Those forces fit exactly into economics 101. The first day is always "What is economics" and the answer is always that is the study of human behavior and choice. The supply/demand curve that makes up most of the class beings with the introduction that choice is variable, but assuming for the sake of argument that we consider them equal, what interesting effects do we observe?
These are extremely powerful forces, despite the fact that they don't fit into the economics-101 thinking that libertarians are so fond of.