邏輯或解經學－初期大乘瑜伽行派「四種道理」理論性格之探究

現代學界處理印度佛教因明的態度，若不將其歸於邏輯史的領域，就是隨順藏傳量論的傳統，視之為知識論的領域。佛教邏輯或佛教知識論成為因明的現代同義詞。這種觀點近來受到一些學者的挑戰，他們認為應該從解經學的角度來看待佛教因明才恰當。佛教因明究竟應該視為邏輯與知識論，或應該視之為解經學，本文回應此問題的切入處是，檢視初期印度瑜伽行派關於「四種道理」（特別是其中的「證成道理」）的相關原始文獻（《聲聞地》、《菩薩地》、《解深密經．如來成所作事品》）與現代學者的詮釋，將「四種道理」論述重置於瑜伽行修道次第的脈絡中，此瑜伽行次第或以「聞、思、修」為架構，或以「四種遍滿所緣」為架構，或以「六事差別所緣」為架構，或以「四種真實」為架構，次第容或不同，作為邏輯論證方法的「四種道理」都擺在修道次第的進階階段，則是各文獻所共同的。本文從徵引文獻看到，「證成道理」所欲論證的問題仍以佛教教義為主，例如：「一切行皆無常性」、「一切行皆是苦性」、「一切法皆無我性」、「一切行皆剎那性」、「他世有性」、「淨不淨業無失壞性」等，都是當時主流佛教所主張的根本命題。其他大乘瑜伽行派所新提出的教義，如阿賴耶識論，亦以「證成道理」的方法予以論證。這說明「證成道理」仍以佛教經典教義的證成為士要任務。即此而言，「四種道理」確屬於解經學的範圍，不能完全等同於現代邏輯，此乃十分明白。總之，作為論證方法的「證成道理」雖可以稱之為佛教邏輯，然而必須從經院的解經學的角度來了解。

關鍵字

因明；量論；佛教邏輯；佛教知識論；解深密經；瑜伽行派

並列摘要

It has been subjected to debate for long time about whether or not Buddhist logic is compatible with Aristotelian formal syllogism. However, taking Buddhist ＂hetuvidya＂ as ＂logic＂ had never been questioned until Ernst Steinkellner argued that as evidenced in the four methods of reasoning (catasro yuktayah) found in the last chapter of the ＂Samdhinirmocanan Sutra＂(SNS.X), it should rather be characterized as a kind of exegetical hermeneutics. If it is correct to view ＂hetuvidya＂ as hermeneutics, then further clarification is required. The question is: how should Buddhist logic or hermeneutics developed in the early period of the Yogacara School be properly treated? Following the scholarly contributions of Kajiyama Yuichi, Yoshimizu Chizuko and Hideomi Yaita, this paper attempts to answer the question by re-contextualizing the four methods of reasoning in the SNS.X, the ＂Sravakabhumi＂ and the ＂Bodhisattvabhumi＂. This paper concludes that Buddhist ＂logic＂ or ＂methods of reasoning＂ is employed in the advanced stage of meditative discipline for correctly understanding the Buddhist fundamental doctrines. It is correct to characterize the practice of logic and epistemological analysis as part of the Buddhist scholastic hermeneutics, whereas it is also important to see it as an essential discipline in the Buddhist soteriological project.