary law and private property prevailed for centuries, but the acceptance of Christianity and, more importantly, of the tithing of money to the church, led to increasing concentrations of wealth in the hands of those overseeing church operations, and what was voluntary became coercive once that concentrated wealth was used to project violent power.
What grows from an atmosphere of mutual respect is unpredictable, differs from place to place, and changes over time. I believe that private property has proven its value, but that it isn’t sustainable without a suspicion of all concentrations of wealth and power, even voluntary. As much as I think anarcho-communists are dead wrong about the need to abolish rent and wages, I think they are dead right about the need to be suspicious of all imbalances of authority and to openly condemn those who take advantage of such imbalances.
Overall though... this guy raises some of your points. It's a pretty balanced article... though, of course, compromise is not an indication of a valid argument

.
But I don't share his optimism. Put anarcho-communists and anarcho-capitalists in the same dream world and disagree with each other so much on property that you wouldn't really have a functioning society, IMO. If a large chunk of the population views another's power as illegitimately obtained, that environment isn't conducive to "cooperation."
The article I linked to even questioned whether we can defend property with violent force, since that is placing the property above the individual.
I think you need to realize that even within people think that the NAP is the beginning, middle and end of ethics, there is massive disagreement on how to define property, which (of course) doesn't mean one isn't right, but it surely means that when applied to the REAL WORLD, your NAP will fail to deliver the happiness you predict..
For the record, I find anarcho-communists to be equally rigid and arbitrary in their thinking, if not more-so in many ways. I just find it interesting to watch anarchists argue with each other so vehemently. Almost makes you think they're going to start aggressing towards each other.