George Webster

Recent discussions of QBism have turned increasingly toward the question of its ontology. I argue that key insights into QBism's ontology of agency can be identified by reconstructing its response to Wigner's friend paradox. I clarify the relation between two formulations of that response: one grounded in the claim that quantum states are agents' personal probability assignments, and another grounded in the injunction to treat all users of quantum theory as agents on equal footing. Once disambiguated, these formulations reveal an implicit commitment to a mutually recognitive conception of agency, according to which the agential status of a user of quantum theory depends constitutively on the acknowledgement of other agents. This analysis clarifies what is at stake in recent QBist engagements with phenomenology - namely, the search for a more philosophically robust account of this conception of agency. I show how Merleau-Ponty's account of intersubjectivity underpins the recognitive structure implicated in QBism before tracing these themes to Hegel's account of mutual recognition. By locating QBism within a longstanding tradition of mutual recognition, I claim that we not only illuminate its theoretical structure but also open up novel conceptual resources for the rigorous articulation and justification of its ontology.

This article is aimed at those interested in the philosophy of Gilles Deleuze and the sciences—and this includes philosophers of science working out of the analytic tradition. Deleuze's writings are riddled with references to science and mathematics. And yet, the relation between these references and his philosophical thought is not well understood. In this essay, I investigate the nature of this relation—and I do so by asking whether it is naturalistic. Importantly, I draw on insights from contemporary philosophy of science to contribute to a proper understanding of this issue. I show that and how commentators are hamstrung by their lack of engagement with the philosophy of science; I present an interpretation of Deleuze's philosophical project as attempting to articulate an immanent and primitive form of objective modality; I draw together parts of Deleuze's corpus that are relevant to his treatment of the sciences but are nonetheless rarely studied in conjunction (including his and Guattari's distinction between ‘major’ and ‘minor’ science and his under-scrutinized statement of interest in ‘the metaphysics science needs’); and I propose a naturalistic interpretation of his engagements with science.

I provide a metaphysically realist interpretation of Hegel’sPhilosophy of Nature—one that allows us to make sense of one of the more puzzling references to nature in hisScience of Logic. I do so by affording William Maker’s under-appreciated account of Hegel’s realism more of the attention and scrutiny it deserves—not least because it involves a distinctively simple and elegant account of the famously obscure move from logic to nature in Hegel’s system. Though I point out its limitations, I claim that Maker’s arguments can be revised in order to recover more of the rigour and complexity of Hegel’s metaphysics.