The law of the Jackalope

The non-aggression principle (or NAP; also called the non-aggression axiom, the anti-coercionzero aggression principle or non-initiation of force) is an ethical stance that asserts that aggression is inherently wrong. In this context, “aggression” is defined as initiating or threatening any forcible interference with an individual or individual’s property.

In contrast to pacifism, the non-aggression principle does not forbid forceful defense. The non-aggression principle is considered by some to be a defining principle of natural-rights libertarianism

The Non-aggression principle is a prominent idea in anarcho-capitalism, liberalism, libertarianism, and minarchism.


The non-aggression principle has existed in various forms. Although the principle has been traced back as far as antiquity, it was first formally described by this name by the Objectivist philosopher Ayn Rand, and then further popularized by libertarian thinkers.

A number of authors have created their own formulation of the non-aggression principle, as shown in the table below.

Historical formulations of the non-aggression principle

Year Author Formulation
1689 John Locke Locke gives the following version of the NAP: “Being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions.”
1816 Thomas Jefferson Jefferson describes the NAP in a letter to Francis Gilmer: “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.”
1851 Herbert Spencer Spencer formulates the NAP as: “Every man is free to do that which he wills, provided he infringes not the equal freedom of any other man.”
1859 John Stuart Mill In his book On Liberty Mill states the NAP as follows: “the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others”.
1923 Albert Jay Nock In the second chapter of his book, Our Enemy, the State, Nock refers to an ancient formulation of the NAP by the legendary king Pausole, who stated it as two laws. The first law was “hurt no man” and the second was “then do as you please”.
1961 Ayn Rand In an essay called “Man’s Rights” in the book The Virtue of Selfishness she formulated “The precondition of a civilized society is the barring of physical force from social relationships. … In a civilized society, force may be used only in retaliation and only against those who initiate its use.”
1963 Murray Rothbard “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.” Cited from “War, Peace, and the State” (1963) which appeared in Egalitarianism as a Revolt Against Nature and Other Essays

Supporters of the NAP often appeal to it in order to argue for the immorality of theft, vandalism, assault, and fraud. Compared to nonviolence, the non-aggression principle does not preclude violence used in self-defense or defense of others. Many supporters argue that NAP opposes such policies as victimless crime laws, taxation, and military drafts. NAP is the foundation of libertarian philosophy.