William James (1841–1910), working primarily out of the United States, and Michel Foucault (1926–1984), working primarily out of France, are two very different figures who both made an impact on current theories of education. Even if the primary focus of their work is not education, their ideas challenge what it is that makes education recognizable as education and takes issue with its very identity as a discipline. William James, who began publishing in the 1870s, is generally described as a philosopher and psychologist. He remains well-known for his work on pragmatism in the wake of Charles Sanders Peirce’s pragmaticism and for his work on religion, ethics, and mind theory, but he also devoted considerable time to the study of parapsychology and gave some attention to teacher education. Foucault has been variously described as a philosopher, historian, historian of ideas, and a social and political theorist. His work addressed an impressive array of fields across the sciences, literature, art, ethics, and institutional, political, and social history, and spanned a wide range of historical periods mainly in European and French history from the 13th century to the 20th century with later excursions into the Ancient Greek and early Christian eras. Foucault’s work has been widely, but selectively, deployed within education studies across the globe, with a strong focus on his notions of power, governmentality, surveillance, subjectivity, discourse, and ethics in their various iterations. James’s work has been relatively less deployed, with emphasis on the application of his version of pragmatism, theories of mind, and talks to teachers. The work of the two thinkers may be considered to overlap in two important ways: first, in their respective approaches to the notion of practice, namely the idea of philosophy as strategic and located in day-to-day concrete experience rather than occupying the rarefied realms of abstraction; and second, their interest in the margins of knowledge – knowledge that has been excluded by mainstream science and accepted ways of thinking. In the case of James, this interest manifests in his long-term studies in the field of parapsychology and in the case of Foucault in his interest in the meandering byways and monstrosities of the history of ideas, of long-forgotten knowledge rejected by the scientific mainstream or formulated on the margins of society.