Denying Antecedents and Affirming Consequents: The State of the Art

David Godden, Frank Zenker


Recent work on conditional reasoning argues that denying the antecedent [DA] and affirming the consequent [AC] are defeasible but cogent patterns of argument, either because they are effective, rational, albeit heuristic applications of Bayesian probability, or because they are licensed by the principle of total evidence. Against this, we show that on any prevailing interpretation of indicative conditionals, the premises of DA and AC arguments do not license their conclusions without additional assumptions. The cogency of DA and AC inferences rather depends on contingent factors extrinsic to, and independent of, what is asserted by DA and AC arguments.


affirming the consequent; Bayesian probability; conditional perfection; denying the antecedent; fallacy; heuristics; total evidence

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ISSN: 0824-2577