The Four Schools of Buddhism Compared: From “Everything Is Real” to “Everything Is Void” — One Doctrine, Four Conclusions, with Western and Vedānta Parallels

Schools of Buddhism: Pratītyasamutpāda; Kṣaṇikavāda, Nairātmyavāda

Official Syllabus: Paper I, Section B, Unit 14

The Buddha refused to answer metaphysical questions; his followers could not. Within a few centuries of his death, Buddhism had split into some eighteen early schools and later into two great vehicles — Hīnayāna and Mahāyāna — with a third, Vajrayāna, growing out of the second. Out of some thirty schools, Indian philosophy remembers four as the classical philosophical schools: the Vaibhāṣika and Sautrāntika (Hīnayāna realists), and the Yogācāra and Mādhyamika (Mahāyāna idealist and dialectical schools). All four accept the Four Noble Truths, dependent origination, momentariness, no-self and nirvāṇa. Yet they reach opposite conclusions about what is real — from “everything is real” to “everything is void“. This article brings the whole unit together: how the schools arose, what divides them, how they argue with each other, and how their journey from realism to idealism to critique mirrors the path of Western philosophy from Locke to Berkeley to Kant.

Context & Problem

Why One Teaching Became Many Schools

• The Buddha’s silence. The Buddha left the ten metaphysical questions unanswered (avyākata, Article 1) and spoke against speculation. But his followers were thinking people, and intellectual curiosity cannot be stopped by a ban; the questions he set aside returned. As one writer put it, the many schools were “the nemesis of neglected metaphysics“.
• The silence read in two ways.
  1. Scepticism — the Buddha knew no answer, or thought none could be known. This fits early (Hīnayāna) realism and its focus on ethics.
  2. Indescribability — the ultimate truth is beyond words. This is the Mahāyāna reading, which led to Nāgārjuna’s śūnyatā and the two truths.
• The councils and the split.
  1. First Council (Rājagṛha) — soon after the Buddha’s death; the Vinaya and Suttas recited.
  2. Second Council (Vaiśālī) — about a century later; disputes over monastic discipline split the order into the conservative Sthaviravāda (“doctrine of the elders”) and the more liberal Mahāsāṅghika (“great assembly”). The Mahāsāṅghika later fed into Mahāyāna.
  3. Third Council (Pāṭaliputra, under Aśoka) — the Abhidhamma added; the Theravāda canon took shape.
  4. Fourth Council (Kashmir, under Kaniṣka) — the Sarvāstivāda commentary, the Vibhāṣā, compiled, giving the Vaibhāṣika its name.

Three Phases of Buddhist Thought

Phase	Character	Schools
1. Realistic and pluralistic	Reality is made of many real, momentary elements (dharmas), mental and physical	Early Buddhism; Vaibhāṣika and Sautrāntika
2. Dialectical (“nihilistic” to its critics)	All elements are empty of own-nature; every theory of essence refutes itself	Mādhyamika (Nāgārjuna, c. 2nd century CE)
3. Idealistic	Only consciousness is real; the external world is its projection	Yogācāra (Asaṅga, Vasubandhu, 4th–5th century CE), continued by the logicians Dignāga and Dharmakīrti

• From pessimism to optimism. Early Buddhism stressed suffering and escape from it; Mahāyāna added a positive ideal — the Bodhisattva’s compassion, the Buddha-nature in all beings, and nirvāṇa as bliss.
• Order of exposition vs order of history. Historically the Mādhyamika (2nd century) came before the Yogācāra (4th century). Logically, many textbooks present the schools as a ladder: realism (Vaibhāṣika) → indirect realism (Sautrāntika) → idealism (Yogācāra) → critique of all views (Mādhyamika).

What All Schools Share

• The Four Noble Truths and the Eightfold Path.
• Dependent origination (pratītyasamutpāda) as the law of all becoming.
• Impermanence, no-self and (in different forms) momentariness.
• Nirvāṇa as the end of suffering, and karma as action bearing fruit without a permanent soul.
• Rejection of God as creator, and of the Vedas as authority.

Core Doctrine

1. Two Questions, Four Answers

The four schools can be classified by asking two questions — one metaphysical, one epistemological:

Question 1 (metaphysical): What is real — mind, external objects, both, or neither?

• Neither mind nor external objects has own-reality → Mādhyamika (Śūnyavāda).
• Mind only is real; external objects are not → Yogācāra (Vijñānavāda).
• Both mind and external objects are real → the Sarvāstivāda (“all exists”) realists.

