
Baby humans need frequent naps. Also, baby libertarians need NAPs (Non-Aggression Principles). In libertarian lore, the Non-Aggression Principle says something like this:
NAP: It is always wrong to initiate force against other people.
Variations on that are known as NAPs. NAPs are good for baby libertarians, because they help bring some statists into libertarianism, once you see that almost all government policies initiate force against people.
But it’s really only baby libertarians who need NAPs, because NAP is an oversimplified and blunt instrument. As written above, it is obviously false. One can qualify it to make it not obviously false, but once one adds enough qualifications, it can’t (plausibly) be used anymore to construct the sort of simple deductive proofs that baby libertarians desire.
Of course, one can still appeal to NAp, the Non-Aggression presumption, which merely requires that one have a good moral reason for initiating coercion against others.
Now, since some of my audience are libertarians, and some of those are probably toddler libertarians who are ready to do less NAPing, let me say more to help them get beyond their NAPs.
Qualified NAPs
Actually, there is a simpler moral theory to which NAP represents a qualified version. So let’s start with the simplest view in the neighborhood:
NAP0 (a.k.a. “pacifism”): It is always wrong to use force against others.
That’s obviously false, and almost no one (including libertarians) believes it, because there are cases of justified self-defense and defense of innocent third parties involving use of force. So we make our first qualification, resulting in:
NAP1: It is wrong to use force against others, unless doing so is necessary to stop someone else from using force against others.
But in fact, almost no one, not even libertarians, believes NAP1 either. It too is obviously false. There are many examples showing this.

Example 1: I promise to mow Ayn Rand’s lawn in exchange for her grading some of my papers. Rand grades the papers, with copious helpful comments (pointing out where students are evading reality, hating the good for being the good, etc.), but then I don’t mow the lawn. I also refuse to do anything to make amends for my failure. Haha.
Almost everyone, including libertarians, thinks that the state can force me to mow the lawn or otherwise make amends (e.g., pay the money value of a mowed lawn).
Example 2: I start deliberately spreading false rumors that Walter Block is a Nazi. This causes him to be ostracized, lose his job, and be blacklisted by the SJW culture that is academia.
Almost everyone, including most libertarians, agrees that Walter should be able to sue me for defamation in court, and collect damages, coercively enforced, of course.
Example 3: Hans-Hermann Hoppe owns a large plot of land around his house. One day, when he emerges from his house to collect his copy of Reason, he sees me sleeping peacefully in a corner of his lawn. Though I haven’t hurt anyone and (being very thin and meek) pose no physical threat to anyone, Hans is nevertheless irritated, and demands that I get off his lawn. I just plug my ears and go back to sleep.
Almost everyone (especially Hans) thinks that Hans can use force to expel me from his lawn.
Example 4: I have become seriously injured by a hit-and-run driver, and I need to be taken to the hospital immediately. The only available car is Murray Rothbard’s car, but Murray is not around to give permission. (I am also not sure he would authorize saving me.)
Almost everyone thinks it is permissible for me to break into Murray’s car (thus initiating force against his property?) to get to the hospital.

Example 5: Powerful space aliens are going to bomb the Earth, killing 3 billion people, unless you deliver to them one recently-plucked hair from the head of Harry Binswanger. Harry, unfortunately, cannot be persuaded to part with the hair for any amount of money. (He really wants to live up to his name, you see.)
Almost everyone thinks it is permissible to forcibly steal the hair.
Of course, all of these examples are easily accommodated: we just have to add appropriate qualifications and clarifications to our NAP. Once we add the needed qualifications, we arrive at:
NAP6: It is wrong to use force against others, unless:
(i) Doing so is necessary to stop them from using force against others (unless: (a) their force was itself justified by one of the conditions listed herein, in which case it is still wrong to use force against them), or
(ii) It is necessary to enforce a contract, or
(iii) It is necessary to force someone to pay compensation for defamation, or
(iv) It is necessary to stop someone from using someone’s property without the property owner’s consent (unless: (b) the use of the property is necessary, in an emergency situation, to prevent something much worse from happening, in which case it is still wrong to use force against that person), or
(v) It is necessary to prevent some vastly greater harm from occurring.
We’ve added five main qualifications ((i)-(v)) and two meta-qualifications ((a) and (b)). Is NAP6 true at last? Well, it’s hard to say whether we’ve included all needed qualifications and sub-qualifications. At least this latest NAP is no longer obviously false. But it’s so complex that it’s hard to claim that it’s obviously true either, and it’s really unclear why someone else cannot propose another qualification, say, “… or (vi) it is necessary to stop the poor from going without health care.”
