On Liberty by John Stuart Mill — Summary, Key Ideas & Quotes

Mill’s most famous contribution is the harm principle: the only justification for society or the state to restrict an individual’s liberty is to prevent harm to others. He draws a sharp distinction between self-regarding actions, which affect only the individual, and other-regarding actions, which impact others. Mill argues that society should not interfere with self-regarding actions, no matter how unwise or unconventional, unless they harm someone else. This principle remains central to debates about free speech, drug use, and personal autonomy.

Mill warns that democratic societies are vulnerable to a new kind of oppression: not from monarchs, but from the majority imposing its will on minorities. This ‘tyranny of the majority’ can be more insidious than traditional tyranny, as it is enforced by social norms and public opinion as much as by laws. Mill insists on protecting individual dissent and diversity as essential safeguards against this threat.