A Naturalistic Theory of (In)justice: How Neurophysiology and Metabolic Energy Ground the Perception of Injustice

Abstract

Across different domains, justice is considered either from a perspective concerning mind-independent features of a situation or from a perspective related to mind-dependent motives, traits or emotions. Although these approaches have generated valuable insights, they remain largely disconnected from each other. What is missing is an integrative framework that can explain how the objective features of situations are translated into subjective experiences and, ultimately, into defensible moral judgements. In this paper, we propose a physiological account of justice perception that explains how the ontologically objective features of a situation are translated into epistemically objective moral judgements. We argue here that the brain's predictive processing and interoceptive systems register unwarranted energy costs imposed by others as a salient, ontologically subjective state of negative affect through prediction errors elicited in specifically social contexts. This affective signal, in turn, provides the motivational and phenomenological basis for the cognitive judgement—mediated by Theory of Mind—that constitutes a specific moral emotion, such as indignation or outrage. Our naturalistic framework thus illuminates the embodied foundations of justice without reducing moral judgement to a mere physiological response. Although we are proposing a neurophysiological mechanism for justice perception, the content of the cognitive judgement (what counts as ‘unjustified’ or a norm of ‘fairness’) is also shaped by cultural, sociological and anthropological context. Thus, rather than replacing existing philosophical, legal or psychological theories, this naturalistic framework complements them by revealing the embodied cognitive processes that underlie our justice judgements across diverse contexts and cultures.