Libertarians will disagree with qualification (vi), but they don’t have a good reason to resist it, if their libertarianism just rests on a NAP. We added (i)-(v) and (a) and (b) in order to accommodate our ethical intuitions (as rationality demands), but then why can’t a leftist add (vi) to accommodate their intuitions?
In other words, NAP6 might be true, but you don’t establish anything interesting by appealing to it, since someone with different starting intuitions can just as reasonably modify NAP6 to fit those intuitions.
Time for Desperate Rationalizations?

Now, I am aware that some toddler libertarians are going to claim that the NAP isn’t really so complicated, because (they will claim) one or more of the qualifications I have included in NAP6 are really redundant or wrong. For example, maybe some doctrinaire libby will say that (iii) should be deleted because defamation is actually okay.
Another unreasonable person will claim that (v) is wrong because actually we should just let the aliens do their worst.
Another desperate person will try to claim that (ii) and (iv) aren’t needed because contract breaches and sleeping on someone’s lawn are “really” a form of force, and thus we won’t really be “initiating force” in examples 1 and 3.
I don’t want to spend time debating those sorts of claims, because I find it silly and tedious. Therefore, I am simply going to report my own reaction before moving on, which is that
- Those moves are silly on their face. You wouldn’t think of any of those things if you were just trying to faithfully describe reality. You’d only think of them if you’re trying to cling to the initial verbal formulation of an ideological position.
- If you’re going to do things like that — like expanding the concept of “force”, or making radically implausible normative assertions — then that’s really no better than statists who do similar things, such as claiming that poverty is a form of coercion, claiming that there’s nothing prima facie wrong with theft, etc.
Liberty without NAPs
You know what I’m going to say next, so I’ll just say it quickly so we can all go home. We don’t need some sweeping, absolutist moral theory. The rational way of evaluating possible government policies is to (i) start by noting the prima facie moral reasons against them, (ii) examine the reasons for the policies, according to those who support them, then (iii) apply moral common sense to judge whether the latter reasons are good enough to justify the bad or wrong-making aspects of government policies.
E.g., it’s usually wrong to take people’s money without their consent. Q: is it a good enough reason for doing so that one can help the poor by giving the money to them? Think about how we’d react if I decided to go out and mug people, then send the money off to UNICEF. This wouldn’t go over very well in most circles. So no, not a good enough reason.
Rationalism Is for Robots
If you’re trying to “prove” a political conclusion by deriving it from some axioms, then you may have succumbed to an intellectual disorder sometimes called “rationalism”. (The disorder that, e.g., Spinoza famously suffered from.) This disorder causes you to think that the way people find out stuff about the world is by sitting in an armchair, pronouncing the first sweeping, simplistic generalization that occurs to them that sort of seems vaguely plausible for the first ten seconds that you think about it, robotically deducing consequences from that, and then dogmatically embracing every absurd consequence that comes out of it.
That isn’t a way to understand the actual world. That almost never works. And by the way, I’m not deducing that it doesn’t work from an axiom; I’m saying that in practice, in actual cases that we observe, that approach almost never goes well. Virtually 100% of the time, the sweeping generalization that seems plausible to you at first glance is wrong. (That happens because reality is actually complex. Orders of magnitude more complex than a typical human’s typical thoughts. I found that out by having many years of experience with reality.)
The rationalist approach is a way to go spectacularly wrong and wind up saying all sorts of ridiculous things. (Examples: almost every philosopher in history.) It’s also, secondarily, a way of convincing other people that you’re crazy. Normal people then tend to just ignore your insane “proof”s.
I suppose this comment would place me in the category of those who claim NAP isn’t so complicated. My understanding of NAP is that it states that one should not initiate acts of force/aggression against a person or their property. Most Rothbardians take the latter to subsume the former, so we could just say “property” and it leave it at that. The way the NAP is formulated by Rothbard and others is, to the best of my understanding, crucially grounded in property rights. The use of “initiate” is also important, because including that allows for instances of self-defense, coercively seeking restitution for damage done, etc.
Applying this to your examples:
1. You initiate an act of aggression against Ayn Rand because you entered into a service contract with her and then violated it – an act of fraud where you have stolen her labor time. According to my understanding of the NAP, she is then justified in seeking restitution, through coercive means if necessary.
2. You do not commit an act of aggression against Walter Block by defaming him, since you are not harming his physical person or property. Walter Block has to defend his character by other means.
3. Hans Herman-Hoppe is not initiating violence by kicking you off his lawn; he’s responding to your initial act of aggression where you violated his property rights.
