Watsuji developed an ethics of ningen (the human being understood as inherently relational, existing "in-betweenness," aidagara) and a philosophy of fūdo (climate or milieu), arguing against Western individualist ethics, and against Heidegger in particular, that human existence is irreducibly social and inseparable from the concrete climatic and cultural environment a people inhabits.
Intellectual setting
Watsuji studied Western philosophy, including Kierkegaard, Nietzsche, and Heidegger, while also rediscovering neglected Japanese thinkers such as Dōgen, and taught alongside Nishida and Tanabe at Kyoto Imperial University before moving to Tokyo; his ethics of collective belonging has since been criticized by postwar scholars for lending philosophical support to wartime Japanese nationalism.
Key ideas
Ningen and the ethics of betweenness (aidagara)
In "Rinrigaku" (Ethics, 1937-1949), Watsuji argued that the Japanese term ningen denotes both the individual person and the web of human relations that constitutes it, so that ethics must study the "betweenness" (aidagara) binding self and others rather than begin from an isolated Cartesian or Heideggerian individual.
Fūdo (climate) as constitutive of culture
In "Fūdo" (Climate and Culture, 1935), written partly as a critical response to Heidegger's "Being and Time," Watsuji argued that human self-understanding is inseparable from climate and terrain, distinguishing monsoon, desert, and meadow climate types to explain how differing environments shape a people's characteristic feeling, society, and culture.
Legacy
Watsuji is regarded, with Nishida and Tanabe, as one of modern Japan's most important philosophers; his relational ethics of aidagara and his climate-based cultural theory remain influential in Japanese ethics, comparative philosophy, and environmental philosophy, even as his wartime political entanglements continue to be debated.