Karin Costelloe-Stephen (1889–1953)

<jats:title>Abstract</jats:title> <jats:p>This chapter traces Karin Costelloe-Stephen’s upbringing, education, familial networks, academic achievements, feminist commitments, and intellectual development, showing how these experiences shape her philosophical correspondence. It examines her participation in the Bebb litigation, her challenge to professional exclusion, and her emergence as a significant advocate of Bergsonian philosophy. The chapter analyses letters to family members, correspondence with Bertrand Russell, and fellowship documents, revealing her studies, publications, debates, ambitions, and collaborations. Through discussions of intuition, duration, abstraction, and criticism, it presents her engagement with Bergson, Cambridge philosophy, public lectures, scholarly societies, and influential contemporaries. Finally, the chapter follows her transition from promising philosopher to published author, traces the completion of her Bergsonian manuscript, records recognition from leading thinkers, and notes her subsequent engagement with psychology, medicine, and broader intellectual pursuits.</jats:p>