Epistemic Displacement Theory: Understanding the Transformation of Consumer Knowledge in the Age of Synthetic Respondents

The proliferation of Large Language Models capable of simulating consumer survey responses poses challenges that transcend methodological concerns. This paper proposes Epistemic Displacement Theory (EDT)—a new theoretical framework—to explain how synthetic respondents may fundamentally transform the nature of consumer knowledge in marketing scholarship. Drawing on Baudrillard's ( 1981/1994 ) theory of simulacra and contemporary validity theory ( Borsboom et al., 2004 ), we argue that synthetic respondents represent an evolving simulacrum that threatens to reconstitute—rather than merely represent—consumer reality. We propose a four-mechanism process model comprising substitution, contamination, atrophy, and reconstitution, each operating through distinct dynamics that interact recursively. The theory generates four testable propositions specifying conditions under which displacement accelerates or decelerates. We then trace the macro-level consequences of these mechanisms for marketing systems, showing how displaced consumer knowledge translates into detachment of market provision from welfare, erosion of consumer sovereignty, declining market responsiveness, and distributive injustice toward under-represented populations. We contribute to marketing theory by offering EDT as a new analytical framework, providing conceptual vocabulary for knowledge transformation, and articulating conditions for preserving authentic consumer understanding.