Abstract: This article examines Seongho Yi Ik's reinterpretation of the Four-Seven debate, focusing on his engagement with both Neo-Confucian thought and Western theories of the soul and physiology. While initially defending Toegye's perspective, Seongho diverged from traditional frameworks by integrating Matteo Ricci's soul theory and Schall von Bell's physiological insights. He redefined xin (心, heart–mind) through the concept of zhijue (知覺, perception and sentience), distinguishing between cognition (知) and sensory perception (覺) by associating them with the xin as a heart organ and the brain, respectively. This shift allowed him to naturalize emotions and introduce gong (公, impartial) and si (私, partial) as moral criteria, moving beyond metaphysical explanations to a practical, socially expansive framework. Seongho's theory represents a pivotal transition in Joseon Neo-Confucianism, aligning with the broader intellectual trend toward practical learning ( silhak , 實學) in the late Joseon period.
Seonhee Kim (Thu,) studied this question.