This essay describes what it means to live with existential self-doubt, explores how such doubt emerges in educational encounters, and examines some educational benefits and challenges of uncertainty and doubt. Mordechai Gordon begins his analysis by describing the type of self-doubt that Paul Cézanne embodied, that is, of an artist who painted throughout his entire life yet was still consumed by existential uncertainty. Drawing on Cézanne's example, as well as poet Rainer Maria Rilke's life and his own experience, Gordon sheds light on what it means to live with existential doubt. Following the discussion of existential uncertainty, he revisits the epistemic self-doubt displayed by Socrates and René Descartes and compares it to existential self-doubt. In the third part of this essay, Gordon draws on the examples of some veteran teachers in order to illustrate how educators have approached the challenge of living with existential self-doubt. The final part of the essay considers both the promises and perils of existential self-doubt in the context of education.