Question 2 (epistemological, for the realists): How are external objects known?

• By inference from mental images — the object is never directly seen → Sautrāntika (bāhyārthānumeyavāda, “the external object is inferred”).
• By direct perception — we see the object itself → Vaibhāṣika (bāhyārthapratyakṣavāda, “the external object is perceived”).

2. The Four Schools at a Glance

	Vaibhāṣika	Sautrāntika	Yogācāra	Mādhyamika
Vehicle	Hīnayāna	Hīnayāna	Mahāyāna	Mahāyāna
Name means	Followers of the Vibhāṣā commentary	Followers of the sūtras (not the Abhidharma)	Practice of yoga; also called Vijñānavāda (“consciousness doctrine”)	Followers of the middle path; called Śūnyavāda by others
Key thinkers	Vasumitra, Saṃghabhadra; Vasubandhu’s Abhidharmakośa (as exposition)	Kumāralāta, Śrīlāta; Vasubandhu’s commentary	Maitreyanātha, Asaṅga, Vasubandhu; later Dignāga, Dharmakīrti	Nāgārjuna, Āryadeva, Buddhapālita, Bhāvaviveka, Candrakīrti
External world	Real; directly perceived	Real; inferred from mental images	Unreal; a projection of consciousness	Empty — neither real by itself nor non-existent
Mind	Real (momentary dharmas)	Real (momentary)	Alone real — the storehouse-consciousness	Also empty
Key idea	Dharmas exist in all three times (75 dharmas)	Only the present moment exists (43 dharmas); time-lag argument	Consciousness-only; ālaya-vijñāna; three natures	Śūnyatā = dependent origination; catuṣkoṭi; two truths
Theory of knowledge	Direct realism	Representative realism	Subjective (or absolute) idealism	Critical dialectic; pramāṇas only conventionally valid
Western parallel	Naïve or direct realism (Reid, Moore)	Locke’s representative realism; Kant’s unknowable thing-in-itself	Berkeley (esse est percipi)	Kant’s antinomies, Wittgenstein, Bradley

3. Same Doctrine, Opposite Conclusions: “All Is Real” vs “All Is Void”

All four schools begin from dependent origination. The two extremes show how one premise can be read in opposite directions.

• The Sarvāstivāda reading (“everything is real”).
  1. Dependent origination is a relation between elements; a relation needs real terms.
  2. Each element (dharma) has its own defining mark (svalakṣaṇa): earth is solid, water is fluid, feeling is felt.
  3. A past cause must be real to produce its effect; a future object must be real to be known. So dharmas exist in past, present and future — sarvam asti.
  4. Only wholes (chariots, persons, forests) are unreal — they are names for collections of real elements.
• The Mādhyamika reading (“everything is void”).
  1. What arises in dependence on other things cannot exist by itself.
  2. To have own-nature is to exist by itself.
  3. So every dependently arisen thing — elements included — is empty of own-nature.
  4. The analysis that the realists applied to wholes (a chariot is only its parts) is applied to the parts too: the elements are as conventional as the chariot.
• Where they part. The realist reads dependence as a link between real things; the Mādhyamika reads it as proof that nothing is independent. The Sarvāstivādin stops the analysis at the elements; Nāgārjuna refuses to stop.
• The middle positions. The Sautrāntika keeps the elements real but makes external objects only inferred; the Yogācāra keeps consciousness real but drops the external object. Each school takes one step further from the realism of the first.

4. How the Sarvāstivādins Differ Among Themselves on Knowledge

“Sarvāstivāda” in the wide sense covers both Hīnayāna realist schools; they agree that external objects exist but disagree on how we know them.

Point	Vaibhāṣika	Sautrāntika
Perception	Direct: we perceive the object itself	Indirect: we perceive a mental image (ākāra) caused by the object
External object	Perceived (pratyakṣa)	Inferred (anumeya) from the image
Main argument	If we never perceived objects, we could never infer them — inference (like smoke to fire) needs earlier perception of the link	Time-lag: the object of a moment has perished by the time consciousness arises; what we see is its copy
Variety of images	Variety comes from the objects themselves	Different images of the same thing (near and far, ill and healthy) show we see images
Time	Dharmas exist in all three times	Only the present moment is real
Weak point	Cannot explain illusions and the time-gap	Like Locke, it cannot check the copy against the original — which leads to idealism

• The Vaibhāṣika critique of the Sautrāntika. If no external object is ever perceived, we cannot even know that our ideas are copies of anything; the relation “image – object” can be known only if both terms have been perceived. Inference of the unperceived from the perceived is like inferring fire from smoke without ever having seen fire.
• The road to idealism. The Yogācāra takes the Sautrāntika’s admission — “we see only images” — and asks: why posit an unseen object at all? Exactly so Berkeley took Locke’s “something I know not what” and abolished it (Articles 7 and 8).

