View source for Non-aggression principle

{{Short description|Core concept in libertarianism in the United States}}{{Puffery|date=March 2024}}{{libertarianism in the United States sidebar|concepts}}
The '''Non-Aggression Principle''' ('''NAP'''), also called the '''Non-Aggression Axiom''', the '''non-coercion principle''', the '''non-initiation of force''' and the '''zero aggression principle''', is a concept in which "aggression" – defined as initiating or threatening any forceful interference with either an individual or their property,<ref group=note>Property is defined in this context as both personal possessions and [[private property]].</ref> or agreements ([[contract]]s) – is illegitimate and should be prohibited.<ref>{{cite encyclopedia |last=Long|first=Roderick |author-link=Roderick T. Long |editor-first=Ronald |editor-last=Hamowy |editor-link=Ronald Hamowy |encyclopedia=The Encyclopedia of Libertarianism |url= https://books.google.com/books?id=yxNgXs3TkJYC  |year=2008 |publisher= [[SAGE Publishing|SAGE]]; [[Cato Institute]] |location= Thousand Oaks, CA  |isbn= 978-1-4129-6580-4 |oclc=750831024| lccn = 2008009151 |pages=357–60 |doi= 10.4135/9781412965811.n219|quote=...except in response to the initiation ... of similar forcible interference .... |chapter=Nonaggression Axiom }}</ref><ref name="Zwolinski2016">Zwolinski, M. (2016). [https://www.cambridge.org/core/journals/social-philosophy-and-policy/article/libertarian-nonaggression-principle/E8CF5446CB1D9601EFA043F7903F1CB1 THE LIBERTARIAN NONAGGRESSION PRINCIPLE]. Social Philosophy and Policy, 32(2), 62-90. doi:10.1017/S026505251600011X</ref> Interpretations of the NAP vary, particularly concerning issues like [[intellectual property]], [[Force_(law)|force]], and [[abortion]].

The Non-Aggression Principle is considered by some to be a defining principle of [[libertarianism in the United States]]<ref name="americanlyyours">{{cite web|url=http://americanlyyours.com/2011/04/14/the-non-aggression-principle/|title=The Non-Aggression Principle (Americanly Yours, April 14, 2011)|author=Phred Barnet|access-date=November 22, 2011}}</ref> and is also a prominent idea in [[anarcho-capitalism]], [[voluntaryism]], and [[minarchism]].<ref>{{Cite web | url=http://fff.org/explore-freedom/article/the-morality-of-libertarianism/ | title=The Morality of Libertarianism | date=October 2015 | publisher=[[The Future of Freedom Foundation]]| access-date=2016-03-16}}</ref><ref>{{Cite web | url=http://archive.lewrockwell.com/block/block26.html | title=The Non-Aggression Axiom of Libertarianism|publisher=[[Lew Rockwell]] | access-date=2016-03-22}}</ref><ref>{{Cite web | url=https://www.theadvocates.org/aggression/| title=What is the "non-aggression principle"? | publisher=[[Advocates for Small Government]] | access-date=2016-03-22}}</ref><ref>{{Cite web | url=http://www.yaliberty.org/posts/discovering-libertarianism-non-aggression-principle-introduction | title=Discovering Libertarianism – Non-Aggression Principle | publisher=[[Young Americans for Liberty]] | access-date=2016-03-22 | archive-url=https://web.archive.org/web/20160409002442/http://www.yaliberty.org/posts/discovering-libertarianism-non-aggression-principle-introduction | archive-date=2016-04-09 | url-status=dead }}</ref>{{primary source inline|reason=These sources are all advocacy orgs; we should find secondary sources discussing the concept rather than advocating it.|date=August 2024}}

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== Justifications ==
{{anarcho-capitalism sidebar|expanded=concepts}}
The principle has been derived through various philosophical approaches, including:
* [[Consequentialism]]: some advocates base the non-aggression principle on [[rule utilitarianism]] or [[rule egoism]]. These approaches hold that though violations of the non-aggression principle cannot be claimed to be objectively immoral, adherence to it almost always leads to the best possible results, and so it should be accepted as a moral rule. These scholars include [[David D. Friedman]], [[Ludwig von Mises]], and [[Friedrich Hayek]].<ref>{{Cite journal|title=Review Article: The New Liberalism|journal=British Journal of Political Science| volume= 13|issue= 1|date= January 1993|pages= 93–123) |author=Norman P. Barry |jstor = 193781|doi=10.1017/s000712340000315x|s2cid=154938624 }}</ref>{{Failed verification|date=October 2012}}
* [[Objectivism]]: [[Ayn Rand]] rejected natural or inborn rights theories as well as supernatural claims and instead proposed a philosophy based on "observable reality" along with a corresponding ethics based on the "factual requirements" of human life in a social context.<ref>{{cite web |url= http://www.theobjectivestandard.com/issues/2013-winter/libertarianism-vs-radical-capitalism.asp |title= Libertarianism vs. Radical Capitalism (The Objective Standard, Vol. 8 No. 4, Winter 2013-2014) |author= Craig Biddle |access-date= 2013-11-11 |archive-url= https://web.archive.org/web/20131112004109/http://www.theobjectivestandard.com/issues/2013-winter/libertarianism-vs-radical-capitalism.asp |archive-date= 2013-11-12 |url-status= dead }}</ref> She stressed that the political principle of non-aggression is not a primary and that it only has validity as a consequence of a more fundamental philosophy. For this reason, many of her conclusions differ from others who hold the NAP as an axiom or arrived at it differently. She proposed that man survives by identifying and using concepts in his rational mind since "no sensations, percepts, urges or instincts can do it; only a mind can". She wrote, "since reason is man's basic means of survival, that which is proper to the life of a rational being is the good; that which negates, opposes or destroys it [i.e. initiatory force or fraud] is the evil."<ref>{{cite web |url= http://www.aynrand.org/site/PageServer?pagename=ari_ayn_rand_the_objectivist_ethics |title= The Objectivist Ethics (The Virtue of Selfishness, 1961) | author=Ayn Rand |access-date=2012-11-05 }}</ref>
* [[Argumentation ethics]]: some modern right-libertarian thinkers ground the non-aggression principle by an appeal to the necessary [[praxeology|praxeological]] [[presuppositions]] of any ethical discourse, an argument pioneered by anarcho-capitalist scholar [[Hans Hermann Hoppe]]. They claim that the act of arguing for the initiation of aggression, as defined by the non-aggression principle, is [[performative contradiction|contradictory]]. Among its advocates are [[Stephan Kinsella]]<ref name="KinsellaNAP&PR2011"/> and [[Murray Rothbard]].<ref>{{cite web |url=http://archive.lewrockwell.com/rothbard/rothbard47.html |title=Hoppephobia (2004 LewRockwell.com reprint from Liberty, Vol. 3 No. 4, March 1990, pp. 11–12.) |author=Murray N. Rothbard |access-date=2012-01-05 }}</ref>
* [[Estoppel]]: [[Stephan Kinsella]] believes that the legal concept of estoppel implies and justifies the non-aggression principle.<ref>Kinsella, Stephan. "Punishment and Proportionality: the Estoppel Approach." Journal of Libertarian Studies 12, No. 1 (1996): 51–73.</ref>

