I just codified a new principle for theories. I believe this is principle is used implicitly by 9/11 conspiracy theorists. The principle states that you should needlessly multiply entities in your explanations.

For example, if you are discussing 9/11 you could say that the Twin Towers were brought down by planes crashing into them. You could instead say that bombs inside the building did it, but you do still have to say planes hit the buildings, so we'll just staple the bombs into the explanation. In fact, why hit everything with planes, when you can staple a missile into the theory? Oh, and the planners should not be terrorists like Osama who is still in the theory somewhere, but instead we will make it done to advance the plans of the Project for a New American Century, and if we can staple in a money interest for someone when building 7 came down, and hell, maybe even staple Israel in there somehow.