John Stuart Mill opens his essay by discussing the historical "struggle between authority and liberty," describing the tyranny of government, which, in his view, needs to be controlled by the liberty of the citizens. He divides this control of authority into two mechanisms: necessary rights belonging to citizens, and the "establishment of constitutional checks by which the consent of the community, or of a body of some sort, supposed to represent its interests, was made a necessary condition to some of the more important acts of the governing power". Because society was—in its early stages—subjected to such turbulent conditions (i.e. small population and constant war), it was forced to accept rule "by a master." However, as mankind progressed, it became conceivable for the people to rule themselves. Mill admits that this new form of society seemed immune to tyranny because "there was no fear of tyrannizing over self." Despite the high hopes of the Enlightenment, Mill argues that the democratic ideals were not as easily met as expected. First, even in democracy, the rulers were not always the same sort of people as the ruled. Second, there is a risk of a "tyranny of the majority" in which the many oppress the few who, according to democratic ideals, have just as much a right to pursue their legitimate ends.
In Mill's view, tyranny of the majority is worse than tyranny of government because it is not limited to a political function. Where one can be protected from a tyrant, it is much harder to be protected "against the tyranny of the prevailing opinion and feeling." The prevailing opinions within society will be the basis of all rules of conduct within society; thus there can be no safeguard in law against the tyranny of the majority. Mill's proof goes as follows: the majority opinion may not be the correct opinion. The only justification for a person's preference for a particular moral belief is that it is that person's preference. On a particular issue, people will align themselves either for or against this issue; the side of greatest volume will prevail, but is not necessarily correct. In conclusion to this analysis of past governments, Mill proposes a single standard for which a person's liberty may be restricted:
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 . . . Over himself, over his body and mind, the individual is sovereign.
Mill clarifies that this standard is solely based on utility. Therefore, when it is not useful, it may be ignored. For example, according to Mill, children and "barbarian" nations are benefitted by limited freedom. Just despots, such as Charlemagne and Akbar the Great, were historically beneficial to people not yet fit to rule themselves.
J.S. Mill concludes the Introduction by discussing what he claimed were the three basic liberties in order of importance:
- The freedom of thought and emotion. This includes the freedom to act on such thought, i.e. freedom of speech
- The freedom to pursue tastes (provided they do no harm to others), even if they are deemed "immoral"
- The freedom to unite so long as the involved members are of age, the involved members are not forced, and no harm is done to others
While Mill admits that these freedoms could—in certain situations—be pushed aside, he claims that in contemporary and civilised societies there is no justification for their removal.
Of the liberty of thought and discussion
In the second chapter, J.S. Mill attempts to prove his claim from the first chapter that opinions ought never to be suppressed. Looking to the consequences of suppressing opinions, he concludes that opinions ought never to be suppressed, stating, "Such prejudice, or oversight, when it [i.e. false belief] occurs, is altogether an evil; but it is one from which we cannot hope to be always exempt, and must be regarded as the price paid for an inestimable good." He claims that there are three sorts of beliefs that can be had—wholly false, partly true, and wholly true—all of which, according to Mill, benefit the common good:
|“||First, if any opinion is compelled to silence, that opinion may, for aught we can certainly know, be true. To deny this is to assume our own infallibility. Secondly, though the silenced opinion be an error, it may, and very commonly does, contain a portion of truth; and since the general or prevailing opinion on any subject is rarely or never the whole truth, it is only by the collision of adverse opinions that the remainder of the truth has any chance of being supplied. Thirdly, even if the received opinion be not only true, but the whole truth; unless it is suffered to be, and actually is, vigorously and earnestly contested, it will, by most of those who receive it, be held in the manner of a prejudice, with little comprehension or feeling of its rational grounds. And not only this, but, fourthly, the meaning of the doctrine itself will be in danger of being lost, or enfeebled, and deprived of its vital effect on the character and conduct: the dogma becoming a mere formal profession, inefficacious for good, but cumbering the ground, and preventing the growth of any real and heartfelt conviction, from reason or personal experience.||”|
Mill spends a large portion of the chapter discussing implications of and objections to the policy of never suppressing opinions. In doing so, Mill explains his opinion of Christian ethics, arguing that, while they are praiseworthy, they are incomplete on their own. Therefore, Mill concludes that suppression of opinion based on belief in infallible doctrine is dangerous. Among the other objections Mill answers, is the objection that the truth will necessarily survive persecution and that society need only teach the grounds for truth, not the objections to it. Near the end of Chapter 2, Mill states "unmeasured vituperation, enforced on the side of prevailing opinion, deters people from expressing contrary opinion, and from listening to those who express them." 
