philosopher, travel writer, and pioneer botanist of the early Tokugawa period (1603–1867) who set forth the Confucian doctrines in simple language that could be understood by Japanese of all classes. He was the first to apply Confucian ethics to women and children and the Japanese lower classes.

Originally trained as a physician, he left the medical profession in 1657 to study the thought of the great Chinese Neo-Confucian philosopher Chu Hsi (Zhu Xi), under the teachers Yamazaki Ansai and Kinoshita Jun-an. He became a highly popular teacher who traveled widely and kept such detailed accounts of his journeys that they were used by others following his routes. He is also considered the father of botany in Japan. His Yamato honzō (“Japanese Plants”) attracted the attention of many Westerners.

Kaibara wrote about 100 philosophical works in which he stressed Chu Hsi's Neo-Confucian conception of the hierarchical structure of society. In his Taigi roku (“Grave Doubts”), however, he took issue with Chu Hsi's dualism in favour of a single creative force. In his Dōji kun (“Instructions for Children”), Kaibara tells parents to severely discipline their children, who must blindly and respectfully accept all that parents tell them, whether it is right or wrong. To Kaibara is usually attributed Onna daigaku (“The Great Learning for Women”), long considered the most important ethical text for women in Japan, which advocates women's obedience to their parents, parents-in-law, husband, and, if widowed, to their eldest son. Kaibara, however, treated his wife, Tōken, to whom he was happily married for 45 years, on terms of equality. She was also a scholar, calligrapher, and poet, and it has been suggested that Tōken was the real author of his books.