If Locke explained why government needs our consent, John Stuart Mill (1806 to 1873) asked how far any authority, including the opinion of our neighbors, may interfere in our lives. His short book On Liberty (1859), which he said was shaped jointly with his wife Harriet Taylor Mill, is probably the most widely read defense of individual freedom ever written.
A new threat to liberty
Earlier liberals feared kings. Mill saw that in a democracy, a different danger appears: the tyranny of the majority. This works not only through law but through social pressure and custom, which can punish unpopular views and unusual lives more thoroughly than any police force.
The harm principle
Mill's answer is a single principle: “the only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others.” This is the harm principle.
It rules out a great deal. A person's own good, “either physical or moral, is not a sufficient warrant.” You may not force an adult to do something simply because it would be good for them, or stop them because the majority finds their choices foolish or immoral. You may argue with them, warn them and try to persuade them, but not compel them. In Mill's words, “over himself, over his own body and mind, the individual is sovereign.”
Mill distinguished conduct that mainly concerns oneself from conduct that affects others' interests. Only the second may be regulated. He also limited the principle to adults “in the maturity of their faculties,” excluding children and, more controversially, societies he regarded as backward, a point critics would later press.
Free speech
Mill gave the most famous arguments for freedom of thought and discussion. Suppose an opinion is silenced:
- It may be true. We are fallible. To silence a view is to assume our own certainty, and history is full of confident majorities who were wrong.
- It may be partly true. Popular opinions are rarely the whole truth, and the missing part often survives only in dissenting views.
- Even if it is false, hearing it helps. A truth never challenged becomes a “dead dogma”: people hold it as a prejudice, without understanding the reasons for it, and in time forget what it even means.
Mill did not defend all expression in every setting. He gave the example of a corn dealer. Publishing in a newspaper the opinion that corn dealers starve the poor should be allowed. Shouting the same words to an excited mob gathered outside a corn dealer's house may be punished, because there it is a direct incitement to harm.
Individuality
Mill also valued individuality for its own sake. He wrote that “he who lets the world, or his own portion of it, choose his plan of life for him, has no need of any other faculty than the ape-like one of imitation.” Choosing for ourselves exercises our judgment and develops our character. And society benefits from “experiments of living”: people who try different ways of life show everyone else what works and what does not, while a society ruled by custom stagnates.
Objections
Critics have pressed several points. Almost any action affects someone else, so where does “harm” begin? Does offense count, or the slow damage to shared moral standards? Conservatives such as the Victorian judge James Fitzjames Stephen argued that law has a proper role in upholding morality. Others ask whether Mill, a utilitarian, can defend liberty firmly, since restrictions might sometimes produce more happiness. Mill replied that over the long run, freedom is what best serves human progress and well-being.
Worked example: applying the harm principle
Mill's principle sounds simple. Try it on four cases.
- An adult wants to go skydiving. The risk falls mainly on her. Under the harm principle, others may warn her but may not stop her.
- A man drives after drinking heavily. He endangers others on the road. Regulation is clearly allowed.
- A street preacher says something many listeners find deeply offensive. Offense alone is not harm in Mill's sense. Unless he incites violence against someone, Mill would protect his speech, and those offended are free to argue back.
- A person wants to sell themselves into lifelong slavery. Mill himself said this should not be allowed, because it would destroy the very freedom the principle protects.
Now try harder cases. Should the law require motorcycle helmets? The rider takes the main risk, but if he is injured, others may pay for his hospital care and his family suffers. Does that count as harm to others? What about smoking, gambling, or using recreational drugs?
Different readers of Mill reach different answers, and that is the point of the exercise. The harm principle does not settle every case automatically. What it does is change the question. Instead of asking “is this choice wise or moral?” it asks “who is harmed, and how directly?” Notice how often public debates slide between those two questions without saying so, and how the answer can change depending on which one is being asked.