This thesis has examined Chootan Oh Yoon-gyum’s (楸灘 吳允謙, 1559～1636) political activities in relation to his sense of reality by dividing into aspects of social reform, diplomatic activities and the theories of propriety(禮論). He held the position of important public official for forty years but his life in the office was not without difficulties. However, sometimes flexible and sometimes with integrity, he held his convictions (所信), successively holding the public official positions for three administrations including King Seonjo, Gwanghaegun and King Injo.
As for his political activities, he witnessed the burden imposed on the farmers due to taxes and looked forward to the relief of them from it in realistic perspective of social reform. Furthermore, he led the reforms in the policies and tried to implement the measurements(量田) of Daedong Law (大同法) in order to impose fair taxes on the farmers. Also he attempted to appoint intelligent and competent individuals in the office by getting rid of the discrimination against the illegitimacy(庶孼). It appears that such a sense of reality played a significant role in improving the policies.
Second, he demonstrated competent diplomatic tactics, seeking not only justification (名分) outwardly, but also the practical benefits (實利) domestically in the diplomatic travel (使行) to Japan and China. He retrieved 150 captives from Japan and banned the smuggling (密貿易) of the envoys, trying to maintain the nation’s dignity. When he was dispatched to China, he behaved properly to prevent Joseon (朝鮮) from being harmed between Ming Dynasty (明) and Manchus(後金) struggles, contributing to the utilitarian diplomacy led by Gwanghaegun(光海君). In the era of King Injo, when the king was placed in a humble pie situation during the Second Manchu Invasion of Korea (丙子胡亂), he demonstrated the flexible sense of reality by changing his attitude of opposing to the friendly relations (和親) with Mancus.
Third, as a Confucian scholar(儒學者) who was knowledgeable in the theories of propriety (禮論) he was placed in a danger of being impeached by the party in power at the time, Greater Northerners Party (大北派), nevertheless, he opposed the disputes over dethroning
Gwanghaegun’s mother (廢母論). In the King Injo era, he opposed to the posthumous crowning (追尊作業) of King Injo’s biological mother (生母) and father(生父) by citing the example of Joojagarye(朱子家禮). However, when the policy (政策) was established, he showed his sense of reality by following the king’s command.