论佛教逻辑中推论前提的真实性问题

Concerning the Truth of Premises in Buddhist Three-part Inference(Tray(?)vayava)

本文将陈那、法称因明与西方传统的三段论相比较,指出佛教逻辑从推论前提是否为真的角度来建立推论的基本规则即因三相;西方传统的三段论从形式是否有效的角度来建立推论的一般规则,这反映了佛教逻辑与西方逻辑的根本差异。本文首先指出佛教逻辑中的典型谬误即似因并非形式谬误,其致误之由在于前提为假。佛教逻辑从实质的角度来探讨有效性,不同于西方逻辑形式有效性的概念。佛教逻辑所说的推论其实都是论证。推论前提的真在何种程度上得到因三相的保证,又因陈那、法称因三相的不同而有区别。陈那的因后二相由于除宗有法的限制,只是前提为真的一种例证,其推论并非演绎;法称的因三相则全面保证了前提的真,其推论达到了演绎。法称恰恰是通过剖析推论前提为真的知识论基础从而改造了陈那因明,这体现了佛教逻辑的知识论性格。实际上,佛教逻辑关注前提的真,这已经预示了它在历史的发展中向佛教知识论(量论)的必然转化。

This paper is a preliminary inquiry into the main difference between Buddhist logic and Western logic. The scope of comparison is limited in the theory of inference by Dignāga and Dharmakīrti on the Buddhist side, and in the classical syllogism on the Western side. As begun with an analysis of one typical fallacy in Buddhist logic, the prameyatva （being cognized） reason for the nitya （eternal） thesis as one of the non-conclusive reasons （anaikāntikahetu） , this paper points out that the inference as such is unsound merely because its major premise is false, when its form is exactly the same as Barbara in Western syllogism. Likewise, all the non-conclusive reasons and contradictory reasons （viruddhahetu） can be reduced only to the falseness of major premise, or in paraphrase, to the failure of establishing the invariable concomitance （avinābhāva） . In fact, the three conditions of a right reason （trairapya） are formulated in order to promise the premises of a three-part inference （trayāvayava） to be true, while the Western rules for a right syllogism are aimed at promising its form to be valid. This difference seems to be essential in illuminating the intensionalism in Buddhist logic and the extensionalism of the Western syllogism. However, to what extent the truth of premises can be guaranteed differs in respect of the different trairūpya formulae as given by Dignāga and Dharmakīrti. According to Dignāga, the object in dispute （dharmin）, i.e. the minor term, shall be ruled out from both the last two conditions of a right reason. As a result, these two conditions can only promise the major premise to be true in those cases other than the minor term, and the inference according to him is therefore non-deductive. As the restriction of excluding the object in dispute is given up by Dharmakīrti, the last two conditions of a right reason become capable of promising the major premise to be universally true, and the inference according to him thus becomes deductive. At last, the author indicates that the intensionalism in Buddhist logic plays a key role in the historical development of Buddhist logic （hetuvidyā） into Buddhist epistemology （pramānavāda ） .