A point about using diagrams to make arguments: If you are attempting to convince a person that something is true, rather than just launching into your evidence and favorite arguments it is often most efficient to begin by asking a series of questions to determine precisely how the person disagrees with you. The questioning allows you to hone in on the most important sticking points that prevent the other party from coming to your conclusion. These points can then be attacked individually, preventing you from wasting time making arguments that the other party already agree with or refuting positions that he or she has never even considered. The reason that this relates to diagrams is that this method of argumentation can be viewed as a tree, with questions at each of the higher level branches, and arguments at the leaf nodes.