It still amazes me that people even discuss “Anarcho-Capitalism” anymore without taking the piss out of such a ludicrously laughable concept. Sadly, Wikipedia is still full of apparently serious discussions on the topic. Good for Wikipedia. All I would ask is that readers interested in genuine viewpoints on the articles should click the “discussion” tab on any anarchist related articles. There you will find a lot of unedited debate that will provide you with many hours of turbulent thought.
Even though you probably couldn’t give a toss, here’s my argument against “Anarcho-Capitalism”: it’s an oxymoron. How can a system that relies on people happily co-existing on two distinct levels (rich and poor) be possible when there are “no leaders” or there is “no hierarchy” ? Both of those last definitions are as pure as you will find when it comes to defining Anarchy. In fact that’s what I like about it – rather than being something intricately defined, it’s simply an umbrella term for a common belief: that rulers, and therefore social hierarchy, are wrong. That’s it! From that starting point you can come up with whichever path suits you (anarcho-syndicalism, anarcho-communism etc etc). The only restriction is that the suffix can’t contradict the prefix (anarcho). For example “anarcho-fascism” is impossible because it’s an oxymoron.
From this definition it’s clear that “anarcho-capitalism” is also an oxymoron: if the market really was “free” then what would stop the people with the riches fucking off and leaving the shareholders with nothing ? In fact, honoring anything like “shares” would also rely on everyone believing that they were worth something. The same holds for money; we only value it because other people do. In fact, we regularly acknowledge that the money we have in our pockets, or the roof over our heads, changes value from one day to the next without us so much as changingav a lightbulb.

My favourite discussion on the subject is with the excellent Anarchist FAQ. Their answer to the question “Are “anarcho”-capitalists really anarchists?” begins:

In a word, no.

Amen.