How to Define Sahabhūhetu: Rethinking Saṃghabhadra’s Use of the Concept of Common Effects

Abstract The co-existent cause ( sahabhūhetu ) is a type of cause proposed by the Sarvāstivāda school, which arises simultaneously with its effects. However, there is significant disagreement on how define a dharma as the co-existent cause of its effects. One of the central debates revolves around how to interpret the common effects ( *ekaphala ) criterion employed by the Vaibhāṣikas, especially Saṃghabhadra, to define the co-existent cause. Previous studies have largely overlooked Saṃghabhadra’s nuanced application of the concept of common effects when discussing specific cases, leading to various misunderstandings. In this article, I begin by analyzing two main scenarios in which Saṃghabhadra applies the concept in question, identifying two distinct usages: common subsequent effects and common simultaneous effects. I then propose an integrated understanding, according to which Saṃghabhadra in fact maintains that if a dharma is the co-existent cause of another by virtue of satisfying the common effects criterion, it must share both common subsequent effects and common simultaneous effects with that dharma . On this interpretation, all cases in which Saṃghabhadra explicitly applies the common effects criterion to define co-existent causes can be coherently explained and no counterexamples arise under this understanding. Finally, I extend this understanding to the third scenario and demonstrate its coherence in that context as well.