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Logic, Models, and Paradoxical Inferences

Authors


  • This research was supported by grant SEJ2006-14714 and Consolider-Ingenio 2010 CSD2008-00048 from the Spanish Government to the first author, and by National Science Foundation Grant SES 0844851 to the second author to study deductive and probabilistic reasoning. We thank David Beltrán, Nick Chater, Jonathan Evans, Vittorio Girotto, Sangeet Khemlani, Klaus Oberauer, Carlos Santamaría, and Walter Schroyens, for their thoughts about the present research. We also thank Mike Oaksford and two anonymous reviewers, for their criticisms of previous drafts of the article.

Address for correspondence: Isabel Orenes, Universidad de La Laguna, Facultad de Psicología, Departamento de Psicología Cognitiva, Social, y Organizacional, Campus Guajara, sn. 38205 La Laguna, Tenerife, Spain. Email: iorenes@ull.es

Abstract

People reject ‘paradoxical’ inferences, such as: Luisa didn't play music; therefore, if Luisa played soccer, then she didn't play music. For some theorists, they are invalid for everyday conditionals, but valid in logic. The theory of mental models implies that they are valid, but unacceptable because the conclusion refers to a possibility inconsistent with the premise. Hence, individuals should accept them if the conclusions refer only to possibilities consistent with the premises: Luisa didn't play soccer; therefore, if Luisa played a game then she didn't play soccer. Two experiments corroborated this prediction for three sorts of ‘paradox’, including a disjunctive paradox.

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