The doctrine of the two truths is usually assigned to Nāgārjuna (fl. c. 200). In his famous commentary Mūla-madhyamaka-kārikā, he systematically subverts all relevant Buddhist concepts of his time and proposes the doctrine of emptiness. This doctrine proposes that all other doctrines are empty of truth-value. Thus formulated, this doctrine of course raises the question as to what, if anything, is true and can be said. Does the doctrine of emptiness imply quietism or absolutism? In this essay, I will explore how the two Japanese philosophers Inoue Enryō (1858–1919) and Watsuji Tetsurō (1889–1960) interpreted the central Buddhist doctrine of the two truths.

Before I take a closer look at these two 20th-century interpretations of the two truths, I would like to examine how Nāgārjuna and his direct successors defined this concept. In the Mūla-madhyamaka-kārikā, (T 30.1564.32) Nāgārjuna suggests that verbal expressions constitute conventional (Skt: saṃvṛti) truth and their emptiness ultimate (Skt: paramārtha) truth. This doctrine is further expounded in the Śata-śāstra by Nāgārjuna’s disciple Āryadeva (fl. c. 250) and the Chinese Madhyamaka (Ch: Sanlun) thinker Jizang (549–622). The former famously declared that “all buddhas preach the Dharma; they continuously rely on the ‘conventional truth,’” (T30. 1569.181) the latter that “the two truths of conventionality and ultimacy are one yet different.” (T 42.1827.262) Ultimately, however, the doctrine of the two truths is nowhere explained better than by Nāgārjuna himself. He announces in his Mūla-madhyamaka-kārikā that “all things that dependently co-arise, I explain as empty; again, these are provisional designations; again, this is the meaning of the Middle Path.” (T 30.1564.33)

In his investigation of the two truths, Inoue focuses especially on Nāgārjuna’s Mūla-madhyamaka-kārikā and Āryadeva’s Śata-śāstra. Following these texts, he identifies the two truths as the first of the “three essentials;” these are the two truths, the eight negations, and the Middle Way. The two truths consist of the paramārtha and the saṃvṛti truths. The former, to Inoue, explicates the substantial, the latter the contingent. However, to Inoue, the two truths constitute merely the “finger that teaches the moon”* and introduces the “language of religious teachings.”*

A closer analysis of the two truths reveals that the “conventional truth is being,”* the “ultimate truth is emptiness.”* He continues that “being is the provisional designation opposed to emptiness”* and “being is the being of non-being.”* Emptiness, on the other hand, “is the provisional appellation opposed to being,”* it constitutes the “emptiness is emptiness of non-emptiness.”* In short, while “being is the being of emptiness,”* “emptiness is the emptiness of being.”*

To interpret these confounding observations, Inoue offers a heuristic key: he claims that the two truths are “originally non-dual,”* “not two but one.”* In fact they reveal three layers: the layer of “being,” the layer of “being of non-being,” and the layer of “being of emptiness.”* Thus understood, Inoue suggests, the three layers evoked by the two truths illustrate Nāgārjuna’s poem that the products of causal process are empty and indicate the mean.

Interestingly, at this point Inoue postulates a fundamental similarity between the Madhyamaka doctrine of the two truths and Zen teachings. Both heuristic models disclose a threefold structure of affirmation-negation-non-duality. The same structure can, for example, be found in a famous poem from the Transmission of the Lamp, in which an old Zen master recounts that “before I began the study of Zen, I said, mountains are mountains, waters are waters; after I received an insight . . . I said, ‘mountains are not mountains, waters are not waters;’ but now . . . I say, ‘mountains are really mountains, waters are really waters.’” (T 51.2077.614)