Philip Pettit has argued that more robust harms are worse than less robust ones, other things equal, and thinks that appealing to this presumption can help us rationalise the appeal of a number of widely-held moral principles. In this paper, I challenge this view. I argue against the presumption and suggest that, even if it were correct, it could not give much support to the moral principles that Pettit discusses. I also claim, however, that Pettit has the resources at his disposal to explain the attraction of the principles in another way, and lay out how such an explanation would proceed. As moral heuristics, at least, these principles can be grounded on the need to maintain social norms necessary to guarantee individuals’ security.