4. You steal Murry Rothbard’s car *knowing* that you are committing an act of aggression and that you will have to provide restitution for it, but you accept this consequence because of the dire circumstances. If you did not acknowledge that you are committing an act of aggression, or do not accept this consequence, Murray would be justified under the NAP to seek restitution, coercively if necessary.
5. You likewise pluck a hair from Harry’s head knowing that you will have to provide restitution to him if he insists on it (and knowing that no reasonable arbitrater would make you pay him more than a quarter in recompense, if they even agreed to arbitrate the case at all).
So I think you have simply misinterpreted the NAP; in particular, that aggression is defined in terms of aggression against a person or their property, and what is meant by “initiate”. When understood correctly, I think the application of the NAP to your examples matches your intuitions about the proper outcome in each case except the defamation one. My own intuition about this case is that the difference between name-calling and “defamation” is simply a matter of degree rather than kind. Neither is an act of aggression because it does not violate anybody’s property rights. I think (but admittedly might be very wrong here) that many liberterians agree with my perspective.
I also think you can take either a rationalist or a “moral commensensical” approach and arrive at the NAP – I’m not arguing for either here. I believe you’ve just misinterpreted the NAP and are therefore presenting something of a straw man in this post. Though to be fair, I’ve certainly heard libertarians advance this same naive misconstrual of the NAP, so I can understand why you might have received this impression. I’d recommend reading Ch. 6, Sec. 16 of Man, Economy, and State, on “Human rights and property rights” for Rothbard’s attempt to ground human rights in property rights. Ch. 2, Sec. 13, “Enforcement against invasion of property” is also highly relevant here.
Thanks for this blog! I always look forward to your posts.
Daniel, the question is whether it is morally wrong to pluck a hair from Harry to save three billion people. If it is not wrong, then the NAP is not a moral principle. My intuition is that it is not wrong, even if we don’t restitute Harry.
My intuition relies on guessing the welfare loss to Harry and the welfare gain to the three billion people. An arbitrator judging the case would make a similar guess.
Why should the burden of saving the 3BN people from aliens fall only on Harry by happenstance? It seems to me that they all benefited from the hair (by not being obliterated) and so they morally owe him restitution.
It’s maybe simpler if we take a different example — if aliens credibly demanded 3M cows or diamonds, it would be morally acceptable (even obligatory) to immediately provide that even without the consent of the property owners. But there is no moral sense that the burden of buying off the aliens should just so happen to fall on ranchers or diamond minders.
Consider also if the aliens credibly demand 3000 cows per month rather than as a one-off. Again, intuition strongly suggests that we ought to to do it, but that imposing this cost on ranchers for the benefit of everyone else is immoral.
I agree that it would be immoral to impose the cost on the ranchers in this situation, but I wouldn’t say that it would be immoral no matter what: After all, suppose the aliens (and these are weird aliens) made it a condition that the ranchers are not to be compensated.
Moral principles are designed to guide everyday life. They are not designed for alien invasions.
But alien invasions don’t negate morality. If an alien invasion happened tomorrow, morality would not disappear. if an alien invasion killed your moral system, than it would not be a very good moral system. Take Schroedinger’s Cat in Physics. https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat
https://plato.stanford.edu/entries/thought-experiment/
“Daniel, the question is whether it is morally wrong to pluck a hair from Harry to save three billion people. If it is not wrong, then the NAP is not a moral principle. My intuition is that it is not wrong, even if we don’t restitute Harry.
My intuition relies on guessing the welfare loss to Harry and the welfare gain to the three billion people. An arbitrator judging the case would make a similar guess.”
Nope, it is still wrong to pluck a hair from Harry. But it is a very small wrong.
So what will happen? If you decide to steal the hair, you make a very small wrong to save 3 billion people. NAP points out that you or 3 billion people owe Harry. And also NAP points out that before you forcibly steal the hair from Harry, you need to make an offer to purchase it from him. If stealing was a legitimate action, Huemer wouldn’t have to think peaceful ways to acquire Harry’s hair in the first place. What Huemer did at the ex.5 is a “negative conclusion from an affirmative premise”
“Example 5: Powerful space aliens are going to bomb the Earth, killing 3 billion people, unless you deliver to them one recently-plucked hair from the head of Harry Binswanger. Harry, unfortunately, cannot be persuaded to part with the hair for any amount of money. (He really wants to live up to his name, you see.)
Almost everyone thinks it is permissible to forcibly steal the hair.”
