In the late 19th and early 20th centuries, rapid scientific growth encouraged a material-centered worldview. Eucken argued that this alone cannot measure human value and proposed “life as spiritual activity.” His philosophy unites a search for truth, rigorous logic, and broad historical awareness, stressing an “active idealism” that demands action as well as thought. In other words, we should not merely contemplate values but use our will to improve society. During the turmoil around World War I, his stance offered guidance for reclaiming humanity. The Nobel Committee valued not only his ideas but also the literary warmth with which he expressed them.

Eucken’s key notion is “aktiver Idealismus” (active idealism), an extension of German Idealism that fuses life-force with praxis. In works like “Geistige Strömungen der Gegenwart” and “Der Sinn und Wert des Lebens,” he critiqued deterministic natural science, contending that the human spirit contains an active energy aimed at self-transcendence. The spirit is not subsumed by nature; rather, it constitutes and valorizes nature, a stance comparable yet distinct from Bergson’s élan vital. By comparing ancient Greek thought, Christian theology, and modern rationalism, he defined humanity’s striving toward ethical ideals as “Kultur-bildung,” the forming of culture. Consequently, at the intersection of philosophy, theology, and pedagogy, he advocated “personality education,” which influenced early-20th-century progressive education movements.

While confronting Neo-Kantianism and Lebensphilosophie, Eucken reconstructed the ontological status of spirit. In “Einheit des Geisteslebens” he outlined a tripartite structure of spiritual life—intuitive apprehension, critical reflection, and creative praxis—aiming at a synthesis of metaphysics and ethics. His methodology combines historical-critical comparative analysis with existential participation, prioritizing axiology over epistemology and foreshadowing the phenomenological concept of intentionality. The thesis that cultural transcendence is mediated by communal achievement prefigures Dilthey’s hermeneutics and Schutz’s social constructionism. Despite contemporary critiques regarding idealist vagueness and scientific insufficiency, Eucken’s active idealism remains instructive for the reconfiguration of 20th-century ethics and philosophy of religion.