The ungrounded argument is unfounded: A response to Mumford

Arguing against the claim that every dispositional property is grounded in some property other than itself, Stephen Mumford presents what he calls the 'Ungrounded Argument'. If successful, the Ungrounded Argument would represent a major victory for anti-Humean metaphysics over its Humean rivals, as it would allow for the existence of primitive modality. Unfortunately, Humeans need not yet be worried, as the Ungrounded Argument is itself lacking in grounding. I indicate where Mumford's argument falls down, claiming that even the dispositions of the simplest particles can have categorical bases.