Kao Tzu (fifth–fourth century B.C.), Chinese thinker and philosophical adversary of Mencius (4th century B.C.). He is referred to in the Meng Tzu (Book of Mencius). A figure of the same name appeared in the Mo Tzu as a (probably younger) contemporary of Mo Tzu (fifth century B.C.), but it is unclear if the two were the same individual. As presented in the Meng Tzu, Kao Tzu held that human nature (hsing) is morally neutral, and that living morally requires learning rightness (yi) from sources (such as philosophical doctrines) outside the heart/mind (hsin), and shaping one’s way of life accordingly. These ideas are opposed to Mencius’s belief that the heart/mind has incipient moral inclinations from which rightness can be derived, and that living morally involves one’s fully developing such inclinations. Ever since the view that Mencius was the true transmitter of Confucius’s teachings became established, largely through the efforts of Chu Hsi (1130–1200), Confucians have distanced themselves from Kao Tzu’s position and even criticized philosophical opponents for holding positions similar to Kao Tzu’s. See also CONFU- CIANISM , MENCIU. K.-l.S.