In Episode #7597, “Answering Objections to the Christian Faith”, in his explanation of evil Trent repeats the assertion that evil does not exist per se, but is rather the lack of some good. (Listen to 1:18~4:00.)
Trent begins around 1:55:
If God is good, why is there evil? … I think there’s a lot of steps we have to go through to answer satisfactorily. One step, we have to … define evil. Evil is not a thing that God made. God doesn’t make evil. Evil is an absence of good. It’s a parasite or a corruption of the good. For example, rust doesn’t exist on its own. You can’t have rust apart from metal. You have to have metal to be corrupted to have rust. You can’t have 100% evil with no good. Evil is good that is corrupted in a certain way. It’s a lack of good.
This assertion is easily disproven. We may proceed via proof by contradiction: Disease and wildfires are two proofs. Illness caused by viruses is not a matter of the body “losing” health, but rather the body has gained foreign matter, viruses, that it is actively trying to destroy and expel.
We could also mention cancer, which can be caused by viruses: Cancer is not merely the lack of proper order within the body: It is the actual presence of a very large number of cells that have grown such that they are depriving other organs of nutrients and pushing against them preventing proper function, hence killing the animal. To put it simply, “Tumors exist. Therefore the premise that evil is a lack of good is false.”
Wildfires are not the absence of whatever you might expect a normal forest to contain, but are rather the presence of heat and an ongoing chemical reaction converting what you expect into ash and more heat.
Catholic Answers cannot expect us to blindly assume antiquated premises with them to effectively beg the question of God’s existence. If Trent Horn wants to argue that evil is merely a lack of good, he must show this premise to be true, not assume it, and he must refute all the positive evidence like this that we have obtained through science showing it to be false.
Incidentally, this points to a fatal problem with his book Answering Atheism: He does not address any serious objections to his arguments, instead only repeating the classic arguments and refuting trivial objections.
(As another example, war is not an absence of good social relations: It is the presence of tanks, bullets, bombs, and people pulling the trigger.)
Can you vindicate Trent’s argument?
I actually wrote all that responding to the bold, not having heard Trent’s full answer. Listening to it now – I typed it out above while listening, his answer is actually even worse than I thought, because he shifted mid-step to a different argument. Instead of saying evil doesn’t exist, he decided not to comment on whether evil positively exists, saying instead it’s “a corruption of a good”, a more nebulous claim. He could still mean that evil doesn’t exist, or he could mean that evil exists but coexists with a good that it is actively perverting to remain existing. He appears to mean the former, though, because he ends by repeating the claim I’m responding to here, “Evil is a lack of good”.
He then argues that God can bring about greater good, making the entire question of whether evil is a lack of good irrelevant, so he might as well not have even said it …
From what he’s said, I can see what he means, like how a wildfire is “energy (heat) run amok”, likewise cancer is body tissue (good) misbehaving (again running amok) … I don’t see that this observation furthers any point, however. If anything, it appears to undermine God’s sovereignty instead of His wisdom (theodicy being an attempt to vindicate God’s wisdom by explaining evil).