Abstract
In this paper, Charles Peirce's ”extreme scholastic realism” is presented and examined from three aspects. First, it is shown that this theory can be formulated in terms of the three universal categories that Peirce himself proposes; and that it holds that his three universal categories (that is, Firstness, Secondness, and Thirdness) are real, and that Thirdness involves and governs the other two categories, which nevertheless have their independent reality. Second, it is pointed out that the principle of identical particles and the quantum vacuum theory-two of the fundamental doctrines in modern quantum physics-agree well with the basic metaphysical theses of this theory. Third, it is argued that this theory can resolve the traditional debate between idealism and realism-as-opposed-to-idealism by accommodating and reconciling their different central philosophical intuitions.