Using the stylometric tool Stylo, we have shown that the writing style of Harriet Taylor Mill is clearly present in On Liberty, the classic of liberalism. We therefore think that at least some parts have almost certainly been co-authored by his wife.
The article describing our results is forthcoming in Utilitas. Further analyses we have since performed confirm these results, further diagrams are avilable here (Diagrams of the analysis from the Utilitas article: Results_Utilitas.zip, Diagrams of analyses where PPE was assigned to JSM: Results_PPE_JSM.zip, Diagrams of analyses where PPE was not part of the corpus: Results_Without_PPE.zip). We are also looking at further collaborative work which might be found in other texts, e.g. „The Enfranchisement of Women“, normally attributed to Harriet Taylor Mill.
We are happy to hear from others working in similar areas. Just get in touch!