Indirect illusory inferences from disjunction: a new bridge between deductive inference and representativeness

Abstract

We provide a new link between deductive and probabilistic reasoning fallacies. Illusory inferences from disjunction are a broad class of deductive fallacies traditionally explained by recourse to a matching procedure that looks for content overlap between premises. In two behavioral experiments, we show that this phenomenon is instead sensitive to real-world causal dependencies and not to exact content overlap. A group of participants rated the strength of the causal dependence between pairs of sentences. This measure is a near perfect predictor of fallacious reasoning by an independent group of participants in illusory inference tasks with the same materials. In light of these results, we argue that all extant accounts of these deductive fallacies require non-trivial adjustments. Crucially, these novel indirect illusory inferences from disjunction bear a structural similarity to seemingly unrelated probabilistic reasoning problems, in particular the conjunction fallacy from the heuristics and biases literature. This structural connection was entirely obscure in previous work on these deductive problems, due to the theoretical and empirical focus on content overlap. We argue that this structural parallelism provides arguments against the need for rich descriptions and individuating information in the conjunction fallacy, and we outline a unified theory of deductive illusory inferences from disjunction and the conjunction fallacy, in terms of Bayesian confirmation theory.

Reasoning AboutWant

“…The model theory predicts and explains such cognitive illusions: they occur whenever, for instance, a reasoner infers that an impossible conclusion is possible, or vice versa. Research has revealed illusory inferences across a wide variety of reasoning domains, such as with reasoning about probabilities and conditionals (Johnson‐Laird & Savary, 1996), disjunctions (Khemlani & Johnson‐Laird, 2009; Sablé‐Meyer & Mascarenhas, 2021), and Boolean concepts (Goodwin & Johnson‐Laird, 2010). The theory accordingly predicts that illusions should occur in bouletic reasoning.…”