Yeah, I've had a lot of discussion with anarcho-cappies. They tend to be sharp and make good points, but none of them have ever convinced me that getting rid of the state solves the problem of defending liberty against abuse of power, or that a institution similar to the state in function wouldn't just reappear with a different structure and name.
It does resolve the abuse of liberty by the state though. This part I am much more amicable towards. If states didn't have the ability to take resources from the population without consent and use it to further its own interests or interests of a select few the liberty would be greatly enhanced. The reasoning behind the negation of a non state action creating a " state" by force by using defense companies seems pretty weak to me, and I haven't been convinced of the practicality as much as I have been convinced of the theory of lowering barriers for labor to move in and out of a state would have a beneficial effect for all involved. It would keep State excesses in check because people would simply move out and allow a State that has it's act in order to gain more citizens or base to further more efficient, equitable methods of governance. I lean more this way, though not completely convinced that a complete release of "state sovereignty" would be beneficial.
The mistake I think Rothbard and his followers made is conflating the state with aggregation of power to the detriment of individual liberty. I think the latter is completely feasible without the former, and, in certain circumstances is actually more likely to be problematic without the democratic republican state acting as (an albeit not entirely impartial) mediator between parties and making an attempt, no matter how half-assed it may be, to protect the rights of those with no power or wealth, and to have some accountability to the people as a whole.
I think while feasible, historically it hasn't been entirely without it's problems. Limiting the power of the government substantially usually helps. ACists deontologicalists usually say that all state power is inherently bad unless given voluntary approval. Consequentialists believe that limited state power could be beneficial in certain areas. I tend toward this area.
The other thing I have a big problem wrapping my head around is why ACs seem to think it is possible to have large disparities of wealth without corresponding large disparities of power, and abuse of that power (to the detriment of the rights and liberties of other people), considering the fact that these two things have always gone hand-in-hand since the beginning of civilization. Control more resources, and you have more power-- way it's always been, and likely the way it always will be.
Meh. They make a good point that wealth gained though "good" ends such as being an entrepreneur and providing goods and services to other people isn't bad all. I would be loathed to say that the guy that invents the cure for cancer and makes a million dollars in the process is bad. Likewise to forceably remove "honestly" earned wealth from someone to give to another is form of an "abuse of power" as well, and would create a state that would have the exact characteristics that have historically abused liberty. But to use strictly deontological arguments ignores the very real fact that people do feel cheated when others have more or that people with more wealth are able to skirt or bend the rules far easier than poorer people.
Finally, the idea of a completely organically self-regulating economy, with no external controls, manipulation or interference, whether that be a Marxian communist society or a purely free-market capitalist society, I find to be utopian and unrealistic.
This is actually the strongest argument for them, mostly because it doesn't come from Anarcho Capitalists but from Austrian Economics which is a legitimate school of economics independent of ACism, but welded together by Rothbard. Austrian economics does work with miniarchism and statism, it simply expounds on the effects of interferences in the market. I label myself as of the Austrian school of economics but not in the AC political theory mindset.