== Definitional issues ==
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=== Abortion ===
{{see also|Libertarian perspectives on abortion}}
Both libertarian supporters and opponents of abortion rights justify their position on NAP grounds. One question to determine whether or not abortion is consistent with the NAP is at what stage of development a fertilized human egg cell can be considered a [[human being]] with the status and rights attributed to [[personhood]]. Some supporters of the NAP argue this occurs at the moment of conception while others argue that since the fetus lacks [[sentience]] until a certain stage of development, it does not qualify as a human being and may be considered property of the mother. On the other hand, [[opponents of abortion]] state that sentience is not a qualifying factor. They refer to the [[#Non-humans|animal rights]] discussion and point out the [[argument from marginal cases]] that concludes the NAP also applies to non-sentient (i.e. mentally handicapped) humans.<ref>{{cite web |url=http://www.libertarianfaq.org/index.php?title=Are_libertarians_pro_choice_or_pro_life%3F |title=Are libertarians pro choice or pro life? (Libertarian FAQ Wikipage, January 2, 2010) |access-date=2011-11-15 |archive-date=2019-02-03 |archive-url=https://web.archive.org/web/20190203130644/http://www.libertarianfaq.org/index.php?title=Are_libertarians_pro_choice_or_pro_life%3F |url-status=dead }}</ref>

Another question is whether an unwelcome fetus should be considered to be an unauthorized trespasser in its mother's body.<ref>{{cite web|url=http://www.str.org/articles/trespassing-in-the-womb#.VXIUO0aRzak|title=Trespassing in the Womb – Stand to Reason|website=www.str.org|access-date=28 March 2018}}</ref> The non-aggression principle does not protect trespassers from the owners of the property on which they are trespassing.<ref>{{cite web|url=http://c4ss.org/content/13144|title=Is Property Theft?|website=c4ss.org|access-date=28 March 2018}}</ref>

[[Objectivist movement|Objectivist]] philosopher [[Leonard Peikoff]] has argued that a fetus has no right to life inside the womb because it is not an "independently existing, biologically formed organism, let alone a person".<ref>{{cite web |url=http://www.peikoff.com/essays_and_articles/abortion-rights-are-pro-life/ |title=Abortion Rights are Pro-Life |author=Leonard Peikoff |date=29 March 2010 |access-date=2011-11-16 }}</ref> [[Pro-choice]] libertarian [[Murray Rothbard]] held the same stance, maintaining that abortion is justified at any time during pregnancy if the fetus is no longer welcome inside its mother.<ref>{{cite web |url=https://mises.org/rothbard/newlibertywhole.asp#p94 |title=For a New Liberty: The Libertarian Manifesto (1973, 1978, 2002 online ed, Chapter 6) |author=Murray N. Rothbard |date=20 July 1973 |access-date=2011-11-16 }}</ref> Similarly, other pro-choice supporters base their argument on criminal trespass.<ref>{{cite web |url=http://libertarianpapers.org/articles/2010/lp-2-32.pdf |title=Rejoinder to Wisniewski on Abortion (Libertarian Papers Vol. 2, Art. No. 32, 2010) |author=Walter Block |access-date=2011-12-21 }}</ref> In that case, they claim that the NAP is not violated when the fetus is forcibly removed, with deadly force if need be, from the mother's body, just as the NAP is not violated when an owner removes from the owner's property an unwanted visitor who is not willing to leave voluntarily. Libertarian theorist [[Walter Block]] follows this line of argument with his theory of [[evictionism]], but he makes a distinction between evicting the fetus prematurely so that it dies and actively killing it. On the other hand, the theory of [[departurism]] permits only the non-lethal eviction of the trespassing fetus during a normal pregnancy.<ref>{{cite journal |last1=Parr |first1=Sean |title=Departurism: Gentleness and Practical Consistency in Trespasses Inside and Outside the Womb |journal=The Christian Libertarian Review |date=2020 |volume=3 |page=65 |url=https://christianlibertarianreview.com/wp-content/uploads/2020/07/CLR-3-Parr.pdf|quote=It is only the lethal (or otherwise debilitating) eviction of a fetus during a normal pregnancy that departurism views as discordant with gentleness and, thus, a violation of the NAP.}}</ref>

[[Anti-abortion]] libertarians such as [[Libertarians for Life]] argue that because the parents were actively involved in creating a new human life and that life has not consented to their own existence, that life is in the womb by necessity and no parasitism or trespassing in the form of legal [[Necessity (criminal law)|necessity]] is involved. They state that as the parents are responsible for that life's position, the NAP would be violated when that life is killed with abortive techniques.<ref name="dutton_2006">{{cite book|last=Dutton |first = Donald G. |title=Rethinking Domestic Violence |publisher=UBC Press |location=Vancouver, BC, Canada |year=2006 |isbn=978-1282741072 }}</ref>

=== Intellectual property rights ===
{{see also|Libertarian perspectives on intellectual property}}
The NAP is applicable to any unauthorized actions towards a person's physical property. Supporters of the NAP disagree on whether it should apply to [[intellectual property]] rights as well as physical property rights.<ref>{{cite book |url=http://www.libertarian.co.uk/lapubs/libhe/libhe014.htm |title=Intellectual Property: The Late Nineteenth Century Libertarian Debate (Libertarian Alliance, 1995) |isbn=1856372812 |author=Wendy McElroy |date=1995 |publisher=Libertarian Alliance |access-date=2011-11-17 |archive-date=2021-01-02 |archive-url=https://web.archive.org/web/20210102150720/http://www.libertarian.co.uk/lapubs/libhe/libhe014.htm |url-status=dead }}</ref> Some argue that because intellectual concepts are non-[[Rivalry (economics)|rivalrous]], intellectual property rights are unnecessary<ref>{{cite web |url=https://mises.org/journals/jls/15_2/15_2_1.pdf |title=Against Intellectual Property (Journal of Libertarian Studies, Vol. 15, No. 2, Spring 2001, pp. 1–53) |author=N. Stephan Kinsella |access-date=2011-11-17 }}</ref> while others argue that intellectual property rights are as valid and important as physical ones.<ref>{{cite web |url=http://www.lysanderspooner.org/intellect/contents.htm |title=The Law of Intellectual Property: An Essay on the Right of Authors and Inventors to a Perpetual Property in Their Ideas (Bella Marsh, Boston, 1855) |author=Lysander Spooner |access-date=2011-11-17 |archive-url=https://web.archive.org/web/20140524005404/http://lysanderspooner.org/intellect/contents.htm |archive-date=2014-05-24 |url-status=dead }}</ref>

