ZAP: The Zero Aggression Principle

"No human being has the right -- under any circumstances -- to initiate force against another human being, nor to threaten or delegate its initiation."

Formulated by L. Neil Smith, this is generally (but not universally) agreed to be the core principle of libertarian philosophy. I DO think this is the basis of libertarianism. This has the same message as The Golden Rule and most other guides for dealing ethically with others. I have heard the argument that "initiating force" can be defined any way the person wishes to define it. I do not believe this. Someone calling you a nasty name has not initiated force; someone pointing a gun at you has. Someone making a threat against you, if it is a credible threat, has initiated force. I don't see that it is a difficult concept to grasp. Once force has been initiated, you have the right to counter that force with defensive actions, including force. You have a moral obligation to use an appropriate amount of force. In other words, if someone shoves you, you can't justify beating that person to death with a statuette of Gandhi. In most common situations, you would be smartest to simply walk away. This isn't always an option. You might need to point a gun at that person and warn them to leave or be shot. At that point, they have a choice to escalate the situation, or leave.

There is also The Coventant of Unanimous Consent which takes the ZAP and uses it as a basis for a system of dealing peacefully with other humans.