Abstract: This book offers a new interpretation and defence of Kant's doctrine of things in themselves. Kant distinguishes things in themselves from phenomena, and in doing so he makes a metaphysical distinction between intrinsic and relational properties of substances. Kant says that phenomena—things as we know them—consist ‘entirely of relations’. His claim that we have no knowledge of things in themselves is not idealism, but epistemic humility: we have no knowledge of the intrinsic properties of substances. This humility has its roots in some plausible philosophical beliefs: an empiricist belief in the receptivity of human knowledge and a metaphysical belief in the irreducibility of relational properties. The interpretation vindicates Kant's scientific realism, drawing on his theory of force, and explains the advantages of his primary–secondary quality distinction. And it answers the famous charge that Kant's tale of things in themselves is one that makes itself untellable.

Keywords: history of philosophy, humility, idealism, ignorance, Kant, Rae Langton, Leibniz, Locke, metaphysics, phenomena, properties, receptivity, scientific realism, thing in itself