If we want to be honest, we can ship the Statue of Liberty back to France or replace the outdated verse with new lines, "America the closed preserve/… - David D. Friedman

Legal rules are to be judged by the structure of incentives they establish and the consequences of people altering their behavior in response to those incentives (p.11)

[T]he assumption describes our actions, not our thoughts. If you had to understand something intellectually in order to do it, none of us would be able to walk.
Economics is based on the assumption that people have reasonably simple objectives and choose means to achieve them. Both assumptions are false-but useful.
Suppose someone is rational only half the time. Since there is generally one right way of doing things and many wrong ways, the rational behavior can be predicted but the irrational cannot. If we assume he is rational, we predict his behavior correctly about half of the tie - far from perfect, but a lot better then nothing. If I could do well at the racetrack I would be a very rich man.
[R]ationality is an assumption I make about other people. I know myself.
[R]ationality is an assumption I make about other people. I know myself well enough to allow for the consequences of my own irrationality. But for the vast mass of my fellow humans, about whom I know very little, rationality is the best predictive assumption available. (pp.3-5)

Perhaps the best way to see why anarcho-capitalism would be much more peaceful than our present system is by analogy. Consider our world as it would be if the cost of moving from one country to another were zero. Everyone lives in a housetrailer and speaks the same language. One day, the president of France announces that because of troubles with neighboring countries, new military taxes are being levied and conscription will begin shortly. The next morning the president of France finds himself ruling a peaceful but empty landscape, the population having been reduced to himself, three generals, and twenty-seven war correspondents. (p.123)