Necessary Laws and Chemical Kinds

Contingentism, generally contrasted with law necessitarianism, is the view that the laws of nature are contingent. It is often coupled with the claim that their contingency is knowable a priori. This paper considers Bird's (2001, 2002, 2005, 2007) arguments for the thesis that, necessarily, salt dissolves in water; and it defends his view against Beebee's (2001) and Psillos's (2002) contingentist objections. A new contingentist objection is offered and several reasons for scepticism about its success are raised. It is concluded that certain higher-level laws describing the behaviours of molecular compounds may be necessary due to their dependence on underlying physical laws, and that the modal status of laws of nature cannot be determined a priori, as the structural features of the substances and properties they govern must first be investigated.