The non-aggression principle is a moral stance which asserts that aggression is illegitimate.
Also called the non-aggression axiom, the anti-coercion principle, the zero aggression principle ZAP, the non-initiation of force, or NAP for short.
Aggression is defined as the initiation or threat of non-consensual physical force against the person or property of another. Aggression is understood to include indirect force such as theft by stealth and fraud. Unlike pacifism, the non-aggression principle does not preclude violence used in self-defense or the defense of others.
The meaning and scope of the NAP is debated. Here are some of the interpretations:
Hogeye Bill: I like 1, 2, and 6. I use my own modal ethics (#2) the most. Note that what constitutes aggression is dependent on some underlying property system. E.g. In a sticky property system the squatter is the aggressor, while in a possession property system the person who attempts to evict the squatter is the aggressor.