Philosophy › Renaissance & the new science › Neo-Confucianism
Yi I (Yulgok)
1536–1584· Philosopher· Asian traditions
Well documentedSolid records, texts or physical evidence.
Joseon scholar-statesman who argued that only material force (qi) acts, with principle (li) 'riding' on it, and pressed practical reforms.
See it on the Philosophy map →The idea
The idea: li is the universal pattern, but only qi moves; in every feeling 'qi issues and li rides on it' (氣發理乘). Yi I (이이), pen name Yulgok, topped the state exams nine times, studied Buddhism briefly after his mother, the artist Shin Saimdang, died, then served as a minister. In 1572 he renewed the Four-Seven Debate against Toegye's view. He wrote Essentials of Sage Learning (1575) and urged tax and military reform. Toegye's followers objected that his view reduced moral feelings to ordinary emotion.
Why it matters
His Giho school became the dominant line of Joseon orthodoxy, and his practical bent foreshadowed Silhak, 'Practical Learning'. He appears on the 5,000-won note, his mother on the 50,000.
Legacy and sources
His collected works, his letters to Seong Hon and his memorials to King Seonjo survive; his birthplace, Ojukheon in Gangneung, is preserved.
Still debated
Whether he really urged training 100,000 troops before Japan's 1592 invasion is debated; the story appears mainly in later accounts by his followers.
Inside this (1)
Connections (3)
▸Yi I (Yulgok) renewed The Four-Seven Debate (Toegye and Gi Daeseung)Well documented
The connection
In letters with his friend Seong Hon, who leaned toward Toegye's view, Yulgok revived the question and sided with Gi Daeseung. Only qi can issue anything, he argued; li is always present, 'riding' on it, so feelings have one source, not two. The Four Beginnings are simply the good part of the Seven Emotions.
When and how
Joseon Korea, 1572, in letters between Yulgok and Seong Hon, two years after Toegye's death.
How we know
The Yulgok–Seong Hon letters survive in their collected works, and Yulgok's 'qi issues and li rides' formula is quoted throughout later Korean debates.
Debates and open questions
Whether Yulgok's view was a different philosophy or a correction within Zhu Xi's system is debated, as is how much factional loyalty later hardened the positions.
▸Yi Hwang (Toegye) met and influenced Yi I (Yulgok)Well documented
The connection
In 1558 the young Yulgok, then in his early twenties, visited the elderly Toegye at his home near Andong and stayed about three days, exchanging poems. They corresponded afterward, and Toegye praised his promise. Yulgok revered Toegye but later rejected his view of li and qi; the two became founders of Korea's rival Neo-Confucian schools.
When and how
Dosan, near Andong, spring 1558; Yulgok stopped to see Toegye during a journey.
How we know
Both men's collected works record the visit, the poems they exchanged and their later letters.
Debates and open questions
How much the meeting shaped Yulgok's thought is unclear; they met in person only once, and his mature views diverged sharply.
▸Yi I (Yulgok) foreshadowed Silhak (Practical Learning) and Jeong Yak-yong (Dasan)Mostly agreed
The connection
Yulgok paired Neo-Confucian theory with concrete reform proposals: lightening tax and tribute burdens, strengthening the military and governing for the people's livelihood. Later Silhak scholars, frustrated by court factions fixed on doctrine, built on that practical streak and turned it into detailed plans for land, taxes and technology.
When and how
Yulgok's memorials to King Seonjo, notably the Ten Thousand Word Memorial (만언봉사, Maneon bongsa, 1574); Silhak writers worked from about 1670 to 1850.
How sure are we?
Historians of Korean thought trace Silhak's reform streak partly to Yulgok's memorials; his tribute-reform idea foreshadowed the Daedong law (대동법), introduced from 1608.
Debates and open questions
Many Silhak thinkers, including Yi Ik and Dasan, belonged to the Southerner (Namin) faction linked to Toegye, not Yulgok's; how direct the lineage is remains debated.