“On Liberty” Now Officially Has Two Authors

An edition of On Liberty published this month is the first to officially name Harriet Taylor Mill as a co-author alongside John Stuart Mill.

The new volume is edited by Piers Norris Turner (Ohio State), Jo Ellen Jacobs (Millikin), Helen McCabe (Nottingham), Lilly Osburg (Karlsruhe Institute of Technology), Michael Schefczyk (KIT), and Christoph Schmidt-Petri (KIT), and is published by Hackett. 

Many know that John Stuart Mill said that his wife, Harriet Taylor Mill, “was the inspirer, and in part the author, of all that is best in my writings […]. Like all that I have written for many years, it [On Liberty] belongs as much to her as to me.” In his Autobiography, he says

With regard to the thoughts [expressed in the book], it is difficult to identify any particular part or element as being more hers than all the rest. The whole mode of thinking of which the book was the expression, was emphatically hers. But I also was so thoroughly imbued with it that the same thoughts naturally occurred to us both.

Yet when Mill published the book in 1859, he did so under his name only, and every version published over the years, until this one, listed only him as the work’s official author.

So why the change now?

In a 2022 article in Utilitas (on which part of the introduction to the new On Liberty is based), Schmidt-Petri, Schefczyk, and Osburg lay out one reason: “stylometric analyses” provide some strong (though not on their own decisive) evidence to “say with some degree of confidence that JSM did not write On Liberty all by himself and that HTM played a part in putting parts of the text into words.” And what are stylometric analyses? “Stylometry extracts the writing style of a person from his or her texts and then compares this ‘stylome’ to the stylome of texts the author of which is yet to be identified.”

Additionally, the authors of the Utilitas article point out some considerations that may have given Mill reason to claim sole authorship of the work that might not have such force today. For example, “the provision of misleading authorship information [might be justified] in bigoted and sexist Victorian times,” but today’s norms “would give no reason to deny HTM the unequivocal status of being ‘the co-author of this classic.’”

At the end of their article, Schmidt-Petri, Schefczyk, and Osburg say, “in the interest of historical accuracy and of giving credit where it is due, we suggest modern editions should list Harriet Taylor Mill as well as John Stuart Mill as authors of On Liberty.” A few years later, they were among the editors to implement that suggestion with the new version, making true their prediction that “it would be the first time that a central text in the history of political philosophy would change authors after its publication.”

The authorship of On Liberty was also discussed by the new edition’s lead editor, Piers Norris Turner, along with Helen McCabe (Nottingham) and Mark Philp (Warwick) on a recent episode of the BBC’s In Our Time.

The publication date of the new edition is listed as March 31st, 2026, but it appears to be already on sale.