Which ethical theory is most natural? Which theory requires the least alteration of our natural inclinations in order for us to live ethically?
There is so much in this question that leads to further questioning. Maybe that's where the greatness of philosophy lies in that there are few answers, and more questions. The fundamental notion of "most natural" is one area where there is a great deal of debate. If one believes a Lockian or classically Liberal approach to human inclinations, then the most natural ethical philosophy is one of self interest, live and let live, and a social contract enacted amongst all human beings to act rationally and to ensure that interests do not conflict with one another. In contrast to this would be a Hobbesian read, in arguing that human nature is one of complete war and antagonism and that the only way an ethical philosophy can be pursued would be through the idea of empowering one ruler to prevent further chaos. If one took a Marxist read, then the most natural ethical theory is one that focuses on the elimination of wealth and class system, which perpetuates disharmony and dissonance amongst human beings. The reason why one cannot find an absolute ethical theory that is "the most natural" is because the actual debate about what is our "most natural" tendencies are debated without much in way of totalizing resolution.