 One of Schopenhauer’s most significant assertions is that the four different modes of explanation only run in parallel with each other, and cannot coherently be intermixed. If we begin by choosing a certain style of explanation, then we immediately choose the kinds of object to which we can refer. Conversely, if we begin by choosing a certain kind of object to explain, we are obliged to use the style of reasoning associated with that kind of object. It thus violates the rationality of explanation to confuse one kind of explanation with another kind of object. We cannot begin with a style of explanation that involves material objects and their associated cause-and-effect relationships, for example, and then argue to a conclusion that involves a different kind of object, such as an abstract concept. Likewise, we cannot begin with abstract conceptual definitions and accordingly employ logical reasoning for the purposes of concluding our argumentation with assertions about things that exist.