While Lange's interpretation of Wolff in the question of the eternity of the world was at best questionable, his view of Wolff and determinism is spot-on. Wolff does believe that world – that is, an entity containing all complex things – is governed by strict rules where the previous states of things determine the further states of the things, just like in a clock the current state of all the bits and pieces determines their next state.
Lange's fear is that the strict determinism of Wolffian world leaves no room for human freedom, or at least it deprives from soul the possibility to control its body – it is strictly speaking not I who lift my hand, but the movement of the material objects in the vicinity of the hand. And if my hand happens to strike body of a fellow soul – well, how could I be accused, because the movement of the hand was necessary and people cannot be punished for necessary actions. The judge could, of course, retort that it is just as necessary for his mouth to utter the condemning words, but still a lingering doubt is left – were truly all these actions necessary?
Wolff's strategy would probably be to deny the necessity of the world. After all, there are many different possible worlds that God could have chosen to actualize and it is in a sense contingent that he happened to pick out this world. Thus, it is not necessary that I hit my neighbour, because in another possible world I – or someone very similar to me – would not have stricken a man in similar circumstances.
Lange would be very unsatisfied with this answer, and it all comes to how to define modalities like necessity and contingency. Necessity Wolff speaks of Lange calls geometric necessity, probably thinking of Spinoza's geometric method – we might call it logical necessity. But it doesn't matter at all to us, whether something happens in another possible world or not. It is our own world we are interested of, and here everything happens deterministically, that is, all the future states are determined once the beginning has been given, without any possibility to actually change the course of nature. This is the sense in which Lange wants to speak of necessity – as the inevitability of events in the context of the actual world. The respective contingency would then not concern possibilities in another world, but indeterminacy of the actual world.
Lange can then conclude that Wolff is in this matter no better than Spinoza, who both rank as extreme materialists. Wolff is in a sense even worse, because he is also an extreme idealist. We shall see next time how this curious combination is possible.