Wolff's Latin series of metaphysical works is finished by his Theologia naturalis. While from the modern perspective this must be the least interesting part of Wolff's system, it is, on the contrary, largest of all the Latin metaphysical works, and indeed, was published in two volumes. The first volume begins with a brief explanation of what natural theology is all about, but is especially characterised by an a posteriori method – that is, Wolff attempts to use experience to determine the existence and properties of God. The second volume should then obviously use an a priori method – a novelty in Wolffian system, and we shall see how it fits in with the more established part of his theology.
Wolff's primary route for God's existence has always been through what Kant would later call a cosmologial proof. Wolff begins by admitting the existence of reader's own soul – if nothing else exists then I at least exist. Then Wolff notes that there must be a complete grounding of the existence of this soul. Complete ground or reason can then be only something which does not require any further explanation or anything external for its own existence. It is clear this proof has a number of weak points. What is this grounding supposed to mean? If it is just a nickname for a mental demand of human consciousness that all things must be fully grounded, then we clearly need not take it seriously as an ontological principle – even if I'd have to insist on God's existence, this would not necessitate God's actual existence. Then again, it appears unreasonable to suppose that the complete ground in an ontological sense couldn't be an infinite series of past events, especially if one believed that such a series would be necessary.
Whatever the case, the rest of the book sets out to discover further characteristics of this final explanation of everything. The most straightforward feature is that while God, like all entities, must have some force, it must be a force that requires nothing external for activating it. In effect, if there is no inherent contradiction in the structure of God, it will, as it were, actualise itself, no matter what – we shall return to this idea, when we are dealing with the second book on natural theology. Figuratively one can say that God existed before anything else and God will exist after anything else.
God's necessity and self-sufficiency reveal at least what God cannot be. God cannot have been generated in a literal sense of the term and he definitely cannot be destroyed – thus, he cannot be material. Then again, because human souls are essentially dependent on the world they represent, God cannot be a human soul. Still, God has chosen to create a particular world and so must have some mental activities or be spirit. In fact, by thinking what sort of spiritual activities are required in an act of creation, one can try to determine what God is like.
Now, in order that God can choose a world to create, he must have first checked out all the possibilities from which to choose the world to be created – in effect, God must have considered all the possible worlds. This means that God must have some cognitive activities, yet, they are of quite different type than human cognition. For starters, God does not have any passive faculties, because he is constantly acting or cognising things. Furthermore, God does not need to move from one aspect of a world to another, but he comprehends immediately everything that would happen in one possible world. Because possible worlds contain all that there might be, God is definitely omniscient.
If God then knows all things perfectly well, can he also know what we know, as we know it? Well, God cannot fail to have a perfect knowledge, thus, he cannot force himself into a mode in which he would have only human type of knowledge of world and cannot therefore have any firsthand experience on the condition of human consciousness. Still, God can know that some other person has a more imperfect view of the world.
Because God can at once see all the past, present and future events, he has complete historical knowledge of all individual things. This does not mean that God could not have universal or philosophical knowledge also. Indeed, God can intuitively know whether certain feature of things is universally connected to another feature, so making him the greatest scientist of all times. Of course, even in universal knowledge God is not restricted to any use of symbols, although he does see that humans usually require such aids for universal knowledge.
Before moving onto more active side of divine attributes, it is good to note in passing that Wolff also used considerable number of pages for determining whether Bible got it right – that is, whether e.g. Bible is correct, if it says that God sees something, or whether it must be using symbolic language. It is a bold move, especially considering accusations of atheism against Wolff and the recent schism with the Wertheimer Bible, that Wolff even considers such questions, even if these questions feel rather dated nowadays. Next time more about the divine will.