=== Force and interventions ===
Although the NAP is meant to guarantee an individual's sovereignty, libertarians greatly differ on the conditions under which the NAP applies. Especially unsolicited intervention by others, either to prevent society from being harmed by the individual's actions or to prevent an incompetent individual from being harmed by his own actions or inactions, is an important issue.{{to whom?|date=May 2019}}<ref>{{cite web |url=http://www.thefreemanonline.org/featured/reflections-on-self-responsibility-and-libertarianism/ |title=Reflections on Self-Responsibility and Libertarianism (The Freeman April 2001, Vol. 51, No. 4) |author=Nathaniel Branden |access-date=2011-11-22 }}</ref> The debate centers on topics such as the [[age of consent]] for children,<ref>{{cite web |url=http://crazyforliberty.com/2008/05/07/anarchism-age-of-consent-laws-and-the-dallas-accord-wayne-allyn-root.aspx |title=Anarchism, Age of Consent Laws and the Dallas Accord (Crazy for Liberty, May 7, 2008) |author=Wayne Allyn Root |access-date=2011-11-22 |url-status=dead |archive-url=https://web.archive.org/web/20111204103329/http://crazyforliberty.com/2008/05/07/anarchism-age-of-consent-laws-and-the-dallas-accord-wayne-allyn-root.aspx |archive-date=December 4, 2011 }}</ref><ref>{{cite web |url=http://lonelylibertarian.blogspot.com/2008/04/age-of-consent.html |title=Age of Consent (The Lonely Libertarian, April 25, 2008) |author=Lonely Libertarian |access-date=2011-11-22 }}</ref><ref>{{cite web |url=http://www.thedegree.org/polin010.pdf |title=Sex, Coercion, and the Age of Consent (Libertarian Alliance, 1981, ISBN 1856371905) |author=Max O'Connor |access-date=2011-11-22 |archive-url=https://web.archive.org/web/20120425235943/http://www.thedegree.org/polin010.pdf |archive-date=2012-04-25 |url-status=dead }}</ref> [[Intervention (counseling)|intervention counseling]] (i.e. for addicted persons, or in case of domestic violence),<ref>{{cite journal |url=http://jme.bmj.com/content/30/5/453.full.pdf |title=Pressure and coercion in the care for the addicted: ethical perspectives (Journal of Medical Ethics, 2004, No. 30, pp. 453–58) |author= M J P A Janssens|journal=Journal of Medical Ethics |date=2004 |volume=30 |issue=5 |pages=453–458 |doi=10.1136/jme.2002.002212 |pmid=15467076 |pmc=1733929 |access-date=2011-11-22 |display-authors=etal}}</ref><ref>{{cite web |url=http://www.psychologytoday.com/blog/enlightened-living/201006/addiction-self-responsibility-and-the-importance-choice |title= Addiction, Self-responsibility and the Importance of Choice: Why AA doesn't work (Psychology Today, June 3, 2010) |author=Michael J. Formica |access-date=2011-11-22 }}</ref> [[involuntary commitment]] and [[involuntary treatment]] with regards to [[mental illness]],<ref>{{cite web|url=http://www.cato-unbound.org/archives/august-2012/|title=Mental Health and the Law|date=1 August 2012|website=cato-unbound.org|access-date=28 March 2018}}</ref> [[Advance health care directive|medical assistance]] (i.e. prolonged life support vs euthanasia in general and for the senile or comatose in particular),<ref>{{cite web |url=https://mises.org/journals/jls/4_3/4_3_2.pdf |title=Libertarianism and Legal Paternalism (The Journal of Libertarian Studies, Vol. IV, No. 3, Summer 1980, pp. 255–265) |author=John Hospers |access-date=2011-11-22 }}</ref><ref>{{cite web |url=http://www.humblelibertarian.com/2011/11/euthanasia-first-in-netherlands.html |title=A Euthanasia First in the Netherlands (The Humble Libertarian, November 9, 2011) |editor=W E Messamore  |access-date=2011-11-22 }}</ref> [[Organ trade|human organ trade]],<ref>{{cite journal |url=https://independent.academia.edu/DannyFrederick/Papers/159192/A_Competitive_Market_in_Human_Organs |title=A Competitive Market in Human Organs (Libertarian Papers, Vol. 2, No. 27, 2010, pp. 1–21, online at libertarianpapers.org ) |author=Danny Frederick |journal=Libertarian Papers, 2, 27 |date=January 2010 |access-date=2011-11-22 }}</ref><ref>{{cite web |url=http://www.graemeklass.com/economics/organ-trading/ |title=Organ Trading (The Libertarian Engineer, April 6, 2011) |author=Graeme Klass |access-date=2011-11-22 |archive-url=https://web.archive.org/web/20110910061239/http://www.graemeklass.com/economics/organ-trading/ |archive-date=September 10, 2011 |url-status=dead }}</ref><ref>{{cite web |url=http://notes.kateva.org/2011/09/humanity-experiment-has-mixed-results.html |title=The humanity experiment has mixed results: Organ trade and enslaving the disabled (Gordon's Notes, September 9, 2011) |author=John Gordon |access-date=2011-11-22 }}</ref> [[Libertarian paternalism|state paternalism]] (including [[economic interventionism]])<ref>{{cite web |url=http://uchicagolaw.typepad.com/faculty/2007/01/libertarian_pat.html |title=Libertarian Paternalism (University of Chicago Law School, January 20, 2007) |author=Cass Sunstein |access-date=2011-11-22 }}</ref><ref>{{cite web |url=https://mises.org/daily/2965 |title=Libertarian Paternalism (Mises Daily, May 21, 2008) |author=David Gordon |date=29 April 2008 |access-date=2011-11-22 }}</ref><ref>{{cite web |url=http://volokh.com/2010/04/19/richard-thaler-responds/ |title=Richard Thaler Responds to Critics of Libertarian Paternalism (The Volokh Conspiracy April 15, 2010) |author=Ilya Somin |date=19 April 2010 |access-date=2011-11-22 }}</ref> and [[Libertarian perspectives on foreign intervention|foreign intervention]] by states.<ref>{{cite web |url=http://www.libertarian.co.uk/lapubs/forep/forep008.pdf |title=A Few Words On Non-Intervention (Libertarian Alliance reprint of J.S. Mill's essay from Fraser's Magazine, 1859) |author=John Stuart Mill |access-date=2011-11-22 |archive-date=2012-02-22 |archive-url=https://web.archive.org/web/20120222052242/http://www.libertarian.co.uk/lapubs/forep/forep008.pdf |url-status=dead }}</ref><ref>{{cite web |url=http://www.nolanchart.com/article8684-nonintervention.html |title=Non-Intervention (The continuing rEVOlution, May 20, 2011) |author=George Dance |access-date=2011-11-22 |archive-date=2012-01-10 |archive-url=https://web.archive.org/web/20120110154106/http://www.nolanchart.com/article8684-nonintervention.html |url-status=dead }}</ref> Other discussion topics on whether intervention is in line with the NAP include [[Nuclear proliferation|nuclear weapons proliferation]],<ref>{{cite web |url=http://www.walterblock.com/wp-content/uploads/publications/theory_gun_control.pdf |title=Toward a Universal Libertarian Theory of Gun (Weapon) Control: A Spatial and Geographycal Analysis (Ethics, Place and Environment, Vol. 3, No. 3, May 2000, pp. 289–298) |author1=Walter Block  |author2=Matthew Block  |name-list-style=amp |access-date=2011-11-22 }}</ref><ref>{{cite web |url=http://www.bestsyndication.com/2005/A-H/DAVIS-Mike/112505_nuclear_weapons.htm |title=Who should Own Nuclear Weapons (Best Syndication, November 25, 2005) |author=Michael Gilson-De Lemos |access-date=2011-11-22 }}</ref> [[human trafficking]] and [[Libertarian perspectives on immigration|immigration]].<ref>{{cite web |url=https://mises.org/library/libertarian-immigration-conundrum |title=The Libertarian Immigration Conundrum (Mises Daily, December 8, 2005) |author=Per Bylund |date=5 December 2005 |access-date=2011-11-22 }}</ref><ref>{{cite web |url=http://www.isil.org/resources/libertydocs/immigration.html |title=Immigration: Controversies, Libertarian Principles and Modern Abolition (International Society for Individual Liberty, 2001) |author=Ken Schoolland |access-date=2011-11-22 }}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=12YDLZq8rT4
 | archive-url=https://ghostarchive.org/varchive/youtube/20211118/12YDLZq8rT4| archive-date=2021-11-18 | url-status=live|title=Globalisation is Good (Channel 4 UK documentary, 2003, on Youtube.com) |author=Johan Norberg | website=[[YouTube]]| date=20 March 2011|access-date=2012-11-18 }}{{cbignore}}</ref>

