What is the Zero Aggression Principle (ZAP)?

Zero Aggression Principle

The Zero Aggression Principle (ZAP)*  is the key libertarian idea. It says — Don’t aggress against others, personally or politically. This means…

  • Limit force to defensive purposes (e.g. criminal justice)
  • Let people live by their own conscience, provided they permit the same to others.

Libertarians want a world where governments only use force defensively — no aggression! If this idea attracts you then please join us. Subscribe! And share this page with others!

Perry Willis

About the Author

Perry Willis

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Perry Willis is the co-founder of the Zero Aggression Project and Downsize DC. He was the National Director of the Libertarian National Committee on two occasions, and ran two Libertarian Party presidential campaigns. He has an extensive background in marketing and fundraising, and has ghost written direct mail appeals for numerous luminaries, including Karl Hess, Ron Paul, Charlton Heston and Harry Browne.

Jim Babka

About the Author

Jim Babka

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Jim Babka is co-founder of the Zero Aggression Project and President of DownsizeDC.org, Inc. He’s an author and former talk show host.
Previously, he was the President of RealCampaignReform.org, Inc., defending free press rights all the way to the Supreme Court. He and Susie are the proud, home-schooling parents of three teenagers. He enjoys theology, UFC, target practice, and Tai Chi.

* – Zero Aggression Principle and the acronym ZAP were first coined by L. Neil Smith as an alternative name for the Non-Aggression Principle with its too pacifist-sounding, lethargic acronym, NAP.

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Show Comments 25


  1. This brings up a couple of questions.To start how far is one supposed to go in avoiding force when faced with a force directed in their direction from another source?e.g.1 I have a neighbor whose dog runs free and finds my lawn the best place to do his business. Do I go to the neighbor and ask him to take control of his dog? The neighbor asks can you prove it is my dog that does that? Later the neighbor is taking a walk and the dog tags along and makes a deposit on my lawn with the neighbor is watching. e.g.2 I am walking down a sidewalk or a mall with my wife and some teenager acting wild crash into my wife nearly knocking her off of her feet, or a man, or woman for that matter, has been drinking a little much and the same result to my wife. I am a southern raised gentleman and have been taught that when accompanying a lady her protection is his obligation and duty.
    Tell me, what am I to do in these scenarios ? Did Jesus take the zero aggression approach? If so why did he tell his disciples to keep a sword (the weapon of the day) in their cloak. Was that the zero aggressive stance?
    I am all for live and let live, but a man has to stand up for what is right and fair. If more men stood up for what they offer endless lip service about our government would not be in the condition it is in now and we would not be facing the threat that we now face with the influx of Islams. It has been stated by one who has studied the facts that by 2020 there would be enough Islams in this country to take over the government at the polls. Tell me that is not scary. Now is this where we are to show tolerance, should we turn the other cheek? Or should we follow the example of the American men of the 30s,40s and 50s? Their approach was by no means zero aggression they stood up for what they believed and what was right and America was one hell of a lot more stable and happier than it is today. So tell me what am I to do, What are you to do? America needs men not wimps, it needs defending not tolerating opposing forces. It needs it’s citizens to stand up and yell at the top of your voice that enough is enough and the BS stops here. If you oppose this description than you don’t deserve to be in America and you assuredly do not have the right to call yourself an American.

    1. Thanks for the question Ed. The word aggression has to do with initiating force. Defensive force is still permitted.
      It’s very important to grasp this, so I’m going to repeat it — initiated force (throwing the first punch) is what’s wrong, NOT throwing a punch in response, which is defensive, and therefore permitted.
      It’s also important to NOT confuse the word aggression with the word assertiveness. A functioning society needs assertive, competitive people. It does NOT need people who aggress against others, or who ask politicians to do that for them. I hope this makes things clearer, and answers your question.

