Ethical appeals make use of what an audience values and believes to be good or true. Presented formulaically, it might look something like this:
Values held by audience + connection to your argument = an argument your audience values.
Ethical appeals are acceptable in most forms of academic argument; however, they are not a substitute for evidence or proof. Use them sparingly. Whatever you do, don't assume your ethical positions are shared by your audience as this may differ radically from one to another.
Typically, such appeals appear in the introduction or conclusion to demonstrate how the argument connects to a belief the audience already holds regardless of whether they have ever thought about your position in the same way before.