That the principle which regulates the existing social relations between the two sexes -- the legal subordination of one sex to the other -- is wrong in itself, and now one of the chief hindrances to human improvement; and that it ought to be replaced by a principle of perfect equality, admitting no power or privilege on the one side, nor disability on the other.

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.