Grounding Physicalism and Opaque Grounding

A growingly popular development of physicalism, grounding physicalism, holds that phenomenal facts are grounded in physical facts. A main selling point of this view – largely due to Jonathan Schaffer – is its apparent ability to swiftly handle well-known anti-physicalist objections that infer an ontological gap from an explanatory gap. According to Schaffer, grounding physicalists can reject this inference by noting that it often fails in other cases of grounding. That is, they can observe that explanatory gaps are ubiquitous in grounding (i.e., grounding is generally opaque), such that the one between the phenomenal and the physical is merely a special instance of a broader unproblematic pattern. In this paper, I raise a novel challenge for Schaffer’s defense of grounding physicalism. I argue that the examples of opaque grounding to which he appeals are either of the wrong kinds or highly contested. As such, they provide little inductive support for grounding physicalism.