Gregory Bateson was a British anthropologist, sociologist, linguist, and cyberneticist. Of his many ideas, the one that currently intrigues me the most is schismogenesis.
Schismogenesis, a term that he created during his research that led to the book "Naven" literally means "creation of division." The idea can be applied to anthropology, sociology, biology, political science, economics, you get the idea. I will focus my description on its application to relationships.
There are two types of relationships: complementary and symmetrical. A complementary relationship is one in which one party takes the "one-up" position (which is not to say it's a superior position) and the other takes the "one-down" position. An example of this is a teacher-student relationship. The teacher is in a one-up position as an authority figure as well as a source of knowledge. A symmetrical relationship is one in which both parties take an equal position. A conventional friend-friend relationship is a good example.
However, within any relationship between any two people there exist numerous relationships of these two types depending on context. For example, a parent-child relationship is a complementary relationship with the parent in the one-up position, but if the parent happens to be a little in-adept at technology (as so many of them are) and asks the child for help (as they all should) the child is put in a one-up position as the knowledgable one. A symmetrical relationship can easily morph into a complementary one when a subject or a situation comes up that one party is more experienced in.
This brings us to the idea of schismogenesis. Schismogenesis is what happens when a relationship doesn't change; when one party stays in the one-up position and the other in the one-down position. The one-up party becomes more dominant and the one-down party becomes more submissive. This is known as "positive feedback." As an example, when I used to tutor my sister in math I would sometimes adopt a condescending attitude (usually if I was already in a bad mood) she would react by becoming more submissive, which would increase my annoyance, and so on. In theory, schismogenesis could spiral out of control until it destroyed the relationship.
This is where the concept of "negative feedback" comes into play. Negative feedback is where something happens that shifts the relationship (to symmetrical or to a reveresed complementary) and stabilizies the relationship. To continue my example: my sister decides she's hungry, and goes to make a sandwich. She comes back with sandwiches for both of us. Now we're in a provider-providee relationship with her in the one-up position.
That's the basic idea of negative feedback. This is a system that has been also been applied to the arms race and human biological systems, among others.