Some Japanese and Western scholars are used to assume that `prajnaparamita` thought violates the rules of formal logic. They regard it as transcending rationality or mystical but neglecting its rational part arrive，in the author's mind, perhaps too rash at this conclusion. The final aim of `prajnaparamita` thought is, of course, transcending rationality or mystical yet many reflections in the preceding stages are rational. This is especially easy to understand in case of the principle of "emptiness by way of absence of self nature." This principle is expressed in several ways like argumentation through the negation of both extremes, the emptiness of emptiness, identity and non-identity etc. The aim of the present paper is to study both this kind of emptiness in `prajnaparamita` thought as well as the said forms of expression.
