SIJIE YANG

Doctoral Student
Philosophy, Western University

Biography

My name is Yang Sijie (Jay). My wide-ranging curiosity—from metaphysics and ethics to physics, economics, and anthropology, all the way to cognitive science and psychoanalysis—stems from a pursuit of universal questions about how human thought engages with the world. At the most universal level, my work asks how core concepts, in their historical becoming, have shaped our very frameworks of understanding. The particular method I employ to investigate this is the history of ideas, which I believe is indispensable for deepening philosophical understanding. My specific focus is the 19th century, where I trace the concurrent evolution of physics and cognitive science. In this particular endeavor, I follow the paths of thinkers like Newton and Maxwell, who formulated foundational theories of nature, and philosophers like Howard Stein, George Smith, and Jonathan Lear, whose work exemplifies how a deep historical engagement with science and ethics reveals its profound philosophical significance.

Research

My research sits at the intersection of history and philosophy of science, with a concentrated focus on the conceptual foundations of physics. I am particularly interested in the metaphysical and epistemological shifts that accompany profound theoretical change. My work is currently organized around two central, interconnected projects. The first project investigates major scientific revolutions—with a current focus on the rise of classical field theory in the 19th century—as transformative experiences. This framework allows me to analyze how such revolutions not only change our factual knowledge but fundamentally alter the epistemic practices of science. I examine how the very criteria for what counts as evidence, how data is turned into evidence, and the underlying values of scientific practice (e.g., ideals of explanation, theoretical virtue, and ontological commitment) are reconfigured. This research asks: once a revolution has occurred, in what sense can we be said to understand the world in the same way as before? My second project delves into the metaphysics of gauge theories, using classical electromagnetism as a historical and philosophical paradigm. I am concerned with the ontological status of non-localized physical structures, such as the electromagnetic potential. As a case in point, consider the utilization of the 4-potential Aμ in electromagnetism. While the physical field is comprised of the electric and magnetic field vectors (E and B), working with these directly is often mathematically cumbersome. The potential Aμ offers a more tractable formalism, from which the local E and B values can be recovered via differentiation. However, this potential is never unique; any two choices related by a gauge transformation (drawn from the “gauge group”) yield identical E and B fields. This gauge freedom means that while the choice of a specific Aμ can render calculations remarkably simple, the potential itself lacks the same absolute ontological status as the field strengths. In a Quinean spirit, we might say: there is no fact of the matter as to how Maxwell’s potential distributes itself across spacetime, despite strict gauge-invariant constraints on observable phenomena. I hope to explore the implications of this underdetermination for our understanding of physical reality, locality, and the nature of theoretical entities. A central question guiding this inquiry is why metaphysical pictures as divergent as Quine’s global ontological relativity and Aristotle’s substance-based taxonomy both prove inadequate to capture the nuanced reality of gauge-dependent structures in contemporary physics.