Reasoning About Causation

Abstract

Despite the importance of effective causal reasoning, people still have trouble answering questions like: Does this chemical cause cancer? Was this economic policy the cause of economic growth? Does this drug prevent COVID-19? Did Thomas Crittendon cause the death of Jesse James? This essay aims to provide tools to help people reason effectively about causation. We use the killing of Jesse James to discuss naturalistic causal analysis, then introduce Pearl’s causal ladder and counterfactual reasoning. Methods, such as random assignment and the kind of observational methods used in epidemiology are discussed in the context of assessing evidence relative to the potential for causal relationships. We take an in-depth look at the evidence and methods that were used to establish a causal relationship between smoking and lung cancer and describe the psychological heuristics that can interfere with effective causal analysis.