The late Harvard professor of education William Perry Jr. (1913-1998), once remarked, “To have any idea of what is going on in a situation, you need at least three good theories.” Perry was trying to promote learning and understanding.
The idea here is that one theory traps you in your own thinking, your own dogma. Overconfidence in one’s own opinions can be an obstacle to learning. With two theories you can be begin to see more—another side to a situation. Yet, two theories are limiting as they can lead you to simple reductions and conclusions brought about by black and white, binary thinking. With three or more theories in play you begin to see the nuances. Your mind becomes open to the fact that there are more explanations to what is going on, giving you a more complete picture. By taking more into account you can create deeper understanding and make decisions more in line with what is really going on.
You can of course take this too far and get caught up in all sorts of mind games and become mired in overanalyzing. This generally isn’t our problem however. We tend to jump to generalizations and oversimplifications without a clear understanding of reality thus repeating the same old thinking. We need to cast a wider net, asking more and different questions. Concerning theories, Perry thought it was worth noting: "The wisdom doesn't come from the theories; the theories come from the wisdom. And the wisdom comes from the defeat of all the more attractive alternatives." And in a cautionary tone, "With all these theories, it would be a good thing, of course, to keep an open mind. But the problem with an open mind is that it's so drafty." Keep a balance and avoid the mind games.