What role does doubt play in education? This article addresses this question, initially via an examination of Søren Kierkegaard's "Philosophical Fragments". Kierkegaard, through his pseudonym Johannes Climacus, draws attention to the potentially debilitating and destructive effects of doubt on both teachers and learners. The work of Paulo Freire is helpful in responding to the problems posed by Kierkegaard's account. It is argued that in Freire's pedagogical theory and practice, doubt has both epistemological and ethical significance. It is linked with other key Freirean virtues such as humility and openness, and it forms part of the process of learning how to question. It is also related, through the Freirean idea of being "less certain of one's certainties", to the ethical priorities we determine, the political commitments we have, and the actions we take as we negotiate our way in the world.