[[Ayn Rand|Randian]] author Ronald Merill states that use of force is subjective, saying: "There's no objective basis for controlling the use of force. Your belief that you're using force to protect yourself is just an opinion; what if it is my opinion that you are violating my rights?"<ref>Merrill, Ronald E. 1991. ''The Ideas of Ayn Rand''. La Salle, Ill.: Open Court. p. 139 {{ISBN?}}</ref>

=== Pollution ===
Prominent libertarian thinkers such as [[Murray Rothbard]] considered pollution an act of aggression, mostly focusing on [[air pollution]], though in absolute terms [[light pollution]], sound, and anything that crosses a boundary into someone's property or person can constitute aggression. In order to avoid having mere existence violate the non-aggression principle, Rothbard, Nozick, and others proposed less strict positions. Nozick suggested that boundary-crossing is permissible up to a certain range as long as it is socially beneficial and compensation is paid for it. Rothbard suggested that a causal connection of objective harm needs to be demonstrated beyond reasonable doubt before prohibiting pollution. These approaches [[#Inconsistency criticisms|appear to contradict the non-aggression principle]] by enabling a permissible amount of harm.<ref name="Zwolinski2016" />

=== States ===
Some libertarians justify the existence of a [[minarchism|minimal]] [[state (polity)|state]] on the grounds that [[anarcho-capitalism]] implies that the non-aggression principle is optional because the enforcement of laws is open to competition.<ref>{{cite web |editor1-last=Long |editor1-first=Roderick T. |editor2-last=Machan |editor2-first=Tibor R. |title=Anarchism/Minarchism: Is a Government Part of a Free Country? |date=2008 |url=http://web.calstatela.edu/faculty/areed2/LongXXXMachan.pdf |access-date=2011-11-24 |publisher=Ashgate Publishing |url-status=dead |archive-url=https://web.archive.org/web/20160306172845/http://web.calstatela.edu/faculty/areed2/LongXXXMachan.pdf |archive-date=2016-03-06}}</ref>

[[Anarcho-capitalists]] usually respond to this argument that this presumed outcome of what they call "coercive competition" (e.g., [[private military companies]] or [[private defense agencies]] that enforce [[Polycentric law|local law]]) is not likely because of the very high cost, in lives and economically, of war. They claim that war drains those involved and leaves non-combatant parties as the most powerful, economically and militarily, ready to take over.<ref>{{cite web |url=http://libertarian.co.uk/lapubs/legan/legan016.pdf |title=Privately Produced Law (Libertarian Alliance reprint, 1991, ISBN 1856370534) |author=Tom W. Bell |access-date=2011-11-24 |archive-date=2008-07-05 |archive-url=https://web.archive.org/web/20080705033822/http://www.libertarian.co.uk/lapubs/legan/legan016.pdf |url-status=dead }}</ref><ref name=FriedmanMOF1989>{{cite web |url=http://www.daviddfriedman.com/Libertarian/Machinery_of_Freedom/MofF_Chapter_29.html |title=Police, Courts and Law – On the Market (The Machinery of Freedom, 1989, Chapter 29) |author=David D. Friedman |access-date=2011-11-12 }}</ref><ref>{{cite web |url=http://www.daviddfriedman.com/laws_order/index.shtml |title=Law's Order: What Economics Has To Do With Law And Why It Matters (Princeton University Press, 2000) |author=David D. Friedman |access-date=2011-11-24 }}</ref> Therefore, anarcho-capitalists claim that in practice, and in more advanced societies with large institutions that have a responsibility to protect their vested interests, disputes are most likely to be settled peacefully.<ref name=MolyneuxTSS2005>{{cite web |url=http://archive.lewrockwell.com/orig6/molyneux1.html |title=The Stateless Society (LewRockwell.com, October 24, 2005) |last=Molyneux |first= Stefan |author-link=Stefan Molyneux |access-date=2011-11-17}}</ref><ref>{{cite web |url=https://mises.org/journals/jls/14_1/14_1_2.pdf |title=The Private Production of Defense (Journal of Libertarian Studies, 14:1, Winter 1998–1999, pp. 27–52) |author=Hans-Hermann Hoppe |access-date=2011-11-24 }}</ref> Anarcho-capitalists also point out that a state monopoly of law enforcement does not necessarily make NAP present throughout society as [[Political corruption|corruption]] and [[corporatism]], as well as [[Lobbying|lobby group]] [[clientelism]] in [[Democracy|democracies]], favor only certain people or organizations. Anarcho-capitalists aligned with the [[Murray Rothbard|Rothbardian]] philosophy generally contend that the state violates the non-aggression principle by its very nature because, it is argued, governments necessarily use force against those who have not [[theft|stolen private property]], [[vandalism|vandalized private property]], [[assault|assaulted anyone]], or [[fraud|committed fraud]].<ref name="MolyneuxTSS2005"/><ref>{{cite web |url=http://praxeology.net/Anarconst2.pdf|title=Market Anarchism as Constitutionalism (Anarchism/Minarchism, 2008, Chapter 9) |author=Roderick T. Long |access-date=2011-11-16 }}</ref><ref>{{cite web |url=http://gaplauche.com/docs/persistentanarchyapsa2006.pdf |title=On the Social Contract and the Persistence of Anarchy (American Political Science Association, 2006) |author=Geoffrey Allen Plauché (Louisiana State University, Baton Rouge, LA) |access-date=2011-11-16 |archive-url=https://web.archive.org/web/20110809185914/http://gaplauche.com/docs/persistentanarchyapsa2006.pdf |archive-date=2011-08-09 |url-status=dead }}</ref>

