I tend to believe that ethics is a sort of sense, a faculty that is developed by making sound and unsound choices and gaining experience from living through the results.
Those aspects of an action (mental, vocal, or physical) that lead to benefit of any sort for any being push the action toward the ethical end of a scale, while harm of any sort to any being push it towards the unethical. In this sense most choices have some mix of the two and it is often the case that we find ourselves having to compromise, though generally through lack of awareness of the true nature of the situation.

