Miki was a native of what is now part of Tatsuno, Hyōgo. He studied philosophy under Nishida Kitarō and Tanabe Hajime at the Kyoto Imperial university. Later he went to Germany, to study the work of Martin Heidegger, Karl Löwith, Blaise Pascal, Søren Kierkegaard and Friedrich Nietzsche. Upon his return to Japan, his outspokenness and outgoing lifestyle, coupled with a controversial affair with an older woman, led to his being denied an academic position at Kyoto. Further trouble engulfed him when he lent money to a friend who used it, unbeknown to Miki, to contribute to the Communist Party of Japan. Miki was then implicated in this development (the far-left movements were being cracked down upon, and such donations were illegal) and after brief imprisonment lost any chance of regaining decent academic standing. While he remained in touch with his mentor, Nishida, and other members of the Kyoto School, he worked outside of academia proper, producing popular writings aimed at a wide audience.
Miki believed that philosophy should be pragmatic and utilized in addressing concrete social and political problems. He wrote articles for the Yomiuri Shimbun newspaper, providing commentary on issues of the day. His firm belief that philosophy should lead politics encouraged the political activism of intellectuals, and when he was offered in 1937 the opportunity to head up the cultural section of the Showa Kenkyu Kai (Showa Research Association), a think tank concerned with building an intellectual basis for Prince Konoe Fumimaro's Shintaisei (New Order Movement), he eagerly accepted. While he formulated the concept of the "Greater East Asian Co-Prosperity Sphere," he was infuriated when the Imperial Japanese Army employed it in justifying its aggressive expansion in China and Southeast Asia. Following the collapse of the Showa Kenkyu Kai, and in an environment of the militarization of society and intensifying warfare abroad, Miki became depressed and isolated. After helping a friend on the run from the authorities, he was imprisoned. Miki died in prison on September 26, 1945 due to an illness resulting from poor prison conditions. His death, at a time when the US Occupation of Japan was already underway, deeply upset Japanese intellectuals. As a result, the American Occupation pressed to release political prisoners. Miki's complete works are available from Iwanami Shoten.
In Shoji Muramoto's psychological article "Historical Reflections for the International Development of Japanese Humanistic Psychology.", Kiyoshi is credited as a "central figure in the Japanese humanistic movement" because of his authoring of "the first book explicitly related to the existentialist tradition written by a Japanese thinker": "Studies of Human Being in Pascal" (1926).
Miki developed a reading of Heidegger's early philosophy as essentially being in the tradition of Christian individualism, reaching back to Saint Augustine and being fundamentally anti-Greek in character. As such, his reading of Heidegger falls with the broad class as Jean-Paul Sartre, in that it ignores the priority Heidegger gives to the ontological question of Being, in favor of seeing Heidegger's philosophy as an analysis of human existence.
- Miki Kiyoshi, 1897-1945: Japan's Itinerant PhilosopherBy Susan C. Townsend Page 157