Mill on Liberty of Expression

There are two things about Mill’s life that it helps to know about when reading On Liberty. The first is that his father, James Mill, and Jeremy Bentham were staunch advocates for enabling more people to vote. John Stuart Mill was not opposed to that. But he was rather worried about the dangers of an intolerant, closed-minded public taking charge.

The second fact is that Mill had an unusual and long-standing relationship with a woman named Harriet Taylor. Harriet Taylor was inconveniently married to John Taylor at the time. Mill was a public figure and I have no doubt that he was highly self-conscious about this. Make of it what you will.

The Harm Principle

In the introductory chapter, Mill says that his project is to find a principle for deciding when society may and may not limit individual liberty. Then he announces what that principle is.

That principle is, 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.

This is known as the Harm Principle. It seems to be quite uncompromising: we are only allowed to limit an individual’s liberty for the sake of preventing that person from harming others, period.

However, Mill himself endorsed several apparent exceptions to this principle. He allowed for limits to individual liberty for the sake of helping others. We will return to this in our next class on Mill.

Utilitarianism and liberty

Mill’s utilitarian case for liberty rests on two propositions:

  1. Liberty is beneficial to the individual.
  2. Liberty is beneficial to society.

While Mill’s case is complex, there are some common themes.

In making the case for the benefits of individual liberty, Mill repeatedly asserts that individuals have to make opinions and ways of living their own and that they can do that only if they are at liberty to make up their own minds or choose their own way of life.

In addition, many of his arguments apply even to cases in which individuals do not make good decisions. In these cases, Mill tries to show that the alternatives to individual liberty would generally be worse.

When making the case for the social benefits of liberty, Mill tends to emphasize how unusual individuals can make discoveries that benefit the rest of society.

Liberty of thought and expression

The official topic of chapter two is liberty of thought and expression. Mill seeks to show that society should never suppress opinions. He makes two broad arguments.

  1. No one can ever have enough confidence that their own opinions are true, and that contrary ones are false, to justify suppressing the contrary opinions.

  2. Even someone who was certain that an opinion is false should not suppress it.

Mill assumes that suppression will always be favored on the grounds that the opinion being suppressed is false. That is what those doing the suppressing will believe.

So he begins by arguing that no one can have good enough reason for believing that an opinion should be suppressed because it is false. He begins with an assertion that those who wish to suppress an opinion must be certain that it is false.

This is a very high standard, of course. We don’t hold that those making other momentous decisions, like decisions to execute a criminal or start a war, have to be completely certain.

Mill recognizes this and moves to a different claim: we are justified in thinking that an opinion is false only if those who hold it have “every opportunity” of supporting their views and “complete liberty of contradicting and disproving” our contrary opinions. But, of course, the only way to meet that condition is never to suppress opinions.

Peter pointed out the problem. Suppose we permit thorough debate before deciding to suppress the opinion. Then we will have met the condition and will possibly be justified in suppressing the opinion, contrary to the conclusion Mill wanted to establish.

So Mill probably needs to rely on the argument he gives for the second possibility: that the opinion to be suppressed is correctly believed to be false. There, Mill argues that false opinions should be tolerated on the grounds that doing so is a necessary condition of ensuring that those who hold true opinions understand the reasons for their beliefs. Otherwise, Mill claims, even true beliefs will be held as dead dogmas that are not genuinely understood.

Let us now pass to the second division of the argument, and dismissing the supposition that any of the received opinions may be false, let us assume them to be true, and examine into the worth of the manner in which they are likely to be held, when their truth is not freely and openly canvassed. However unwillingly a person who has a strong opinion may admit the possibility that his opinion may be false, he ought to be moved by the consideration that however true it may be, if it is not fully, frequently, and fearlessly discussed, it will be held as a dead dogma, not a living truth. (chapter 2, par. 21)

If Mill can make this argument stick, he will have a case against the suppression even of false opinions: that even true beliefs will be lost if they are not confronted with false ones. The idea is that those who hold the true beliefs will not understand them if they are insulated from the expression of contrary opinions, even if they are false.

Mill takes for granted a link between knowing the truth and producing social utility. That is the only way that his arguments about truth would be relevant to a utilitarian.

However, a utilitarian will need to know more about both how true beliefs lead to utility and also how the process of acquiring true beliefs works. Kamyab gave an example of people who believe that vaccines cause more sickness than they prevent. I think it is highly likely that they are wrong. If Mill is correct, a thorough discussion of their views is necessary for the rest of the public to fully understand why they are wrong. But while their views are being discussed, plenty of people will be convinced that they are right and withhold vaccines from their children. That will have obvious costs when children get sick. So even if the truth eventually emerges, the costs of acquiring it might be quite high. A utilitarian would have to convinced the value of the end state exceeds the costs of getting there.

Key concepts

  1. How Mill argues that individual liberty benefits the individual.
  2. How Mill argues that individual liberty benefits society.
  3. How Mill argues against the suppression of opinions in particular.


Mill, John Stuart. (1859) 2000. On Liberty. Edited by Mark C. Rooks. British Philosophy: 1600-1900. Charlottesville, VA: InteLex Corporation.