Nagarjuna Buddhism

Nagarjuna (Sanskrit m., नागार्जुन, Nāgārjuna, [naːˈgaːrdʒunɐ]; c. 2nd century) is considered the first historically significant figure in the context of Mahāyāna Buddhism.

The central motive behind Nāgārjuna's teaching activity, which laid the foundation for the "Middle Way School" (Mādhyamaka) and bequeathed numerous works to Buddhist philosophy, was to restore the Buddha's teaching, the core idea of which, according to Nāgārjuna, was in danger of being lost from view due to rampant school teaching in some schools of Hīnayāna.

To support his approach, Nāgārjuna systematically made use of a special argumentation tool, the "judgment square" (Sanskrit catuṣkoṭi), with the help of which he tried to point out and deconstruct logical contradictions in the postulates of his philosophical environment.

The aim of this methodology, which was characterized by a rigorous rejection of extreme viewpoints, was to make Buddhist teaching comprehensible again as a consistent middle way, which fundamentally excludes all unwholesome views counteracting the process of cognition - especially the "belief in eternity" (Sanskrit śāśvatavāda) and the "doctrine of annihilation" (Sanskrit ucchedavāda) - and to defend this view against the school opinions prevalent in his time.

The detailed elaboration of the concept of emptiness (Sanskrit śūnyatā) in direct connection with "arising in dependence" (Sanskrit pratītyasamutpāda) as well as the further development of the doctrine of the "two truths" (Sanskrit satyadvaya) are among the contributions made by Nagarjuna, which make him one of the influential Buddhist thinkers of Indian origin, especially in the Vajrayāna and Zen traditions after Buddha.

Nāgārjuna's Life and Work - Myths and Legends

About the person of Nāgārjuna there is almost no secured knowledge available. The hagiographies written within the Buddhist tradition long after his death, including testimonies in Chinese and in Tibetan by Paramārtha (499 - 569) and Xuanzang (603 - 664), among others, are very heavily embellished with myths and legends, and therefore highly unreliable with regard to an elaboration of historically verifiable facts.

Among these legends, mostly pedagogically conceived and characterized by great veneration, are stories whose contents have been handed down from tradition to tradition with slight variations.

One of them - from the pen of the translator Kumārajīva (344 - 413) - depicts Nāgārjuna as a magician who uses his ability to make himself invisible to seduce the mistresses of an influential ruler together with his companions. Nāgārjuna and his two companions sneak into the palace unnoticed and put their joint plan into action.

On the way back, Nāgārjuna misses the effectiveness of the spell on his two friends. The two unsuspecting companions are discovered by the palace guards and executed. This painful event, which directly confronts Nāgārjuna with suffering, finally causes him to devote himself henceforth only to the Buddha's teachings.

In another tale of unknown origin, Nāgārjuna's teaching attracts the attention of a mythical race of dragon-like serpentine beings, the Nāgas.

They invite Nāgārjuna in appreciation to their homeworld lying at the bottom of the sea and there hand him the Prajñāpāramitā scriptures, which the Buddha himself is said to have given them for safekeeping, with the request that they not be made available to the world public until people had become ripe for their message.

This legend alludes to the meaning of the name "Nāgārjuna", which translated means something like "white snake". Indian mythology associates the color white (arjuna) with purity and the symbol of the snake (nāga) with wisdom.

A distinctive feature of Nāgārjuna are therefore the snakes that rise behind his head in traditional representations (see figure above).

Many more legends surround the figure of Nāgārjuna, including accounts of an incurable childhood illness that he conquered by joining a monastic order and persistently studying early Buddhist scriptures, of alchemy and immortality elixirs that allowed him to reach a biblical age, and of his death by decapitation with Kuśagrass (Poa cynosuroides), a tall sedge with sharp stalks used in sacred ceremonies (puja) in India.

The execution wish, which according to that story is expressed by Nāgārjuna's philosophical opponents, whom he defeated in all debates, and to which Nāgārjuna himself agrees out of compassion for his opponents, can only be realized with this particular grass, since Nāgārjuna is said to have unintentionally killed an insect with it in one of his previous lives, as which one of these opponents was embodied at that time.

