Chapter 7 publishes the text of Pitcairneana, MS Eng 1114 in the Houghton Library, Harvard. In it, a spokesman for atheism, ‘Incredulous’, argues against ‘Credulous’, a spokesman for Christian orthodoxy, and makes various points, notably concerning the relationship between spiritual and non-spiritual bodies and the issue of motion being intrinsic to matter; he also argues in favour of the world’s being eternal rather than the result of a divine act of creation and offers a cyclical rather than progressive view of human development. The authors referred to in the dialogue include Samuel Clarke, Henry More, John Toland and Robert Hooke, while the treatise ends by invoking ‘axioms’ in an essentially Newtonian mode.

The Physical and Philosophical Opinionsilluminates our understanding of Cavendish's position on the intellectual equality or otherwise of women and men. Cavendish's basic ontology permits two interpretations – that women and men are intellectual equals, or that they are not (usually with the claim that men are intellectually superior). However, the book, which includes significant autobiographical musings, helps explain why Cavendish finds the questions so difficult. For, because women's knowledge claims are routinely rejected as carrying value, evidence that women can bring to the question is frequently lost. Moreover, that women sometimes internalize these dismissive treatments of them as epistemic authorities means that women discount their own capacity as knowers. With so much loss of epistemic points of view and the knowledge that comes with them, it is unclear that the question at hand is yet one that Cavendish and others at her time have sufficient evidence to answer. Turning to the wide range of genres in Cavendish's oeuvre, rather than works that we currently deem 'philosophical', is crucial for a full understanding of her approach to philosophical questions.

Brandie R. Siegfried “considers three characteristics of [Cavendish's] volume of verse,” Poems and Fancies, arguing first that the book is "thoroughly engaged with philosophers and mathematicians, both ancient and modern: understanding the import of her poems often requires setting them in dialogue with those thinkers.” Second, Siegfried investigates the prefaces of Cavendish's poetry, further contending that they demonstrate a feminist sensibility as they explain her views for an audience that pointedly included women. Finally, Cavendish’s eclectic ideas are not simply the musings of a careless author, but rather are the works of a committed philosopher who uses the form of poetry to clarify her theories, making them more accessible to readers while “enhancing aesthetic pleasure through increased complexity and wit.” Giving special attention to Cavendish’s poetic revisions in Poems and Fancies, Siegfried further emphasizes the importance of Cavendish’s poetry for understanding the natural philosophy espoused in Philosophical and Physical Opinions, Philosophical Letters, and Observations upon Experimental Philosophy.