[Essay] Mill's Harm Principle

Guillaume Hansali
Guillaume Hansali
[Essay] Mill's Harm Principle
John Stuart Mill (courtesy of Wikipedia)

Essay's question

What is Mill’s Liberty Principle? Does it correctly set out the grounds on which government interference with individual lives is justified?

Essay written for the Introduction to Political Philosophy online course at Oxford: https://www.conted.ox.ac.uk/courses/political-philosophy-an-introduction-online
Constraint: 1500 words.


"The struggle between Liberty and Authority is the most conspicuous feature in the portions of history with which we are earliest familiar […]" (Mill 2021, p.1)

In this essay, I will first introduce John Stuart Mill’s Liberty Principle, also commonly called ‘Harm Principle.’
I will then argue that while Mill’s principle is not a sufficient condition, it is nonetheless a necessary prerequisite for government interference in individual lives, and therefore can be used to set the grounds on which to justify when such interference is illegitimate.

To simplify the argument, I will limit the notion of government interference to anything that directly restricts individual liberties, and I will not include policies that may indirectly coerce individuals into not exercising their liberties because of other obligations such as taxation or military service.

Definition of the Liberty Principle

Mill, strongly influenced by Tocqueville’s argument that public opinion can undermine the independence of thought (Williams 1991, p.126), believed that freedom of thought was the only way to ensure that society would improve over time (MacKenzie 2009, p.40).
Without allowing individuals to experiment beyond well-accepted conventions, we leave ourselves at the mercy of the ‘despotism of custom’ (MacKenzie 2009, p.41)

Mill claimed that we did not have any agreed-upon principle or rule by which we could judge the legitimacy of government intervention in individual lives (Mill 2021, p.8). Without such a rule, we are bound to decide based on our preferences (Mill 2021, p.7); in a free society, the will of the majority is law, and minorities are at risk of oppression and abuse of power (Mill 2021, p.3).
In order to protect freedom of thought, society must put safeguards against such ‘tyranny of the majority’ (Mill 2021, p.4)

In one of his most influential essays, On Liberty, Mill offers a simple principle to that effect. His ‘Liberty Principle’, commonly called the ‘Harm Principle’, states that only self-protection justifies interfering with the liberties of others; the only rightful exercise of power is harm prevention (Mill 2021, p.8).


Now that we have introduced Mill’s Liberty Principle, we need to assess whether it correctly sets the grounds on which government interference in individual lives can be justified.

It may be worthwhile to clarify what is meant here by government interference; interfering with individual liberties is by definition what a government does, and interference could potentially refer to any governmental activity.

For the sake of simplicity and clarity of the argument, I decided to limit the scope of interference to any activity that directly restricts an individual’s freedom against her will and shall therefore exclude activities related to obligations, such as taxation, and duty, such as military service.

The question may now be read as follows: does the Liberty Principle correctly set the grounds on which government can justifiably restrict individual liberties?

To answer this question, we need to assess whether the principle is
(1) a sufficient condition, and
(2) a necessary condition.
If we can demonstrate that it is both, we would have a strong argument that it does indeed set grounds correctly.

It may, unfortunately, be challenging to establish the sufficiency of Mill’s principle, and Mill himself voices his reservations; harm does present a ‘prima facie’ case for interference (Mill 2021, p.9), but such interference may not always be defensible (Mill 2021, p.78). Prevention of such harm through liberty restriction raises ethical questions that need to be resolved under the principle of maximum utility (Mill 2021, p.9); depending on the type or degree of the harm, preventing it may not make up for the amount of utility lost restricting freedom.

According to Mill, consented harm, for example, does not warrant preventive restrictions.
If I decide to enter a boxing tournament, I am well aware of the risks and should not expect the government to step in when I get my nose broken (Brink & David 2018).
Self-harm is also in the same category. I am entitled to drink myself to death or (literally) shoot myself in the foot cleaning my gun.

Is the non-sufficiency of the principle its demise? While Mill is offering his principle to guide our judgment regarding government interference legitimacy, his primary concern is too much interference rather than not enough.
On its face value, Mill’s principle indeed seems to be a very intuitive necessary condition.

One way to argue for its necessity is to assess whether there could be any other condition or principle that would be sufficient to legitimize government interference.

