Evil is a concept that heavily relies upon perception. When doing "evil" deeds in order to execute an act of great goodness, does society consider an evil to have been committed? What if this goodness is only in the mind of the one who executes the deeds? In both cases, goodness exists, but only in the former is the goodness agreed upon by all (or at least most) members of society. Does this trivialize the pure intentions of the person engaging in so-called evil acts?

If the individual intentionally goes against the morals of society, has an evil necessarily been committed? What if those morals are in themselves evil (as viewed by a person from another society with different morals)? Under the assumption that evil is the opposite of good, then a good has been committed, but at the same time, an evil has also been committed, as the morality of society has been challenged.

This leads us to the conclusion that the only way to judge what is good and what is evil is to take a society and its morals and use them as a guideline. Societies do change, however, and it must be noted that morals change as well. As morals develop and evolve, the definitions of good and evil can be drastically altered, or, in the rare case, completely transposed. Due to these constantly-changing rules of societies, good and evil are destined to only be defined moral and immoral, respectively.