  In seeking to reconcile the Abhidharma analysis of mind, and its  synchronic model of momentary cognitive events, with the diachronic  phenomenon of karmic activity, the Abhidharma philosophers came up  with different solutions. The Vaibhāṣika (also referred in the literature as the Sarvāstivādins), solved the problem  of the continuity of karmic potential by proposing an ontology of the constitutive elements of reality (or dharmas) as existing in all three temporal dimensions: past, present, and future. On this  ontological model, dharmas do not change, only their temporal  condition does. The principal reason for adopting this peculiar  ontology is the theory of the momentariness  (kṣaṇikavāda) of all phenomena: if nothing  endures for more than a moment how, then, can a cause that is no  longer present lead to a manifest result? Similarly, if the  accumulated karmic potential from past experience is no longer  present, how could it affect the present condition? But in  postulating the existence of the constituent elements of experience  throughout the three temporal dimensions, the  Sarvāstivādins simply shifted the Abhidharma problematic:  having presumably explained what accounts for the efficacy of  accumulated karmic potential, the question now is why a karmic result arises at one time rather than another? [for detailed discussions of  Vaibhāṣika ontology and its analysis of mind see Williams  1981, Bastow 1994, and Cox 1995] 