The new scholarly edition of _On Liberty_ from Hackett lists Harriet Taylor Mill as coauthor.
https://hackettpublishing.com/on-liberty-with-related-writings
PS: Kudos to Hackett for this good decision. I taught this book more than a dozen times in my career and always did what I could to bring out Harriet's contributions and John's acknowledgment of them. Perhaps now it will be easier to read the book fairly. We should not assume that all its arguments fit squarely into the utilitarian box, just because JS Mill was the author. We should be ready to recognize its non-utilitarian arguments, if only because Harriet was coauthor.
I'd argue that Harriet was less utilitarian than John. But either way, it's notable that under her influence he agreed to put his name on a work that departs more than his other works from "Millian" utilitarianism.
#Philosophy