Grounding, mental causation, and overdetermination

Recently, Kroedel and Schulz have argued that the exclusion problem-which states that certain forms of non-reductive physicalism about the mental are committed to systematic and objectionable causal overdetermination-can be solved by appealing to grounding. Specifically, they defend a principle that links the causal relations of grounded mental events to those of grounding physical events, arguing that this renders mental-physical causal overdetermination unproblematic. Here, we contest Kroedel and Schulz's result. We argue that their causal-grounding principle is undermotivated, if not outright false. In particular, we contend that the principle has plausible counterexamples, resulting from the fact that some mental states are not fully grounded by goings on 'in our heads' but also require external factors to be included in their full grounds. We draw the sceptical conclusion that it remains unclear whether non-reductive physicalists can plausibly respond to the exclusion argument by appealing to considerations of grounding.