Margaret Cavendish sets up feminine utopias in her plays Bell in Campo (1662), The Female Academy (1662), and The Convent of Pleasure (1668). In Bell in Campo, women build a ‘feminine army;’ in The Female Academy, a school for women scholars; and in The Convent of Pleasure, a utopia intended as a pleasurable escape from courtship and marriage. All three ultimately fall apart. This raises an interpretive puzzle: why does Cavendish keep setting up these feminine utopias only for each one to crumble in a spectacular fashion? While these works are iterations of Cavendish’s politics of gender, I want to suggest that they also illustrate her larger feminist social epistemological project. I argue that across these three frustrated feminine utopias, Cavendish develops an account and critique of an epistemic dimension of patriarchy, specifically, that patriarchy undermines women’s epistemic nature – it makes them unknown and unknowable, even to themselves, and their attempts to resist are cast as absurd, liminal things. Cavendish does so by highlighting practices of silencing and distorted speech, ignorance and knowledge, and being (un)known in gender-asymmetric ways. I also argue that Cavendish has a proposed solution: for Cavendish, women ought to become mermaids and hermaphrodites – at least, in a manner of speaking. To make my case, I will present the three plays in Section 2, highlighting Cavendish’s criticisms of the epistemic dimension of patriarchy and what I take to be revealed by the plays’ dramatic conclusions. Section 3 illustrates Cavendish’s formulation of the epistemic problem of patriarchy for women. Section 4 provides a brief reconstruction of Cavendish’s implied solution to this epistemic problem and responds a concern about its potential departure from nature. I close with some final thoughts in Section 5.