Harriet Taylor, the daughter of Thomas Hardy, a London surgeon, and his wife Harriet Hurst, was born in Walworth, on 8th October, 1807. At the age of eighteen she married John Taylor, a wealthy businessman from Islington. In the next few years Harriet had two sons and one daughter, Helen Taylor.
John and Harriet Taylor both became active in the Unitarian Church and developed radical views on politics. They became friendly with William Johnson Fox, a leading Unitarian minister and early supporter of women's rights.
Harriet Taylor moved in radical circles and in 1830 she met the philosopher John Stuart Mill. Taylor was attracted to Mill, the first man she had met who treated her as an intellectual equal. Mill was impressed with Taylor and asked her to read and comment on the latest book he was working on. Over the next few years they exchanged essays on issues such as marriage and women's rights. Those essays that have survived reveal that Taylor held more radical views than Mill on these subjects. She argued: "Public offices being open to them alike, all occupations would be divided between the sexes in their natural arrangements. Fathers would provide for their daughters in the same manner as their sons."
Taylor was attracted to the socialist philosophy that had been promoted by Robert Owen in books such as The Formation of Character (1813) and A New View of Society (1814). In her essays Taylor was especially critical of the degrading effect of women's economic dependence on men. Taylor thought this situation could only be changed by the radical reform of all marriage laws. Although Mill shared Taylor's belief in equal rights, he favoured laws that gave women equality rather than independence.
In 1833 Harriet negotiated a trial separation from her husband. She then spent six weeks with Mill in Paris. On their return Harriet moved to a house at Walton-on-Thames where John Start Mill visited her at weekends. Although Harriet Taylor and Mill claimed they were not having a sexual relationship, their behaviour scandalized their friends. As a result, the couple became socially isolated.
John Roebuck later argued: "My affection for Mill was so warm and so sincere that I was hurt by anything which brought ridicule upon him. I saw, or thought I saw, how mischievous might be this affair, and as we had become in all things like brothers, I determined, most unwisely, to speak to him on the subject. With this resolution I went to the India House next day, and then frankly told him what I thought might result from his connection with Mrs. Taylor. He received my warnings coldly, and after some time I took my leave, little thinking what effect my remonstrances had produced. The next day I again called at the India House. The moment I entered the room I saw that, as far he was concerned, our friendship was at an end. His manner was not merely cold, but repulsive; and I, seeing how matters were, left him. His part of our friendship was rooted out, nay, destroyed, but mine was untouched."
Except for a few articles in the Unitarian journal Monthly Repository, Taylor published little of her own work during her lifetime. However, Taylor read and commented on all the material produced by John Stuart Mill. In his autobiography, Mill claimed that Harriet was the joint author of most of the books and articles that were published under his name. He added, "when two persons have their thoughts and speculations completely in common it is of little consequence in respect of the question of originality, which of them holds the pen."
In 1848 John Stuart Mill's Principles of Political Economy was published. Mill planned to include details of the role that Taylor had played in the production of the book, but when John Taylor heard about this he objected and references to his wife were removed. However, in his autobiography, Mill pointed out thatthe book was "a joint production with my wife".
John Taylor died of cancer on 3rd May, 1849. Still concerned about gossip and scandal, Harriet insisted that they wait two years before they got married. A few months after the wedding the Westminster Review published The Enfranchisement of Women. Although the article had been mainly written by Taylor, it appeared under John Stuart Mill's name. The same happened with the publication of an article in the Morning Chronicle (28th August, 1851) where they advocated new laws to protect women from violent husbands. A letter written by Mill in 1854 suggests that Harriet was reluctant to be described as joint author of Mill's books and articles. "I shall never be satisfied unless you allow our best book, the book which is to come, to have our two names on the title page. It ought to be so with everything I publish, for the better half of it all is yours".
John Stuart Mill had always favoured the secret ballot but Harriet disagreed and eventually changed her husband's views on the subject. Taylor feared that people would vote in their own self-interest rather than for the good of the community. She believed that if people voted in public, the exposure of their selfishness would shame them in voting for the candidate who put forward policies that were in the interests of the majority.
Harriet Taylor and John Stuart Mill both suffered from tuberculosis. While in Avignon, seeking treatment for this condition in November, 1858, Harriet died. Mill and Taylor had been working on a book The Subjection of Women at the time. Helen Taylor, Harriet's daughter, now helped Mill to finish the book. The two worked closely together for the next fifteen years. In his autobiography Mill wrote that "Whoever, either now or hereafter, may think of me and my work I have done, must never forget that it is the product not of one intellect and conscience but of three, the least considerable of whom, and above all the least original, is the one whose name is attached to it."