Tony Chae

The Brain–Computer Interface (BCI) is not just a technological progress but an ontological rupture—a disruption of the fundamental structure of human cognition and learning. Existing definitions of BCI focus on its clinical functionalities and applications, with the following ethical discourse remaining confined to outcome-oriented frameworks of normative ethics. Yet BCI’s media-formal specificity, namely its capacity to link brain and world directly and bypassing natural sensorimotor pathways, remains philosophically unexamined. In particular, its potential to reconfigure the first-principle conditions of human cognition and the formation of the self is still undertheorized. A philosophical definition capable of accounting for this disruptive specificity is therefore urgently needed. Here, we propose a new philosophical definition that treats BCI as a novel cognitive media interface, and uses metaphysics as a tool to examine how its formal structure deconstructs not only traditional epistemology, but also the Kantian framework of sensibility, understanding, and the transcendental conditions of experience. Just as digital media externalized memory and perception, and artificial general intelligence (AGI) outsourced discernment, BCI threatens to bypass the bodily foundations of learning and expression altogether, risking a human subject reduced to a reactive mechanism without awareness. Through an interdisciplinary inquiry drawing on engineering, neuroscience, and metaphysics, we develop a theoretical framework, the Philosophy of BCI, to analyze how such cognitive transformations fundamentally reconfigure ontological conditions of selfhood, free will, moral judgment, emotion, aesthetic perception, and the shaping of tacit experience. Ultimately, the paper poses a critical question: In the age of BCI, does the human still exist through the body, or must we now redefine human subjectivity upon new cognitive conditions—those of disembodied awareness? Copyright © 2025 Tony Chae & Kyuin Chae. All rights reserved. This work is made available on PhilArchive for scholarly communication purposes. No part of this work may be reproduced, distributed, or transmitted in any form or by any means without the prior written permission of the authors. Date: August 11, 2025.