This is a sophisticated question, as it assume that philosophy is important in ethics from a sociological point of view. I agree with this line of reasoning. In light of this, let me offer a few points.
First, from the beginning philosophy was ethical. If you think about the dialogues of Plato, many of them are about ethical concerns. What is piety? What is honor? What is courage? This approach assumes that what we think of these virtues leads to behaviors - ethics.
Second, modern philosophy also has this framework, as ethics is under philosophy. This basically means that what we deem as ethical in time trickles down to the general populous and this in turn effects our society, which shapes our personal ethics. This is why each nation differs in certain ways from an ethical point of view. Their philosophical system of the world differs.