来世の論証にみるPrajñākaraguptaの未来原因説=Can the Next Life be Proved from the Present Life? : Prajñākaragupta's Peculiar Theory of Causality (bhāvikāraņa-vāda) in the Context of His Proof of the Paraloka
According to Dharmakīrti, valid inference should be based on any one of three logical reasons, i.e. kārya-hetu, svabhāva-hetu, or anupalabdhi-hetu. How, then, is it possible to infer one's future life from one's present existence within this system of logic? As has been clearly shown by Steinkellner (1991) and Iwata (1989), Dharmakīrti deals with the inference of an effect from its cause as a sort of inference in which the svabhāva-hetu functions, because the arising of an effect is an essential property (svabhāva) of the complete cause insofar as it is understood as fitness for the production of the effect (kāryotpādayogyatā), although he does not seem to apply this argument specifically to the proof of the existence of the next life. But Prajñākaragupta (=Prajñākara), the author of a commentary on the Pramā?avārttika (=PV) named Pramā?avārttikabhā?ya (=PVBh), seems to give a different solution to this problem on the basis of his peculiar concept of causality, according to which the future can cause the present. M. Ono has already clarified this theory, the bhāvikāra?a-vāda, in the context of the prāmā?ya-vāda, in which he concludes that there is no serious divergence between Dharmkīrti and Prajñākara with regard to the concept of causality. The present paper is a modest attempt to show that the analysis of the PVBh on PV II k.47 may well lead to the conclusion that Prajñākara deviates from Dharmakīrti, or at least from the preceding commentators of the PV, in his understanding of a inference of the future life. 1. Prajñāakara asserts that the proof of a future life from the present is explicable in terms of a kārya-type of logical reason because it is an inference from the effect that is the present to the cause that is the future. 2. He bases this assertion on his peculiar view that the future can cause the present. To demonstrate this, he adduces some instances from everyday life, such as the inference of a future death from a death omen, which is the effect of the future death. 3. Moreover, he tries to show that this explanation is not inconsistent with the formula of Dependent Origination (asmin sari idam bhavati; asyotpādāt idam utpadyate) because it is grammatically possible to interpret this statement to mean that X is the cause of Y if there is non-deviation (avyabhicāritva) between the two. In addition, he criticises the interpretation of the formula ascribable to Devendrabuddhi and ?akyabuddhi, by which a cause must immediately precede an effect. 4. In his criticism of Prajñākara's bhāvikāra?a-vāda, Bhārarvajña says that Prajñākara is opposed to Dharmakīrti in his understanding of the method of establishing the causal relationship. 5. Finally, the present author suggests that it might be necessary in this connection to pay attention to a possible difference in ontological basis between Dharmakīrti and Prajñākara. Whereas the former depends on the Sautrāntika ontology of external reality in the present context, the latter discusses the problem of causality only on a conventional level (samv?tti/ lokavyavahāra), which is conditioned by the beginningless stream of latent impressions (vāsanā).
