There are five main branches of philosophical study in Tibetan Buddhism that are common to all schools:
Without the Abhidharma teaching, the disciples wouldn’t be able to discriminates dharmas.La Vallée Poussin. L’Abhidharmakosa de Vasubandhu
With regard to these five branches, the great Indian masters wrote reference works that were elucidated through commentaries written by their principle disciples.
The original texts and their commentaries were progressively translated into Tibetan language.
Tibetan masters then wrote their own commentaries in order to clarify the meaning of these reference texts from the point of view of their respective schools.
The objective of Buddhist epistemology is to establish a valid knowledge of phenomena.
Through the use of analysis, valid modes of knowledge are established and erroneous modes of knowledge – the source of suffering – are abandoned.
Indian sources
The study of Buddhist epistemology (Tib: tshad ma) is based on Dharmakirti’s work, the Pramana-vartartikka (Tib: tshad ma rnam 'grel), a commentary on the Pramana-samuccaya (Tib: tshad ma kun btus), the compendium of valid cognition by Dignaga, master of Buddhist logic.
Tibetan commentaries
The Karma Kagyu lineage uses a commentary of the Pramana-vartartikka composed by the 7th Karmapa, the rig chung rgyam tshog.
The Madhyamaka philosophy is concerned with the nature of phenomena, including both the mind that perceives and the objects perceived by the mind.
Indian sources
The Madhyamaka philosophy was developed by Nagarjuna whose works include the Mula-Madhyamaka-karika, (Tib: dbu ma tsa ba’i shes rab).
Chandrakirti wrote two commentaries on the root text, the Madhyamaka-avatara (Tib: dbu ma 'jug pa), and the Madhyamaka-ravrti-prasannapada (Tib: tshigs gsal ba). Because Chandrakirti’s commentaries give a clear, concise understanding of Nagarjuna’s more detailed work, they are often preferred to the original. In Tibetan Buddhism, the Madhyamaka-avatara is the most frequently studied.
Tibetan commentaries
In the Karma Kagyu lineage, the 8th Karmapa composed a commentary based on the above authors’ works. The Madhyamaka-alankara (Tib: dbu ma rgyan) written by Shantarakshita, an Indian master, contemporary of Guru Rinpoché, has been clarified by a widely-used recent commentary by Mipham Rinpoché.
The Abhidharma does not focus on the mode of existence of phenomena, but rather on the cause of this appearance of phenomena and the manner of manifestation. It deals with both outer, physical phenomena and those belonging to the mind.
Vasubandhu was born in 6th century Kashmir in the region of Purusapura (Peshawar). His treatises hold an important place in Buddhist philosophy. He is one of Buddhism’s “Six Ornaments”, along with Nagarjuna, Dharmakirti, etc. He first was an adept of the Sarvastivadin school, but later wrote a commentary on the Abhidharmakosha based on the Sautrantika view: the Abhidharmakoshabhasaya. Influenced by his brother, Asanga, he eventually adopted the vision of the great vehicle.
When Vasubandhu wrote the Abhidharmakosha, he called it “The Explanation of the Abhidharma as taught by the Vaibhashikas from Kashmir”. His text is considered to be a resumé of the Mahavibhasa, the principal Vaibhashika treatise.
The Abhidharmakosha is based on the dissertations of Vaibhashika masters. Instead of mapping out his teachings in a systematic manner, Buddha Shakyamuni gave them in answer to questions asked by his followers. Based on this, the Indian masters wrote root texts that serve as references which present a synthesis of the Buddha’s words.
The Abhidharmakosha is divided into two sections
The Karika, “verses to be memorized”, in which the author impartially exposes the orthodox vision of the Vaibhashika School.
The Bhasya, “commentary”, comments written in prose explaining the root text verse by verse and nearly word by word. He transmits and criticizes the opinions of other schools and presents his personal theory, often quite different from the Vaibhashika view.
The original text and its translations
Composed in Sanskrit, the original integral text has been lost. In the 8th century, it was translated into Tibetan by the Indian pandit Jinamitra and the translator Peltsek Rakshi.
(Reference: P. Cornu, dictionnaire encyclopédique du bouddhisme)
When we speak about the Abhidharma in Tibet, the text is generally understood to be the Abhidharmakosha. This reference work is studied in all the shedras (Tibetan institutes of higher learning of the Dharma), although it does not directly propound the Mahayana viewpoint.
The original text was the basis for a number of commentaries written by Tibetan masters, such as the commentary by the Sakya master Gorampa:
go rams pa bsod nams seng ge: kun mkhyen go bo rab 'byams pa bsod nams seng ge'i bka' 'bum kha skong, (kun mkhyen go rams pa bsod names seng ge gsum 'bum supplemental texts series), Kangra (India), Yashodhara Publications, 1996, dam pa'i chos mngon pa mdzod kyi 'grel pa gzhung don rab tu gsal ba'i ni ma, a commentary of the fundamental text of Tibetan Buddhist abhidharma, the Abhidharmakosha of Vasubandhu by mus chen rab 'byams pa thugs rje dpal bzang, 4 volumes dpe cha
In the Karma Kagyu tradition, Mikyö Dorjé, the 8th Karmapa, wrote an extensive two-volume commentary of the Abhidharmakosha: mi bskyod rdo rje: chos mngon pa’i mdzod kyi 'grel pa rgyas par spros pa grub bde’i dpyid 'jo, 2 volumes dpe cha
Abhidharmakosha (Tib: mngon pa mdzod) presents the difference between “pure” and “impure” phenomena. Phenomena defined as being contaminated (Tib:zag bcas) refer to samsara, whereas phenomena defined as being “pure” (Tib: zag med) are part of nirvana. The Tibetan word “zag” can also mean “to fall”, hence the Dharma is what keeps one from falling, while mind’s veils are what leads one to fall into the lower realms.
"In this way, dharmas are impure, because they are connected to corruption, or pure, because they are free from such."
La Vallée Poussin : L'Abhidharmakosa de Vasubandhu ; chapitre 1
“Abhi” means obvious or clear, “dharma” here refers to phenomena. Abhidharma could be translated as “the wisdom that analyses the true nature of phenomena.”
There are two categories of phenomena that should be analysed: those belonging to samsara and those belonging to nirvana. The object of the Abhidharma is to know how samsara functions and therefore to understand how to become free of it.
The Abhidharma is based on the Four Truths of the noble ones taught by the Buddha Shakyamuni: suffering, the cause of suffering, the cessation of suffering and the path that leads to cessation.
The Abhidharmakosha stresses the importance of definitions. “Mind” is that which is capable of knowing or perceiving. “Nirvana” is the cessation of all forms of suffering, in contrast to “samasara”.
Vasubandhu uses logic and absurdity to show us what nirvana isn’t. He illustrates this by explaining that all beings desire lasting, stable happiness. Through analytical reasoning, the Abhidharmakosha identifies what enduring happiness is not, and what the cause of such happiness is not.