Science-based medicine is, among other things, a tool. Science helps us sequester our biases so that we may better understand reality. Of course, there is no way to avoid being human; our biases and our intuition still betray us, and when they do, we use other tools. Ethics help us think through situations using an explicitly-stated set of values that most of us agree upon (and in order to get wide agreement, these precepts must be pretty general).
Ethical problems are a normal part of medical practice. In medical school I received a bit of formal didactic education on ethics, and on the floors we often have formal ethical discussions to help understand and resolve conflicts. But ethics are not a weapon used to obtain a result we want; they are a tool to give a framework for understanding and resolving dilemmas. Ethical dilemmas can arise out of may types of conflicts, for example when our personal beliefs clash with those of our patients, or when patients’ and families’ desires conflict. They can also arise when we as physicians are constrained in our actions by outside forces.