Theoretical psychology is concerned with theoretical and philosophical aspects of psychology. It is an interdisciplinary field with a wide scope of study. It focuses on combining and incorporating existing and developing theories of psychology non-experimentally. Theoretical psychology originated from the philosophy of science, with logic and rationality at the base of each new idea. It existed before empirical or experimental psychology. Theoretical psychology is an interdisciplinary field involving psychologists specializing in a wide variety of psychological branches. There have been a few prominent pioneers of theoretical psychology such as Wilhelm Wundt, William James, Sigmund Freud, and John B. Watson. There has also been a number of notable contributors which include Jerome Kagan, Alan E. Kazdin, Robert Sternberg, Kenneth J. Gergen, and Ulric Neisser. These contributors may publish in a variety of journals, including journals for general psychology, like American Psychologist. There are several journals dedicated specifically to theoretical psychology, like Theory & Psychology and Journal of Theoretical and Philosophical Psychology. Many other organizations are beginning to recognize theoretical psychology as a formal subdivision of psychology. Origin Theoretical psychology emerged from philosophy, more specifically, from the philosophy of science. Philosophy strives to understand nature and structure of concepts, the laws in which these concepts occur, and the theories that combine the laws together. One of these specific branches of philosophy of science is theoretical psychology. Philosophy of science does not use the scientific method to empirically derive ideas about the physical world through conducting experiments and interpreting results. However, it is still about science with an emphasis on the logic and rationality behind science itself, bringing to light what cannot be explained by empirical measures. It is also metaphysically and epistemologically focused on all humans while incorporating the nature and essence of human knowledge. Just as the philosophy of science is to science, theoretical psychology is to psychology in that it is the logic and rationality applied to concepts, laws, and theories. Theoretical psychology is not in place to discern which theories are more truthful or more correct. Many consider theoretical psychology as the support or rationalization of an "idea" within psychological theory that is more "truthful". However, this is not the case. Theoretical psychology is scientifically grounded in ideas of what is known through epistemology. Theoretical psychology existed long before any branches of traditional empirical and experimental psychology. Because of this, there is much more depth and breadth of knowledge