Simple minds: A cognitive account of theoretical simplicity and the epistemology of human understanding

Abstract

Why should anybody care about theoretical simplicity? It is pretty clear that simpler theories don't stand a better chance of being true, just because they are simpler than their competitors. Of course, simpler theories are easier to use in technological applications, and they are more tractable. But that is something engineers should be concerned about. Why should the theoretical scientist be interested in simple theories? The principal virtue of simple theories is their facilitation of scientific understanding in virtue of their greater explanatory power. Simple theories are more unified, and they allow important kinds of reasoning about the world. If a theory yields a unified but structure-rich picture of the world, and thereby a high degree of understanding, we can design relevant experiments, form rational expectations, and in general are in a better position to gather relevant data than when we confront the world without any understanding whatsoever. Simple theories are therefore, in virtue of increasing our understanding, epistemically advantageous. That's why the theoretical scientist should be interested in simple theories. Of course, since the choice of simple theories does not guarantee getting closer to the truth, the claim that such a choice is epistemically advantageous presupposes that we draw a distinction between the explanatory power of theories and their accuracy. This distinction has not received sufficient attention in the existing literature, and that's why it was so difficult to say exactly what the virtue of simple theories is. Recognizing that explanatory power and accuracy are orthogonal aspects of scientific theories allows us to assign simplicity the role of facilitating understanding and thereby guiding controlled experimentation.