Verifiable data on Nāgārjuna's actual life outside these legends are largely in the dark. It is approximately certain that Nāgārjuna was born in the 2nd century AD as the son of a Brahmin family in the central Indian region of Vidarbha in the present-day state of Maharashtra.

He probably spent his later life until his death around Amaravati, located in southern India and belonging to present-day Andhra Pradesh. On the Sri Parvata mountain located in this area near Nāgārjunakoṇḍa, Nāgārjuna is said to have founded a monastery on the lower reaches of the Krishna River and taught there.

Nāgārjuna's association with the monastic university of Nālandā is most likely among the many legends, as this structure was not built until around the 5th century CE and thus does not fall within Nāgārjuna's widely recognized lifespan.

From various sources, including the literary works attributed to Nāgārjuna, Precious Garland (ratnāvalī) and Letter to a Friend (suhṛllekha), which particularly emphasize the ethical aspect of Buddhist teachings, it appears that Nāgārjuna probably maintained a long-standing friendship with a ruler of the Śātavāhana dynasty, to whom these letters were addressed.

However, it cannot be fully reconstructed which of the rulers who ruled between 230 BCE and 199 CE maintained this active contact with Nāgārjuna.

Nāgārjuna's works are invariably written in Sanskrit and not in "hybrid Sanskrit," the more common language combination in Māhayāna literature of Sanskrit and elements of local Prakrit dialects, which had replaced Pali as the commonly understood lingua franca in India at the time.

This may be due to the fact that Nāgārjuna, as a native Brahmin, was most familiar with Sanskrit as a written language. In style, his works show a clear influence of Prajñāpāramitā literature, but at the same time are deeply rooted in the Buddha's doctrinal discourses, which are frequently referred to in them.

Nāgārjuna's most important treatise is the "Mūlamādhyamakakārikā" ("Teaching Stanzas on the Fundamental Teachings of the Middle Way"), divided into 27 chapters. In addition, other treatises, some philosophical and some ethical in nature, can be considered authentic works of Nāgārjuna. These include:

Śūnyatāsaptati (Seventy Stanzas on Emptiness)
Vigrahavyāvartanī (Rejection of Accusations)
Pratītyasamutpādahṛdayakārikā (Teaching stanzas about arising in dependence)
Yuktiṣaṣtikā (Sixty stanzas of proof)
Vaidalyaprakaraṇa (Refutation of the expositions [of the Nyāya])
Vyavahārasiddhi (enlightenment in the world of everyday life)
Bodhicittavivaraṇa (explanation of the spirit of enlightenment)
Catuḥstava (Four Hymns)
Ratnāvalī (Precious Garland)
Sūtrasamuccaya (Sūtra Collection)
Bodhisaṃbharaka (prerequisites for enlightenment)
Suhṛllekha (letter to a friend).

Starting Points for Nāgārjuna's Methodology - the Philosophical Environment and His Theories

In the philosophical environment of his epoch, which was a heyday of Indian philosophy, Nāgārjuna was confronted with a multitude of different Buddhist and non-Buddhist schools and their points of view.

That era, which began around the 1st century B.C. and heralded a systematic period in Indian philosophy, was characterized by a lively debating culture in which the wars of words were conducted according to the categories (padārtha) of a fixed set of rules.

It was also the time of the written fixation of doctrinal contents in Sūtraform and other supplementary commentaries. In this philosophical contest, for the first time in its history, Buddhism was subjected to rigorous scrutiny by competing non-Buddhist systems and had to answer questions on a variety of topics.

These included epistemological questions, such as which means of knowledge (pramāṇa) enabled a reliable establishment of truth, as well as the recurring need for explanations about the process of rebirth and the nature of reality.

Two basic models had developed in the orthodox systems recognizing the Veda as an authority with respect to the important question, directly connected with the law of karma, in which way causality takes place:

The theory of satkāryavāda (literally, "doctrine of the being of the effect") favored by the Sāṃkhya philosophical system, which holds that the effect is already potentially contained in the cause (identity of cause and effect).

