Just like with ontology, in cosmology Baumgarten appears to be rather close on Wolff's ideas, but a more careful study reveals important differences. One interesting point of distinction concerns the question what belongs in a world. With Wolff, it appears that souls do not exist within deterministic universe, but follow their own causal series. With Baumgarten, on the other hand, souls appear to be just as much part of the world as material objects. Thus, while for Wolff, egoism is a statement on what there exists in general (nothing but one soul), for Baumgarten it is a cosmological proposition (world consists of one soul or is simple).
Reason for Baumgarten's inclusion of souls in world might be his commitment to Leibnizian notion of monads. True, even Wolff had said that monads do correspond to what he called elements, but this admission was a bit halfhearted. Baumgarten, instead, is quite insistent on using the term monad. He even endorses the notion that these monads have some soul-like properties, by stating that materialists must deny monads, either in general or at least as parts of the world – because Baumgarten, like Wolff, believes that all complex substances consist of simple substances, which he identifies with monads, he can then simply deny materialism as contradictory.
While it is difficult to say what is the relation of elements and space in Wolff's philosophy – and even more difficult to say what is the relation of souls and space – Baumgarten states at once that monads are located at some point in space. They are still not mere points in space, because they also represent the world around them, some darkly, others clearly (idealism is then defined as the idea that all monads represent world clearly or are spirits).
Wolff was almost silent on how his elements combined into, first corpuscles, then visible material bodies – for instance, should we need an infinity of them? Baumgarten does not provide a full explanation either, but he at least has a more detailed story to tell. First of all, monads are spatially located, that is, they must be in some sense positioned in relation to one another. Now, this positionality was reduced in Baumgarten's philosophy to interactions – being near another thing meant just affecting it.
Now, Baumgarten held that monads in some sense affect one another. In fact, when one monad acts one another, this other monad must also react on the other monad. Such interlocking combinations of monads form them more stable connections. Their interaction forms their contact, and if no external reason makes them lose their contact, the monads stay together, forming a relatively stable material body.
Just like in Wolffian philosophy, with Baumgarten the activities of monads explain all phenomena on the level of bodies. Indeed, Baumgarten even says that because all monads are active and e.g. change constantly their relative positions (that is, start and cancel interactions with one another), bodies also must be in constant movement.
Although Baumgarten thus uses the language of monads interacting one another, it is still unclear how seriously this statement is to be taken. Does Baumgarten, like Wolff, admit interactions only with some primary elements, but deny it between spiritual and other monads? Or does he accept or deny all monadic interactions? These questions, along with the problematic of a perfection of the world, will be dealt next time.