5. Mādhyamika and Yogācāra: The Two Mahāyāna Schools

Point	Mādhyamika	Yogācāra
Founders	Nāgārjuna, Āryadeva; later Buddhapālita, Bhāvaviveka, Candrakīrti	Maitreyanātha, Asaṅga, Vasubandhu; later Dignāga, Dharmakīrti
Key texts	Mūlamadhyamakakārikā, Vigrahavyāvartanī	Laṅkāvatāra Sūtra, Viṃśatikā, Triṃśikā, Trisvabhāvanirdeśa
Central doctrine	Śūnyatā: everything lacks own-nature	Vijñapti-mātratā: only consciousness is real
Status of the mind	Empty, like everything else	Real (as a stream); the storehouse-consciousness
External objects	Empty, but conventionally valid	Unreal; projections of consciousness
Framework	Two truths: conventional and ultimate	Three natures: imagined, dependent, perfected
Meaning of emptiness	Absence of own-nature in all things, mind included	Absence of subject–object duality; non-dual consciousness remains
Self-awareness (svasaṃvedana)	Rejected: “a sword cannot cut itself”	Accepted: consciousness is self-luminous
Pramāṇas	Valid only conventionally; mutually dependent	Developed into a full logic by Dignāga and Dharmakīrti
Liberation	Seeing emptiness; calming of all concepts	Transformation of consciousness (āśraya-parāvṛtti) into non-dual wisdom
Criticism of the other	Yogācāra reifies consciousness and makes the ālaya a hidden self	If mind is unreal, all reasoning — including the Mādhyamika’s — is unreal; “to say that everything is unreal is suicidal“

6. Hīnayāna, Mahāyāna and Vajrayāna

Point	Hīnayāna (Theravāda and the early schools)	Mahāyāna	Vajrayāna
Meaning	“Lesser vehicle” (a name given by Mahāyānists)	“Great vehicle” — able to carry all beings	“Diamond / thunderbolt vehicle“
Origin	Sthaviravāda after the Second Council; 18 early schools	Grew from about the 1st century BCE–1st century CE, with links to the Mahāsāṅghika	Tantric movement, about the 6th–7th century CE
Ideal	The Arhat — one who wins his own liberation	The Bodhisattva — who postpones final nirvāṇa to save all beings	The Siddha — the accomplished master who attains liberation in this life
Texts	Pāli canon (Tipiṭaka)	Sanskrit sūtras: Prajñāpāramitā, Lotus Sūtra, Laṅkāvatāra	Tantras
Buddha	A great human teacher who showed the way	A divine principle: the three bodies (trikāya) — Dharmakāya, Sambhogakāya, Nirmāṇakāya	A cosmic principle embodied in many Buddha-forms
Means	Self-effort: morality, meditation, wisdom	Wisdom and compassion; the six perfections (pāramitās); devotion and grace	Mantra, maṇḍala, ritual, and the guru
Nirvāṇa	Mostly described negatively — extinction of craving	Positive — bliss, Buddha-nature; not different from saṃsāra	Union of wisdom and method; enlightenment in one life
Philosophical schools	Vaibhāṣika, Sautrāntika	Mādhyamika, Yogācāra	Draws on both Mahāyāna schools
Spread	Sri Lanka, Myanmar, Thailand, Cambodia, Laos	China, Japan, Korea, Vietnam, Tibet	Tibet, Bhutan, Mongolia, Nepal

Hīnayāna as a religion without God.

• The Buddha is a teacher, not a saviour; there is no creator God; one takes refuge in the three jewels (tisaraṇa) — Buddha, Dharma, Saṅgha.
• Self-help: “Be a light unto yourselves” (ātmadīpo bhava); the Buddha’s last words — “decay is inherent in all compounded things; work out your liberation with diligence“.
• The path rises through four stages: the stream-enterer (srotāpanna), the once-returner (sakṛdāgāmin), the non-returner (anāgāmin) and the Arhat.
• Nirvāṇa can be attained consciously in this life by one’s own effort.

