Beyond Substrate Localization: Relational Ontology and the Polyvagal Theory Debate

The debate between Stephen Porges and Paul Grossman et al. over Polyvagal Theory represents one of the most sustained and unresolved controversies in contemporary autonomic neuroscience. Despite nearly two decades of exchange and a recent high-visibility confrontation in this journal, the dispute has reached a structural impasse: neither party has succeeded in falsifying the other's position, nor in generating the empirical resolution both claim to seek. This paper argues that the impasse is not a failure of evidence but a symptom of a shared ontological assumption: that autonomic regulation is a property of individual organisms, locatable in specific neural substrates, with explanatory priority running from biology to behavior to relation. Drawing on relational ontology and a principle of scale-invariant relational dynamics, developed and formalized elsewhere, this paper argues that co-regulation, social engagement, and the clinical phenomena most successfully described by Polyvagal Theory are constitutively relational processes that cannot be fully specified at any single biological level alone. This is not a dismissal of biological explanation but a claim about its sufficiency: substrate-level mechanisms are necessary but insufficient to account for the organizing principle that renders these phenomena coherent across scales. The paper does not adjudicate between competing neurophysiological claims but reframes the explanatory terrain, showing how both positions capture genuine phenomena within their respective levels of analysis while remaining structurally unable to access what makes those phenomena cohere. The implications for a more productive research agenda, one that treats relational dynamics as a primary rather than derivative explanatory category, are developed in the concluding section.