Bertrand Russell, in a passage quoted earlier, affirms that if there is a first cause, it might as well be the world:
If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument.
As we saw at the time, Russell misunderstands the argument, since he supposes that it depends on saying that “everything has a cause.” But in any case, by the argument regarding the first cause and distinction, there is only one first cause, and that cause is not the world. It is not the world because the world has things in it which are distinct from one another, and the first cause cannot have anything within it distinct from anything else within it, since otherwise at least one of the two distinct things would have a cause. Instead, the first cause is absolutely simple. St. Thomas makes this argument, saying, “Every composite has a cause, for things in themselves different cannot unite unless something causes them to unite. But God is uncaused, as shown above, since He is the first efficient cause.”
There are two things that should be noted about this argument relative to Catholic theology. First, as was already stated, the first cause at which this argument arrives would be the person of the Father; otherwise it would be wrong to say that there is nothing in the first cause distinct from anything else within it.
Second, this argument does not prevent one from saying that the first cause is both a part of the world, and the cause of the whole world. My discussion of whole and part does not prevent any two distinct things from being taken as parts of a whole, as long as we can think of something that would include them both. And in the case under consideration, we can think of such a thing: “reality”, which which is intended to include both causes and effects. Thus the first cause is a part of reality. Nonetheless, it is also the cause of reality as a whole. This is not hindered by the fact that nothing can be the cause of itself, since a part is not the whole, and the whole is not the part. Rather, if we think of it in this particular way, the first cause causes the whole of reality by causing other things distinct from itself, and by causing them to be also in some way united with itself, in other words, by causing them to be part of the whole of reality. In a similar way the Council of Constantinople stated that “the Father is the source of the whole Trinity.”
It is not customary in Catholic theology to say that God is a part of anything else. But in order to avoid saying this, one would deal with the issue of “reality as a whole” by distinguishing between real and conceptual wholes, and saying that “reality as a whole” is a conceptual whole rather than a real whole.
I have not made such a distinction mainly because it is not clear to me what such a distinction would mean. I pointed out that distinction always involves something conceptual, but we can distinguish between real distinctions and conceptual distinctions insofar as it is one thing to say, “this thing is not that thing,” and another to say, “the concept of this is not the concept of that.” The idea of distinction leads to the ideas of parts and wholes, and the distinction between real distinctions and conceptual distinctions would allows us to distinguish between “real wholes” and “conceptual wholes” if we intended to say that a conceptual whole is something composed of parts which are conceptually distinct but not really distinct. But this does not apply to the case of the first cause and its effects, since these are really distinct from one another. Thus it is not clear to me what one would be intending to say if one asserted that “reality as a whole” is only a conceptual whole.
In any case, nothing opposed to Catholic doctrine follows of necessity from the argument. If God is a part of reality as a whole, it does not follow that reality is better than God. It does not follow that God created of necessity, nor that anything other than God is necessary or uncaused, and so on.