Within Indian Buddhist schools, theories regarding the concept of “neither identical nor different” are developed in three different ways, namely by the Ābhidharmikas, Mādhyamikas, and Vijñānavādins.
The characteristic of the Abhidharmic theory of the concept of “neither identical nor different” is that it accepts partial identity of “factors,” such as “omnipresent real factors” and “non-omnipresent real factors,” or “nominal momentary existences” (impermanent existences) and “real eternal existences” (permanent existences).
The characteristic of the Mādhyamika theory is that it applies the concept of “neither identical nor different” for the “conditioned” and “empty” conceptual factors with no real existences, such as causes and results. These conceptual factors are neither completely identical nor completely different, but rather they are in a relation of seamless similarity with each other. There are no ethical value judgments included in this theory.
The characteristic of the Vijñānavādin theory is that it understands that factors can be ontologically identical yet different in their ethical values. From the ontological perspective, both “conditioned” and “non-conditioned” factors can transcend and naturalize their differences and be synthesized in the realm of dharmatā or tathatā. However, from the perspective of ethical values, they still retain differences as “tainted” and “untainted” factors.
In the chapter of the Bodhisattvabhūmi of the Viniścayasaṃgrahaṇī in the Yogācārabhūmi examined in this paper, all three theories of the concept of “neither identical nor different” are discussed. The reason for this rather confusing lack of uniformity in the understanding of the concept of “neither identical nor different” might pertain to the fact that this text belongs to the period of the early development of Yogācāra theory. As is already known, in the theory subsequently developed by Vasubandhu, which marked the intermediate period of the Yogācāra school, we only find the Vijñānavādin theory of the concept of “neither identical nor different” that is posited between sacred and mundane factors.
