Analysts of the book have primarily focused on themes of power and language use, particularly as it relates to marginalized people. In 1994 Patrick McGrath of The New York Times claimed that one of Coetzee's central themes throughout his body of work is the "linkage of language and power, the idea that those without voices cease to signify, figuratively and literally"; McGrath pointed to Foe as the "most explicit expression" of that theme. Barton longs to tell her own story, but lacks the language to do so in a way that the public will accept. The agent she chooses to help give her the words necessary to communicate persists in erasing her history, by minimizing what she perceives as important and supplanting her remembered facts with adventurous fiction. As Foe takes over her tale, McGrath said, Barton "loses her voice in history, and thus her identity."
In addition to trying to preserve herself and her history, Barton is attempting to give voice to the even more graphically silenced Friday. Denis Donoghue of New York University stated that "the political parable [of the novel] issues from Friday's tonguelessness", as one of the central themes of the novel is the imperative to give voice to the oppressed. Barton sees Friday as caught on the edge of birth by his speechlessness, though she believes that his desire for liberation is explicit, if unspoken; Foe – though wondering if those who are not speechless "are secretly grateful" for the opportunity to project their thoughts onto Friday – believes that Friday could overcome his speechlessness by learning to write. While the book depicts the struggle to control text, Donoghue concludes that the undefined narrator of the book's finale (which Sam Durrant in "J. M. Coetzee, Elizabeth Costello and the Limits of the Sympathetic Imagination" pointed out could only have been written after the deaths of Barton and Defoe) is "the voice of the poetic imagination, its sympathies expanding beyond all systems to reach the defeated, the silenced…" Friday is afforded a final opportunity to tell his story, but can only communicate through the release of bubbles from his waterlogged corpse, a communication which neither the narrator nor the reader can interpret.
David Attwell in J.M. Coetzee: South Africa and the Politics of Writing saw this inability of a silenced black character to communicate as central to the book, indicating that "Friday's enforced silence represents what a monocultural, metropolitan discourse cannot hear". South African writer Rian Malan also felt the racial gap was key, describing Foe as "the most profound book ever written about race relations in a society where whites were often separated from blacks by an abyss of linguistic and cultural incomprehension." When Malan interviewed Coetzee for Time Magazine, he questioned the writer about this theme, who only replied, "I would not wish to deny you your reading." Professor Manju Jaidka of Panjab University, Chandigarh noted that Barton, as a woman in a very masculine text, in herself represents "the minority, the marginalised, or the silenced other." Jane Poyner in J.M. Coetzee and the Idea of the Public Intellectual highlighted the inherent tension in Barton's role, as she simultaneously struggles against the efforts of Foe to appropriate and misrepresent her story and unintentionally "'colonizes' Friday's story" herself as she interprets his silence.