Abstract
We divide analytic metaphysics into naturalistic and non-naturalistic metaphysics. The latter we define as any philosophical theory that makes some ontological (as opposed to conceptual) claim, where that ontological claim has no observable consequences. We discuss further features of non-naturalistic metaphysics, including its methodology of appealing to intuition, and we explain the way in which we take it to be discontinuous with science. We outline and criticize Ladyman and Ross's [2007] epistemic argument against non-naturalistic metaphysics. We then present our own argument against it. We set out various ways in which intellectual endeavours can be of value, and we argue that, in so far as it claims to be an ontological enterprise, non-naturalistic metaphysics cannot be justified according to the same standards as science or naturalistic metaphysics. The lack of observable consequences explains why non-naturalistic metaphysics has, in general, failed to make progress, beyond increasing the standards of clarity and precision in expressing its theories. We end with a series of objections and replies.