The Development of Conditional Reasoning: An Iffy Proposition

Abstract

Publisher Summary This chapter attempts to make some sense of the competing claims concerning conditional-reasoning competence. The competence model is based on the natural deduction approach to standard logic; modus ponens and the schema for conditional proof provide inference rules for simple conditionals and, together with the recognition of the constraints imposed by universal quantification, they provide a model for reasoning with universally quantified conditionals. Piaget's account of conditional reasoning is inadequate on logical grounds, that is, it confuses simple and quantified conditionals, but it is possible to make fairly clear empirical predictions when quantifiers are assumed. Ennis and Brainerd have argued that Piaget's account of formal operational thought is wrong because children have some ability to evaluate conditional syllogisms correctly. However, Piaget argued that successful performances on many conditional reasoning tasks can be obtained without a formal operational appreciation of the conditional. Given that the class-inclusion logic structure of concrete operational thought should be sufficient for reasoning with simple conditionals; this does not appear to be a warranted dismissal of the theoretical expectations. Rather, the appropriate assessment of formal operational competency with conditionals appears to concern performances in judging universally quantified conditionals.