I read the Humument cover-to-cover a while ago, but I don’t remember too many details about the content.
However, I feel that the concept of the book itself can be related to post-structuralist ideas of authorial control as well as Lacanian linguistic concepts. The post-structuralists assert that the author does not have control over the meaning of a text once it is produced. Texts function as a sort of autonomous object that can produce infinite meanings. Tom Phillips seems to be toying with this idea by taking a text and deliberately alternating in a way that produces a different meaning. By doing this he is de-centering and destabilizing meaning itself. Tom also denies the author total control of a text by using the novel to create a new text.
Similarly, Lacan thought that there was no continuity between the signifier and signified. There is always a failure of signs to achieve their proper meaning because there is no direct or innate relationship between the signifier and signifier. By altering a Victorian novel, the Humument draws our attention to the inability for the original ‘sign’ (A Human Document) to achieve its ‘proper’ meaning (the original plot of the text). The ambiguity of the Humument is also a reflection of the disconnection between signifier and signified.