Abstract.There is a long tradition in formal epistemology and in the psychology of reasoning to investigate indicative conditionals. In psychology, the propositional calculus was taken for granted to be the normative standard of reference. Experimental tasks, evaluation of the participants' responses and psychological model building, were inspired by the semantics of the material conditional. Recent empirical work on indicative conditionals focuses on uncertainty. Consequently, the normative standard of reference has changed.I argue why neither logic nor standard probability theory provide appropriate rationality norms for uncertain conditionals. I advocate coherence based probability logic as an appropriate framework for investigating uncertain conditionals. Detailed proofs of the probabilistic non-informativeness of a paradox of the material conditional illustrate the approach from a formal point of view. I survey selected data on human reasoning about uncertain conditionals which additionally support the plausibility of the approach from an empirical point of view.Keywords: coherence, conditionals, formal epistemology, paradoxes of the material conditional, probability logic, psychology of reasoning
Introduction and overviewThere is a long tradition in formal epistemology and in the psychology of reasoning to investigate indicative conditionals. 1 In the psychology of reasoning, the propositional calculus was taken for granted to be the correct normative standard of reference for investigating conditionals [14]. The chosen normative standard of reference guided the construction of psychological theories like a roadmap [37]. Proof-theoretic semantics, for example, stimulated the emergence of two prominent psychological theories of reasoning: Rips' theory of mental rules [47] and Braine and O'Brien's theory of mental logic [6]. Both are rule-based. Likewise, model-theoretic semantics influenced Johnson-Laird's psychological mental models theory [27].Not only psychological theories but also the experimental paradigms for investigating human conditional reasoning were strongly influenced by the Presented by Name of Editor; Received ** **,**** 1 Indicative conditionals are of the form "If A, then C", where the antecedent A and the consequent C are propositions. The ¬A ∧ C and ¬A ∧ ¬C cases are not irrelevant. They rather make A ⊃ C true. Thus, propositional logic also provided rationality criteria for evaluating human inference: Logical validity and the interpretation of indicative conditionals as material conditionals were the most important rationality criteria for assessing human reasoning performance. The participant's interpretation of indicative conditionals was classified as "rational" if, and only if the participant's interpretation is consistent with the semantics of the material conditional. For about ten years now, empirical work on indicative conditionals focuses on uncertainty. Consequently, the normative standard of reference has changed: More and more psychological studies of reasoning adopted proba...