Can Ethics be taught?

Adams references Rawls and Kohlberg throughout chapter 12 in order to point out the limitations of their theories of virtue, justice, and ethics.

In chapter 12, Adams displays a certain skepticism towards the manners in which the ethics of certain theories of justice and morality of philosophers like Rawls and Kohlberg can be integrated and made effective. His skepticism, it seems to me, is rooted in his intense will to preserve the dignity of people, specifically children, in that even the smallest of flaws within said philosophers theories are breaking points in the argument. I support Adams in his skepticism.

I believe that since there has been no establishment of a fundamental truth regarding humanity and its moral significance since the time of Descartes, it is impossible to effectively teach and render a non-controversial, non-debatable view on ethics. How can an ethics be taught when there is no ethical truth that has been fully established? Of course the majority of ethicists can come to agreements, ranging from minor to vast ones, but there are still people like Nietszche and even others who would argue points just the opposite of what many might consider ethical.