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On Liberty

‘One very simple principle’

Gerard Casey breaks down Mill’s core principle.

If a classic is a book that everybody thinks they’ve read but few actually have, then John Stuart Mill’s essay On Liberty is definitely a classic. Over the years a consensus has emerged that the core of On Liberty is this “one very simple principle”:

“[T]he 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 … 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 … The only part of the conduct of anyone for which he is amenable to society is that which concerns others. In the part that merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign.” (On Liberty, pp.68-69. All page references are to the Penguin Books edition, 1974.)

Mill describes the object of his essay as being to assert this one very simple principle, which is all very well except that what we have in this passage isn’t obviously one, certainly isn’t simple, and may not, in the end, even be the guiding principle.


The ‘one very simple’ passage contains three similar propositions expressed very differently. The three propositions are:

(1) Interference with the liberty of action of another is justified only for self-protection;

(2) The will of an agent can forcibly be overborne only to prevent harm to others; and

(3) Only conduct concerning others can be amenable to society’s influence. (This proposition makes no mention of harm.)

Many commentators are either unaware of or ignore the complexities of this passage, reducing it in effect to proposition (2), which has come to be known as the harm principle. But matters become yet more complex. In Chapter IV, a remote region many travellers never reach, Mill presents two maxims which, he says, form the entire doctrine of his essay. These are:

(A) “the individual is not accountable to society for his actions in so far as these concern the interests of no person but himself” and

(B) “for such actions as are prejudicial to the interests of others, the individual is accountable and may be subjected either to social or to legal punishment if society is of the opinion that the one or the other is requisite for its protection.” (p.163)

How do these two maxims ‘forming the entire doctrine of the essay’ relate to the one simple principle that Mill earlier described as the object of his essay? Proposition (A) is recognisably similar (though not identical) to (3), yet while proposition (B) might be taken to be equivalent to (2), it makes no mention of ‘harm’. Furthermore, it appears to run elements of (2) and (3) together, and to extend them by hinting at a notion of society as something that can have opinions and, it seems, be the agent of punishment.

Therefore there seems to be at least five different principles which are claimed to be the fulcrum of On Liberty.


If Mill’s ‘one very simple principle’ is dubiously one, it’s clearly not simple. Even assuming we can reduce the propositions to proposition (2) we encounter further problems. The notion of harm in Mill’s essay is systematically ambiguous, as is evidenced by his use of a range of near-synonyms in his discussion (‘evil’, ‘injury’, ‘damage’, ‘hurt’, ‘concern’, ‘affect’, ‘molest’, etc).

This indicates that getting the right idea of harm is not simple. If Algernon takes the last cucumber sandwich before Jack can get to it, or if Tom buys the last seat for the opera as Harry stand fretting behind him in the ticket queue, we might say that in one sense Jack and Harry have been harmed. Even so, it is difficult to see how anyone could object to the actions of Algernon or Tom unless there’s some other element of their conduct which is independently reprehensible.

Towards the end of his essay, and somewhat belatedly, Mill recognises that an action which negatively affects the interests of another doesn’t necessarily justify intervention by society: “Whoever succeeds in an overcrowded profession or in a competitive examination, whoever is preferred to another in any context for an object which both desire, reaps benefit from the loss of others, from their wasted exertion and their disappointment” but “society admits no right, either legal or moral, in the disappointed competitors to immunity from this kind of suffering” (p.164) How is Mill, or anyone else, to make a judgement that an action is harmful in the requisite sense, that is, to justify intervention? This question brings us to a consideration of Mill’s fundamental operating principle in matters of conduct.


Within a page of the passage containing the one very simple principle, Mill makes it absolutely clear that all ethical questions are to be referred to the principle of utility: “I regard utility as the ultimate appeal of all ethical questions; but it must be utility in the largest sense, grounded on the permanent interests of man as a progressive being” (p.69-70)

Utility is a notoriously slippery notion, but unless it is to become irredeemably vague, it must at the very least mean that the moral status of human actions is to be determined by an evaluation of their consequences. Therefore Mill has a problem, for it is not even particularly difficult to conceive of circumstances in which utility might demand either the performance of acts that contravene the harm principle or the prohibition of acts that do not. Consider the following cautionary tale. In the remote and isolated town of Desperation live a sheriff and ninety nine other inhabitants. Some years earlier, the sheriff was responsible for sending the Wild Bunch to jail, and they’ve sworn vengeance on him. On escaping from jail, they ride into Desperation, corral everyone in the stockyard, and present them with the following choice: “If you shoot the sheriff, we’ll ride out of town. If you don’t shoot the sheriff, we’ll kill him and all of you nice people too. You have fifteen minutes to decide.” What should the townspeople do?

Assuming the sheriff is unwilling to shoot himself, or is unable to affect rescue, there seem to be only two possibilities. If the townspeople shoot the sheriff, we end up with one dead body. If the townspeople don’t shoot the sheriff, we end up with a hundred dead bodies. In each case, the sheriff dies. A utilitarian approach to this problem seems to dictate that we shoot the sheriff. But if killing someone isn’t interfering with their liberty or overbearing their will, it’s hard to know what is.

It might be claimed that shooting the sheriff is consistent with propositions (1) and (2) of Mill’s very simple principle of liberty: it could be argued that in shooting the sheriff the townspeople are simply protecting themselves. The problem with this claim is that the natural and plausible way to read (1) is that it only permits one to interfere with the liberty of an aggressor against oneself. One may read (1) as permitting the kind of third party interference as sketched in the ‘shoot the sheriff’ scenario, but then principle (1) becomes intuitively much less plausible. But wouldn’t (2) justify the townspeople’s shooting the sheriff? Once again, a plausible reading of (2) requires the harm to emanate from the one whose will is overborne, and not from some innocent third party such as the sheriff.

