We live in a universe where humans cannot fly like superman. But we live in a universe that has the idea of flying like superman. So it clearly can be the case that we could have a universe *without *evil but *with *the idea of moral evil.
There’s nothing natural about flying to being human. That is, an individual could certainly desire to fly, and there’s nothing perverse about that, but there’s nothing about being human in itself that creates a desire to fly. However, there are some things to that belong to simply being human, such as thirst. That a human being has a natural desire for water implies that there is water (not that he will get water, but that this natural desire is towards water is not in vain and that there is such a thing as water).
Likewise, I think it’s fairly east to argue in favor of the existence of goodness. You are probably familiar with the argument that “there’s no such thing as altruism, people are selfish and do what they think is best for themselves, and if that means they get more out of helping another at cost for themselves, it’s still selfishness.” (Now, I think the conclusion from this that there is no altruism is as absurd as those who say that there’s no such thing as suction, it’s just pressure differentials in the air, but that’s not the point.) I bring this up because there us a kernal of truth to that. Rational people always choose what seems most good to them. Even the criminal does a criminal act because it seems like it’ll net him some good he favors over other goods, so it follows that humans have a natural desire towards “the good,” whether we agree on how we prioritize that or not, and so it would follow that this tendency is not towards something non-existent, but to something real (not that it’s floating out there in some realm of forms, but that it is a rwal property that can be found in things).
But if we have the idea of the good and, as a subset of that, as the moral good, we naturally deal with different grades of goodness, and if evil is to good as darkness/shadow is to light, it follows that there is evil as well. That’s really where moral evil stems from, the choosing to frustrate a greater good in order to achieve an objectively lesser good because a person makes a subjectively poor decision. If you have goodness, and if you have grades of it, you inevitably have evil.
A universe without evil is a universe without grades, without variety, without change. It is a universe in which the creation never acts and never gives. It is a universe which is further from being in the image of God.
