Editor’s note: This is the 18th in a series of essays about political liberalism and conservatism and the two-party system.
What is a free society? It is one that guarantees liberty to everyone. But just what does liberty encompass?
John Stuart Mill identifies three “domains” of liberty. First, he considers individuals alone; that is, that every individual is free to think and feel whatever he or she pleases. Second, he considers individuals abroad, in the world, setting out on a desired course of life or engaging in pursuits of happiness, following their dream. Third, he considers individuals with others, pursuing a common interest or cultural or social ends—that may benefit society, and exercising their right of the freedom of assembly.
In the first domain, liberty is absolute. Alone, by oneself, a person is free to think and feel as he or she pleases. In its purest state, the mind is spontaneous or inner directed. But it is not invulnerable, and its sanctity ought to be respected.
In all other cases regarding the freedom of expression, vocational or recreational pursuits or engagements in common causes, liberty is qualified. In all these endeavors, one must do no harm, where doing harm means purposely or carelessly causing others to suffer physical or emotional pain, or the loss of some rightful benefit. Neither shall they restrict others’ freedom of thought or actions by promoting prejudices directed against them, or imposing orthodoxies, religious or secular, or by deceiving or intimidating them, or preying on the inner sanctum of their conscience, fear-mongering, or in any way seeking to inhibit their chosen pursuits or their curiosity. 
Mill stipulates that to be free presupposes that an individual be mentally and emotionally mature and of sound mind. Children and persons mentally or emotionally challenged are not regarded by him as competent to be free. They must be nurtured, trained and protected, and in instances where their words and deeds are judged to be harmful to others or themselves, there should be legal means to restrain them.
Here the utilitarian takes over. And this has led to a major transformation of liberalism after Mill.
During the 20th century, Liberals came to espouse the welfare state, whose aims include not only economic regulation and the redistribution of wealth, but the authority to nurture, train and protect individuals, not arbitrarily, but according to law and always with respect to individuals or groups. In all other respects, freedom of expression must not be infringed.
Mill is insistent that there should be no publicly enforced standard of speech or expression. Lying, for instance, may be morally reprehensible, but there should be no law against it, nor should custom or public opinion prevent it. This applies to expressions that are morally offensive. From his standpoint, white nationalists have a right to express their opinions, but opponents of their ideology must feel equally free to contradict them and have the opportunity to do so.
The point is that in a free society, no one should be prevented from speaking one’s mind. “If all mankind minus one, were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind.”
What Mill is aiming at is an open society. Public orthodoxies or prevailing opinions should not go unchallenged, although those who promote them may not be silenced. The tyranny of the majority, whether liberal or conservative, must be prevented by sustained freedom. It may be recalled that a concern about a public tyranny was a motive in framing the American constitution.
Mill, the Utilitarian, expressed optimism of a good outcome of such policies, in spite of his doubts, which is to say, he hoped that it would be in the long run beneficial, because he believed that uninhibited public discourse is a way, perhaps the only way, of making truth apparent to everybody. This was consistent with his liberalism.
Mill was an economic liberal, who believed in the free market and the phrase, “the marketplace of ideas,” has been applied to his views regarding truth. But the phrase was not used by Mill. Rather, it was first mentioned by Justice Oliver Wendell Holmes. In recent scholarly discussion, it has been argued that the expression does not accurately represent Mill’s opinion.
On the contrary, he would have been troubled by the notion of the commercialism of thought that it conveys, which is not a sure way to truth, but the very opposite of it; where fashions are made standards of truth, where ambition displaces honest inquiry, and where power is used to inhibit the search for truth or lead it astray.
Rather than a marketplace, a more neutral name for the place of public discourse is the public sphere, where one encounters others and where values and truth may be openly discussed without limit. This is a place where controversies may erupt and everyone is free to take sides, defend their position, express their opinions, find fault with contrary opinions, and not be shouted down or self-righteously dismissed, and always to accord the same liberty to others who differ from you.  
It is not surprising that Mill regarded the golden rule, “Do unto others, as you would have others do unto you,” as a perfect summary of Utilitarianism and as a proper foundation for liberalism. It is a rule of reciprocity, whereby an individual does not deal out like for like, but always reciprocates offenses with good. Mill would advocate that we always answer lies with truth; selfishness with generosity; hatefulness with charity; dogmatism with doubt; fear mongering with calm rationality; and, in general, evil with good.
These are fine thoughts, but whether Mill has adequately grounded them, or whether, in the free marketplace of ideas or public sphere, they will come to prevail, or whether unscrupulous media will allow them, remains uncertain. It seems, nevertheless, a worthwhile course to follow; there does not seem to be any better. It would be perverse to argue against it.
Yet, what is troubling about Mill’s version of liberalism and utilitarianism is that it seems eminently rational, morally commendable, even commonsensical, but also innocent and one fears easily dispersed or sidetracked by darker, more sinister motives, or by mere stupidity.
Postscript: When preparing to write this essay, I was enlightened by reading an article by Jill Gordon, a professor of philosophy at Colby College, entitled “John Stuart Mill and the Marketplace of Ideas.” It is available online at jstor.org.