The theory of asatkāryavāda ("doctrine of the non-being of the effect [before and after its manifestation]") advocated by the Vaiśeṣika system, which takes the diametrically opposed standpoint to the Sāṃkhya.

According to this doctrine, the effect is not potentially contained in the cause, but the two are completely distinct and separate from each other (difference of cause and effect).
All other causality models of the non-Buddhist schools represented merely variations of these two positions:

The Jains' view was expressed epistemologically in the "syādvāda" (doctrine of the validity of a statement depending on the individual standpoint) and ontologically in the "anekāntavāda" (doctrine of the multiplicity of expressions) and took the position of a synthesis.

According to this position, every statement is true from the particular perspective of the person who makes it. And reality does not have only one expressible aspect, but can be verbalized only by naming several aspects.

The Jainist philosophy relied on the possibility of "both and" with regard to the question of the mode of action of causality, a view also held by the later theistic manifestation of the Sāṃkhya.

The fatalists (Ājīvikas), on the other hand, taught a strict determinism that excluded a morally and ethically based causality. They rejected the law of karma in favor of a thesis according to which world events were completely arbitrarily controlled by the course of fate (niyati).

Accordingly, there was no possibility for man to free himself from the cycle of rebirths (Saṃsāra) through his own efforts, since salvation for them did not depend on the quality of deeds (akriyavāda).

The materialists (Lokāyatikas) rejected all generally accepted principles of philosophical-religious Indian thought. For them, there was neither rebirth nor karma, and life ended for them with physical death. In their view, the world came into being purely by chance, without any particular lawfulness or order, from the four elements of earth, fire, water and air.

Based on this attitude, they propagated hedonism and the dissolution of the rigid caste structure.

In this polyphonic concert of views, two of the altogether 18 schools of the Hīnayāna joined in: the schools of the Sarvāstivāda and the Sautrāntika, which dealt intensively with the doctrine of the fundamental components of reality, the factors of existence (dharmas), systematized in the Abhidharma.

The vehement discussion about the status of these constitutive elements, which, among other reasons, had led to the Sautrantikas splitting off from the Sarvastivada as an independent school in the first place, also included a dispute about the causal relationship between the factors of existence, and in the course of this, the two schools applied the models of the satkāryavāda and the asatkāryavāda to their representations.

The Sarvāstivādin advocated the model of a coexistence of all future, present and past factors of existence in an eternal state of latency, which they leave in each case due to their karmically conditioned activation in order to constitute the world and things in changing combinations.

After the respective bond, which the existence factors have entered, falls apart again, they do not extinguish completely, but always remain so long in their potentiality, until they are activated again (therefore also the name "Sarvāstivāda", from Sanskrit "sarvam asti" = everything exists).

The Sarvastivadin attributed a "self-existence" (svabhāva) to the elements of reality and thereby upgraded their status to a "supreme reality" (paramārtha).

For the Sautrāntikas, this view was tantamount to a violation of the central Buddhist doctrine of the "non-self," since the elevation of the factors of existence to a level of reality superior to things and subjects brought the factors of existence, for their part, back into the position of an "unchanging self"-comparable to the Ātman of the Upaniṣaden.

In contrast, they advocated a doctrine of instantaneousness (kṣaṇikavāda), according to which the factors of existence flash up only momentarily, only to pass away completely at the same moment.

Therefore, the factors have no temporal extension and no linear cause-effect relation to each other. Before their coming into being, the existence factors were completely non-existent and into this non-existence they are also transferred again after their passing away.

Nāgārjuna rejects all these prevailing models of causality as contradictory already at the beginning of the first chapter of his "Teaching Strophes on the Root of the Middle Teaching":

Nowhere and never do you find things, originated from themselves, from other,
out of themselves and other together, without reason (i.e., neither out of nor from other).
na svato nāpi parato na dvābhyāṃ nāpy ahetutaḥ |
utpannā jātu vidyante bhāvāḥ kva cana ke cana||
(MMK 1.1)

According to Nāgārjuna, the attitude of the Sarvāstivādins with their version of the satkāryavāda went along with the extreme view of the "belief in eternity" (śāśvatavāda), since they elevated the factors of existence to something eternal and permanently existing.