Mahāyāna’s three changes.

1. The Bodhisattva ideal. Liberation for oneself alone is “spiritual selfishness“; the Bodhisattva vows to save all beings, joining wisdom (prajñā) and compassion (karuṇā). Like a lotus that grows in the mud yet stays clean, he lives in the world without being stained by it. He can transfer his merit (pariṇāmanā or parivarta) to others — unlike the strict Hīnayāna rule that each reaps only his own karma. The Bodhisattva ideal is grounded in a vision of one transcendental reality in which all beings share.
2. Buddha as God. The Buddha becomes the Dharmakāya — the cosmic body of truth — and saviour figures such as Amitābha offer grace to devotees. The human need for devotion reasserts itself.
3. Restoration of the Self. Against the strict no-self of Hīnayāna, some Mahāyāna texts speak of a great Self (mahātman) or Buddha-nature in all beings — the empirical ego is denied, but a higher, universal self is affirmed.

The stream analogy. The Hīnayāna follower is like one who swims across a flooded river alone; the Mahāyāna Bodhisattva is like one who builds a great ferry to carry everyone across, and stays to steer it.

7. Was Mahāyāna a Departure or a Fulfilment?

• The departure view. Mahāyāna changed the Buddha’s teaching: it made a teacher into a God, brought back a Self, and added ritual and grace — moving towards Hindu theism.
• The fulfilment view. Mahāyāna claims to bring out what the Buddha really meant:
  1. The Buddha’s silence pointed to an indescribable ultimate, not to scepticism.
  2. He adapted his teaching to his hearers (skill in means, upāya-kauśalya); the Hīnayāna teachings were a first step for those not ready for more.
  3. On this view, the Buddha came “not to destroy but to fulfil” the spiritual insight of the Upaniṣads; later Buddhism, especially Mahāyāna, recovered that link.
• Balanced view. Both vehicles keep the core: suffering, dependent origination, no permanent ego, and liberation through wisdom and conduct. Mahāyāna adds compassion as universal duty and a more positive picture of the goal.

Critical Evaluation

A. How the Schools Criticise Each Other

• Vaibhāṣika → Sautrāntika. If objects are never perceived, how do you know your images are copies of anything? Inference needs prior perception.
• Sautrāntika → Vaibhāṣika. The momentary object has already perished when it is known; illusions prove we see images, not things.
• Yogācāra → Sautrāntika. An object that is never perceived is an idle hypothesis; drop it. Atoms cannot combine; objects and their awareness are always found together.
• Sautrāntika → Yogācāra. Even the Yogācāra says ideas appear “as if external” — which makes sense only if there is an outside. A pot is felt outside while consciousness is felt within; no one says “I am the pot“.
• Mādhyamika → Yogācāra. Consciousness depends on its objects; if objects are empty, so is consciousness. Self-awareness is impossible — “a sword cannot cut itself“. The ālaya is a hidden self.
• Yogācāra → Mādhyamika. If mind too is unreal, the Mādhyamika’s own reasoning is unreal; “to say that everything is unreal is suicidal“.
• Mādhyamika → realists. If dharmas had own-nature, they could not arise, change or cease; the realist’s real elements make dependent origination impossible.

B. External Critiques of the Whole Buddhist Project

• Nyāya-Vaiśeṣika. Momentariness destroys memory, recognition and karma (Article 4); denying substance leaves qualities without a bearer.
• Mīmāṃsā (Kumārila). Dreams borrow their content from waking experience; cognition is formless and reveals real objects.
• Jaina. Momentariness leads to kṛtapraṇāśa (the doer loses the fruit of his action) and akṛtābhyupagama (one gets fruit he did not earn); one-sided views are each partial truths, not the whole truth.
• Śaṅkara (Advaita). Attacks every school: the realists cannot explain how momentary atoms combine without a uniting intelligence; the idealists confuse “known by the mind” with “part of the mind“; the doctrine of the void contradicts all means of knowledge. Yet his two levels of truth closely follow the Mādhyamika — and critics called him a “crypto-Buddhist” (pracchanna-bauddha).
• The general Brahmanical objection. Every school assumes a unifying subject — one who remembers, compares, suffers and is liberated — while denying it. “He who experiences the flux must stand above the flux.“

