Summary: In the Paṭṭhāna, paccaya names a conditional relation by which dhammas support, precede, accompany, or otherwise stand in dependence on one another. The canonical heart of the concept is the list of twenty-four paccayas and their direct definitions in the opening Paccayuddesa and Paccayaniddesa of the Paṭṭhāna; later Abhidhamma complexity expands those relations widely, but it does not replace that canonical list (Paṭṭh 2-59).
Canonical locus
The Paṭṭhāna first names the twenty-four paccayas in its Paccayuddesa. (Paṭṭh 2)
Paṭṭh 2 (patthana1.1:2.1)
Hetupaccayo, ārammaṇapaccayo, adhipatipaccayo, anantarapaccayo, samanantarapaccayo, sahajātapaccayo, aññamaññapaccayo, nissayapaccayo, upanissayapaccayo, purejātapaccayo, pacchājātapaccayo, āsevanapaccayo, kammapaccayo, vipākapaccayo, āhārapaccayo, indriyapaccayo, jhānapaccayo, maggapaccayo, sampayuttapaccayo, vippayuttapaccayo, atthipaccayo, natthipaccayo, vigatapaccayo, avigatapaccayoti.
The book then defines those relations one by one in the Paccayaniddesa. (Paṭṭh 4-59)
Paṭṭh 4 (patthana1.1:4.1)
Hetupaccayoti—hetū hetusampayuttakānaṁ dhammānaṁ taṁsamuṭṭhānānañca rūpānaṁ hetupaccayena paccayo.
Paṭṭh 40-41 (patthana1.1:40.1-41.1)
Kammapaccayoti—kusalākusalaṁ kammaṁ vipākānaṁ khandhānaṁ kaṭattā ca rūpānaṁ kammapaccayena paccayo. Cetanā sampayuttakānaṁ dhammānaṁ taṁsamuṭṭhānānañca rūpānaṁ kammapaccayena paccayo.
Vipākapaccayoti—vipākā cattāro khandhā arūpino aññamaññaṁ vipākapaccayena paccayo.
Analysis
The canonical concept of paccaya is narrower and more concrete than a general modern appeal to "causality." The Paṭṭhāna does not give one abstract law and then derive everything from it. It gives twenty-four named relations and defines each as a distinct way dhammas condition one another (Paṭṭh 2-59).
The twenty-four are the canonical core
The safest canonical summary is simply the one the Paṭṭhāna itself provides: root-condition, object-condition, dominance-condition, contiguity, co-arising, mutuality, dependence, support, kamma-condition, result-condition, nutriment-condition, faculty-condition, path-condition, presence-condition, absence-condition, and the other listed relations form the book's basic conditional vocabulary (Paṭṭh 2).
Conditional relation is broader than single-line causation
Some paccayas are easy to hear as straightforward causes, such as hetupaccaya or kammapaccaya. Others are not well described by the single English word "cause": anantarapaccaya and samanantarapaccaya concern sequence, sahajātapaccaya and aññamaññapaccaya concern co-arising and reciprocity, while atthi/natthi/vigata/avigata concern presence, absence, and disappearance (Paṭṭh 4-59). This is why "conditional relation" is a safer English gloss for the family as a whole.
The later body of the Paṭṭhāna repeatedly applies the same twenty-four paccayas through anuloma, paccanīya, pañhāvāra, and related sections. That scale of repetition can make the book look merely combinatorial, but the opening list and definitions show what the repetition is repetition of: the canonical task is to trace how these twenty-four relations actually operate across many dhamma-groupings (Paṭṭh 60ff; Paṭṭh 1379ff).
Abhidhamma perspective
Within the current merged Abhidhamma pages, paccaya is most visible in the patthana, where it becomes the explicit organizing principle of the whole book (Paṭṭh 2-59). It also clarifies why later Abhidhamma pages repeatedly distinguish accompanying mind, associated factors, matter, and results: those pages are readable partly because the Paṭṭhāna makes the relations among such dhammas analytically explicit (Paṭṭh 4-59).
Textual notes
- This page stays with the canonical Paṭṭhāna opening rather than later Theravāda systematizations about how the paccayas should be grouped or hierarchized.
- "Conditionality" is a useful English heading, but the canonical Pali term is paccaya; the page therefore treats the English label as a gloss for the canonical term, not as a separate doctrine.
- The Paṭṭhāna later expands these relations through vast triadic and dyadic applications. This concept page intentionally does not attempt to summarize that whole expansion.