Nirvana Ribić & Igor Bajšanski
University of Rijeka
This research paper examines verbal reasoning through the lens of the suppression effect, a robust phenomenon in which the introduction of a disabler leads reasoners to withhold otherwise valid inferences and instead endorse uncertain conclusions. Situated at the intersection of logic and the psychology of reasoning, the study contributes to an interdisciplinary understanding of how formal validity interacts with content-sensitive cognitive processes. While prior research has focused primarily on modus ponens and modus tollens argument forms, the present work extends the investigation to hypothetical syllogism, thereby introducing a different paradigm for examining context effects. Across three experiments, this study tests two main hypotheses: first, that suppression generalises to hypothetical syllogisms, and second, that the effect is modulated by the perceived relevance of the disabler. Experiment 1 replicates the suppression effect using novel materials, Experiment 2 shows that the effect persists in the context of hypothetical syllogisms, and Experiment 3 shows that reducing the perceived relevance of the disabler increases participants’ willingness to endorse logically valid conclusions. These findings pose a challenge for dominant accounts of reasoning. Mental models theory struggles to accommodate the reinstatement of valid inferences in different contexts, while probabilistic approaches do not straightforwardly explain the observed sensitivity to arbitrary contents. By contrast, formal rules theories may interpret the results in terms of enthymematic reasoning, where implicit premises are contextually added or withdrawn. Non-monotonic logic offers a particularly promising framework, as it allows additional information to alter the status of defeasible conclusions. Overall, the results place new empirical constraints on theories of reasoning and emphasise the value of integrating logical analysis with empirical insights from cognitive psychology.
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SOPhiA 2026 