The Sautrāntikas, on the other hand, with their elaboration of the asatkāryavāda, fell into the other extreme of the "doctrine of annihilation" (ucchedavāda) in Nāgārjuna's eyes, in that they declared the factors of existence to be entirely non-existent before their coming into existence and after their passing away.

Both views were incompatible for Nāgārjuna with the "Middle Way" (madhyamā pratipad), which he defined with reference to Buddha with the complete equivalence of "conditional arising" and "emptiness".

The factors of existence are not eternal, since they in turn exist in dependence on conditional factors, but they are also not annihilated, since they are wholly empty of self-existence due to their dependence. Nāgārjuna summarizes this understanding in the following sentence:

Arising in mutual dependence (pratītyasamutpāda), this is what we call 'emptiness'. This is [but only] a dependent concept (prajñapti); it (emptiness) is precisely what constitutes the Middle Way."

yaḥ pratītyasamutpādaḥ śūnyatāṃ tāṃ pracakṣmahe |
sā prajñaptir upādāya pratipat saiva madhyamā ||
(MMK 24.18)

The approach to this fact, which can only be fully comprehended in the highest insight (prajñā), is the central motive behind Nāgārjuna's entire philosophy. Nāgārjuna analyzed the major Buddhist themes against this background.

Nāgārjuna's Philosophy - The Doctrine of Emptiness (śūnyatāvāda)

Nāgārjuna's concern was a return to the "middle" of the Buddha's teachings, which, in view of the dispute between Sarvāstivādin and Sautrāntikas, threatened to fall victim to mere academic speculation about metaphysical realities.

Thus, he was not the founder of a new school, nor was he the founder of the Mahayana itself. Nāgārjuna analyzed the most important core Buddhist themes from the point of view of the equivalence of Conditioned Arising and Emptiness (see Shunyata), which he emphasizes at the beginning of his "Doctrinal Verses on the Fundamental Teachings of the Middle Way" with the "eight negations":

Non-perishing, non-arising, non-terminating, non-perpetuating, non-unity, non-muchness, non-arising, non-arising-from-it.
anirodham anutpādam anucchedam aśāśvataṃ |
anekārtham anānārtham anāgamam anirgamaṃ ||

In his view, the Sarvāstivādin and the Sautrāntikas, had not sufficiently internalized this "middle", which led them to fall into extremes: the Sarvāstivādin into the "It is always" position of eternal duration and the Sautrāntikas into the "It is and will be no more" position of annihilation.

Both schools had deviated in this respect from the Buddhist path, the quintessence of which Buddha explains in one of his doctrinal discourses with the following short sentence: "Only one thing do I teach: suffering and the abolition of suffering" (Majjhima-Nikaya, MN 22).

For Nāgārjuna, as was already emerging as a trend in the Prajñāpāramitā literature, ignorance (avidyā) in particular is one of the main sources of suffering, and it must be eliminated above all others in order to replace it in return with knowledge (prajñā) and insight (jñāna).

According to him, this is also possible on the logical-argumentative way via theory, to which he ascribes a practical use.

He proceeds deconstructively in his argumentation in order to dissolve step by step all tendencies of grasping in the practitioner, and thereby to reveal the "middle", which shows itself in the knowledge thus gained.

To establish emptiness on the basis of conclusive arguments, Nāgārjuna subjects the impermanence of phenomena to rigorous analysis. Only because phenomena are entirely empty in their dependence on conditional factors, Nāgārjuna argues, can they arise and pass away.

And it is only because they are empty that the overcoming of suffering through the Four Noble Truths and the treading of the Noble Eightfold Path to salvation are possible in the first place.

If phenomena were non-empty, i.e. if they existed by themselves, there would be no development in the world at all, everything would be completely static, unchanging, as it were "frozen in infinity".

Things would be uncaused and, not needing any support for their existence, would be frozen in eternity. But this cannot be reconciled with the observation of constant change in the world. Nowhere are imperishable things to be found. And therefore, Nāgārjuna concludes, nowhere are things found that are not empty.

