The emergence of inferential rules - The use of pragmatic reasoning schemas by preschoolers

This study contrasts the pragmatic view with the natural logic view regardi ng the origin of inferential rules in conditional reasoning. The pragmatic view proposes that pragmatic rules emerge first, and the generalizations of these produce formal rules. In contrast, the natural logic view proposes t hat the formal rules emerge first and serve as a core that is then suppleme nted by pragmatic rules. In an experiment, scenarios involving conditional rules in different contexts, permission and arbitrary, were administered to independent groups of preschool children. To rule out the matching bias [E vans, J. St. B. T, & Lynch, J. S. (1973). Matching bias in the selection ta sk. Br J Psychol 64, 391-397] as a possible explanation of reasoning perfor mance, children were given conditional rules with a negated consequent. The results show that in the arbitrary context modus tollens (MT) was unavaila ble, and the use of modus ponens (MP) was unstable. In contrast, children i n the permission context reliably used both MP and MT. In addition, they re alized that a conditional rule does not imply a definite answer when the co nsequent holds. These findings suggest that, in their explicit forms, pragm atic rules emerge earlier than formal rules and in particular, even as basi c a rule as MP is generalized from a context-specific form to a context-gen eral one in preschool children. (C) 2000 Elsevier Science Inc. All rights r eserved.