John Stuart Mill
19th century English philosopher and Member of Parliament, John Stuart Mill was an influential liberal thinker of the 19th century whose works championed freedom of the individual in opposition to state control. He was an exponent of "utilitarianism", an ethical theory developed by Jeremy Bentham.
Mill's book "On Liberty" addresses the nature and limits of the power that can be legitimately exercised by society over the individual. In this he articulates the fundamental libertarian tenet that each individual has the right to act as he wants, so long as these actions do not harm others.
If an individual action only directly affects the person undertaking the action, argued Mill, society has no right to intervene even if it feels that the person is harming him/herself or the action is generally considered immoral.
Mill defined "social liberty" as protection from the tyranny of political rulers which he was first to recognise could dwell within an otherwise free and democratic state as the “tyranny of the majority”.
Anticipating the modern libertarian argument that while criminals could violate your rights only governments could take them away, Mill argued that social liberty was obtained by placing constitutional limits on government power so that individual freedom was protected. The political efforts to achieve this, he believed, marked the evolution of human civilization.
"I cannot but conclude that the struggle between liberty and authority is the most conspicuous feature of history."