01 Non Aggression Principle

Non Aggression Principle

Starting at the foundation once again, libertarianism has at its core the Non Aggression Principle.

Murray Rothbard said

The libertarian creed rests upon one central axiom: that no man or group of men may aggress against the person or property of anyone else. This may be called the “nonaggression axiom.” “Aggression” is defined as the initiation of the use or threat of physical violence against the person or property of anyone else. Aggression is therefore synonymous with invasion. If no man may aggress against another; if, in short, everyone has the absolute right to be “free” from aggression, then this at once implies that the libertarian stands foursquare for what are generally known as “civil liberties”: the freedom to speak, publish, assemble, and to engage in such “victimless crimes” as pornography, sexual deviation, and prostitution (which the libertarian does not regard as “crimes” at all, since he defines a “crime” as violent invasion of someone else’s person or property). Furthermore, he regards conscription as slavery on a massive scale. And since war, especially modern war, entails the mass slaughter of civilians, the libertarian regards such conflicts as mass murder and therefore totally illegitimate.
While fundemental to librtarian thinking, this is not a new idea. Here are some other's thoughts:

Epicurus said

Natural justice is a symbol or expression of usefullness, to prevent one person from harming or being harmed by another.

John Locke said

Being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions.

Thomas Jefferson said

Rightful liberty is unobstructed action according to our will within limits drawn around us by the equal rights of others. I do not add 'within the limits of the law', because law is often but the tyrant's will, and always so when it violates the rights of the individual.
and
No man has a natural right to commit aggression on the equal rights of another, and this is all from which the laws ought to restrain him.

Murray Rothbard said

No one may threaten or commit violence ('aggress') against another man's person or property. Violence may be employed only against the man who commits such violence; that is, only defensively against the aggressive violence of another. In short, no violence may be employed against a nonaggressor. Here is the fundamental rule from which can be deduced the entire corpus of libertarian theory.
An important point:

"Early formulations that use terms such as "harm" or "injury," such as those of Epicurus and Mill above, are today generally considered imprecise. "Harm" and "injury" are too subjective; one man's harm may be another man's benefit. For example, a squatter may make "improvements" that the owner considers detrimental. Modern formulations avoid such subjectivity by formulating the NAP in terms of individual rights or observable conduct (initiation of force/violence)."

There are some dissenting viewpoints with the full on 100% adoption of the NAP, some stretching and cherry picking to make the point, others having some legitimacy and worth discussion. The Mises Wiki outlines the three areas of critism:

"The non-aggression principle faces three kinds of criticism: the first holds that the principle is immoral, the second argues that it is impossible to apply consistently in practice, while the third holds that the interpretation of the principle is too ambiguous to be useful; respectively, the consequentialist criticism, the inconsistency criticism, and the ambiguity criticism."
(Principle of non-aggression - Mises Wiki, the global repository of classical-liberal thought)

But as we've seen in our story, there is no observation or factual evidence to show that one human has a right over another, so logically we can conclude this extends to aggression from one person onto another and their possessions.

don't intentionally hurt someone, don't threaten to hurt someone
don't steal or wreak their stuff