[All] things are without intrinsic being because change of essence is seen in them. Because of the emptiness of [all] things, [however,] there is no thing without inherent being.

bhāvānāṃ niḥsvabhāvatvamanyathābhāvadarśanāt |
asvabhāvo bhāvo nāsti bhāvānāṃ śūnyatā yataḥ ||
(MMK 13.3)

For example, a tree is dependent on a wide variety of conditioning factors: Roots, trunk, branches, twigs, leaves, nutrients in the soil, wind, rain, sunlight, etc. From this point of view, the tree is not "there" by itself, but only through the interlocking of the various factors that "raise it into existence" - this includes, for example, the perception and the linguistic assignment.

The whole universe works with at this one tree, since all conditions are conditioned again by other factors for their part. If one factor would fall away, all others would fall away likewise, they are inseparably interwoven.

If the tree were a consistently isolated and independent phenomenon, which existed independently of conditions, it could not grow and prosper, since it would need for its existence nothing else than itself.

It would not be subject to arising and passing away, always the same, unbound, deathless. But this contradicts the fact that it changes incessantly, from the seed to the gnarled plant with dense leaf growth, which also falls sometime again to the decay and dies.

Thus, according to this view, things are without self (nairātmya), insubstantial (asvabhāva) and empty (śūnya), since they do not have any "self-existence" due to their dependence on conditional factors.

"Self-existence" (Sanskrit svabhāva, also called "self-nature" or "selfhood") is a technical term used in Indian philosophy to describe the quality of something that exists by its own power, something without support, that does not need any conditions for its existence.

The Atman treated in the Upaniṣaden, for example, is provided there, among other things, with the predicate "self-existent". In this capacity, it holds the status of an "ultimate reality" superior to the relative; in contrast to the constantly changing, conditioned world, it is grounded in itself, eternal, unchanging, pure, and undeveloped.

These are the attributes attributed to "self-existence" in this context. And it is this self-existence that Nāgārjuna excludes in principle in relation to phenomena.

For Nāgārjuna, the world is not a world of being but of constant becoming precisely because of this lack of self-existence. Things are not, but happen, like a melody, which is also not, but takes place in the succession of notes.

The factors of existence also fall into this category, for as such they do not exist independently, they are directly involved in the network of relationships of the "pratītyasamutpāda". Now, since dependence and emptiness mean the same thing, according to Nāgārjuna, things do not really arise and pass away.

For you, it may be true that arising and passing away are [yet] seen. One sees arising and passing away [yet] only from delusion.
dṛśyate saṃbhavaś caiva vibhavaś caiva te bhavet |
dṛśyate saṃbhavaś caiva mohād vibhava eva ca ||
(MMK 21.11)

The two unwholesome views of "belief in eternity" and "doctrine of annihilation" endow things with a substance or essence, which in the former case is regarded as something indestructible and in the latter case comes into existence along with the phenomenon and is then lost again when the phenomenon decays.

But since everything conceived in becoming in Buddhism has no permanent nucleus, it neither lasts (eternity) nor ceases to be (annihilation), is neither one (monism) nor many (pluralism).

Nāgārjuna therefore compares the substantial - and thus absolute - arising and passing away with mirages and chimeras, with magic tricks and dreams. What depends on conditions is empty.

What is empty has no independent reality. Just as waves appear on the surface of the sea without gaining water, and just as waves return to the ocean without losing water, phenomena come into being and pass away:

Like magic, like a dream, like a mirage, arising, existence, and passing away are conceived.
yathā māyā yathā svapno gandharvanagaraṃ yathā |
tathotpādas tathā sthānaṃ tathā bhaṅga udāhṛtam ||
(MMK 7.34)

Things do not come into existence in an absolutely real way, since their coming into existence also depends on conditions - and this dependence makes it impossible to find a first cause, a tangible root; it gets lost in the conditional nexus, the vast web of conditionality.

Phenomena do not exist eternally (ananta), nor do they come out of nothingness (vibhāva) to disappear again into the same nothingness after their existence. They are neither existent nor non-existent due to their emptiness, which excludes these two extremes.

