Abstract: This chapter explores the role ethos played in the genesis of Newman's theory of development. It begins with an analysis of Wood's theory of doctrinal development, and Newman's and Manning's negative response to it. The chapter tries to trace the intellectual difficulties and tensions Newman faced before his acceptance of doctrinal development, and shows how the concept of ethos contributed to the solution of those objections and to the formulation of his theory.

Keywords: development of doctrine, ethos, Wood, Newman, Manning, Antiquity, heresy,