The neo-Platonists, among others, argued on philosophical grounds that goodness has substantial existence while evil is a privation, and therefore lacks substantial existence.
I disagree that, "The evidence of evil is simply not accounted for by regarding evil as an absence or a void." Consider the following: why does a man commit evil? It can be argued on perfectly sound philosophical grounds that he does so either because of ignorance (traditional Platonist) and therefore there is a lack of knowledge, or that the person possesses a will that is corrupted (more neo-Platonist), which is also a lack of a properly function will. To deny substantial existence to evil is not to say that there is no evil, only that evil is not a thing.
One argument for the positive existence of goodness and non-substantive nature of evil:
1. Existence is good. (This could be a separate argument, but consider that to argue the contrary is to maintain that the entire universe is evil.)
2. When something is corrupted it becomes less good, and is less of what it was.
3. If something becomes entirely corrupted it becomes not good at all, but also non-existent.





