John Stuart Mill’s classic philosophical text is probably best known for the expression of libertarianism’s fundamental principle, that “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.”
It is a principle that, in its striking simplicity, still frequently recurs in modern discourse to oppose itself to any infringement of the individual’s freedom to do as he pleases without harming others: it is the bar by which prohibitive laws are measured in the public’s mind. See for instance the ban on cigarettes, which only gained momentum when it became accepted that smoking is not just a danger to the individual smoker, but also to others. Similarly, the principal argument against euthanasia is not that people should not be free to end their own lives, but that allowing people to do so might indirectly result in situations where others feel they are in some way being coerced to do so.
It is a philosophical equation that is astoundingly easy to grasp, which is why it remains such a powerful guardian against the encroachment of individual liberty. And yet, what is fascinating about Mill’s essay is the way in which, having established this principle in the opening pages, it goes on to discuss the practical implications of abiding by it in everyday life. Firstly, Mill explores the importance of freedom of thought and how it relates to what we consider to be ‘right’ and ‘wrong’: “if any opinion be compelled to silence, that opinion may, for aught we know, be true.” However, much more radically for the mid-nineteenth century, Mill then asserts that “though the silenced opinion be in error, it may, and very commonly does, contain a portion of the truth.” The idea that truth of any kind is multi-faceted, and must therefore be consistently challenged, is harder to accept because it takes the position that you can never be certain of what you know; it is an idea that introduces the spectre of doubt, which is something we all naturally recoil from. In fact, it seems to me that this is why we recoil from the idea of pluralism generally, often accepting the natural logic of the assertion that “we can’t all be right”. This is an assumption that Mill definitively rejects, making the point that it is for the individual to weigh competing opinions for himself in a world of doubt and half-truths. To turn away from challenging prevailing custom and modes of thought is to deny one of the great virtues of humanity:
“Thus the mind itself is bowed to the yoke: even in what people do for pleasure, conformity is the first thing thought of; they live in crowds; they exercise choice only among things commonly done: peculiarity of taste, eccentricity of conduct, are shunned equally with crimes: until by dint of not following their own nature they have no nature to follow: their human capacities are withered and starved: they become incapable of any strong wishes or native pleasures, and are generally without either opinions or feelings of home growth, or properly their own. Now is this, or is this not, the desirable condition of human nature?”
It is for its espousal of individualism that On Liberty deserves to be reread in the twenty-first century.