Abstract

Hume’s empiricist reason for rejecting “school metaphysics” makes it natural to assume that Hume rejects all metaphysics. A.J. Ayer certainly reads Hume this way. The natural assumption is wrong, however. Hume only rejects the aprioricity of metaphysics, and not the science itself. I will argue that his empirical science of human nature supports three basic metaphysical principles. (1) The Contradiction Principle: The clearly conceivable implies no contradiction. (2) The Conceivability Principle: The clearly conceivable is possible. (3) The Conceptual Separability Principle: Things are different if and only if distinguishable, and distinguishable if and only if separable in conception. On these principles the rest of Hume’s metaphysics is based, including his atomistic ontology and his denial of necessary connection. And so, for Hume metaphysics is an empirical science.