Chapter 4. The development of the schools and the accounts of eighteen or twenty¶

The preceding chapter examined the root division of the saṅgha into Sthaviras and Mahāsāṃghikas. The present chapter follows the further branching of each into the traditional "eighteen schools," or twenty in some accounts. The number is approximate, and the lists do not agree. The chapter therefore serves as a map of differences in enumeration, the principal schools, their territories, and their main claims. Detailed examination of their doctrines is reserved for Essay 3. The judgment of 2.3 still applies. Schools emerged through differentiation of ordination lineages and doctrinal tendencies, and most were not "schisms" in the disciplinary sense.

1. "Eighteen schools" is an approximate number¶

"Eighteen schools" is a traditional, almost formulaic round number, which need not reflect a precise count. The main sources for the schools' genealogies disagree over numbers, names, sequence, and relationships:¹

The reasons for disagreement are not difficult to understand. Schools formed gradually over several centuries through ordination lineages, doctrine, and region. Traditions remembered events differently and had motives for arranging genealogies to their own advantage. Theravāda, for example, represented itself as orthodox and others as having "split away." The position taken in the present book is that no single list should be treated as an exact historical register. It is safer to read them as competing maps. The difference between eighteen and twenty probably reflects different counting conventions, particularly whether the two root schools are included.

2. The schools that emerged from each branch¶

Taking the Samayabhedoparacanacakra as representative, the branches developed roughly as follows:

• The Mahāsāṃghika branch, with about nine schools including the root school, comprised Mahāsāṃghika, Ekavyāvahārika, Lokottaravāda, Kukkuṭika, Bahuśrutīya, Prajñaptivāda, and southern Indian schools associated with Caitya Hill, the Western Mountain, and the Northern Mountain.
• The Sthavira branch, with about eleven schools including the root school, comprised Sarvāstivāda, Haimavata, understood as the original Sthaviras who remained in place, Vātsīputrīya and its Dharmottarīya, Bhadrayānīya, Saṃmitīya, and Saṇṇāgarika offshoots, as well as Mahīśāsaka, Dharmaguptaka, Kāśyapīya, and Sautrāntika.

Together they total approximately twenty, or eighteen when the two root schools are subtracted. The discrepancy between accounts of eighteen and twenty schools largely lies in that counting convention. It must again be stressed that the arrangement is Sarvāstivāda's. The names and relationships change in Theravāda or Bhāviveka's versions.

The diagram sketches the principal branches within the Samayabhedoparacanacakra framework. Dates in parentheses are scholarly estimates with broad margins, and should not be treated as a precise chronology:

The text does not assign a settled date to Sautrāntika's emergence. It identifies the Abhidharmakośa as the point at which the name of a distinct group becomes reliably clear.

The Chinese diagram shows Lokottaravāda / Ekavyāvahārika and Caitika / Aparaśaila as parallel branches of Mahāsāṃghika. It dates the former, Vibhajyavāda, Vātsīputrīya, and Dharmaguptaka / Mahīśāsaka to approximately the third century BCE. The English diagram adds a link between the two branches, dates the former to the second century BCE, and omits the other three dates.

3. Principal schools, territories, and doctrines¶

The following table lists several major schools, their affiliations, territories, and central claims. Doctrinal details appear in the indicated chapters:

Several points require further comment.

Vibhajyavāda and the southern tradition. The table's "Theravāda, or Vibhajyavāda" refers to the Sri Lankan branch that transmitted the Pāli Tipiṭaka, sometimes called Vibhajyavāda, the "doctrine of distinction." The term expresses the tradition's own position. Against the Sarvāstivāda claim that all dharmas in all three times really exist, it insists that no blanket assertion about everything is possible. Judgments must distinguish the particular characteristics of dharmas. After entering Sri Lanka, the transmission became generally known as Theravāda. Modern scholars distinguish "southern Theravāda" from the historically earlier Sthavira, or original community of elders. The Chinese term "上座部" (Shangzuobu) can refer to either, depending on context, and readers must attend to which is meant. The three names belong to different levels, with some matters settled and others uncertain. They need to be considered separately.²

Vātsīputrīya and Saṃmitīya. The school proposed a pudgala to answer the problem of "continuity without a self" and was often accused by others of concealing a self within its account. Section 5 and Essay 3 discuss the argument in detail. Yet the school was once extremely successful in India. Xuanzang observed considerable numbers of Saṃmitīya monasteries and monks during his western journey, even exceeding those of the Sarvāstivāda. The later impression of "orthodox versus heretical," preserved in southern and Chinese accounts, differs considerably from the schools' actual standing at the time.