On individuality, as one of the elements of wellbeing
In the third chapter, J.S. Mill points out the inherent value of individuality since individuality is ex vi termini (i.e. by definition) the thriving of the human person through the higher pleasures. He argues that a society ought to attempt to promote individuality as it is a prerequisite for creativity and diversity. With this in mind, Mill believes that conformity is dangerous. He states that he fears that Western civilization approaches this well-intentioned conformity to praiseworthy maxims characterized by the Chinese civilization. Therefore, Mill concludes that actions in themselves do not matter. Rather, the person behind the action and the action together are valuable. He writes:
|“||It really is of importance, not only what men do, but also what manner of men they are that do it. Among the works of man, which human life is rightly employed in perfecting and beautifying, the first in importance surely is man himself. Supposing it were possible to get houses built, corn grown, battles fought, causes tried, and even churches erected and prayers said, by machinery—by automatons in human form—it would be a considerable loss to exchange for these automatons even the men and women who at present inhabit the more civilised parts of the world, and who assuredly are but starved specimens of what nature can and will produce. Human nature is not a machine to be built after a model, and set to do exactly the work prescribed for it, but a tree, which requires to grow and develop itself on all sides, according to the tendency of the inward forces which make it a living thing.||”|
On the limits to the authority of society over the individual
In the fourth chapter, J.S. Mill explains a system in which a person can discern what aspects of life should be governed by the individual and which by society. Generally, he holds that a person should be left as free to pursue his own interests as long as this does not harm the interests of others. In such a situation, "society has jurisdiction over [the person's conduct]." He rejects the idea that this liberty is simply for the purpose of allowing selfish indifference. Rather, he argues that this liberal system will bring people to the good more effectively than physical or emotional coercion. This principle leads him to conclude that a person may, without fear of just punishment, do harm to himself through vice. Governments, he claims, should only punish a person for neglecting to fulfill a duty to others (or causing harm to others), not the vice that brought about the neglect.
J.S. Mill spends the rest of the chapter responding to objections to his maxim. He notes the objection that he contradicts himself in granting societal interference with youth because they are irrational but denying societal interference with certain adults though they act irrationally. Mill first responds by restating the claim that society ought to punish the harmful consequences of the irrational conduct, but not the irrational conduct itself which is a personal matter. Furthermore, he notes the societal obligation is not to ensure that each individual is moral throughout adulthood. Rather, he states that, by educating youth, society has the opportunity and duty to ensure that a generation, as a whole, is generally moral.
Where some may object that there is justification for certain religious prohibitions in a society dominated by that religion, he argues that members of the majority ought make rules which they would accept should they have been the minority. He states, "unless we are willing to adopt the logic of persecutors, and say that we may persecute others because we are right, and that they must not persecute us because they are wrong, we must beware of admitting a principle of which we should resent as a gross injustice the application to ourselves." In saying this, he references an earlier claim that morals and religion cannot be treated in the same light as mathematics because morals and religion are vastly more complex. Just as with living in a society which contains immoral people, Mill points out that agents who find another's conduct depraved do not have to socialise with the other, merely refrain from impeding their personal decisions. While Mill generally opposes the religiously motivated societal interference, he admits that it is conceivably permissible for religiously motivated laws to prohibit the use of what no religion obligates. For example, a Muslim state could feasibly prohibit pork. However, Mill still prefers a policy of society minding its own business.