Where liberty and utility clash, which is to take precedence?

Misplaced Concreteness & Metaphor

There is a deeper problem underlying On Liberty. Who is it directed against? Who is Mill’s target? Who or what does he think is the most significant threat to human liberty?

Well, governments, to some extent, although Mill is relatively dismissive of the possibility of tyrannical governments in contemporary 19th century society. He accepts as a matter of historical fact that rulers were generally antagonistic to those whom they ruled, but believes that the growth of representational democracy has increased the possibility that the rulers will identify with the ruled, and thus the antagonism will lessen or even disappear. (A welcome breath of realism is felt when Mill notes that “The ‘people’ who exercise the power are not always the same people as those over whom it is exercised.” (p.62) Of much more concern to Mill as a danger to liberty, is what he calls ‘society’. As he conceives it, society is an agent that can do things: “Society can and does execute its own mandates.” (p.63) Society protects us, and as a result, we owe it a return for this protection. But the actions of society are not always beneficent, for while it can protect it can also tyrannise, not necessarily in obvious ways: “There needs protection also against the tyranny of the prevailing opinion and feeling, against the tendency of society to impose, by other means than civil penalties, its own ideas and practices as rules of conduct on those who dissent from them” (p.63).

Mill thinks there are positive acts which one may be compelled by society to perform. These include giving evidence in court, sharing in common defence, and contributing to other works necessary to the society of which one enjoys the protection (p.70). Mill also thinks one can be compelled to perform certain acts of individual beneficence, such as saving another’s life or protecting the defenceless against abuse. It is apparently one’s duty to do such things: “things which whenever it is obviously a man’s duty to do he may rightfully be made responsible to society for not doing” (p.70). So we can see that Mill’s principle, which is generally interpreted purely negatively, not only is consistent in his eyes with positive duties and obligations, it sometimes actually requires them. These obligations are not the consequences of contractual agreements freely entered into, but result simply from our membership of society. Mill explicitly rejects any contractual foundation for society: “society is not founded on a contract, and… no good purpose is answered by inventing a contract in order to deduce social obligations from it …” (p.141). Those who look upon On Liberty as the charter of libertarianism should be concerned by the extensive list of liberty-restricting positive obligations that one acquires not as the result of any explicit agreement, or the free assumption of responsibility, but simply by virtue of living with others.

Throughout the whole of his essay Mill is, I believe, guilty of the fallacy of misplaced concreteness. Society is not an entity. The term ‘society’ is a convenient shorthand used to refer to the aggregate of individual human actions and interactions, just as ‘the market’ is a shorthand way of referring to the aggregate of economic exchanges. Society has no way of acting that is not reducible to the actions of individual agents, and neither can any person claim to act as its agent. We may, and often do, owe this or that individual a debt; but to whom, except by way of metaphor, do we repay a debt to society? We owe society nothing, because there is nothing to owe anything to.

In addition to inappropriately concretising the notion of ‘society’, Mill also confounds the literal and the metaphorical senses of ‘tyranny’. Politico-legal coercion based on the use of force through specific agencies (eg armies, police) or through ordinary criminal violence against a person or property, is not at all the same thing as social pressure unaccompanied by force or by the threat of force. For example, the disapproval of one’s peers, however forcibly expressed, and however much resented or unwelcome, is not coercive, and so cannot be an expression of tyranny. To take another example: however affable your local inspector of taxes may be, taxation is coercive, and, I would argue, tyrannical. Or consider the film Ronin, where would-be tough guy Sean Bean challenges Robert de Niro with: “You ever kill anybody?” to which de Niro responds, “I hurt somebody’s feelings once.” Hurting someone’s feelings isn’t nice, but don’t list it on your CV if you want a job with the Mafia.

But while significant, the distinction between acts of violence and acts of rudeness is not the central issue: one might kill another human being and be justified in so doing, and one might be rude to one’s friend and not be justified. If the harm principle is to be defensible, harm must be understood not just as damage to another’s interests but as unjustified damage to another’s interests. Thus, the harm prohibited by the principle would cover those actions that infringe another’s rights to person and property. The reason Algernon’s taking the last cucumber sandwich is not prohibited by the harm principle is that Jack had no right (or no more right) to that sandwich than Algernon did. Unfortunately, Mill is unable to give such an account, since his commitment to the principle of utility is coupled with a refusal to employ any independent abstract notion of right: “I forego any advantage which could be derived to my argument from the idea of abstract right as a thing independent of utility.” (p.69-70).


Mill’s one very simple principle isn’t obviously one, clearly isn’t simple, and may not in fact be his guiding principle. Mill conflates genuinely tyrannical actions which are liberty-limiting with merely metaphorically tyrannical non-liberty-limiting actions. This conflation results, at least in part, from Mill’s tendency to think of society as something which can both do things and have things done to it. Finally, Mill’s commitment to utility as “the ultimate appeal of all ethical questions” makes it difficult, if not impossible, for him to give an account of harm that could render the ‘harm principle’ morally coherent.

Mill’s ‘one very simple principle’ is definitely at the heart of On Liberty. It is a thought-provoking and still provocative idea. However, if Mill’s principle is re-evaluated, On Liberty will also need to be reconsidered, both in terms of Mill’s own thought and for the broader context of political philosophy.

© Prof Gerard Casey 2009

Gerard Casey is a professor in the School of Philosophy at University College Dublin.

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