 This approach is appealing, but faces several challenges. First, it has been argued that there are no clear methods of distinguishing between causal and constitutive relationships in mechanisms (e.g., Leuridan 2011); if this is correct, there seems to be no reason to posit that “mechanistically mediated” effects are non-causal. Second, the idea of “normal” intralevel causation is problematic in the framework of levels of mechanisms (Eronen 2013). As we have seen in section 2.2, the idea of “being at the same level” has little if any significance in this framework, so same-level causation cannot be the default or normal type of causation. The idea seems to be rather that there is no causation from a mechanism as a whole to the components of that same mechanism, but this is just one specific form of putative downward causation, and how other forms should be treated is left open in this account (Eronen 2013). Third, it is not clear whether higher-level causal processes in mechanisms can be distinct from causal processes at lower levels of the mechanism—if not, there are no higher-level causal processes that could have mechanistically mediated effects downwards in the mechanism to begin with (Fazekas &amp; Kertész 2011).