In Japanese Buddhism, the theory of the degenerate dharma was widely accepted, while there were also monks who posed questions about the three periods 三時 of the Buddhaʼs dispensation. In this paper, I reexamine Shōkū’s 證空 (1177–1247) doctrine that all three periods consist of the degenerate dharma. What I found is that, although he insisted that all three periods consist of the degenerate dharma, he directed his strong attention to various theories of the three periods, and this doctrine was not insisted upon in the Tahitsushō 他筆鈔, which is one of his most important writings.