C. Significance of Buddhism

• Practical and spiritual together. Buddhism joins rigorous philosophical analysis with a way of life; its metaphysics serves liberation.
• Ethics without God. It grounds morality in causality and compassion, not in divine command — a model of secular ethics.
• Philosophical depth. It produced Indian philosophy’s sharpest logic (Dignāga, Dharmakīrti), its most radical critique of metaphysics (Nāgārjuna), and its richest philosophy of mind (Yogācāra).
• Stimulus to other schools. Nyāya logic, Mīmāṃsā epistemology and Advaita’s two truths were all sharpened in debate with Buddhists.
• Wisdom and compassion. The Mahāyāna union of prajñā and karuṇā gave Asia an ideal of the enlightened person as one who serves all beings.
• Social message. It rejected caste as a measure of worth and opened the path to all — later central to Dr B.R. Ambedkar’s Navayāna Buddhism.

Critics and Defenders

Cross-Tradition Comparison

The same journey in two traditions:

Buddhist school	Western counterpart	Shared move
Early Buddhism	Heraclitus (“everything flows”), Hume (bundle of perceptions), William James (stream of consciousness), Bergson (life as flux)	No permanent substance or self; reality as process — a “dynamic phenomenalism“
Vaibhāṣika	Direct realism (Reid, Moore)	We perceive objects themselves
Sautrāntika	Locke (representative realism); Kant (unknowable thing-in-itself)	We perceive ideas; the object is inferred
Yogācāra	Berkeley (esse est percipi); Hegel-style absolute idealism in the absolute reading	The inferred object is dropped; only minds and ideas remain (Berkeley keeps God; Yogācāra uses karmic seeds)
Mādhyamika	Kant’s antinomies, Wittgenstein’s therapy of language, Bradley’s critique of relations	Every metaphysical view contradicts itself; reason has limits
Sautrāntika refuted by Yogācāra	Locke refuted by Berkeley	“Something I know not what” is abolished
Yogācāra refuted by Sautrāntika	Berkeley refuted by Moore (“Refutation of Idealism”)	Awareness and its object are distinct

Buddhist schools and Vedānta:

Buddhist school	Vedānta parallel	Difference
Mādhyamika	Advaita — two levels of truth; the world as māyā; the ultimate beyond words	Advaita’s ultimate is positive (Brahman = being, consciousness, bliss); Mādhyamika names no ultimate
Yogācāra	Gauḍapāda’s dream argument; the Advaitic witness-consciousness (sākṣin)	Advaita’s consciousness is eternal and one; Yogācāra’s is a momentary stream, many in number
Ālaya-vijñāna	Like Brahman or the ātman as ground of experience	The ālaya is changing and ceases at liberation
Svabhāva-śūnya / prapañca-śūnya	Māyā / nirguṇa Brahman	Śūnyatā is not called “being” or “self”
Hīnayāna realism	Nyāya-Vaiśeṣika pluralist realism	Buddhists deny substance and permanence; Nyāya affirms both

Synthesis (Siddhānta)

• One root, four branches. All four schools grow from dependent origination, momentariness and no-self. They differ on what is real (mind, matter, both or neither) and on how it is known (directly, by inference, as consciousness itself, or only conventionally).
• A dialectical progression. Vaibhāṣika direct realism gives way to Sautrāntika inference; the inferred object is dropped by the Yogācāra; and the Mādhyamika shows that both object and mind are empty. Each step answers the difficulty of the one before.
• Two vehicles, one core. Hīnayāna stresses self-effort and the Arhat; Mahāyāna adds compassion, the Bodhisattva and a positive nirvāṇa; Vajrayāna adds ritual and the guru. All keep the Four Noble Truths.
• The lasting debate. The realist–idealist–dialectical debate within Buddhism anticipated the great debates of Western epistemology and shaped the whole of Indian philosophy, above all Advaita Vedānta.
• Contemporary relevance.
  1. Philosophy of perception. Direct realism, representationalism and idealism remain live positions in philosophy of mind and cognitive science — the Buddhist debate maps onto them closely.
  2. Process philosophy and science. The flux-view of early Buddhism echoes modern physics and biology, where “things” are stable patterns of process.
  3. Ethics of compassion. The Bodhisattva ideal inspires engaged Buddhism — social service, peace work and ecological action.
  4. Social equality. Buddhism’s rejection of caste remains a resource for social justice in India.
  5. Pluralism. The fact that one teaching supports many readings models how traditions can hold diversity within unity.

“Be a light unto yourselves; be a refuge unto yourselves.” — The Buddha