=== Taxation ===
Some proponents of the NAP see [[Taxation|taxes]] as a [[Taxation as theft|violation of NAP]], while critics of the NAP argue that because of the [[free-rider problem]] in case security is a [[Public good (economics)|public good]], enough funds would not be obtainable by voluntary means to protect individuals from aggression of a greater severity. [[Geolibertarians]], who following the [[classical economics|classical economists]] and [[Georgism|Georgists]] adhere to the [[John Locke|Lockean]] [[labor theory of property]], argue that [[land value tax]]ation is fully compatible with the NAP.

[[Anarcho-capitalism|Anarcho-capitalists]] argue that the protection of individuals against aggression is self-sustaining like any other valuable service, and that it can be supplied without coercion by the [[free market]] much more effectively and efficiently than by a [[government monopoly]].<ref name="libertarianpapers">[http://libertarianpapers.org/articles/2011/lp-3-3.pdf "Review of Kosanke's Instead of Politics – Don Stacy"] Libertarian Papers Vol. 3, Art. No. 3 (2011)</ref> Their approach, based on [[Proportional justice|proportionality]] in justice and [[Damages|damage]] [[Non-economic damages caps|compensation]], argues that full restitution is compatible with both [[Retributive justice|retributivism]] and a utilitarian degree of [[deterrence (psychology)|deterrence]] while consistently maintaining NAP in a society.<ref name="FriedmanMOF1989"/><ref>{{cite web |url=http://www.la-articles.org.uk/libertarian_restitution.htm |title=Why Libertarian Restitution Beats State-Retribution and State-Leniency (2005) |author=J. C. Lester |access-date=2011-11-12 }}</ref><ref>{{cite web |url=https://mises.org/daily/2496 |title=Punishment and Proportionality (The Ethics of Liberty, 1982, Chapter 13) |author=Murray N. Rothbard |access-date=2011-11-12 }}</ref> They extend their argument to all public goods and services traditionally funded through taxation, like security offered by dikes.<ref>{{cite web |url=https://mises.org/daily/2537 |title=Can Dikes Be Private? : An Argument Against Public Goods Theory (Journal of Libertarian Studies, Vol. 20, No. 4, Fall 2006, pp. 21–40) |author=Philipp Bagus |date=27 March 2007 |access-date=2011-11-17 }}</ref>

== Support ==
Supporters of the NAP often appeal to it in order to argue for the immorality of [[theft]], [[vandalism]], [[sexual assault]], [[assault]], and [[fraud]]. Compared to [[nonviolence]], the non-aggression principle does not preclude violence used in [[self-defense]] or defense of others.<ref>{{cite web |url= http://archive.lewrockwell.com/block/block26.html |title= The Non-Aggression Axiom of Libertarianism (LewRockwell.com, February 17, 2003) | author=Walter Block |access-date=2011-11-12 }}</ref> Many supporters argue that NAP opposes such policies as [[victimless crime]] laws, [[taxation]], and [[military draft]]s. NAP is the foundation of libertarian philosophy.<ref name=KinsellaNAP&PR2011>{{cite web |url=http://blog.mises.org/18608/the-relation-between-the-non-aggression-principle-and-property-rights-a-response-to-division-by-zer0/ |title=The relation between the non-aggression principle and property rights (Mises Economics Blog, October 4, 2011) |author=Stephan Kinsella |access-date=2011-11-25 |archive-url=https://web.archive.org/web/20111114021240/http://blog.mises.org/18608/the-relation-between-the-non-aggression-principle-and-property-rights-a-response-to-division-by-zer0/ |archive-date=November 14, 2011 |url-status=dead }}</ref>

== Criticism ==
NAP faces two kinds of criticism: the first holds that the principle is immoral, and the second argues that it is impossible to apply consistently in practice; respectively, [[Consequentialism|consequentialist]] or [[Deontological ethics|deontological]] criticisms, and [[Consistent|inconsistency]] criticisms. Libertarian academic philosophers have noted the implausible results consistently applying the principle yields: for example, Professor Matt Zwolinski notes that, because pollution necessarily violates the NAP by encroaching (even if slightly) on other people's property, consistently applying the NAP would prohibit driving, starting a fire, and other activities necessary to the maintenance of industrial society.<ref name="Matt Zwolinski">{{cite web |url=http://www.libertarianism.org/blog/six-reasons-libertarians-should-reject-non-aggression-principle|title=Six Reasons Libertarians Should Reject the Non-Aggression Principle |author=Matt Zwolinski |access-date=2014-12-01}}</ref>

