Online discussions are performed in the gaze of fellow users. To increase engagement, platforms typically let these users evaluate the comments made by others through rating systems (e.g., via Likes or Down/Up votes). Understanding how such ratings shape, and are shaped by, features of the underlying discussion is important for our understanding of online behavior. In this study, we focus on an increasingly concerning aspect of online discussions: incivility. We draw on the theory of normative social behavior to analyze a data set of over 6,000 online newspaper comments. We find that repeated incivility by the same person is more likely when their initial incivility was affirmed by both descriptive norms (incivility in nearby comments) and injunctive norms (Up votes). Repeated incivility receives more Up votes if nearby comments also include incivility but fewer Up votes if they do not, suggesting that injunctive norms are contextual and shaped by descriptive norms. We conclude that online incivility is a dynamic, normative process that is responsive to both positive feedback and proximate incivility.