Realism and the Principle of the Common Cause

Abstract

Contemporary arguments for scientific realism are typically based on some form of inference to the best explanation. Sometimes such arguments concern the methods of science: given the success of scientific methodology, realism offers the best explanation of this success. Sometimes such arguments concern the content of scientific theories: given observed regularities in nature, explanations must be given of those regularities; the best such explanations will be realist. One forceful explanationist argument about the content of science can be based on Hans Reichenbach’s Principle of the Common Cause (CC). Roughly, CC says that whenever an enduring correlation between two events is observed, there must be some preceding event which is the common cause of the two, and is the explanation for the correlation. Rigid adherence to this demand for a common cause, however, supposedly goes beyond the instrumentalist explanatory resources available to the antirealist, and hence CC is taken to be a sufficient condition for realism. Further, one might claim that any argument that realism has greater explanatory power than antirealism depends either explicitly or implicitly on CC, and hence CC is also a necessary condition for realism.