Why Conceptual Rigour Matters to Philosophy: on the Ontological Significance of Algebraic Quantum Field Theory

Abstract

I argue that algebraic quantum field theory (AQFT) permits an undisturbed view of the right ontology for fundamental physics, whereas standard (or Lagrangian) QFT offers different mutually incompatible ontologies. My claim does not depend on the mathematical inconsistency of standard QFT but on the fact that AQFT has the same concerns as ontology, namely categorical parsimony and a clearly structured hierarchy of entities.

Effective theories and infinite idealizations: a challenge for scientific realism

“…Although more work needs to be done in order to give a full defense of these features, they suggest nonetheless that effective theories provide us with a reliable epistemic standpoint to identify unobservable entities or structures in the regimes where our best theories are known to be successful. This extends Williams and J. Fraser's recent claim beyond the context of QFT and provides a further response to philosophers who deem EFTs unfit for interpretative purposes (e.g., D. Fraser 2009Fraser , 2011Kuhlmann 2010). And if we are to interpret effective theories in realist terms, their structure provides us with one central constraint for making more reliable ontological commitments than those commonly made across physics: namely, we should only commit to the existence of concrete physical objectsentities, structures, properties, quantities, states, phenomena, dispositions, and so onspecifiable within the domain of empirical validity of the theory.…”

The sky is blue, and other reasons quantum mechanics is not underdetermined by evidence

“…But these comments seem to be based on a very outdated picture of quantum field theory, in which renormalization is miraculous black magic, which has been obsolete for fifty years. I'm not aware of any advocate of this response who engages critically with either the development of the effective field theory concept in physics in the 1970s or 1980s, or the developing consensus in more recent philosophy of physics that effectivefield-theory approaches to QFT are legitimate and the old criticisms of mainstream QFT are outdated (see, e. g. , (Wallace 2011;Williams 2015;Miller 2018;Fraser 2020; Rivat and Grinbaum 2020) -though see Fraser (2009Fraser ( , 2011 and Kuhlmann (2010) for more skeptical views).…”

Scientific realism and underdetermination in quantum theory

“…Insofar as scientific realism is motivated by the empirical success of science, there is thus a clear incentive to focus one's attention on conventional QFT, because it is within this framework that most of the successful applications of QFT to high‐energy physics, most notably the standard model of particle physics, are derived (Wallace, 2006, 2011). On the other hand, scientific realists (like philosophers in general) should care for conceptual rigour and clarity, and some have argued that this should direct their interests towards algebraic QFT (Fraser, 2009, 2011; Kuhlmann, 2010). 7…”