Starting from this statement, Nāgārjuna pushes his argument one step further and describes the indistinguishability of samsara and nirvana at the summit of knowledge (prajñā) in a verse that is one of the most cited sentences of the Mūlamadkyamakakārikā:

There is nothing that distinguishes samsara from nirvana and nirvana from samsara. The boundary of nirvana is also the boundary of samsara. Not even the subtlest difference is found between these two.

na saṃsārasya nirvāṇāt kiṃcid asti viśeṣaṇam |
na nirvāṇasya saṃsārāt kiṃcid asti viśeṣaṇam ||
nirvāṇasya ca yā koṭiḥ saṃsaraṇasya ca |
na tayor antaraṃ kiṃcit susūkṣmam api vidyate ||
(MMK 25.19-20)

From the standpoint of salvation, there is no longer any differentiation between the conditional phenomena of the world of existence and unconditional nirvana. "Conditioned" and "unconditioned" are dualistic and interrelated terms.

Only the one who has not reached the wisdom experience of universal emptiness clings to them, and this blocks his way to insight - he erects a border between samsara and nirvana that does not exist. Since emptiness equals salvation, all beings are already in the state of essential salvation.

Thus, it is only necessary to become aware of and recognize this redeemed state, which is free of all limitations, distinctions and extremes.

But this recognition, Nāgārjuna cautions, is not to be understood as a personal process as a result of the anatta teaching. He calls attention to the contradiction evident in the notion of wanting to "have," "attain," or "realize" nirvana:

'Extinction will be mine without grasping; nirvana will be mine!' - Those who are caught in such delusion, they are especially caught by grasping.[8]
nirvāsyāmy anupādāno nirvāṇaṃ me bhaviṣyati |
iti yeṣāṃ grahas teṣām upādānamahāgrahaḥ ||
(MMK 16.9)

The concept of "emptiness" as a central element in Nāgārjuna's teaching thus has primarily a soteriological function. It serves to relativize the everyday perception of reality, which is shaped by conventions such as language and thinking, from the perspective of salvation, in order to clear up certain basic assumptions that stand in the way of a deeper insight and thus the experience of emptiness.

Entrenched patterns of thought and ideas that result in mutually exclusive extremes-including those of "selfhood" (svabhāva) and "alienhood" (parabhāva), "identity" and "difference"-are to be broken down in order to calm the gripping and clinging tendency of thought that Nāgārjuna renders with the expression of "conceptual unfolding" (prapañca) and to dissolve the fixations that accompany it:

Salvation comes through the annihilation of karma and attachment. Karma and attachment come from discriminating conceptions (vikalpa), they come from conceptual unfoldment (prapañca). The unfoldment, however, is annihilated in emptiness.

karmakleśakṣayān mokṣaḥ karmakleśā vikalpataḥ |
te prapañcāt prapañcas tu śūnyatāyāṃ nirudhyate ||
(MMK 18.5)

However, Nāgārjuna warns several times against confusing emptiness with a "reality" that lies behind the world or a view that represents that reality.

One should be careful not to make it, in turn, the bearer of a substance or even the "true essence" of phenomena, an absolute. Emptiness, for Nāgārjuna, is to be understood primarily in terms of an auxiliary that must not be objectified as such:

Emptiness was taught by the "victorious ones," the Buddhas, as a rejection of any view. But those for whom emptiness is a view, they were declared incurable.
śūnyatā sarvadṛṣṭīnāṃ proktā niḥsaraṇaṃ jinaiḥ |
yeṣāṃ tu śūnyatādṛṣṭis tān asādhyān babhāṣire ||
(MMK 13.8)

Thus, according to Nāgārjuna, it is extremely important to be careful with the concept of emptiness. It is meant as a wholesome concept to liberate from extreme views, but if misunderstood as a view, it can also have the opposite effect and cause harm.

Misconceived emptiness wrecks the one who is of weak insight - like a badly grasped snake or misapplied magic.
vināśayati durdṛṣtā śūnyatā mandamedhasam |
sarpo yathā durgṛhīto vidyā vā duṣprasādhitā ||
(MMK 24.11)

For this reason, it is also important to recognize that emptiness, as a dependent term, is itself empty-a statement that brought Nāgārjuna accusations of nihilism (nastitva) and "self-refutation" from within his own ranks, since it was misunderstood as a theory.

