Causal reasoning under ambiguity requires subjects to estimate and evaluate ambiguous observations. This paper proposes a hierarchical model that accounts for the uncertainty of both the distribution of the functional form selection and distribution of the ambiguity treatment selection. The posterior distribution of the causal estimates is determined by both the functional form and the ambiguity processing strategy adopted by the reasoner. A model is tested in a simulation study for its ability to recover the strategy and functional form adopted by subjects across a range of hypothetical conditions. The model is further applied to the results of an experimental study.

Previous studies found that the likelihood of subjects to choose a deontological judgment (e.g., allowing harm) or a consequentialist judgment (e.g., doing harm) varied across different moral dilemmas. The present paper explored if the variation can be explained by the differentiation of the perceived outcome probabilities. We generated moral dilemmas that were similar to the classical trolley and footbridge dilemmas, and investigated the extent to which subjects were sensitive to the outcome probabilities. Results indicated that the majority of subjects, including both those who initially chose a deontological decision and those who initially chose a consequentialist decision could be sensitive to outcome probabilities. The likelihood of being sensitive to the probabilities was invariant across different dilemmas. The variation of the choice behaviors across different dilemmas might be associated with the variation of the estimated outcome probabilities