Having blogged through to the end of On Liberty, I know that what John Stuart Mill claims in the 9th paragraph of the “Introductory” to On Liberty is simple is anything but simple. He writes:

The object of this Essay is to assert one very simple principle, as entitled to govern absolutely the dealings of society with the individual in the way of compulsion and control, whether the means used be physical force in the form of legal penalties, or the moral coercion of public opinion. That principle is, that 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. That the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient warrant. He cannot rightfully be compelled to do or forbear because it will be better for him to do so, because it will make him happier, because, in the opinions of others, to do so would be wise, or even right. These are good reasons for remonstrating with him, or reasoning with him, or persuading him, or entreating him, but not for compelling him, or visiting him with any evil in case he do otherwise. To justify that, the conduct from which it is desired to deter him, must be calculated to produce evil to some one else. The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign.

The first complexity is that the idea of “self-protection” or preventing harm to oneself as a necessity for setting down a social rule  is not an adequate principle for preserving liberty. No doubt slaveholders felt they were harmed when Harriet Tubman helped slaves to escape on the Underground Railroad. That harm to their interests did not justify them in setting up rules requiring the return of runaway slaves. More generally, the principle of self-protection or preventing harm to oneself does not provide adequate guidance when someone’s actions harm one person and help another. In such cases, it matters how much one person is helped and how much another person is harmed. 

The slavery case may seem easy, but consider this one. If one homeowner rents out a basement that might create more noise and somewhat exacerbated parking problems for the neighbors. On the other hand, it might greatly help the person who is now able to find a place to live because of this opportunity to be a renter. Is the community justified in prohibiting renting out basements because of the negative externality to the neighbors, or does the benefit to the person who now can find an affordable place to live in someone’s basement outweigh that negative externality? 

On this first complexity, see for example “John Stuart Mill on Legitimate Ways to Hurt Other People.”

The second, related complexity is that the boundary between “self” and “other” for the purposes of establishing liberty is not always so easy to establish. Liberty is more than simply having one’s body untouched. At a minimum, some freedom of motion is needed for liberty; if one is confined to a prison, it is an affront to liberty no matter how well one’s body is taken care of. At another level, if one’s personal diary is confiscated every day and burned in the flames, that is an affront to liberty. Sometimes this kind of reasoning is taken to include all of the things an individual has produced as if they were a part of the person, with any affront to a person’s property being an affront to liberty.

But in some ways, an individual’s sensibility and feelings are a more central part of a person than that individual’s property. And yet, we dare not count an affront to someone’s sensibility as an affront to liberty in all cases since many people are quite offended by other people’s private behavior–for example, other people’s religious beliefs and worship practices or other people’s sexual expression. To treat an individual’s sensibility as an inviolable part of that person is to tread on other people’s liberty too much. So we dare not give an individual so wide a sphere of personal rights as to include too many sensibilities about other people’s actions.

The bottom line is that drawing lines between what is my personal sphere in which I have a broad freedom of action and what is your sphere in which you have a broad freedom of action is tricky. On this complexity, see for example my discussion in “John Stuart Mill on Being Offended at Other People’s Opinions or Private Conduct.” To me it seems that workable principles of liberty must draw boundaries for one’s own private interests–the extended “self”–that are (a) as nearly as possible the same size or extensiveness for each individual (equality in the size of extended self), (b) as large as possible, without (c) overlapping too severely. Thus, interestingly, equality comes in as part of the definition of liberty–not equality of result or even equality of opportunity, but equality of size of the extended self. That is, to the extent possible, there should be equality of the sphere of each individual’s interests that are recognized as that individual’s personal sphere in which shehe has great autonomy.  

See links to other John Stuart Mill posts collected here.