We discussed Nozick’s claim that rights are what he calls “side-constraints,” meaning that they constrain actions: no one can do anything that would violate another person’s rights.
Nozick’s first point is that we do not treat rights as goals. I illustrated this with one of the stylized examples that are used to raise objections to utilitarianism: suppose the town sheriff can execute one innocent person to save ten innocents from dying in a riot that will happen if the innocent person is not executed.
On the face of it, utilitarianism has a quick answer: the sheriff should execute the innocent man. However, it will rarely be that easy. There could be many consequences of doing so that might have outweighed the ten innocent lives.
There is another point that utilitarians could make. The orphans are innocent too and, if they are really genuinely honestly cornered into making a choice between one innocent life and ten innocent lives, they are comfortable with using an old standby: arithmetic. The choice is terrible, but if it’s forced on you, it’s better to lose one life than it is to lose ten.
Still, Nozick points out that this is not the way we think about rights. We do not think that whether someone’s rights are to be respected or not depends on calculating the effects of doing so. And we are not willing to engage in the kinds of trade-offs that the utilitarians claim are sensible. (Which is not to say that we are right to resist making those trade-offs, just that we do so.)
He thinks this showed that we do not treat rights as goals, where we would try to maximize achievement of the goal. Instead, we treat rights as what he called side-constraints.
Will asked an interesting question here. Why doesn’t our poor sheriff face a dilemma? The side constraint “never kill” tells him not to kill the innocent guy and the side constraint “protect the innocent from being killed” tells him that he must kill the innocent guy (in these admittedly weird circumstances).
I think Kamyab had the answer that Nozick believes: there is only one side constraint. We are forbidden from killing, but we are not required to prevent others from killing. Thus there is no dilemma here. The sheriff may not kill the innocent person. If he can save the innocents without violating a side constraint he may do so. But he is not required to do that and so there is no conflict of requirements here.
Nozick’s attempts to explain why we have rights with this feature take him through several long and interesting digressions. He takes it for granted that our rights must be based on some natural features that we all share and he went on a search for those features.
He concluded that the natural features in question are ones that enable us to guide our lives by plans. That, in turn, is said to be important because it is how we give meaning to our lives (Nozick 1974, 48–50).
We had a number of questions about this.
I expressed concern about people who, in my opinion, have rights but are incapable of guiding their lives according to plans, such as those with mental disabilities.
Josh did not think Nozick ever explained the connection between plans and the meaning of life.
Will noted that you can follow a plan and find that it leaves you feeling that your life is meaningless.
Nozick and Mill endorse quite similar principles. Mill’s harm principle holds that individuals should be left free to do anything that does not harm others: “the sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number, is self-protection” (Mill  2000, ch. 1, par. 9).
Similarly, Nozick holds that “there is no justified sacrifice of some of us for others” and that there is “a libertarian side constraint that prohibits aggression against another” (Nozick 1974, 33).
However the philosophical bases of their respective versions of libertarianism are quite different. Nozick thinks the state is limited to protecting rights. Mill has to think it is committed to maximizing overall utility, even if this comes at the cost of rights. Furthermore, Nozick maintains that individual rights are derived from features of the individuals themselves and that one person’s rights cannot be balanced against another’s. Mill, on the other hand, derives individual rights from overall utility. If protecting individual liberty were not the best way of promoting the social good, Mill would have to reject it.
Furthermore, they have different opinions about what kinds of liberty are most important. Nozick emphasizes economic liberty. He thinks that “the state may not use its coercive apparatus for the purpose of getting some citizens to aid others.” Its sole function is to protect people “against force, theft, fraud,” and violations of contractual agreements. Anything more is “redistributive,” limiting one person’s liberty for another person’s sake (Nozick 1974, ix). Mill believes that there is a utilitarian case for economic liberty. But he also believes that it is separate from the one he made in On Liberty (Mill  2000, ch. 5, par. 4). On Liberty defends individual liberty of thought, expression, association, and determining how to live. Mill regards commercial activity as something different.
Mill, John Stuart. (1859) 2000. On Liberty. Edited by Mark C. Rooks. British Philosophy: 1600-1900. Charlottesville, VA: InteLex Corporation.
Nozick, Robert. 1974. Anarchy, State, and Utopia. New York: Basic Books.