An Empiricist View on Laws, Quantities and Physical Necessity

In this article I argue for an empiricist view on laws. Some laws are fundamental in the sense that they are the result of inductive generalisations of observed regularities and at the same time in their formulation contain a new theoretical predicate. The inductive generalisations simultaneously function as implicit definitions of these new predicates. Other laws are either explicit definitions or consequences of other previously established laws. I discuss the laws of classical mechanics, relativity theory and electromagnetism in detail. Laws are necessary, whereas accidental generalisations are not. But necessity here is not a modal concept, but rather interpreted as short for the semantic predicate “... is necessarily true”. Thus no modal logic is needed. The necessity attributed to law sentences is in turn interpreted as “necessary condition for the rest of the theory”, which is true since fundamental laws are implicit definitions of theoretical predicates use in the theory.