What Is the Role of Theories in the Study of Schizophrenia?

As an epilogue to the themed papers on "Theories of Schizophrenia" in this issue of Schizophrenia Bulletin, this article reviews some basic philosophy of science principles in regard to the role of theories in the evolving state of a natural science discipline. While in early phases inductive and abductive logic are the primary vehicles for organizing observations and developing models, when a critical set of "facts" have been elucidated which can be explained by competing theoretical perspectives, hypothetico-deductive logic provides a more robust and efficient approach to scientific progress. The key principle is to determine where two or more theories predict different observations and then to devise studies that collect critical observations-025EFcorrelations or experimental outcomes that are predicted differentially by the competing theories. To a large extent, current theories of schizophrenia (eg, focusing on aberrant dopaminergic signaling, neural dysconnectivity, and disrupted neural development) are not (and are not intended by their authors to be) mutually exclusive of each other. Rather, they provide explanations that differ in relative emphases, eg, on distal vs proximal causes and on broad vs narrow behavioral end points. It is therefore possible for all of them to be "right" at least in a general sense. This non-exclusivity is problematic when considered in light of the strong inferences principles characteristic of a mature natural science discipline. The contrast points are likely to be found in constructions that integrate influences across different levels of analysis, as in additive vs interactive models, direct effects vs mediation models, and developmental vs deteriorative models.