A necessity illusion for modal inferences from conditionals. (3rd July 2018)

• Record Type: Journal Article
• Authors: Wang, Moyun; Yin, Pengfei; Zheng, Liyuan
• Is Part Of: Thinking & reasoning. Volume 24:Number 3(2018)
• Page Start: 366
• Page End: 385
• Publication Date: 2018-07-03
• Subjects: Conditionals -- possibility inferences -- necessity inferences -- the necessity illusion -- the evidence-matching heuristic; Thought and thinking -- Periodicals; Reasoning (Psychology) -- Periodicals; 153.43
• DOI: 10.1080/13546783.2018.1439102
• Languages: English
• ISSNs: 1354-6783

Abstract

ABSTRACT: Three experiments examined how people reason about what is possible or necessary when a conditional is true. Participants were asked to indicate whether it was necessary, possible or impossible for a specific instance to conform to one of the truth-table cases ( pq, p ¬ q, ¬ pq and ¬ p ¬ q ) (¬ = not), given the truth of the conditional. It was found that most participants, inconsistently, judged the pq case as necessary but the ¬ pq or ¬ p ¬ q cases as possible. Logically, these two kinds of judgments are contradictory. Moreover, a true conditional doesn't imply that a specific instance under the conditional must be pq . Therefore, people demonstrate a necessity illusion for pq cases which contradicts their commitment to the possibility of ¬ pq or ¬ p ¬ q cases. Existing accounts of conditionals are unable to explain the contradiction and the necessity illusion. We propose an inference dissociation account and explore the theoretical implications of this necessity illusion.