I agree, the primary problem is the concept of legitimate aggression. However, the counterargument is that perhaps people would be killing each other at even higher rates without the state there to intervene. There really are no good counterexamples to point to,
...except everyone in your life who doesn't kill, rape or rob you, even when they could get away with it easily?
I get the feeling that this (rather common) counterargument -- aside from not really being an argument but rather an allegedly untested hypothesis according to their proponents -- stems from a very creationist / religious / Original Sin form of conceptualizing one's fellow man.
That is, the idea that without a government everyone turns into evil Motorcycling Mad Max in Mohawks, is really no different from the belief that roads will "instantly vanish" if "government disappears"
But then again, we've been telling religious people that for decades, and they still believe -- against all observable evidence -- that without the Bible, people will suddenly become evil.
Now, there's absolutely every reason to believe that a tiny minority of the populace will most definitely turn evil, because they already were evil and believe that committing evil doesn't matter, only getting caught does. We call these people "psychopaths". They're about like 5% of the people. And it is a problem (for which theoretical and practical decentralized solutions exist).
Now, don't quote me on this, but even if we don't have a solution to the psychopath problem, I much prefer a system where a psychopath gets shot in the face while attempting to rape a little child, to a system where the same psychopath is worshipped by useful idiots and empowered to firebomb children, give syphilis to Negroes, or trigger nuclear bombs. Democide, remember?
so the argument descends into one of opinion on both sides.
No, not really. I don't think there are two opinions on each side here. What is there, is an irrational belief about pervasive human malevolence rooted in Original Sin, being battled (and increasingly being proven wrong and conquered) by facts that demonstrate the ample majority of people are voluntaryists when left to their own devices, and only really resort to violence to defend themselves and their loved ones.
I mean, there's research proving this. Even frigging soldiers won't fire into each other during war (a fact that is described as a "serious problem" by the psychopaths who run these murderer gangs). People, even strangers, even when they are children, help each other and have altruism.
I can show you videos of this shit. The question really only is: will you believe your eyes, or will you reject it and believe what you were told about your Evil Cousin, Man?