The NAP also faces definitional issues regarding what is understood as forceful interference and property, and under which conditions it applies.<ref name="Friedman 1993">Friedman, Jeffrey (1993). "What's Wrong with Libertarianism". ''Critical Review''. 11 (3). p. 427.</ref><ref name="Sterba 1994">Sterba, James P. (October 1994). "From Liberty to Welfare". ''Ethics''. Cambridge, Massachusetts: Blackwell. '''105''' (1): 237–241.</ref><ref name="Patridge 2004">Partridge, Ernest (2004). [http://gadfly.igc.org/papers/liberty.htm "With Liberty and Justice for Some"]. In Zimmerman, Michael; Callicott, Baird; Warren, Karen; Klaver, Irene; Clark, John. ''Environmental Philosophy: From Animal Rights to Radical Ecology'' (4th ed.), Pearson. {{ISBN|978-0131126954}}.</ref><ref>{{cite journal |last1=Wolff |first1=Jonathan |title=Libertarianism, Utility, and Economic Competition |journal=Virginia Law Review |date=22 October 2006 |url=http://www.virginialawreview.org/content/pdfs/92/1605.pdf |url-status=dead|archive-url=https://web.archive.org/web/20130112210848/http://www.virginialawreview.org/content/pdfs/92/1605.pdf|archive-date=12 January 2013|access-date=10 February 2020 |ref=Wolff 2006}}</ref><ref name="Fried 2009">{{cite book|title=The Progressive Assault on Laissez Faire: Robert Hale and the First Law and Economics Movement|last=Fried|first=Barbara|publisher=Harvard University Press|year=2009|page=50|isbn=978-0674037304}}</ref><ref name="Bruenig October 2013">{{cite web|url=https://www.demos.org/blog/10/28/13/libertarians-are-huge-fans-economic-coercion|archive-url=https://web.archive.org/web/20190218082051/https://www.demos.org/blog/10/28/13/libertarians-are-huge-fans-economic-coercion|title=Libertarians Are Huge Fans of Economic Coercion|last=Bruenig|first=Matt|publisher=Demos|date=28 October 2013|archive-date=18 February 2019|access-date=19 August 2016}}</ref><ref name="Bruenig November 2013">{{cite web|url=http://www.demos.org/blog/11/17/13/libertarians-are-huge-fans-initiating-force|archive-url=https://web.archive.org/web/20181215065938/https://www.demos.org/blog/11/17/13/libertarians-are-huge-fans-initiating-force|title=Libertarians are Huge Fans of Initiating Force|last=Bruenig|first=Matt|publisher=Demos|date=17 November 2013|archive-date=15 December 2018|access-date=19 August 2016}}</ref> The NAP has been criticized as [[circular reasoning]] and a rhetorical obfuscation of the coercive nature of [[Right-libertarianism|right-libertarian]] property law enforcement because the principle redefines aggression in their own terms.<ref name="Reiman 2005">{{cite journal|title=The Fallacy of Libertarian Capitalism|last=Reiman|first=Jeffrey H.|year=2005|journal=Ethics|volume=10|issue=1|pages=85–95|doi=10.1086/292300|jstor=2380706|s2cid=170927490|quote=This progression of ideas must be at least temporarily embarrassed by the obvious fact that the holders of large amounts of property have great power to dictate the terms upon which others work for them and thus in effect the power to "force" others to be resources for them. I place quotation marks around the word "force" since much hinges on whether this power should count as force in the sense used above in the first principle of libertarianism.}}</ref>

=== Moral criticism ===
{{main|Morality}}

==== Positive rights ====
Critics argue that the non-aggression principle is not ethical because it opposes the initiation of force even when they would consider the results of such initiation to be morally superior to the alternatives that they have identified. In arguing against the NAP, philosopher Matt Zwolinski has proposed the following scenario: "Suppose that by imposing a very, very small tax on billionaires, I could provide life-saving vaccination for tens of thousands of desperately poor children. Even if we grant that taxation is aggression, and that aggression is generally wrong, is it really so obvious that the relatively minor aggression involved in these examples is wrong, given the tremendous benefit it produces?"<ref name="Matt Zwolinski"/>

==== Incompatibility with driving and other civilizational necessities ====
Zwolinski also notes that the NAP is incompatible with any practice that produces any pollution, because pollution encroaches on the property rights of others. Therefore, the NAP prohibits both driving and starting fires. Citing [[David D. Friedman]], Zwolinski notes that the NAP is unable to place a sensible limitation on risk-creating behavior, arguing:
{{blockquote|Of course, almost everything we do imposes some risk of harm on innocent persons. We run this risk when we drive on the highway (what if we suffer a heart attack, or become distracted), or when we fly airplanes over populated areas. Most of us think that some of these risks are justifiable, while others are not, and that the difference between them has something to do with the size and likelihood of the risked harm, the importance of the risky activity, and the availability and cost of less risky activities. But considerations like this carry zero weight in the NAP's absolute prohibition on aggression. That principle seems compatible with only two possible rules: either all risks are permissible (because they are not really aggression until they actually result in a harm), or none are (because they are). And neither of these seems sensible.<ref name="Matt Zwolinski"/>}}

Some supporters argue that no one initiates force if their only option for self-defense is to use force against a greater number of people as long as they were not responsible for being in the position they are in. [[Murray Rothbard]]'s and [[Walter Block]]'s formulations of NAP avoid these objections by either specifying that the NAP applies only to a civilized context (and not "lifeboat situations") or that it applies only to legal rights (as opposed to general morality). Thus a starving man may, in consonance with general morality, break into a hunting cabin and steal food, but nevertheless he is aggressing, i.e., violating the NAP, and (by most rectification theories) should pay compensation.<ref>{{cite web |url=https://mises.org/daily/1628 |title=Lifeboat Situations (The Ethics of Liberty, 1982, Chapter 20) |author=Murray N. Rothbard |date=October 2004 |access-date=2011-11-15 }}</ref> Critics argue that the legal rights approach might allow people who can afford to pay a [[sufficiently large]] amount of [[Blood money (restitution)|compensation]] to get away with murder. They point out that local law may vary from proportional compensation to capital punishment to no compensation at all.<ref name="FriedmanMOF1989" />

