“Laws” and “Theories” in Chemistry Do Not Obey the Rules

Abstract

Most philosophers’ discussions of issues relating to “laws of nature” and “scientific theories” have concentrated heavily on examples from classical physics. Newton’s laws of motion and of gravitation and the various conservation laws are often discussed. This area of science provides very clear examples of the type of universal generalization that constitutes the widely accepted view of what a law of nature or a scientific theory “ought to be.” But classical physics is just one very small branch of science. Many other areas of science do not seem to throw up generalizations of nearly the same breadth or clarity. The question of whether there are any laws of nature in biology, or of why there are not, has often been raised (e.g., Ghiselin, 1989; Ruse, 1989). In the grand scheme of science, chemistry stands next to physics in any supposed reductive hierarchy, and chemistry does produce many alleged laws of nature and scientific theories. An examination of the characters of these laws and theories, and a comparison with those that arise in classical physics, might provide a broader and more balanced view of the nature of laws and theories and of their role in science. From the outset, we should very carefully define the terms of our discourse. The notion of laws of nature has medieval origin as the edicts of an all-powerful deity to his angelic servants about how the functioning of the world should be arranged and directed. It may be helpful to distinguish three quite different senses in which laws of nature are considered in modern discussions. On occasion, the discussion has become sidetracked and obscure because of conflation and confusion of two or more of these senses. In the first, or ontological, sense, laws of nature may be considered as a simply expressed generalization about the way an external world does operate. Laws of nature are often seen as principles of the way the world works. They are an objective part of the external world, waiting to be discovered. The laws that we have and use may be only approximations of the deeper, true laws of nature.