Comparing Theories with the Ising Model of Explanatory Coherence

Theories are among the most important tools of science. Lewin (1943) already noted “[t]here is nothing as practical as a good theory”. Although psychologists discussed problems of theory in their discipline for a long time, weak theories are still widespread in most subfields. One possible reason for this is that psychologists lack the tools to systematically assess the quality of their theories. Thagard (1989) developed a computational model for formal theory evaluation based on the concept of explanatory coherence. However, there are possible improvements to Thagard’s (1989) model and it is not available in software that psychologists typically use. Therefore, we developed a new implementation of explanatory coherence based on the Ising model. We demonstrate the capabilities of this new Ising Model of Explanatory Coherence (IMEC) on several examples from psychology and other sciences. It is also available in the R-package IMEC so that it can help scientists to evaluate the quality of their theories in practice.