the only way in which a human being can make some approach to knowing the whole of a subject, is by hearing what can be said about it by persons of every variety of opinion, and studying all modes in which it can be looked at by every character of mind. No wise man ever acquired his wisdom in any mode but this; nor is it in the nature of human intellect to become wise in any other manner.

During his time as an MP Mill advocated easing the burdens on Ireland. In 1866 Mill became the first person in the history of Parliament to call for women to be given the right to vote vigorously defending this position in subsequent debate. And as most opinions are neither completely true nor completely false he points out that allowing free expression allows the airing of competing views as a way to preserve partial truth in various opinions.

He was a proponent of utilitarianism an ethical theory developed by Jeremy Bentham. Mill's conception of liberty justified the freedom of the individual in opposition to unlimited state control.