The difficulties facing Humean regularity accounts of laws have led some philosophers to a theory that takes laws to be necessitation relations between universals. In this paper I evaluate David Armstrong's version of this theory by considering two of its key elements: its solution to the so-called “Inference Problem” and its denial of uninstantiated universals. After considering some potential problems with each of these elements on their own, I argue that Armstrong's solution to the Inference Problem and his denial of (...) uninstantiated universals are not two independent aspects of his view. His solution to the Inference Problem depends upon his denial of uninstantiated universals. (shrink)