Mill's On Liberty

In February 1859, the English philosopher John Stuart Mill published On Liberty in London. In it, he states what is now called the harm principle: the only purpose for which power can rightly be used against any member of a civilized community, against his will, is to prevent harm to others. A person's own good, physical or moral, is not enough reason to compel them. Mill divides the book into five chapters, covering liberty of thought and discussion, individuality, the limits of social authority and some applications. He wrote it with his wife Harriet Taylor Mill, who died in 1858 before it appeared, and dedicated it to her memory.¹²

His case for free speech has several parts. If an opinion is silenced, it may be true, so we lose truth. If it is false, we lose the chance to see the truth more clearly by contrast. If it is partly true, we lose the missing part. And even a true opinion, if never challenged, becomes dead dogma held as prejudice. Mill also warns that the tyranny of the majority works through social pressure as well as law, and he praises individuality and experiments in living. He did not reject utilitarianism but argued that freedom serves the long-term happiness of humanity. The book has limits that readers dispute, as Mill excludes children and societies he regarded as backward, and later critics such as James Fitzjames Stephen said society can rightly enforce morality.¹²

The book became a founding text of liberalism. Its logic runs through arguments on censorship, drug laws, sexual morality and campus speech, and courts and legislators still cite the harm principle.¹