I posted this a while back at Metaphysical Frameworks and I thought I’d include it here at Summa:
I want to suggest what I think are two of Anselms motivations for his insistence that God is metaphysically simple and see what everyone thinks of them. He says in the Monologion:
It would seem, then, that the supremely good substance is called ‘just’ by its participating in a quality (in this case, justice), rather than through itself.
But this is contrary to the already ascertained truth. The supreme nature is what it is–good, great, existing–precisely through itself and nothing else. So then, it is just through justice and it is just through itself. And if so, then what is more necesarily and clearly the case than that the supreme nature is justice itself?…And so if you ask ‘what is this supreme nature we are talking about?’, you my answer ‘justice.’ What could be truer?
Here, I think we find one of Anselm’s motivation, namely, his notion that God cannot be what He is through any other than Himself. I think Anselm might see this in the suggestion that God exists a se. According to the aseity thesis, God is completely self-sufficient and requires nothing for His being. Since His existence is entirely of Himself, there cannot be anything that causes Him to be. But if this is true, then His essence (that is, His essential attributes or properties) cannot be what they are through any other existing thing either. For consider the matter that ‘God is just’: The statement attributes some real thing–justice–to God. But if God is just, then because of his aseity, He cannot be just through justice (in Platonist talk), or He cannot be just by exemplifying the property justice (in contemporary essentialist talk).
So if Anselm is right, God does not stand in the “subject-exemplifiable” realtion to justice as other just persons do (Abraham, Moses, Mother Teresa), and since He doesn’t instance justice, and yet He is just, we must surmise that He just is justice.
Here is another principle I think that motivates Anslem:
So the supreme nature is many good things. Is it then a composite of these many good things? or is it not rather one good tihng, signified by many names?
The question is pertinent for Anslem because he wants to mantain that if God is a composite, then He cannot be a perfect being.
One might conceive of a composite either as a heap or an organisation of proper parts. A heap seems to have all its parts essentially while an organisation of proper parts can admit of accidental as well as essential parts. In either case however, it seems that a composite depends on its (essential) parts. In this sense, the essential parts of a composite, are more fundamental than the composite itself. For while the composite C depends on its parts x, y, and z for its existence and character, it doesn’t seem that x, y, and z depend on C for the same.
Now if God is not simple, then it appears He exists in an asymmetrical realtion of dependency with His parts. Accordingly, His essential properties such as omnipotence are more fundamental than He. But how can this be true of a perfect being?
Consider further: if God is composed of metaphysical parts then it seems that He is conceivably corruptible. For like other material composites, His parts can be divided up and separated. Of course, He isn’t a material being so there are no material parts to be separated, but He would be at least separable in intellectu.
But a greater being is conceivable. That is, one who is such that it is not even possible that He be divided up metaphysically and separated. And that of course could only be a simple being.