  2. First, you did not adequately answer Ed regarding the cancerous growth of intolerant and terrorist Islam. Does ZAP mean waiting until they get the upper hand before acting defensively?
    Secondly, most libertarian politicians I’ve heard are in favor of eliminating government agencies like the EPA and FDA on the grounds that they stifle business. Yet who can argue against clean air, clean water and safe food and drugs. Agencies such as these have enforcement powers, weak as they are. But again what would be the ZAP defensive posture against pollution and unsafe products by industry?
    I like the idea of ZAP but you guys need to apply your own principles and think through some of these issues we face every day.

    1. Hi Bob. Thanks for the questions. We have a short article that covers our basic approach to regulation here: How to think about regulation.
      The air pollution aspect of this is a bit trickier, but a summary statement can be made. Pollution is trespass, and therefore an appropriate area for government action. The trick comes in creating regulations that actually address the problem without falling victim to regulatory capture. Regulatory capture is when regulations are written in such a way as to serve special interests. One way to reduce that problem is to reduce the number of things The State is involved in. Another way would be to have voluntary funding. This would force the government to respond to consumer demands, thereby limiting their behavior. Alas, the details of this cannot be addressed in a comment. We hope to write more about it for the site at a future date.
      With regard to radical Islam — there is ZERO evidence that political government has done anything to control this problem. But there is MASSIVE evidence that they have done much to foster it. For instance, it’s pretty clear that our politicians were essentially co-founders of ISIS. They created the conditions for its birth, and then provided training and weapons. We think the full history of government intervention in foreign affairs is so bad that a conclusion can be drawn. Political government must get out of the intervention business. We review this history here: Has U.S. military power been a force for good or evil?
      Thanks for the questions. We hope you will continue to consider our work and mission.

      1. Perry, in my opinion the term government is not applied correctly. The real government is the grand jury, local elected sheriff, local elected judge, and the random lot chosen jury (Common Law). A national government is only needed to coordinate the national defence and international trade. The meaning of our original Constitution was government = a limited protectorate of God given individual rights. The income tax amendment and the laws to enforce it are the primary source of our national government power. The Federal Reserve Banking Act is the co conspirator that establishes the complete compliance to our debt slave national citizenship. A national grand jury could in theory bring down the abuse of federal power but we need more people to wake up to the need stop the Feds and the need to abandon collectivist ideas about the role of government. With that in mind we need what the Convention of States Project is proposing. and Article V States Convention to amend our US Constitution with new limits on Federal powers. http://www.conventionofstates.com/

        1. Hi Karl. We would agree on the importance of juries as institutions. But we think all of the other positions you list should be subordinate to that institution.

      2. Perry, thanks for your reply including the informative links that you included. I’m somewhat familiar with the sad history of our foreign aid and your post on regulation gave me some food for thought.
        Regarding foreign aid/policy I have for some time been advocating that since we have such an abysmal track record in this area that we should eliminate it all together. I put forward some ideas in a blog post, https://flbob42.wordpress.com/2011/02/13/end-all-foreign-aid-now/ and I fully agree that we should get out of the intervention business not necessarily to become isolationists but to fully participate and encourage other countries to participate in free and fair trade. At the same time we need to have a strong defense.
        The idea of giving, for example, $3.5B tax dollars annually to Egypt, a country that does not share our values, does not like us and is mostly controlled by the Muslim Brotherhood is repugnant to me. The Muslim Brotherhood, by the way, funds and controls most of the Islamic organizations in the U.S. and has been raising them up to push their Sharia Law agenda.
        Lately, the Iranian nuclear deal is yet another example of poor foreign policy. This deal has a foundation of quicksand and enough loopholes to float an aircraft carrier through. (Sorry for the mixed metaphors)
        As for business regulation I fully understand where you are coming from and wish that your conclusion to “Leave their regulation to consumers, investors, competition, and insurance companies” would work. Unfortunately this works only sometimes. As long as big industry and their lobbies have the financial upper hand with our politicians and often author legislation favoring their position, consumer groups, etc. will have little influence. Cases such as efforts to remove toxic chemicals from food and other products along with efforts to get companies to curb environmental pollution not leaving the cleanup and the effects of disease up to the tax payer to remedy are numerous and legendary. These cleanup efforts are after the fact while regulation needs to be proactive and before the fact.

