Ever since Plato it has been thought that one knows only if one's belief hits the mark of truth and does so with adequate justification. The issues debated by Laurence BonJour and Ernest Sosa concern mostly the nature and conditions of such epistemic justification, and its place in our understanding of human knowledge. * Presents central issues pertaining to internalism vs. externalism and foundationalism vs. virtue epistemology in the form of a philosophical debate. * Introduces students to fundamental questions within epistemology while engaging in contemporary debates. * Written by two of today's foremost epistemologists. * Includes an extensive bibliography.