Emptiness was never intended by Nāgārjuna as a theory to replace another theory. Rather, he was concerned with ultimately leaving behind all theories, including that of emptiness.

When emptiness has served its purpose as an aid and has been able to open one's eyes to a deeper insight, it should be abandoned, just as one leaves behind a raft that brought one to the saving shore and from then on is no longer needed. Even just speaking of it can have unwholesome effects if what is spoken is reified, which is why Nāgārjuna emphasizes:

One should neither say 'empty', nor 'non-empty', nor 'both at the same time', nor 'neither'. For the purpose of understanding, however, one may speak thus.
śūnyam iti na vaktavyam aśūnyam iti vā bhavet |
ubhayaṃ nobhayaṃ ceti prajñaptyarthaṃ tu kathyate ||
(MMK 22.11)

This example shows Nāgārjuna's argumentation technique by means of the "judgment quadrant" (catuṣkoṭi), which will be explained in more detail below.

The judgment square (catuṣkoṭi)

The logical stylistic device of the "judgment quadrant" (catuṣkoṭi), also called Buddhist tetralemma, which Nāgārjuna uses in his argumentation as a didactic instrument, is a figure of thought that presumably goes back to the skeptic Sañjaya Belaṭṭhiputta mentioned in the Dīghanikāya and is composed of four links corresponding to four possible logical alternatives.

According to tradition, it was already applied by Buddha to questions that, in his understanding, proceed from the wrong premises and are therefore not correctly posed from the outset according to the context.

This approach of Buddha is handed down in several places of the Pali canon. A textual example of this is found in a chapter from the "Saṃyuttanikāya" ("Grouped Collection"), where Kassapa, a wandering ascetic and later disciple of the Buddha, is enlightened by the Buddha about the origin of suffering:

Kassapa: Is suffering, Lord Gotama, self-caused?
Buddha: Not so you shall speak, Kassapa.
Kassapa: Or else is suffering caused by another?
Buddha: Not so thou shalt speak, Kassapa.

Kassapa: Is suffering both self-caused and caused by another?
Buddha: Not so thou shalt speak, Kassapa.
Kassapa: Or is suffering both not self-caused and not caused by another, but caused by chance?

Buddha: Not so thou shalt speak, Kassapa.
Kassapa: Then, Lord Gotama, is there no suffering at all?
Buddha: There is suffering, Kassapa.

Kassapa: So does Mr. Gotama not know suffering and not see it?
Buddha: I know suffering well, I see suffering well, Kassapa.
Kassapa: So may the exalted one explain suffering to me, may he proclaim it to me.

Thereupon the Buddha answered summarizing: "If one claims that it is the same one who carries out the action and who feels the consequences, then there is one who is there from the beginning - if one says that the suffering is self-caused, then one comes thereby to an eternally lasting one.

If one claims that it is another who carries out the action and who feels the consequences, then there is one who is affected by sensation. If one says that the suffering is caused by another, one comes to a complete annihilation.

Avoiding these two ends, Kassapa, in the middle of the Tathāgata proclaims the true teaching: Through ignorance are conditioned the formations, through the formations is conditioned the consciousness ..." (Saṃyutta Nikāya SN 12.17)
In this example, the Buddha argues with the negation of all four limbs of the catuṣkoṭi.

He is thus trying to point out the extreme views of belief in eternity and the doctrine of annihilation, which already tend to be hidden in the questions, and which are to be avoided according to Buddhist thought.

The "Urteilsvierkant" as a theoretical model includes in its basic structure both the theorem of contradiction and the theorem of the excluded third:

Something is (so)
Something is not (so)
Something is both (such) and not (such)
Something is neither (such) nor not (such).

Buddhist logic, according to the central doctrine of non-self, assumes that A is not identical with itself, that is, A is not A (the self believed to be isolated is actually a faulty impression created by confusing the process of constantly reassembling and disassembling groupings of factors of existence with a consistent I, and reinforcing and maintaining this confusion through attachment).

