" the trouble about arguments is, they ain't nothing but theories, after all, and theories don't prove nothing, they only give you a place to rest on, a spell, when you are tuckered out butting around and around trying to find out something there ain't no way to find out There's another trouble about theories: there's always a hole in them somewhere, sure, if you look close enough." .
-Tom Sawyer Abroad.
"It is theory that decides what can be observed." .
-Albert Einstein.
Whether one believes Mark Twain's fictional street smart character or the brilliant architect of the theory of relativity, it must be acknowledged that theories are a valuable way to think (and argue) about the world. For the scientific method of discovery, theories are essential. Theories are the starting point from which all systematic efforts can be directed for a theory is fundamental in the first step of the scientific method- conceptualizing the problem. Specifically, a theory is a set of interconnected statements that describe imperceptible, unobservable processes, events, or structures and relate them to each other and to observable events. In psychology, a theory provides general principles that help us to observe, explain, and predict behavior. In other words, it allows us to ask non trivial questions and to provide meaningful, interesting answers. There have been numerous theories that attempt to lay a framework of reference for examining changes in development or in other words changes in behavior over time. The use of the word "development" implies just that; for the theory should describe, explain, and predict behaviors or mental processes over time. The five major developmental theories are the psychoanalytic, cognitive, behavioral and social learning, ethological, and ecological. This paper will summarize each of these theories and elucidate their relevance to middle childhood and adolescence.