==== Non-physical aggression ====
Other critics state that the NAP is unethical because it does not provide for the violent prohibition of, and thereby supposedly legitimizes, several forms of aggression that do not involve intrusion on property rights such as verbal<!-- Physical sexual harassment (e.g. unwanted touching) unambiguously violates the nonaggression axiom. --> [[sexual harassment]], [[defamation]], [[boycott]]ing, noninvasive<!-- Invasive striking (e.g. sitdown striking without the consent of the owner (provided ownership was obtained and maintained legitimately) unambiguously violates the nonaggression axiom. --> [[Labour strike|striking]] etc. If a victim thus provoked would turn to physical violence, they would be labeled an aggressor according to the NAP. However, supporters of the NAP state that boycotting<ref name="boycott-FANL">[[Murray N. Rothbard]], "Freedom of Speech," §1 of "Personal Liberty," ch. 6, in "Libertarian Applications to Current Problems," pt. 2 of ''[[For a New Liberty: The Libertarian Manifesto]]'' ([[Auburn, AL]]: [[Ludwig von Mises Institute]], 2006; orig. 1973, 1978), pp. 117–18.</ref><ref name="boycott-TEOL">[[Murray N. Rothbard]], "The Boycott," ch. 18, in "A Theory of Liberty," pt. 2 of ''[[The Ethics of Liberty]]'' ([[New York, N.&nbsp;Y.]]: [[New York University Press]], 1998; orig. 1982), pp. 131–32.&nbsp; ''Cf.'', pp. 77, 79, 240.</ref> and defamation<ref name="libel and slander-FANL">[[Murray N. Rothbard]], "Freedom of Speech," §1 of "Personal Liberty," ch. 6, in "Libertarian Applications to Current Problems," pt. 2 of ''[[For a New Liberty: The Libertarian Manifesto]]'' ([[Auburn, AL]]: [[Ludwig von Mises Institute]], 2006; orig. 1973, 1978), pp. 116–17.</ref><ref name="libel and slander-TEOL">[[Murray N. Rothbard]], "Knowledge, True and False," ch. 16, in "A Theory of Liberty," pt. 2 of ''[[The Ethics of Liberty]]'' ([[New York, N.&nbsp;Y.]]: [[New York University Press]], 1998; orig. 1982), pp. 121–122, 126–28.</ref> both constitute [[freedoms of speech]] and that boycotting,<ref name="boycott-FANL" /><ref name="boycott-TEOL"/> noninvasive striking<ref name="boycott-TEOL"/><ref name="anti-strike laws">[[Murray N. Rothbard]], "Anti-Strike Laws," §4 of "Involuntary Servitude," ch. 5, in "Libertarian Applications to Current Problems," pt. 2 of ''[[For a New Liberty: The Libertarian Manifesto]]'' ([[Auburn, AL]]: [[Ludwig von Mises Institute]], 2006; orig. 1973, 1978), pp. 102–04.&nbsp; ''Cf.'', pp. 93, 118.&nbsp; ''Cf.'', ''[[The Ethics of Liberty]]'', pp. 77, 132.</ref> and noninvasive discrimination<ref name="discrimination">[[Murray N. Rothbard]], "Street Rules," §2 of "The Public Sector, II: Streets and Roads," ch. 11, in "Libertarian Applications to Current Problems," pt. 2 of ''[[For a New Liberty: The Libertarian Manifesto]]'' ([[Auburn, AL]]: [[Ludwig von Mises Institute]], 2006; orig. 1973, 1978), pp. 255–256.&nbsp; ''Cf.'', pp. 103, 128.</ref> all constitute [[freedoms of association]] and that both freedoms of association and of speech are nonaggressive. Supporters also point out that prohibiting physical retaliation against an action is not itself [[wikt:condonement|condonement]] of said action,<ref name="morality v. legality">[[Murray N. Rothbard]], in "Natural Law and Natural Rights," ch. 4, in "Introduction: Natural Law," pt. 1 of ''[[The Ethics of Liberty]]'' ([[New York, N. Y.]]: [[New York University Press]], 1998; orig. 1982), p. 24. {{blockquote|"Right" has cogently and trenchantly been defined by Professor Sadowsky: <blockquote>When we say that one has the right to do certain things we mean this and only this, that it would be immoral for another, alone or in combination, to stop him from doing this by the use of physical force or the threat thereof. We do ''not'' mean that any use a man makes of his property within the limits set forth is necessarily a ''moral'' use?</blockquote>

Sadowsky's definition highlights the crucial distinction we shall make throughout this work between a man's ''right'' and the morality or immorality of his exercise of that right.  We will contend that it is a man's right to do whatever he wishes with his person; it is his right not to be molested or interfered with by violence from exercising that right.  But what may be the moral or immoral ways of exercising that right is a question of personal ethics rather than of political philosophy—which is concerned solely with matters of right, and of the proper or improper exercise of physical violence in human relations.  The importance of this crucial distinction cannot be overemphasized.  Or, as Elisha Hurlbut concisely put it: "The exercise of a faculty by an individual is its only use. The manner of its exercise is one thing; ''that'' involves a question of morals. The ''right'' to its exercise is another thing."}} ''Cf.'', pp. 25, 77, 79, 98 (note 2), 100–101, 107, 121, 124 (note 2), 127, 131–133, 136, 138, 142, 146, 151–153, 173–174, 220, 222.</ref> and that generally there are other, nonphysical means by which one can combat social ills (e.g., discrimination) that do not violate the NAP.<ref name="boycott-TEOL"/><ref name="discrimination"/> Some supporters also state that while most of the time individuals choose voluntarily to engage in situations that may cause some degree of mental battering, this mental battering begins to constitute unauthorized physical overload of the senses (i.e., eardrum and retina) when it cannot be avoided and that the NAP at that point does apply.<ref name="dutton_2006"/>

Many supporters consider verbal and written threats of imminent physical violence sufficient justification for a defensive response in a physical manner.<ref name="verbal/written threats of physical force">[[Murray N. Rothbard]], "Self-Defense," ch. 12, in "A Theory of Liberty," pt. 2 of ''[[The Ethics of Liberty]]'' ([[New York, N. Y.]]: [[New York University Press]], 1998; orig. 1982), pp. 77–78, 80. ''Cf.'', ''[[For a New Liberty]]'', p. 27.</ref><ref name="use of/threat of/substitution for physical force">[[Linda & Morris Tannehill]], ''[[The Market for Liberty]]'' ([[San Francisco]]: [[Fox & Wilkes]], October 1993; orig. March 1970), pp. 4, 10.&nbsp; ''Cf.'', pp. 77, 80.</ref> Those threats would then constitute a legitimate limit to permissible speech. Because freedom of association entails the right of owners to choose who is permitted to enter or remain on their premises, legitimate property owners may also impose limitation on speech. The owner of a theatre wishing to avoid a stampede may prohibit those on her property from calling 'fire!' without just cause.<ref name="yelling fire">[[Murray N. Rothbard]], "Property Rights and "Human Rights"," §5 of "Property and Exchange," ch. 2, in "The Libertarian Creed," pt. 1 of ''[[For a New Liberty: The Libertarian Manifesto]]'' ([[Auburn, AL]]: [[Ludwig von Mises Institute]], 2006; orig. 1973, 1978), pp. 52–53.&nbsp; ''Cf.'', pp. 85–86, 115.</ref> However, the owner of a bank may not prohibit anyone from urging the general public to a [[bank run]], except insofar as this occurs on the property of said owner.<ref name="boycott-FANL"/>

In a 1948 interview with Donald H. Kirkley for the [[Library of Congress]], [[H. L. Mencken]], a writer who influenced many libertarians, puts an ethical limit on the freedom of speech:
{{blockquote|I believe there is a limit beyond which free speech cannot go, but it's a limit that's very seldom mentioned. It's the point where free speech begins to collide with the right to privacy. I do not think there are any other conditions to free speech. I've got a right to say and believe anything I please, but I have not got a right to press it on anybody else. [...] Nobody's got a right to be a nuisance to his neighbors.<ref>{{cite web |url=http://blog.infinitemonkeysblog.com/?q=node/7319 |title=Fred Phelps, Freedom of Speech and "the Last Limits of the Endurable" (Ben's Blog on Infinite Monkeys, Fri, 10/08/2010) |author=Ben's Blog |access-date=2011-11-26 |archive-url=https://web.archive.org/web/20120111041922/http://blog.infinitemonkeysblog.com/?q=node%2F7319 |archive-date=2012-01-11 |url-status=dead }}</ref>}}

