In an earlier post, I showed that different subjects cannot be unified in knowledge. However, in some cases, one cause can unify another cause. Unifying one cause is done when one cause explains why the other one is true.
The material cause of something is always unified by the formal cause. If we are considering a living thing, then we might claim that it is made out of flesh. More biological knowledge will always tell us that it has a particular kind of cell and particular structural organization because it is the kind of animal or plant that it is. Even single celled organisms have a particular organization and structure because of the kind of organism that they are. If we are considering a non-living thing, then the form always explains the matter to some extent. The sun is hot and formed of plasma because it is a star. A rock is made of minerals because it is granite. This is similarly true for all other forms.
The efficient cause is always unified by the formal cause. We explain why the efficient cause exists by explaining the powers and potentials of the various objects. The rock broke the window because the window was breakable and the rock was hard. If one of those were not true, then the rock would not have broken the window. This is even true when we consider a particular efficient cause. The window will always be broken by a rock. It is always that way because rocks are always hard and windows are always breakable. Hard things will always break breakable things. But rocks could not be anything other than hard without ceasing to be rocks at all. Glass windows are always breakable. They could not be glass and fail to be breakable. So the explanation for the efficient cause is always the formal cause.
This leaves the formal cause and the final cause. Yet the final cause always unifies the formal cause. The form of something is not just what category of thing it belongs to. It is also the structure of the potentials and powers that the thing has. But we can only order these by explaining how their existence is explained by the form in general. But the form in general is explained by what the purpose of that form is. So living things exist to continue living, rocks exist to be hard and animals exist to perceive. We cannot explain the nature of something completely without describing what sort of activities they engage in. Therefore, the final cause explains the formal cause.
This means that knowledge of the final cause is the highest form of knowledge. If we truly understand the purpose of something’s existence, then we will also understand what it is made out of, what it is and how it can change other things and be changed by them. So knowledge of the final cause of a thing is what unifies any knowledge of that thing.
Next, I will discuss the relationship of various things to each other. There are two possibilities for the relationship of the knowledge of things: knowledge of some things will provide an advantage to knowing other things or not. If not, then knowledge is like an encyclopedia. Otherwise, it is like a monarchy.