The philosophical concept of other-emptiness (zhentong) has long since been a lightning rod for controversy on the Tibetan plateau. Some of its most ardent supporters have had their works banned. Yet it not only endured, it gained the support of prominent adherents of almost every one of the major Tibetan schools. Its roots are intertwined with the concept of buddha-nature, though in particular it was via the so-called meditative tradition (sgom lugs) of exegesis of the Ratnagotravibhāga associated with Tsen Khawoche that zhentong's origins are traced. In fact, the label zhentongpa has been retroactively applied to various figures in this lineage that actually predate its usage—to individuals that may have never heard the term, let alone utilized it in their own compositions. Another such line of assumed zhentong antecedents is connected with the Kālacakra Tantra and is traced to the early Jonang forefather Yumo Mikyö Dorje. Both of these lines were received by the revolutionary thinker Dölpopa, who is generally credited with coining, or at least codifying, the term as a philosophical position in the fourteenth century. He placed it in opposition to self-emptiness (rangtong), a reference to the views of the Madhyamaka school and their position on emptiness as representing the lack of inherent existence of relative phenomena that, in and of itself, was the ultimate truth. However, for Dölpopa, this type of emptiness could only account for relative truth, whereas the emptiness of the ultimate truth could only be described as being empty of that which is adventitious to it. Hence, the ultimate is not empty of itself but only empty of that which is other. He called his system "Great Madhyamaka" (Uma Chenpo).
While we tend to mostly credit Dölpopa with the rise of zhentong, in many respects he was merely giving voice to a trend that had been percolating in certain Tibetan circles for hundreds of years. Though he was certainly innovative in his unique articulation of other-emptiness, the Jonang never held any sort of monopoly on the concept. And though others adopted his terms, other-emptiness and Great Madhyamaka, their usage often referenced very different perspectives depending upon their affiliation with the various Tibetan schools, though even such affiliations could not guarantee conformity of opinions. For the most part these positions evolved from Tibetan scholars addressing issues surrounding buddha-nature, a concept that challenged long-standing Tibetan beliefs on the primacy of the second of the so-called turnings of the dharma wheel over the third, the assumed superiority of Madhyamaka over Yogācāra, the proper categorization of the five texts attributed to Maitreya, and so on. Therefore, it appears that, for those Tibetan scholars that were sympathetic to these causes, zhentong and the Great Madhyamaka provided an avenue to voice positions that had been historically unpopular and thus underrepresented. It also provided an intermediary between the views of Sūtra and Tantra—an intersection where the worlds of philosophers and yogis overlap. After all, many of the figures involved with the other-emptiness movement were both.
In India, Yogācāra had been an important precursor to the rise of tantric Buddhism, as it marked a shift toward a positive view of the ultimate, one in which philosophers could speak of what it is rather than only describing what it is not. However, in Tibet, Madhyamaka reigned as the refutation method supreme, and Yogācāra, often merely equated with the notion of Mind-Only (cittamātra), was viewed as little more than one of its many defeated rivals. Zhentong was able to fill the void created by that demotion of Yogācāra and thereby resurrect many of its most salient contributions in the name of Great Madhyamaka. Therefore, for the followers of the Tibetan traditions, which typically included specific conglomerations of teachings drawn from both Sūtra and Tantra, Great Madhyamaka could help bridge this divide and bring their philosophy in line with what they considered to be their highest teachings. Thus, for Dölpopa and his Jonang descendants, zhentong was connected with the Kālacakra Tantra. For the Kagyu, it was connected with Mahāmudrā. And for the Nyingma, it was connected with Dzogchen. Though, eventually such traditional divisions would blur, as was the case in the eighteenth century when the Nyingma scholar Khatok Rigdzin Tsewang Norbu passed the Kālacakra teachings onto the important Kagyu hierarch the Eighth Tai Situpa Chökyi Jungne and encouraged him to adopt the other-emptiness view in the process. Therefore, while inter-tradition, or even intra-tradition, conformity on other-emptiness seems to have rarely materialized, the fluidity of the concept and the patterns of its ebb and flow over the course of centuries of Tibetan history are a testament to its perceived value, a value that shifted considerably based upon the circumstances in which it was employed.
In sum, though there are some obvious commonalities between those that espouse other-emptiness, there is also a surprising amount of diversity and nuance in the various expressions of this view. Though often considered to be representative of the assumed debate between rangtong and zhentong, most positions on other-emptiness came to employ aspects of self-emptiness as well. In terms of Great Madhyamaka, this is often discussed as a reconciliation of the views of Nāgārjuna and Asaṅga. So while modern presentations of this position have been couched in the apparent controversy it spawned, in another sense it can be seen as an attempt to remedy the bias upon which such perceived controversy was based. As Jamgön Kongtrul states in his Treasury of Knowledge,
The supreme traditions of these two chariots do not contradict each other: one emphasizes outer principles, the other inner principles. Therefore, the judicious thing to do is equally engage their points for study, reflection, and meditation.
- 'Jam mgon kong sprul. The Treasury of Knowledge Book Six, Part Three: Frameworks of Buddhist Philosophy: A Systematic Presentation of the Cause-Based Philosophical Vehicles, trans. Elizabeth Callahan, Kalu Rinpoché Translation Group (Boulder, CO: Snow Lion Publications, 2007), 262.