The origins and later implications of Sautrāntika. Sautrāntika emerged late from within Sarvāstivāda. Scholars have not settled the exact date of separation. The earliest reliable references to Sautrāntika as an identifiable group become clear only in sources from around the Abhidharmakośa. Its central disagreement was with Sarvāstivāda's "real existence in all three times." To explain how karmic results persist through time, Sarvāstivāda assigned some form of reality to past and future dharmas. Sautrāntika thought that went too far and maintained that only present dharmas really exist. An immediate difficulty followed. If the present arises and ceases moment by moment, how can karmic results continue? Sautrāntika answered with "seeds" (bīja). Although a dharma in the previous moment ceases, it leaves a seed in the continuing stream of consciousness which passes to future moments. The seed theory connects directly to the problem later addressed by Yogācāra's ālaya-vijñāna, or store consciousness. Ālaya-vijñāna can be seen as the result of making the Sautrāntika seed function explicit and giving it the status of an entity. From Sarvāstivāda's enduring dharma entities to Sautrāntika's "only the present exists, with seeds," and then to Yogācāra's ālaya-vijñāna, a fairly continuous sequence of problems can be traced. The following two essays pursue that sequence.³

4. How geographical distribution determined later directions¶

The schools' distribution almost predetermined Buddhism's later directions of transmission. Aśoka's missions, discussed in 2.2, and trade routes helped establish the main regional patterns:

The four regional cases are separate. The arrow from the transmission to China to Sri Lanka and Southeast Asia does not represent the sequence described in the text.

The diagram connects several themes of the book's later parts. Scriptures from northwestern schools, especially Sarvāstivāda and Dharmaguptaka, passed through Central Asia and were translated in China, forming the source of the northern transmission. The transcendent conception of the Buddha and ideas close to Mahāyāna among southern Indian Mahāsāṃghikas supplied an important background for Mahāyāna's rise, discussed in Essay 4. Vibhajyavāda entered Sri Lanka and became southern Theravāda, discussed in Essay 5. Yet schools such as Saṃmitīya, once among the strongest within India, disappeared with the overall decline of Indian Buddhism. Flourishing and declining do not necessarily coincide with surviving and disappearing.

The following map places the main territories geographically. Five colored areas correspond to five principal directions, with transmission routes marked by dashed arrows:

The discussion here identifies southern India, especially Andhra, as an important region in the rise of Mahāyāna. The map places that description under Magadha.

The northward arrow from Sri Lanka to Magadha does not depict the southern transmission described in the text, from India to Sri Lanka and onward to Southeast Asia.

5. Coexistence and dispute among the schools¶

As argued in 2.3, most schools did not split one another's saṅghas in the disciplinary sense. They shared many rules and differed chiefly in ordination lineage and doctrine.⁴ Residence in the same monastery was also common, approaching normal practice at least in monasteries of the centuries CE.⁵ The absence of schism did not mean an absence of argument. The age of the schools was a period of intense debate.

The best surviving evidence is the Theravāda Kathāvatthu, one of the southern Abhidhamma books. It sets out other schools' claims one by one and refutes them, including Vātsīputrīya's pudgala, Sarvāstivāda's real existence in all three times, and certain schools' views of arhats.⁶ A treatise devoting most of its length to refuting other Buddhist schools shows that, even when the groups did not separate their assemblies and meals, they opposed each other directly in doctrine and took each other seriously.

The pudgala controversy is a particularly representative example and deserves further discussion. The early teaching of not-self (anattā) denies a permanent, unchanging self, but immediately raises a practical difficulty. Without a "self," how do karmic results persist across many lives? Vātsīputrīya posited a "person" (pudgala), described as "neither identical with nor separate from the aggregates." It is neither identical with any of the five aggregates nor independently existent outside them. The proposal is a carefully designed compromise. The pudgala is not an eternal self, but it is not merely a concept either. It really exists in a way that cannot be fully specified, sufficiently to account for the continuity of karmic results.⁷

The Kathāvatthu's objection is direct. Any identifiable entity must ultimately be either permanent or impermanent. "Neither identical nor separate" merely avoids the question, disguising an implicit self with evasive wording. Vātsīputrīya replies that its opponents themselves say "this person has attained arhatship," and asks what that "person" is. The exchange exposes a deeper tension. The gap between not-self and the continuity of karmic results cannot be closed by changing terminology. Yogācāra and tathāgatagarbha thought would later address that gap in very different ways. Essays 3 and 4 pursue the question.

The culture of debate made Abhidharma increasingly detailed. The next chapter examines its emergence, and Essay 3 analyzes the arguments and difficulties within the schools' claims individually.

The development of the schools was ultimately a long history of differentiation. The Sthavira and Mahāsāṃghika branches came first, followed by competing genealogies of eighteen or twenty schools. Distributed across the northwest, southern India, and the islands, the schools disputed with one another while coexisting for long periods. Their differentiation produced independent textual transmissions and promoted Abhidharma, while supplying historical conditions for Mahāyāna and the later three main directions of transmission.

References¶