To be ethical, one bases their actions on a standard of value and a set of morals. If one doesn't stick to their standard of ethics then they'll be committing evils by their own code. Some people have higher ethical values than others. This helps expand the grey area of what is good and what is evil. Those with higher ethical values will hold themselves to do good in times when their integrity is questioned. Others won't perform so well. An example of this would be the idea of charity. Those with higher ethical values and moral standards will be more inclined to do things such as help out a friend, return a lost wallet, or volunteer at a soup kitchen whereas those with lower ethical standards may not see the point in helping others and possess a more selfish motive. So in general, ethics and evil are based upon your own core values and what you consider to be evil.