What is photography? Is it a source of knowledge or an art? Many have said the former because it records the world automatically, others the latter because it expresses human subjectivity. Can photography be both or must we choose? In On Photography: A Philosophical Inquiry, Diarmuid Costello examines these fascinating questions and more, drawing on images by Alfred Stieglitz, Berenice Abbott, Paul Strand, Lee Friedlander, James Welling, and Wolfgang Tillmans, among others, and the writings of Elizabeth Eastlake, Peter Henry Emerson, Edward Weston, Siegfried Kracauer, André Bazin, and Stanley Cavell. This sets the scene for the contemporary stand-off between "sceptical" and "non-sceptical" Orthodoxy in the work of Roger Scruton and Kendall Walton, and a New Theory of Photography taking its cue from László Moholy-Nagy and Patrick Maynard.