Supporters also consider physical threats of imminent physical violence (e.g. pointing a firearm at innocent people, or stocking up nuclear weapons that cannot be used discriminately against specific individual aggressors) sufficient justification for a defensive response in a physical manner. Those threats would then constitute a legitimate limit to permissible action.<ref name="physical threats of physical force-TEOL">[[Murray N. Rothbard]], "Self-Defense," ch. 12, in "A Theory of Liberty," pt. 2 of ''[[The Ethics of Liberty]]'' ([[New York, N.&nbsp;Y.]]: [[New York University Press]], 1998; orig. 1982), pp. 77–78, 80.&nbsp; ''Cf.'', pp. 81–82, 189–191, 194.</ref><ref name="physical threats of physical force-FANL">[[Murray N. Rothbard]], "The Nonaggression Axiom," §1 of "Property and Exchange," ch. 2, in "The Libertarian Creed," pt. 1 of ''[[For a New Liberty: The Libertarian Manifesto]]'' ([[Auburn, AL]]: [[Ludwig von Mises Institute]], 2006; orig. 1973, 1978), p. 27. ''Cf.'', p. 335.</ref><ref name="use of/threat of/substitution for physical force"/>

=== Inconsistency criticisms ===
{{main|Applied ethics}}

==== Natural resources and environmental pollution ====
Critics argue it is not possible to uphold NAP when protecting the [[Natural environment|environment]] as most [[pollution]] can never be traced back to the party that caused it. They therefore claim that only general broad government regulations will be able to protect the environment. Supporters cite the theoretical "[[tragedy of the commons]]"{{Clarify|date=May 2019}} and argue that [[free-market environmentalism]] will be much more effective in conserving nature.<ref>{{cite web |url=http://www.cato.org/pubs/journal/cj2n1/cj2n1-2.pdf |title=Law, Property Rights, and Air Pollution (Cato Journal, Vol. 2, No. 1, Spring 1982, pp. 55–99) |author=Murray N. Rothbard |access-date=2011-11-24 |url-status=dead |archive-url=https://web.archive.org/web/20110911075448/http://www.cato.org/pubs/journal/cj2n1/cj2n1-2.pdf |archive-date=2011-09-11 }}</ref><ref>{{cite web |url=http://libertarianpapers.org/articles/2011/lp-3-10.pdf |title=Free Markets, Property Rights and Climate Change: How To Privatize Climate Policy (Libertarian Papers, Vol. 3, No. 10, 2011, pp. 1–29) |author=Graham Dawson |access-date=2011-12-04 }}</ref>
Political theorist [[Hillel Steiner]] emphasizes that all things made come from natural resources and that the validity of any rights to those made things depends on the validity of the rights to the natural resources.<ref>{{cite web |url=http://bleedingheartlibertarians.com/2012/04/left-libertarianism-and-the-ownership-of-natural-resources/ |title=Left-Libertarianism and the Ownership of Natural Resources (Bleeding Heart Libertarians, April 24, 2012) |author=Hillel Steiner |date=24 April 2012 |access-date=2012-07-07 }}</ref> If land was stolen then anyone buying produce from that land would not be the legitimate owner of the goods. Also, if natural resources cannot be privately owned but are, and always will be, the property of all of mankind then NAP would be violated if such a resource would be used without everybody's consent (see the [[Lockean proviso]] and [[free-market anarchism]]).<ref>{{cite web |url=http://bleedingheartlibertarians.com/2012/04/natural-rights-and-natural-stuff/ |title=Natural Rights and Natural Stuff (Bleeding Heart Libertarians, April 23, 2012) |author=Eric Mack |date=23 April 2012 |access-date=2012-07-07 }}</ref> Libertarian philosopher Roderick Long suggests that, as natural resources are required not only for the production of goods but for the production of the human body as well, the very concept of [[self-ownership]] can only exist if the land itself is privately owned.<ref>{{cite web |url=http://bleedingheartlibertarians.com/2012/04/self-ownership-and-external-property/ |title=Self-Ownership and External Property (Bleeding Heart Libertarians, April 25, 2012) |author=Roderick Long |date=26 April 2012 |access-date=2012-07-07 }}</ref>

==== Relative rather than absolute concept ====
[[Consequentialist libertarian]] [[David D. Friedman]], who believes that the NAP should be understood as a relative rather than absolute principle, defends his view by using a [[Sorites argument]]. Friedman begins by stating what he considers obvious: a neighbor aiming his flashlight at someone's property is not aggression, or if it is, it is only aggression in a trivial technical sense. However, aiming at the same property with a gigawatt laser is certainly aggression by any reasonable definition. Yet both flashlight and laser shine photons onto the property, so there must be some cutoff point of how many photons one is permitted to shine upon a property before it is considered aggression. However, the cutoff point cannot be found by deduction alone because of the [[Sorites paradox]], so the non-aggression principle is necessarily ambiguous. Friedman points out the difficulty of undertaking any activity that poses a certain amount of risk to third parties (e.g., flying) if the permission of thousands of people that might be affected by the activity is required.<ref name=FriedmanMOF1989_ii>{{cite web |url=http://www.daviddfriedman.com/Libertarian/Machinery_of_Freedom/MofF_Chapter_41.html |title=Problems (The Machinery of Freedom, 1989, Chapter 41) |author=David D. Friedman |access-date=2013-01-03 }}</ref>

== See also ==
{{div col|colwidth=30em}}
* [[Ahimsa]]
* [[Harm principle]]
* [[Law of equal liberty]]
* [[Libertarian pledge]]
* [[Libertarian theories of law]]
* [[Negative liberty]]
* [[Nonviolent resistance]]
* ''[[Primum non nocere]]''
* [[Wiccan Rede]]
* [[Pacifism]]
* [[Silver Rule]]
* [[Taxation as theft|Taxation is theft]]
* [[Victimless crime]]
* [[Voluntaryism]]
{{div col end}}

==Notes==
{{reflist|group=note}}

== References ==
<!-- This article uses the Cite.php citation mechanism. If you would like more information on how to add footnotes to this article, please see http://meta.wikimedia.org/wiki/Cite/Cite.php -->
{{reflist}}

== External links ==
* [http://archive.lewrockwell.com/block/block26.html The Non-Aggression Axiom of Libertarianism] by [[Walter Block]] at LewRockwell.com.
* [https://web.archive.org/web/20050802010353/http://www.isil.org/resources/introduction.html The Philosophy of Liberty], an animated production which derives a [[Libertarianism in the United States|libertarian]] philosophy from the principle of [[self-ownership]].  Central to this is the non-aggression principle.
* [http://antiwar.com/who.php Antiwar.com], a website devoted to opposing aggressive war, imperialism and assaults on freedom associated with both. The editors describe their political view as libertarian.
* [https://www.zeroaggressionproject.org ''Zero Aggression Project''], a website devoted to teaching the concepts of the zero aggression principle with easy to use Heuristics and a project of DownsizeDC.org

{{anarcho-capitalism}}

{{DEFAULTSORT:Non-Aggression Principle}}
[[Category:Anarcho-capitalism]]
[[Category:Ethical principles]]
[[Category:Libertarian terms]]
[[Category:Libertarianism in the United States]]
[[Category:Social concepts]]