Introduction

On Liberty was conceived together by Mill and his wife Harriet and published the year after her death. Its heart is one very simple principle: the sole end for which mankind are warranted in interfering with the liberty of action of any of their number is self-protection; the only purpose for which power can rightfully be exercised over any member of a civilised community, against his will, is to prevent harm to others. He makes the classic defence of freedom of thought and speech: if all mankind minus one were of one opinion, mankind would be no more justified in silencing that one; a suppressed opinion may be true, and even if false, the collision with it makes the truth clearer. He also defends individuality and originality against 'the tyranny of society'. Utilitarianism defends the principle of 'the greatest happiness of the greatest number' and distinguishes higher and lower pleasures: 'It is better to be a human being dissatisfied than a pig satisfied.'