Dispositional Essences and the Laws of Nature

Abstract: To understand possibility properly, an understanding of the laws of nature is inevitable. But how are these laws best understood? Should they be seen as regularities of some sort, following the common intuition that the laws of nature are contingent, or should they be seen as more necessary than this? This paper investigates the ontology of dispositional essences or powers, understood as fundamental properties with a certain kind of essence. This essence can be understood or characterized in a dispositional way. The notion of a dispositional essence is a fruitful concept on which we may build a theory of laws which does not see them only as regularities, but rather as grounded in precisely these dispositional essences of properties.

I compare the dispositional account with the regularity based theory of David Lewis. His theory is based upon the principle of Humean supervenience, and laws are understood as those regularities that are included in our best deductive systems. While his theory does not allow modal properties in objects, and concludes that the laws are contingent, the theory of dispositional essences states the exact opposite. Objects having modal properties are key features in this theory, as the essential properties are modal in character, and grounding the laws in the essences of fundamental properties makes them metaphysically necessary. I focus mainly on work by Alexander Bird and Brian Ellis in this part, but there are several theories around invoking this kind of terminology and framework. These are often using the terms in slightly different ways, thus making the area of research harder to penetrate. I present and defend a particular form of dispositional essentialism, where the concept of a natural kind is of crucial importance. Natural kinds reflect the divisions in nature that are completely independent of human intervention, and the laws of nature reflect the essential properties of these kinds. In the same way as natural kinds organize the things that exists in a form of hierarchy, the laws are also structured in a hierarchical way. Some laws are very specific, and reflect only the essential properties of some very limited part of nature, while others have the whole world as their domain, and the theory of laws presented here reflects this.

I argue that the dispositional theory is better suited than regularity based theories to give an accurate picture of the laws. This entails that we will have to give up on the intuition that the laws of nature are contingent, and as a consequence of this, what may be seen as possible is narrowed down substantially.