Children's Understanding of Class Inclusion and their Ability to Reason with Implication

Abstract

Fifty-six Dutch school children (aged 6-0 and 14-4 years) participated in a study designed to investigate the relationship between class inclusion and reasoning with logical implication. Subjects each answered a total of 32 syllogisms containing conditional implication premises. Before or after each question they were asked a class inclusion question. Results suggested a high degree of correspondence between class inclusion responses and reasoning with logical implication. The child's understanding of the subordinate and superordinate characteristics of the premises appeared to contribute to evaluation of the arguments, although many correct responses appeared to be based on incorrect understanding of premises. Further, there appeared to be a developmental pattern of understanding of implication with exclusion being the first level of understanding, then equivalence, and finally inclusion appearing most consistently in eighth graders. It was concluded that when children fail to respond correctly to questions about the validity of syllogisms, they may do so because they lack sufficient understanding of the premises.