To be sure, Mill does concede a certain number of exceptions under which liberty restrictions are legitimate. Children who have not yet reached the age of reason need to be protected from themselves (Mill 2021, p.8-9).
He also disapproves of any willful action that would result in incapacitating oneself from performing one’s public duty (Mill 2021, p.67) and condemns self-enslavement as it renders the principle void by forgoing one’s individual liberties (Mill 2021, p.85)

However, this is as far as Mill’s ‘soft paternalism’ goes; Mill is fundamentally opposed to any form of paternalism and moral oppression (Brink & David 2018).
A society is not more entitled to repress one person’s opinion than that one person is entitled to repress the entire society (Mill 2021, p.14), and therefore, a shared sense of morality is not a sufficient reason to restrict individual liberties.
Devlin disagrees and argues that societies cannot subsist without a commonly accepted moral code that govern its members (Devlin, R&W, p.139); the institution of marriage, for instance, is a pillar of our society, and adultery ought to be condemned because it would threaten its integrity (Devlin, R&W, p.139).
Against Devlin’s counter-argument, Hart justly points out that such statement lacks empirical evidence, and seems to be accepted as an ‘a priori assumption’, a ‘necessary truth’ (Hart, R&W, p.140)

If we reject the infringement of paternalist values as a sufficient condition for government interference, we may have a stronger case for the necessity of Mill’s principle.
However, we are not yet out of harm’s way, so to speak, with our argument.
If we see the Harm Principle as the first line of defense against excessive government intervention, it rapidly becomes evident that we need a clear definition of what constitutes harm.

While Mill does not define harm, he suggests that any time someone behaves in a way that ‘affects prejudicially the interests of others’ (Mill 2021, p.62), society can rightfully discuss whether restrictions are in order.
But ‘prejudice of interests’ seems very broad, and Mill does not seem to offer much clarification on what these ‘interests’ are.
Anything can be offensive to somebody, so simply being offended surely cannot be considered a legitimate form of harm.

To make matters worse, Mill also distinguishes personal offense from public offense, condemning the latter, such as public indecency (Mill 2021, p.81), or drinking myself to death, but publicly.
But what makes an offense public? Surely, its mere publicity cannot be sufficient; otherwise, a public speech of offensive nature could legitimately be banned, and we know that Mill is opposed to censure.

How about hate speech, racism, and the oppression of minorities through offensive speech?
However noxious these ideas may be, Mill believes that they still belong to the free market of ideas and ought to be defeated by better ones (Mill 2021, p.13).
Can oppressed minorities really defend themselves against a one-sided opinionated majority?
Well, Mill’s principle does not give us a clear-cut rule book to deal with such complex topics and conveniently refers us to utility as the ultimate authority on ethical questions.

Nevertheless, as long as we accept some degree of uncertainty regarding what constitutes harm, Mill’s Harm Principle appears to stand as a robust necessary condition for government intervention.

The absence of harm is, therefore, a sufficient condition to render government interference illegitimate, and Mill’s principle, thus, sets the grounds to justify such illegitimacy.


In this essay, I have briefly introduced Mill’s Liberty Principle, and argued that it is not a sufficient condition to set the grounds on which government interference in individual lives can be justified.
However, I also argued that it is nonetheless a necessary condition and concluded that it could set the grounds to justify when such interference is illegitimate.

While Mill’s Harm Principle may not be the guiding rule we hoped for, it is a sincere plea for the overall illegitimacy of restrictions on freedom of speech; the only legitimate case is preventing harm, and that leaves us with the conundrum of determining what actually constitutes harm.

The debate surrounding freedom of speech and its limitations is as relevant today as it was one and a half centuries ago.

In a world of political correctness and cancel culture, we may see Mill’s harm principle as a lucky charm, simple but powerful protection against moral oppression from the majority, and against thought restriction through the relentless normalizing power of customs on the pretense of a somewhat superior sense of morality.


  • Mill 2021: John Stuart Mill, On Liberty, 2021, Kindle edition (ASIN: B09CZ7BW44) (total number of pages: 100)
  • Brink & David 2018: Brink, David, “Mill’s Moral and Political Philosophy”, The Stanford Encyclopedia of Philosophy (Winter 2018 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/win2018/entries/mill-moral-political/
  • Devlin, R&W, 1999: Michael Rosen & Jonathan Wolff, From ‘Patrick Devlin: The Enforcement of Morals’, in Political Thought (Oxford University Press, 1999)
  • Hart, R&W, 1999: Michael Rosen & Jonathan Wolff, From ‘H.L.A. Hart: The Changing Sense of Morality’, in Political Thought (Oxford University Press, 1999)
  • MacKenzie 2009: Iain MacKenzie, Politics Key Concepts In Philosophy (Continuum, 2009)
  • Williams 1991: Geraint Williams, Political Theory In Retrospect (Edward Elgar, 1991)

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