曾天從(1910-2007)是日治時期主要的哲學家之一，其哲學仍為臺灣今日的哲學界所遺忘。在本論文中，我們將重心置於其主要的哲學著作（出版於1937年的《真理原理論》）。在這本著作中，曾天從開啟了一個真理論的領域，並且創造出一種「真理原理論」來作為其哲學體系的基礎。在筆者看來，曾天從的整個哲學的事業皆集中在「純粹現實學」落實上，因而要了解、評價其對哲學的貢獻，我們有必要先了解其對「真理自體」領域的解明。由於其「純粹現實學體系」仍然是未完成的理想，這一點讓曾天從哲學的洞見、以及許多哲學的概念仍然處於晦暗之中。在本文中，我們將論題集中在「真理自體」的領域，致力於真理自體的「純粹形相」的解明。本論文的目標在透過釐清其概念、強化其論證方式，以解明曾天從的哲學洞見。

Zeng Tiancong (1910-2007) was one of the major Taiwanese philosophers in the period of Japanese rule, though his philosophy has since been neglected. In this article I will focus on his main philosophical work, Theory of the Principle of Truth (published in 1937), in which he opens an alethiological field of inquiry and creates a theory of the principle of truth, which serves as a basis for his own philosophical system. In order to understand and evaluate his contribution to philosophy, it is important to clarify his explication of “truth-in-itself.” It is my view that his entire philosophical career served to illuminate this thesis. But his plan was left unfinished, obscuring some of his creative ideas and philosophical concepts. In this article I will focus on the inquiry into “truth-in-itself”, to clarify its “pure eidos.” My primary aim is to shed light on Zeng’s insight, by explicating his concepts and reinforcing his arguments.