Inter-level Causal Compatibility Without Identity

The paper investigates and refines the proportionalist solution to the causal exclusion problem developed by Menzies and List. First and foremost, it explores the implications of their inter-level compatibility result. It is highlighted that in theory the inter-level causal compatibility of realizer and realized properties allows for scenarios where the higher-level property is multiply realized. By developing concrete illustrations, the paper proves this to be an empirically plausible option. Further non-trivial implications of the framework are unpacked to show that the sensitivity of causal relations to background conditions is as important in deciding on the existence and the direction of exclusion as sensitivity to the realization of the cause. This insight also opens the way to further refinements: a richer reconceptualization of upwards exclusion and a plausible answer to a critic of the Menzies and List project.