Scientific explanation and the Troubles with Causal Explanations in physics

Abstract

Fifty years ago, Carl Gustav Hempel published his famous book Aspects of Scientific Explanation. Since then the number of publications on this subject has grown exponentially. An occasion like this deserves to be commemorated. In this article I offer a modest tribute to this great methodologist of science. 

This paper tackles the uses of explanation in theoretical sciences. In particular it is concerned with the possibility of causal explanations in physics. What I intend to do is to focus on the issue of whether the explanation of Kepler’s empirical laws of the planetary motions can be a causal explanation. More specifically my point is: can the deductive subsumption of Kepler’s 3rd Law (also known as Kepler’s 1-2-3 law) under theoretical principles provide a causal explanation for the planetary motions? 

My answer is a definitive no. As a matter of fact, on occasion subsumptions occur under differing theoretical principles that are incompatible with one another. In such cases we would have incompatible scientific explanations. This is precisely the situation facing the scientific explanation of Kepler’s laws, in particular the third law. Since there exist incompatible gravitational theories, it is impossible for the scientific account of Kepler’s law to be a causal explanation of the planetary motions. This is just one example of the difficulties faced by causal explanations in sciences such as theoretical physics.