Epistemic Anti-Mastery and the Fragility of the Bayesian Subject: Marguerite Porete and the Architecture of Epistemic Agency

Debates on ontological underdetermination—from scientific realism to Bayesian epistemology—typically assume that epistemic agents remain structurally intact even when evidence fails to determine theory. This paper argues that such debates tacitly preserve a “posture of mastery”: indeterminacy is treated as a problem for theory selection rather than as a destabilization of epistemic agency itself. I introduce the concept of epistemic anti-mastery to describe a rational reconfiguration of epistemic posture under conditions of radical opacity. Through a structural reading of Marguerite Porete’s account of annihilation in The Mirror of Simple Souls, I demonstrate that: (i) Bayesian conditionalization presupposes an architectural stability that radical underdetermination undermines; (ii) scientific realism’s convergence rhetoric depends on an untenable mastery-orientation; and (iii) under structural opacity, epistemic anti-mastery is rationally required. The aim is conceptual intervention: rational engagement requires revision of epistemic stance rather than refinement of theoretical control.