Varieties of Necessity

It is argued that there are three main forms of necessity --the metaphysical, the natural and the normative--and that none of them is reducible to the others or to any other form of necessity. In arguing for a distinctive form of natural necessity, it is necessary to refute a version of the doctrine of scientific essentialism; and in arguing for a distinctive form of normative necessity, it is necessary to refute certain traditional and contemporary versions of ethical naturalism