Mill says in chapter 1 of On Liberty that the object of the essay is to assert one very simple principle: “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” (CW XVIII, 223 [1, 9]). A person's own good, if of adult age and in a civilized community, “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” (CW XVIII, 223–4 [1, 9]).

Mill says that the basis for his argument for this principle is utility: “I forgo any advantage which could be derived to my argument from the idea of abstract right, as a thing independent of utility. I regard utility as the ultimate appeal on all ethical questions; but it must be utility in the largest sense, grounded on the permanent interests of man as a progressive being” (CW XVIII, 224 [1, 11]).

This essay is addressed to the way in which Mill makes his case for liberty on the basis of utility “in the largest sense, grounded on the permanent interests of man as a progressive being.”

Utilitarianism as a distinct tradition in ethical thought was founded by Jeremy Bentham (1748–1832). The principle of utility, that the production of happiness and elimination of unhappiness should be the standard for the judgment of right action and for the criticism of social, political, and legal institutions, was proposed by many writers in the eighteenth century, but it was Bentham who attempted to build a complete system of moral and legal philosophy upon that basis, and it was Bentham whose doctrine became the basis of a reform movement in the nineteenth century. A brief statement of Bentham's philosophy will be given at the end of this chapter.

John Stuart Mill was a direct heir of Bentham's philosophy. His father, James Mill (1773–1836), had moved from Scotland to become a freelance journalist in London, where he edited two journals, translated books, and in the period of John Stuart's childhood wrote a multivolume History of British India. This became the standard work on the subject and earned him a post with the East India Company, which, as a quasi-governmental bureau, managed British colonial interests in India. Soon after moving to London, James Mill became acquainted with Bentham. John Stuart writes in his Autobiography that his father was “the earliest Englishman of any great mark, who thoroughly understood, and in the main adopted, Bentham's general views of ethics, government, and law.”

Utilitarianism is the ethical theory that the production of happiness and reduction of unhappiness should be the standard by which actions are judged right or wrong and by which the rules of morality, laws, public policies, and social institutions are to be critically evaluated. According to utilitarianism, an action is not right or wrong simply because it is a case of telling the truth or lying; and the moral rule against lying is not in itself correct. Lying is wrong because, in general, it has bad consequences. And the moral rule against lying can be subjected to empirical study to justify some cases of lying, such as to avoid a disastrous consequence in saving someone's life.

Utilitarianism is one of the major ethical philosophies of the last two hundred years, especially in the English-speaking world. Even if there are few philosophers who call themselves utilitarians, those who are not utilitarians often regard utilitarianism as the most important alternative philosophy, the one to be replaced by their own. Examples of the latter are intuitionists, such as E. F. Carritt and W. D. Ross, early in the twentieth century, and, more recently, John Rawls, whose book A Theory of Justice contrasts his principles of justice with utilitarian principles and contrasts his contractarian foundation for his principles with the grounds for utilitarian principles. Some of the most prominent ethical philosophers of recent years have explicitly considered themselves utilitarians. Examples would be Richard Brandt, J. J. C. Smart, and R. M. Hare.

The purpose of this appendix is to give an overall view of Mill's essay entitled Utilitarianism. No attempt will be made to engage in critical discussion of the issues that it raises. This appendix is merely a summary of the structure and the main points of the essay.

The essay has five chapters, the first of which, entitled “General Remarks,” might be regarded as a preface. The second chapter, “What Utilitarianism Is,” presents a succinct formulation of the utilitarian “creed” and then attempts to answer objections to it, objections supposedly based on mistaken interpretations of its meaning. Chapter 3, “Of the Ultimate Sanction of the Principle of Utility,” is a discussion of the sources of motivation for conformity to a morality based on the general happiness. Chapter 4 is Mill's presentation “Of What Sort of Proof the Principle of Utility Is Susceptible.” The final and longest chapter, which Mill had begun writing as a separate essay, is “On the Connexion between Justice and Utility.” This last chapter is in the form of an answer to another objection to utilitarianism, but in this case the objection could be better described as due to an inadequate and incomplete analysis of the idea and sentiment of justice, rather than a mistaken interpretation of utility. Mill's project in the chapter is to show that, when properly understood, justice is consistent with, subordinate to, and an important branch of utility, rather than opposed to it.

In Chapter 3 of Utilitarianism, Mill is addressing the question of what motives there are to be moral. He points out that the question arises whenever a person is called upon to adopt a standard. Customary morality, which education and opinion have consecrated, presents itself as being in itself obligatory, and when one is asked to believe that morality derives its obligation from a more general principle around which custom has not thrown the same halo, the assertion is a paradox. The specific rules, such as not to rob or murder, betray or deceive, seem to be more obligatory than simply a matter of promoting the general happiness, which is proposed as their foundation. So the question, “What motives are there to follow the utilitarian morality?” will arise until the influences that form moral character have taken the same hold of the principle of utilitarianism as they have taken of some of the rules of morality that could be derived from that principle – until the feeling of unity with our fellow creatures has become as deeply rooted in our character as the horror of crime is in an ordinarily well-brought-up young person. In the meantime, until such a happy moment arrives, the difficulty is not peculiar to the doctrine of utility, but is inherent in every attempt to analyze morality and to reduce it to principles.

