To say that people have a moral sense is not the same thing as saying that they are innately good. A moral sense must compete with other senses that are natural to humans - the desire to survive, acquire possessions, indulge in sex, or accumulate power - in short, with self-interest narrowly defined. How that struggle is resolved will differ depending on our character, our circumstances, and the cultural and political tendencies of the day. But saying that a moral sense exists is the same thing as saying that humans, by their nature, are potentially good.