This last chapter applies the principles laid out in the previous sections. He begins by summarising these principles:
|“||The maxims are, first, that the individual is not accountable to society for his actions, in so far as these concern the interests of no person but himself. Advice, instruction, persuasion, and avoidance by other people if thought necessary by them for their own good, are the only measures by which society can justifiably express its dislike or disapprobation of his conduct. Secondly, that 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 opinion that the one or the other is requisite for its protection.||”|
Mill first applies these principles to the economy. He concludes that free markets are preferable to those controlled by governments. While it may seem, because "trade is a social act," that the government ought intervene in the economy, Mill argues that economies function best when left to their own devices. Therefore, government intervention, though theoretically permissible, would be counterproductive. Later, he attacks government run economies as "despotic." He believes that if the government ran the economy, then all people would aspire to be part of a bureaucracy which had no incentive to further the interests of any but itself.
Next Mill investigates in what ways a person may try to prevent harm. He first admits that a person should not wait for injury to happen, but ought try to prevent it. Second, he states that agents must consider whether that which can cause injury can cause injury exclusively. He gives the example of selling poison. Poison can cause harm. However, he points out that poison can also be used for good. Therefore, selling poison is permissible. Yet, due to the risk entailed in selling poison or like products (e.g. alcohol), he sees no danger to liberty to require warning labels on the product. Again, Mill applies his principle. He considers the right course of action when an agent sees a person about to cross a condemned bridge without being aware of the risk. Mill states that because the agent presumably has interest in not crossing a dangerous bridge (i.e. if he knew the facts concerned with crossing the bridge, he would not desire to cross the bridge), it is permissible to forcibly stop the person from crossing the bridge. He qualifies the assertion stating that, if the means are available, it is better to warn the unaware person.
With regard to taxing to deter agents from buying dangerous products, he makes a distinction. He states that to tax solely to deter purchases is impermissible because prohibiting personal actions is impermissible and "[e]very increase of cost is a prohibition, to those whose means do not come up to the augmented price." However, because a government must tax to some extent in order to survive, it may choose to take its taxes from what it deems most dangerous.
Repeat offences to public through private action
Mill expands upon his principle of punishing the consequences rather than the personal action. He argues that a person who is empirically prone to act violently (i.e. harm society) from drunkenness (i.e. a personal act) should be uniquely restricted from the drinking. He further stipulates that repeat offenders should be punished more than first time offenders.
On the subject of fornication and gambling, Mill has no conclusive answer, stating, "[t]here are arguments on both sides." He suggests that while the actions might be "tolerated" in private, promoting the actions (i.e. being a pimp or keeping a gambling house) "should not be permitted." He reaches a similar conclusion with acts of indecency, concluding that public indecency is condemnable.
Suicide and divorce
Mill continues by addressing the question of social interference in suicide. He states that the purpose of liberty is to allow a person to pursue their interest. Therefore, when a person intends to terminate their ability to have interests it is permissible for society to step in. In other words, a person does not have the freedom to surrender their freedom. To the question of divorce, Mill argues that marriages are one of the most important structures within society; however, if a couple mutually agrees to terminate their marriage, they are permitted to do so because society has no grounds to intervene in such a deeply personal contract.
Mill believes that government run education is an evil because it would destroy diversity of opinion for all people to be taught the curriculum developed by a few. The less evil version of state run schooling, according to Mill, is that which competes against other privately run schools. In contrast, Mill believes that governments ought to require and fund private education. He states that they should enforce mandatory education through minor fines and annual standardised testing which tested only uncontroversial fact. He goes on to emphasise the importance of a diverse education which teaches opposing views (e.g. Kant and Locke). He concludes by stating that it is legitimate for states to forbid marriages unless the couple can prove that they have "means of supporting a family" through education and other basic necessities.
J.S. Mill concludes by stating three general reasons to object to governmental interference:
- if agents do the action better than the government.
- if it benefits agents to do the action though the government may be more qualified to do so.
- if the action would add so greatly to the government power that it would become over-reaching or individual ambition would be turned into dependency on government.
He summarises his thesis, stating:
The worth of a State, in the long run, is the worth of the individuals composing it; and a State which postpones the interests of their mental expansion and elevation to a little more of administrative skill, or of that semblance of it which practice gives, in the details of business; a State which dwarfs its men, in order that they may be more docile instruments in its hands even for beneficial purposes—will find that with small men no great thing can really be accomplished; and that the perfection of machinery to which it has sacrificed everything will in the end avail it nothing, for want of the vital power which, in order that the machine might work more smoothly, it has preferred to banish.