        1. Hi Bob. I think we largely agree. As I said in my previous reply, pollution is the one area where prior-restraint forms of regulations might be justified, but great care must be taken to make sure industry does not craft these regulations to benefit themselves. Such care is more likely if The State is vastly reduced, perhaps only to that function. If there’s too much that we need to keep our eyes on then we will surely fail. Corruption benefits from largeness.

    2. The definition of defensive violence has always been the question. As you point out, the use of a preemptive first strike depends on your point of view. This is why ZAP libertarian thinking is childish and dangerous. I think the Jews in Nazi Germany should have used violence to free themselves. History proves me correct but ZAP says I am wrong. The real value of Libertarian thinking is where it values the individual as the primary consideration and the State as a limited protectorate of the individual. The collective (State) has no rights. Only living, breathing, individuals have rights. From this point of view must come the VOLUNTARY actions of individuals to protect the environment and go to war if needed.

      1. Hi Karl. All human questions suffer from a knowledge problem. This is just as true of your preferred formulation as ours. How do you define making the individual the primary consideration? How do you limit the state’s protectorate of the individual/ These are likewise definitional problems. But I do not consider your position childish just because it has this difficulty. I simply suspect that you will have to rely on some human institution for defining what your terms mean. For us, that institution is the unanimous verdict of a jury. Does a jury believe you initiated force? If so, then you’ve committed a crime. If not, then you used force defensively and are therefore innocent of any crime.

    3. I agree; we need to nip problems in the bud. Start dealing with ISIS now, while we still can, wherever they are. Of course, the nutless wonders in D.C. won’t do that.This concept of letting other countries deal with their problems there, is BULLSHIT. We -the good guys- SHOULD be the world’s police so that the lunatics can’t run the asylum. No more Neville Chamberlains. Have we learned NOTHING? This is my only issue with Libertarians. Can I get an amen.

    4. Millions of Muslims have found peace in converting to Christianity. There is nothing wrong with asserting the Truth of the Gospel to Muslims and leading them to a truly peaceful but very assertive love for God and man. The fact that far too many Christians are totally passive with their faith is truly tragic with deadly consequences.

  3. To fellow Christians: We are not to use violence even in self-defense. At the last supper Jesus said, “Now let whoever has a coat sell it and buy a sword.” The apostles said, “We have two swords,” and Jesus replied, “It is enough.” One of those swords was used by a disciple during Jesus’ arrest, as Jesus intended, so that He could tell the disciple, “Put away your sword. He who lives by the sword dies by the sword. Do you think that I could not call upon my Father and at once have 12 legions of angels? But then how would we fulfill the scriptures?” The scripture is “He shall be peace.”

    Yes, others will take advantage of us, but we can offer up our suffering and injustice done to us upon the cross with Jesus Christ as part of His sacrifice, for our salvation and that of the whole world. This redemptive sacrifice is especially explicit for Catholics who are part of the body of Christ through Holy Eucharist. As St. Paul says, “Bear your share of the suffering which the Gospel entails.” This redemptive suffering is our strongest witness to truth of the Gospel, and the love of God, even for our enemies.

  4. It is not possible to come up with a simple explanation to equate fraud with initiating force. We have two different words to convey two different meanings. Most people have an adequate understanding of the meanings of those words and “appropriate defensive actions”, so very little explaining and arguing would be needed to convey this version of ZAP: “Do not initiate force or fraud against others and take only appropriate defensive actions against anyone who initiates force or fraud against you.”

    1. No one is arguing to do away with borders. Borders define political jurisdiction. The argument is whether borders can morally be used to limit the freedom of association.

    1. You own your yard. You don’t own the country. Other people who share this country with you DO want foreign visitors without having to ask your permission to associate with them. Their freedom of association is just as important as your freedom to control your property.

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