Fan Zhu

Jun Otsuka’s trialist ontology posits the causal model as a third-layer entity representing inter-world laws. This paper challenges Otsuka’s framework by focusing on a key yet overlooked element, abductive reasoning in Pearl’s three-step model of counterfactuals. We argue that a third-layer entity is sufficient for interventions, but cannot account for abduction. Handling abduction, which involves updating the law itself based on evidence, requires a fourth-layer entity—a meta- inter-world law—embodied by the full Structural Causal Model. However, rather than advocating for this new ontological layer, we use its necessity to perform a reductio ad absurdum against this project. By highlighting the principled inferential gap between probabilistic and causal layers, we ultimately defend a modest two-layer ontology, viewing higher-level models as powerful epistemological constructs rather than metaphysical realities.

Halpern and Hitchcock appealed to the normality of witness worlds to solve the problem of isomorphism in the Halpern-Pearl definition of actual causality. This paper first proposes a new isomorphism counterexample, called “bogus permission,” to show that their approach is unsuccessful. Then, to solve the problem of isomorphism, I propose a new improvement over the Halpern-Pearl definition by introducing default worlds. Finally, I demonstrate that my new definition can resolve more potential counterexamples than similar approaches in the current literature, including the Lewisian causal dependence, Menziesian causal dependence, and modified version of the Halpern-Pearl definition. Some other advantages of my definition are also discussed.

Halpern and Hitchcock appealed to the normality of witness worlds to solve the problem of isomorphism in the Halpern-Pearl definition of actual causality. This paper first proposes a new isomorphism counterexample, called “bogus permission,” to show that their approach is unsuccessful. Then, to solve the problem of isomorphism, I propose a new improvement over the Halpern-Pearl definition by introducing default worlds. Finally, I demonstrate that my new definition can resolve more potential counterexamples than similar approaches in the current literature, including the Lewisian causal dependence, Menziesian causal dependence, and modified version of the Halpern-Pearl definition. Some other advantages of my definition are also discussed.