I promised some examples of the point made in the previous post. I will give just a few here, although the point could easily be extended to many more.
Parmenides argues that nothing can come to be, since “what is not” cannot be or become. He also claims that “it is the same thing that can be thought and that can be,” and apparently this is intended to cover not only what is, but also the way that it is. Consequently, his position seems to imply a perfect identity between thought and being, even if it is ultimately inconsistent, since he says that human beings are wrong about change and the like, and this implies a discrepancy between thought and being.
Alexander Pruss argues that all words are sharply defined, at least in the mind of God. He makes the argument, “Words are part of the world, so if there is vagueness in words, there is vagueness in the world.” This is no different, of course, from arguing that since words are part of reality, and some words are universal, there are universal things. There are universal things, if we mean by that universal terms or concepts, and there are vague things, if we mean by that vague words or concepts. But there are no universal cats or dogs, nor are there vague cats or dogs, despite the words “cat” and “dog” being vague.
C.S. Lewis argues, “Either we can know nothing or thought has reasons only, and no causes.” As I argued in the linked post, reasons in fact are a kind of final cause relative to their consequences, and they do not exclude efficient causes. This case might be somewhat less evident than the two previous cases, but I would argue that the cause of Lewis’s error here is the fact that, as St. Thomas says, the human mind can understand many things at once only by understanding them as one. Consequently, we can understand that an efficient cause can be for the sake of an end, but if the efficient cause and the final cause are presented as simply two causes, without the order that they actually have, they are not intelligible in this way.
These are examples of speculative errors resulting from confusing the mind’s way of knowing with the way that things are. I asserted in the last post, however, that practical errors can also result from this confusion. There is a very fundamental way this can happen: by nature we know things only if they have some relation to ourselves. The corresponding practical error would be to suppose that those things are real and important only in relation to ourselves. Look around you, and it appears that the world is centered on you. If you take this appearance and attribute an absolute truth to it, you will conclude that everything else has its being and importance in relation to you. Consider that you exist, and that all of the past has past out of existence. It might seem that the past only existed to bring you about.
St. Therese says about humility, “To me it seems that humility is truth. I do not know whether I am humble, but I do know that I see the truth in all things.” This is related to the examples I gave above. Since we know things in relation to ourselves, there is the temptation to suppose that things exist in the very same way. This leads to a false idea about our place in reality. Humility consists, on the contrary, in the truth about our place in reality, as I noted here.