Private Law Theory

ABSTRACT
The theory of degrees of causation in philosophical accounts assumes that causation comes in degrees. This article examines the conceptual implications of this theory for the apportionment of legal liability, aiming to provide a coherent account of causation-in-fact and causation-in-law, as well as judicial approaches to causation in insurance law and tort law. Drawing on the ‘four senses’ of degrees of causation in philosophical discourse, the article adopts a concept of ‘causal degrees of legal liability’ in contrast to apportionment of liability that is, to some extent, influenced by non-causal factors. By examining how causal degrees of legal liability operate in torts and insurance cases, the article identifies three different models to demonstrate that the ‘causal degree of legal liability’ conceptually operates only with multiple causes-in-fact, while proportionate liability is generally manipulated by non-causal factors. This article further suggests that it is analytically incorrect to pair a principled application of the efficient cause test with proportionate indemnity from the perspective of degrees of causation.

€ (Westlaw)

Meixian Song, ‘Degrees of causation: revisiting the efficient cause test and the “winner-takes-all” principle in English insurance law’ [2025] Journal of Business Law (8) 643-661.