John Stuart Mill was a prominent English philosopher and political economist in the 19th century.  Mill is considered to be one of the most influential liberal thinkers in history and he was a significant contributor to many fields such as social theory, political theory, and political economy. Mill is also notable for being the first Member of Parliament to argue in favor of women's suffrage.

On Liberty, published in 1859, is generally considered to be Mill's most famous work.  Mill applies his ethical system of utilitarianism to society in order to establish a relationship between liberty and authority.