In Chapter 5 of Utilitarianism, entitled “On the Connection between Justice and Utility,” Mill acknowledges that one of the strongest objections to utilitarianism as a complete account of ethics is the apparent independence of the idea of justice from the idea of what produces the greatest happiness, even if adherence to principles of justice does, in the long run, have that effect. If considerations of justice are independent of considerations of utility, it is possible that the two could come into conflict, that an unjust social arrangement could produce more happiness than a just one. In that case even someone sympathetic to utilitarianism on other grounds might feel that justice should take precedence in some or all such cases and that utilitarianism is not a complete ethical system. It is often said that utilitarianism is only an “aggregative” doctrine, not a “distributive” one. Or it is said that utilitarianism does not take seriously the separateness of persons: it seeks to maximize happiness without regard to whose happiness it is.

Before turning to an interpretation of Chapter 5 of Utilitarianism, I want to discuss the intuition that justice and utility are in conflict, using an example of a conflict between equality of utility and greater total utility.

Suppose for the sake of argument that it is possible to make interpersonal comparisons between quantities of utility.

If one holds a view in moral philosophy, how is it to be supported? Basically, there are two ways. One is to argue in favor of one's own position either positively by stating reasons for holding it or defensively by answering objections to it. The other is to show that there are problems with alternative views.

Most of Mill's Utilitarianism is a defense of the utilitarian view. In Chapter 2 he answers a series of objections to utilitarianism and in Chapter 5 answers the major objection that justice is independent of utility. In Chapter 3 Mill analyzes sources for motivation to be moral and claims that utilitarianism has a source of motivation lacking in other theories. In Chapter 4 he gives psychological evidence for a hedonistic theory of ultimate value. It is primarily in Chapter 1 that Mill explicitly criticizes alternative ethical theories, and his remarks are very brief. He says that to show the deficiencies of his opponents “would imply a complete survey and criticism of past and present ethical doctrine,” and that it is not his present purpose to do so. In some of his other writings, however, he goes into greater detail in showing the deficiencies of other views. Those readers who are narrowly concerned with the interpretation and significance of the explicit controversies of Utilitarianism may wish to skip or to skim this chapter. For those interested in the status of utilitarianism as a viable ethical theory, however, I believe that this chapter is important.

Mill's claim that some pleasures are superior to others on grounds of difference in quality is one of the most controversial claims in his utilitarian ethics. Many critics have asserted that he abandoned hedonism in supposing that there are qualitative differences among pleasures. Some defenders of Mill have used passages from other writings to analyze the distinction as merely one of quantity. Mill's presentation leaves a number of questions unanswered. I claim, however, that Mill is correct in analyzing pleasures and pains as differing in quality as well as quantity, and that this is a consistent hedonist position. I deny, however, that those experienced in the pleasures that employ our distinctively human faculties always prefer them to those involving only animal faculties.

In this chapter I first summarize the section of Chapter 2 of Utilitarianism in which Mill introduces the notion of qualitative differences in pleasures and point out the probable influence of Francis Hutcheson. Next I seek to give the most charitable interpretation to what Mill says, so as to make the theory as plausible as possible, but I do point out ambiguities and objections. Then I present other criticisms and discuss the extent to which they can be dismissed or answered.

Mill introduces the notion of qualitative differences between pleasures as an answer to the objection that hedonism, the theory of life on which Mill's utilitarianism is founded, is a doctrine worthy only of swine.

The “Principle of Utility” is that happiness is desirable, and the only thing desirable, as an end; all other things being only desirable as means to that end. In Chapter 4 of Utilitarianism, Mill addresses himself to the question: “Of What Sort of Proof the Principle of Utility Is Susceptible.” In Chapter 1, Mill has explained that “this cannot be proof in the ordinary and popular meaning of the term. Questions of ultimate ends are not amenable to direct proof. Whatever can be proved to be good, must be so by being shown to be a means to something admitted to be good without proof.” If “it is asserted that there is a comprehensive formula, including all things which are in themselves good,” the formula “is not subject of what is commonly understood by proof …” (208 [I, 5]). But he then goes on to say, “We are not, however, to infer that its acceptance or rejection must depend on blind impulse or arbitrary choice. … The subject is within the cognizance of the rational faculty; and neither does that faculty deal with it solely in the way of intuition. Considerations may be capable of determining the intellect either to give or withhold its assent to the doctrine, and this is equivalent to proof” (208 [I, 5]).

The twelve paragraphs of Chapter 4 present an argument that, if successful, is one of the most important arguments in all of moral philosophy, for it would establish hedonism, in the broad meaning that Mill attaches to pleasure, as the valuational foundation for all of life and for morality as a part of that.