Substance and Emptiness: A Comparative Study of the “Absolute Being” in Kant’s Philosophy of Religion and Tathāgatagarbha–Dharmakāya Thought in the Ratnagotravibhāga

This article compares the concept of the “Absolute Being” in Kant’s philosophy of religion with tathāgatagarbha–dharmakāya thought in the Ratnagotravibhāga, focusing on their conceptual forms and philosophical functions. In the theoretical reason, Kant restricts the most real being to a transcendental ideal of pure reason and permits only its regulative use; in the practical reason, Kant grants the idea of God the legitimacy of rational faith by treating it as a moral postulate. By contrast, the Ratnagotravibhāga uses dharmakāya, tathāgatagarbha, and buddha-nature to explain the ground of sentient beings’ attainment of Buddhahood, and develops an emphatically affirmative soteriological discourse through the four qualities of “permanence, bliss, self, and purity” and the nine similes. The article argues that the two are not substantially the same kind of “absolute”. Kant’s “Absolute Being” has only the status of an idea and a postulate: critical philosophy denies theoretical knowledge of it without removing the personal determinations of the practical idea of God. Tathāgatagarbha–dharmakāya, for its part, must be understood within the limits imposed by dependent origination, no-self, and twofold emptiness. Even so, the two display a limited but identifiable functional correspondence insofar as both mark the limits of cognition, sustain the meaning of practice, and contribute to systematic unity. By submitting each position to the reciprocal scrutiny of Madhyamaka emptiness and Kantian critique, the article further argues that this correspondence is illuminating only when their ontological, epistemological, and soteriological differences are fully acknowledged. The tension between substance and emptiness is therefore not an opposition that can simply be dissolved; it is an occasion on which two traditions can disclose one another’s theoretical presuppositions and boundaries.