Breaking Symmetry: A New Directionality Criterion for Regularity Theories of Causation

It is one of the most frequent criticisms of regularity theories of causation that they cannot distinguish between causes and effects based on Boolean determination relations of sufficiency and necessity alone—jeopardizing their goal of reducing causation to Boolean determination. The criticism rests on the fact that determination relations can be symmetric but causation (in acyclic structures) cannot. Regularity theorists have countered by arguing that only simplistic determination structures are symmetric, and by insisting that structures with a minimal complexity of two alternative causes per effect exhibit non-symmetric determination relations. In this paper, we show that this regularity-theoretic response is insufficient to break symmetries of determination and, thus, to identify the direction of causation. To solve this problem, we introduce a new directionality criterion and demonstrate that it suffices to distinguish causes from effects solely on the basis of Boolean determination relations.