Kwan Hong Tan argues that the classical opposition between existence and non-existence is insufficient for describing phenomena that occupy a threshold between being and non-being. His central claim is that certain entities—quantum states, artificial intelligence systems, virtual objects, consciousness, and social constructs—cannot be adequately understood through binary ontology. To address this, he proposes Ontological Liminality Theory, a framework built around five concepts: modal oscillation, perspectival ontology, ontological gradience, relational manifestation, and emergent phenomenality. Modal oscillation describes entities that shift between ontological states; perspectival ontology shows that existence can depend on the observer’s standpoint; ontological gradience treats being as a spectrum rather than an all-or-nothing property; relational manifestation argues that entities emerge through relations; and emergent phenomenality explains how consciousness-like properties may arise from complex systems. The case of artificial intelligence is central: advanced AI may not possess full human consciousness, yet it displays forms of self-assessment, interaction, and apparent cognition that complicate simple claims of non-existence or mere mechanism. Tan’s Liminal Ontology Matrix synthesises these ideas into a multidimensional model for analysing entities that resist fixed classification. The conclusion is that ontology must move beyond rigid binaries toward a dynamic, relational, and interdisciplinary account of liminal being.
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