Good and evil are often portrayed as opposing choices in an individual’s life, or opposing forces of history. Yet, good and evil are not opposites and this mis-characterization often leads to confused thinking on the part of philosophers, storytellers, and others.
The first thing that should be noted about good and evil is that they are adjectives that apply to different things. Good and bad can describe just about anything, but evil only applies to things that people do. One might have a good apple or a bad apple, but one would never have an evil apple. On the other hand, one could say that what someone does is good, bad, evil or the opposites of those.
As examples, one might say that it is good to exercise, bad to over-eat, evil to murder and not-evil to read a book. Aside from evil and not-evil, these adjectives are not mutually exclusive. So one might say that it is good, bad and not-evil to eat ice cream. Something can be good and bad in different ways, so there is nothing wrong with describing eating ice cream as both good and bad.
Similarly, as good and evil are not opposites they can be used to describe the same thing. An action that someone takes might be good and evil at the same time. For example, murder is an archetypal evil. Yet, if a politician that a farmer does not like is murdered, the farmer might consider that a good thing, making the murder both good and evil. Another scenario might be if a man robs a bank to buy medicine for his sick mother.
The linguistic distinction that evil only describes actions helps to clarify the meaning of evil, but the boundaries of what is described as evil can be tightened even further for additional insight. This is because evil does not describe all things that people do, but only those things that affect others. Theft, murder, rape, etc, all involve some sort of interaction between different people. One would not say that a man took an evil walk by himself through the forest, but as soon as there are other people involved there are many evil things he might do. So, a little reflection on how the term is used greatly improves ones understanding of what it means.
The other important difference between good and evil is that whether something is good depends on an individual’s subjective values. A person might consider apples to be good or bad. Yet, murder is always evil, regardless of whether one considers any particular murder to be a good thing or bad thing. This means that the distinction between evil and not-evil has some objective definition that everyone can agree to regardless of their own personal value system. People may not understand this explicitly, but there is a reason why that the words murder and kill have been distinguished.
As evil and not-evil describe the things that people do, and the goal is to define them in an objective, value-free way, it makes sense to use praxeology to draw the dividing line. So the question becomes: how can praxeology define an adjective that only applies to things people do, specifically things that people do to other people, and how can it do so in a way that is value free?
Praxeology is founded on the idea of human action, so we can take that for granted. Interaction assumes the existence of other actors and that each actor can affect the lives of the others somehow. It is not enough to assume that other actors exist because they might exist in a world of superabundance, without scarcity and nothing to fight over.
Given that there are at least two people who can affect each other, we can look at three cases. The first is that the two actors never interact. For example, two men each on their own island. The second is that they interact, but they do so in a way that does not interfere with each other. Imagine the men waving at each other. The third is that they take actions that interfere with each other. For example, one man might be building a sand castle and the other man throws a coconut at it. Whether there is no interaction, peaceful interaction or conflict, praxeology can describe each state in a value free way.
The second and third cases are value-free ways of describing human interaction. The third case in particular seems to correspond with the idea of evil. It is when people do things that interrupt the lives of others. Being acquainted with a praxeological definition of evil should make it easier to identify evil in theory and in practice. Thus one will be more able to follow the motto of Ludwig von Mises: tu ne cede malis sed contra audentior ito.