On the Cognitive Efficacy of Euler Diagrams in Syllogistic Reasoning: A Relational Perspective

Although logic diagrams are widely used as methods for introducing students to elementary logical reasoning, it is still open to debate in cognitive psychology whether diagrams can aid untrained people to successfully conduct deductive reasoning. In our previous work, some empirical evidence was provided for the effectiveness of a certain type of logic diagrams in the process of solving categorical syllogisms. However, the question of why certain diagrams but not others have such inferential efficacy in performing syllogism reasoning has not been fully answered. Based on a proof-theoretical analysis of categorical syllogisms and diagrammatic reasoning, we supplement our previous study of cognitive efficacy of diagrams and argue that the relational information underlying quantified sentences plays a crucial role in understanding the efficacy of diagrams in syllogistic reasoning. The distinctive features of our conception of diagrammatic reasoning are made clear by comparing it with the model-theoretic conception of ordinary reasoning developed in the mental model theory.