Not much. I'm going to use what I think is a great description of the basis of so-called 'anarcho-capitalism' I found elsewhere online. I believe the author went by 'phoenix_insurgent' on Reddit's anarchism subreddit, which I read occasionally. I thought it worth saving and sharing here:
In my evaluation, ancaps have a religious-style view of capitalism and they react to fact-based criticism in the ways you would expect religious fanatics to respond. They have an origin myth (two guys on an island), a fall from grace (the evil state shows up and ruins everything) and a redemption, "second coming" myth (the state is slain and paradise returns). Of course, anyone who has studied capitalism know that's all bullshit, but don't expect ancaps to be experts on capitalism. They are not. Indeed, they basically have not to be in order to continue to maintain their beliefs.
Anyhow, towards defending this mythology, they have a particular nomenclature that redefines things to maintain the circular loop that is their a priori, axiomatic worldview. Think of how the ancap redefines capitalism to mean "voluntary exchange." This is a stupid fucking definition of capitalism, obviously, but what it does is remove capitalism from reality, so that any criticism of actually-existing or historical capitalism can be safely bypassed with a no true Scottsdman fallacy. Basically, this is how they selectively embrace or reject aspects of capitalism in real life. If they like it, it's the free market. If they don't like it, it's the state. Beyond that, on the rare occasion that they do acknowledge the reality of capitalism as experienced by people, they just invoke a post hoc ergo propter hoc fallacy, and tell us that past does not determine present and that through some magical process that no one yet knows, capitalism can be disentangled from its best friend, the state.
Their philosophy rejects facts in favor of logically-consistent thought experiment. The problem with this, of course, is made evident by the example of the murder mystery novel. A murder mystery novel must be consistent above everything else. But, when we finish reading a murder mystery novel, no one thinks an actual murder has taken place. Well, except for the ancap. Since it's logically consistent, it must be true.