Harm 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. His own good, either physical or moral, is not a sufficient warrant."
- John Stuart Mill, On Liberty (1859), chapter I
Overview
The harm principle is Mill's rule for the legitimate limits of state and social coercion: a person's liberty may be restricted only to prevent harm to others. It may not be restricted for the person's own good, for the moral improvement of society, or because others find the conduct offensive.
Notes
- The principle does most of the work in my social positions. It is why I support free speech including the right to offend, the legalisation of Cannabis, the decriminalisation of Prostitution, and Gay Marriage: in each case the conduct harms no third party and the objection reduces to distaste. It is also why I support gun control, since firearms very clearly do harm third parties.
- "Harm" means harm: injury, loss, coercion, fraud. It does not mean offence, discomfort, or disagreement. The principle is only useful if this line is held, because almost any conduct offends someone.
- The hard cases are those where the harm is diffuse, probabilistic, or self-inflicted with knock-on costs to others (drink-driving, refusing vaccination, the public cost of private risk). The principle does not settle these on its own, but it tells you what the argument has to be about: the harm, not the morality.