John Stuart Mill was an influential British philosopher and politician in the 19th century. His ideas merged Enlightenment philosophy dating back to the 18th century with special considerations of the types of governments and societies he observed in his own lifetime in the post-Enlightenment era. Mill received an elite education through his childhood that included academic study in classical languages, history, economics, and mathematics. This education prepared him for high-profile careers in the British government. He worked his way up in the British East India Company and eventually won a seat in Parliament as a member of the Liberal Party in 1865. He was also notable for his religious skepticism and his appreciation for and emphasis on mental well-being.

Mill started publishing essays as a young man. He became known as one of the great British radical philosophers even for his early work. He published A System of Logic in 1843, Essays on Some Unsettled Questions of Political Economy in 1844, and Principles of Political Economy in 1848. On Liberty was one of his later works, published in 1859 after the death of his wife, Harriet Hardy Taylor, who had influenced Mill greatly during their relationship. He dedicated On Liberty to her.