In 1a.58.5, Aquinas asks if angels can fall into error. He’s working up towards a theory of why the devil exists, so pay attention. He starts off by saying angels can fall into error, which – hang on, that’s not right. If you know anything about the Summa, you know that Aquinas starts with a bunch of bad opinions arguing the wrong side of the argument, and then turns around and shows why they’re all bad and wrong. But he’s starting here by saying that the angels can fall into error, which means that they… can’t?
The arguments in favour of angel-error are pretty simple – Dionysius says the devils are in error, Dionysius says the devils are in error again, and Dionysius – okay all the arguments are just quoting Dionysius in different ways. Aquinas then moves to his counter-argument, which takes a little bit of explaining. In the previous article (1a.58.4), Aquinas talks about different types of reasoning. For instance, we might think of a premise, and then follow its implications through to a conclusion – so, uh, say you think about jumping off a rooftop. That’s your premise. You think about the act of jumping, and then you follow the idea through and you realise ‘Hey, I’ll get hurt when I hit the ground,’ and then you don’t do it. And Aquinas says that this process of reasoning is part of our flawed human nature: “our first apprehension of any object does not immediately show us whatever is implicitly contained in it. And this is due to what I have called the dimness of the intellectual light in our souls.” When angels think, then, they observe all possible conclusions instantly as they observe a premise. So if they think about jumping off the roof, they immediately also comprehend, as part of knowing about jumping off the roof, all possible conclusions or outcomes that could possibly come about as a result of that action: “When an angel understands the essence of anything, he at once understands whatever can be predicated or denied of it.” That’s – I mean it seems ridiculous, frankly, but if it was real it’d be pretty cool.
So anyway – back to 58.5. Aquinas’s definition of how angels know things causes a problem for our current question about angels and error. Basically, Aquinas says, you can’t misunderstand an essence. Say you see a dog, right – you get the image into your mind and now you understand the essence of dogs – basically you know what dogs are. You have the idea present in your mind. Following Aristotle, Aquinas argues that you if the idea is present, it can’t be wrong. You can’t have the wrong idea of what a dog is. Now that might seem really obviously stupid – of course people can be mistaken, right? Say someone points out a wolf and tells you it’s a dog. You might start believing that wolves are dogs – so you’ve got the wrong idea then, haven’t you? In that instance, Aquinas would say that you don’t really understand what wolves are because you’ve misunderstood them as dogs – so the idea of wolves as wolves is not present in your brain. “Either one wholly fails to grasp [an essence], and so does not understand [it] at all, or else one knows [it] as [it is].” Either you know correctly and you possess an idea, or you know incorrectly in which case you don’t really possess the idea at all. Again, this theory might still seem stupid – and I’m not going to defend it. But that’s the basic idea – you can’t misunderstand an essence. You either possess the essence through correct understanding, or you do not possess the essence at all.
It’s also worth noting that if humans are getting ideas confused, like with the wolf stuff, Aquinas says the issue is with how we think. As noted above, he says that we think through cause and effect. That development of an idea is where the problems start – we can attribute false causality, or mix and match ideas in some other incorrect way. Thus Aquinas says our mistaken understanding “is always because of some combining of concepts: either we take the definition of one thing as valid for another, or we define a thing in terms which do not hang together.”
But remember, Aquinas has already said that angels don’t combine ideas like us, right. If they understand an idea, they implicitly see every single effect that it might have. They see every interaction it can have with literally everything else in the universe. So logically, then, angels can’t make mistakes like humans, because they don’t have our thought processes. In that sense, Aquinas argues, angels can’t fall into error. They can’t mis-combine ideas like humans do.
Okay, well, that’s all well and good, but it’s a really weird argument and we kinda just want to know why the devils became devils. Aquinas spent the whole intro quoting Dionysius saying that the devils were in error, so what about that stuff? Aquinas does get back to it: he says that angels might intuitively know every natural interaction that things can have, but they don’t necessarily know all the supernatural possibilities. So angels wouldn’t necessarily know about resurrection and so on, because that’s all supernatural. The same goes for, say, walking on water, or any of the other miracles – angels don’t necessarily know about that stuff because it’s not within the bounds of how the created universe normally works. It is, by definition, super-natural. Basically the difference between angels and devils is that angels understand things in the light of the divine plan, and devils don’t. I guess the focus is more on the real world in this article – Aquinas isn’t directly concerned with the whole ‘why are devils bad’ thing. Well, not yet, anyway. For now, he’s happy to say that yeah, devils can make mistakes about how things happen in the world. In that sense, he says, they do fall into error.