You see Huemer says that “it is unfortunate that Harry cannot be persuaded”. This means that if Harry persuaded for some amount of money it will be better. Why is it a better option than stealing? The answer is clear. Because it is not violating the NAP.
typo correction: “This means that if Harry was persuaded for some amount of money it would be better. “
Daniel,
you’re defining ‘aggression’ in function of the underlying property rights in order to avoid criticism. In doing so, as noted by Huemer himself, you are over-expanding the concept of aggression, and in this case, up to the point that you are not really appealing to aggression anymore to ascertain what’s right or wrong, but to property rights. This and additional serious problems with this argument are already well treated by Zwolinski https://www.cambridge.org/core/journals/social-philosophy-and-policy/article/libertarian-nonaggression-principle/E8CF5446CB1D9601EFA043F7903F1CB1
Every theory of aggression relies on property rights, or my masturbation is aggression.
Actually, some Christians do think my masturbation is aggression, they think it violates God’s property right in the body he entrusted to my stewardship.
Martin, I’m curious enough about the Zwolinski article to skim or read it, but not enough to pay $25 for the privilege. Thanks for the citation, though.
“and knowing that no reasonable arbitrater would make you pay him more than a quarter in recompense”
On what grounds (assuming a libertarian judge)? Almost every libertarian I know — including myself — believes that economic value is not external to agents, but derives from revealed preference. What if Harry has already offered to sell a fresh hair, for no less than a trillion dollars?
If I agree with Michael’s moral intuition — which I clearly do — it’s not because I agree that a given hair is *objectively* worth a tiny amount, when the potential seller is requesting more. It can only be because I think I ought to abrogate Harry’s special role in creating the *subjective* value of the hair, in favor of my own subjective value (or those of a large majority of fellow humans, etc).
I ought to immediate acknowledge, of course, that the subjective theory of value I’ve just advocated has immense problems with tort law in general, or any sort of interaction that’s trade-like but occurs after the fact.
Daniel, your understanding coincides with my own. Thank you for the clear thinking and declaration.
Daniel, This is so, so right. I love Huemer’s work, but this essay really stuck in my craw. I came back to look at this comments, and this is pure gold. Thanks.
When I say I don’t believe in the NAP in libertarian circles, some look at me like a traitor. I like the rhetorical approach of blunting the impact by asserting believe in the non-aggression presumption instead.
Ed Feser brought a few years ago a similar idea. A libertarian. I forget the exact example but it was something along the lines of a libertarian on a desert beach.
Steven Dutch wrote on this in a similar vein: https://stevedutch.net/Pseudosc/ProblemWithPacifism.htm
Did you not write on some paper that rationalism is the only alternative to implausible skepticism? I am confused!
Yes, however, in that paper he did clearly state that there are problems with rationalism but that that wasn’t the focus of his paper. He was only addressing the problems concerning empirical reasoning although he certainly made— in the face of such problems with empiricism—rationalistic reasoning seem as a favourable alternative, rationally speaking of course.
“Rationalism” is said in many ways.
To step away from outlying examples into the commonplace, what are the thoughts here on someone who approaches a stranger in a bar, calling him various slurs for a male homosexual and insisting that his mother held a particular nocturnal occupation, versus the addressee when he throws the first punch?
This is why I eat meat. There is nothing wrong with aggression against nonhuman animals.
Dr. Huemer, I think this is a very important issue and I am personally undecided on this issue since I read your post, prior I was a Rothbardian.
I think it’s worth it to respond to some of the comments on this post and to start a longer back and forth on this topic. Maybe find someone of the opposing view to partner with?
I make similar-sounding points at http://ultimatephilosopher.blogspot.com/2019/03/kooky-counter-intuitive-libertarianism.html
At the same time, Prof Huemer, in https://philpapers.org/rec/HUERI, you recommend _well-tested_ abstract axioms. That is consistent with this post, of course. Just saying.
Could it not be thought of in this way: by not giving up a hair, Harry is the one doing harm? If I could pluck a hair from his head, as a caretaker, I would be protecting my charges from harm. Harry would cease being a caretaker for his charges (and in this case, my charges) and would have no moral requirements on himself, except to himself. Wouldn’t he be the one contributing to harm due to the knowledge that his inaction would harm others? He is being an ethical actor that may be causing imminent harm.
How about extending the hypothetical…what if, instead of a hair on a head, it was Banting and Best discovering insulin and REFUSING to divulge it? What is the moral position here? Are they being immoral? Could I be moral in taking their work? What if their work resulted in deaths? What if their insulin was instead, poison? What’s the moral position then? Would I have been doing harm even though I didn’t know?
How about extending the hypothetical…what if, instead of a hair on a head, it was Banting and Best discovering insulin and REFUSING to divulge it? What is the moral position here? Are they being immoral? Could I be moral in taking their work? What if their work resulted in deaths? What if their insulin was instead, poison? What’s the moral position then? Would I have been doing harm even though I didn’t know?