SYNTHESE, vol.207, pp.1-22, 2026 (SCI-Expanded, AHCI, SSCI, Scopus)
For decades, metaontological debates have been structured around paradigmatic examples: Sherlock Holmes for fictional objects and the number 7 for abstract objects. These examples, while useful, are philosophically “safe” and historically entrenched. However, 21st-century technology creates entities that defy these clean categorizations. In this paper, I argue that the digital twin—a dynamic virtual model of a physical system—serves as a useful contemporary test case for metaontological reflection. It brings together the problematic features of both fiction and abstract objects while introducing a new, critical dimension: causal efficacy. This novel constellation of attributes forces refinements in debates between Quineanism, fictionalism, Meinongianism, and grounding-based approaches. Analysis shows that digital twins strengthen Quinean indispensability arguments, challenge fictionalist and Meinongian views due to their active role in the causal order, and are best elucidated as dependent entities through grounding relations. By applying these frameworks to digital twins, I aim not to declare any single framework victorious but to show where different theories must extend, qualify, or recalibrate their core commitments when confronted with this kind of entity. The goal is to demonstrate how ontological inquiry can illuminate emerging technologies—including their normative and institutional dimensions—and how these technologies can, in turn, reinvigorate metaontological theory.