Grounding Relations Are Not Unified

Jonathan Schaffer, among others, has argued that metaphysics should deal primarily with relations of " grounding. " I will follow John Heil in arguing that this view of metaphysics is problematic as it draws on ambiguous notions of grounding and fundamentality that are unilluminating as metaphysical explanations. I understand Heil to be arguing that grounding relations do not form a natural class, where a 'natural' class is one where some member of that class has (analytic or contingent a posteriori) priority among others and explains order among other members in the class. To strengthen Heil's criticism that grounding is a non-natural class of relations, I will draw on an unlikely ally. St. Thomas Aquinas's " analogy of being " doctrine, if accurate, offers reasons that no categorical relations (like grounding relations) form a natural class.