This means, the basic premise of formal logic - self-identity (A = A) - is denied from the beginning.

But in the next step, difference is likewise negated: A is thus just as little non-A (there is also no self to be found inside and outside the factors of existence). Finally, the two following steps, since they are only combinations of the first two steps, are to be rejected as equally false.

According to this approach, with the help of the catuṣkoṭi, it is not a matter of proving something as an incontrovertible truth, that is, of falsifying an assertion or replacing a false truth with the correct one, but rather of pointing out the weak points in certain forms of argumentation and trains of thought that work against insight.

The only valid criterion by which a statement can ultimately be evaluated, therefore, is whether or not what is said is wholesome and conducive to deeper insight.

Statements, even if they belong to the relative level, are necessary in order to convey and transport teaching contents with it, but they have to prove themselves as "salutary tested" and therefore derive their truth content from practical applicability.

The actual, complete understanding then takes place in the non-verbal insight, what is also known in Zen as "non-thinking thought" (jap. hishiryo).

Thus, the application of the "judgment quadrant" has two aspects: a deconstructive one, i.e., the function of pointing out the "dead ends" of limiting, constricting, and unwholesome thinking, and at the same time a constructive one, namely, the function of transforming ignorance (avidyā) into wisdom (prajñā), i.e., of interpreting beyond and guiding away from limiting thinking.

Elements from the catuṣkoṭi can still be found in some mondos and Kōan of the Zen tradition.

The doctrine of the "two truths" (satyadvaya).

In preaching the Dharma, the Buddhas relied on the two truths: One is the worldly, 'veiled truth' (saṃvṛtisatya), the other is the 'truth in the highest sense' (paramārthasatya).

Those who do not recognize the difference between the two truths also do not recognize the profound truth (tattva) in the Buddha's teaching.

dve satye samupāśritya buddhānāṃ dharmadeśanā |
lokasaṃvṛtisatyaṃ ca satyaṃ ca paramārthataḥ ||
ye 'nayor na vijānanti vibhāgaṃ satyayor dvayoḥ |
te tattvaṃ na vijānanti gambhīraṃ buddhaśāsane ||
(MMK 24.8 - 24.9)

Without not relying on the application [of words] (vyavahara), truth in the highest sense cannot be shown; and without having advanced to truth in the highest sense, nirvana is not attained.
vyavahāram anāśritya paramārtho na deśyate |
paramārtham anāgamya nirvāṇaṃ nādhigamyate ||
(MMK 24.10)

The methodology of distinguishing between a truth in the highest sense and a veiled truth based on convention alluded to in the above quotation from Nagarjuna, which was consistently carried forward in the later Madhyamaka, has survived in this form through all Buddhist schools to the present day.

The view that no statement has absolute validity, but must be examined for its salubrity as a relative and conditional statement, has had a firm place in all Buddhist directions since Nagarjuna's formulation of the "Two Truths."

Already in the "Basket of Treatises" a first early Buddhist approach to the model of the "Two Truths" can be found by differentiating between the levels of reality "samutti sacca" and "paramattha sacca". In this early form, the "Two Truths" refer to the reality status of the factors of existence (dharmas) in contrast to the worldly conditions that depend on their conditional interaction.

The factors of existence as not further reducible constituents of the empirical reality have here highest reality, they are therefore also called "paramattha dhammas". What the factors of existence constitute - the everyday idea of "I", "my", of concrete, substantial, independent things and persons - is assigned to the level of the veiled reality.

Nagarjuna took up this model, but in doing so, now using the Sanskrit terms "samvritti satya" and "paramartha satya," fundamentally changed the division of degrees of reality.

The factors of existence described before still in the abhidharmic sense as "highest reality" he transferred - like everything verbally expressible - to the level of "samvritti satya", the veiled truth.

The highest truth cannot be said, one can only point to it by means of conventional truth - in order to experience it thereupon directly in a deeper, intuitive insight. This basic attitude is illustrated e.g. in the Zen saying "The finger pointing to the moon is not the moon".