The Problem of Evil?

What is the problem of evil? Well, I would say the main conjecture about the "problem of evil" is the assumption that there is in fact evil [meaning evil exists and is real].  However, the assumption [there is evil] presupposes there is good. To actually believe there is evil in this world one would have to presuppose there is good to begin with.  Else, how would we know there is evil without knowing the good?  Is it possible to know evil without knowledge of the good at all?  I don't think it is possible.  Take for example if the universe were to shrink, could we come know the universe had shrunk without comparing it to something-else?  No, we would have to have something to compare [before it shrunk and after it shrunk] with the size of the universe in order to know it had shrunk.  In as much, there has to be some sort of defining factor which allows me to come to some sort of understanding of what evil is.  The only thing I can think of that would acquiesce me to differentiate evil is good.  If evil is a disruption of goodness or at the very least the opposite of good, and let's say such is the case, then good would be able to give us different defining factor(s) of what good is and evil is not.  Therefore, any human being holding to a position that commits them to believing there is evil has to also be assuming there is a certain good.

If what I said above is true, is it fair to accept the following?

[1] Evil exists.
[2] In order to know evil exists good has to also exists.
[3] Therefore, good exists.