Syllogistic Reasoning and Cognitive Bias of Senior High School Students in Ambon, Indonesia

Students need the reasoning skill as an important part of intelligence. The purposes of this study were to map and illustrate syllogism-based reasoning and cognitive bias related to the concepts of science. This study was conducted by qualitative design with phenomenology approach. Samples of this study were 20 students from 5 senior high school in average 15-16 years old (formal reasoning level). Instruments of this study were essay test to analyse the structure of syllogistic reasoning and interview to identify the cognitive bias.This study deduced that (1) a syllogism reasoning was an inherent part of the development of human’s thinking order, (2) the smoothness of syllogisms reasoning process relied heavily on individual comprehensive understanding of materials analysed, (3) a valid reasoning process was begun from meaning interpretation and premise truth, (4) a cognitive bias within syllogism reasoning was a confirmation bias. Someone accept the premise truth as an a priori without confirming the existing mental model or knowledge structure. Based on the findings, teachers need to empower and increase the students’ reasoning skill in science lesson. Further research is need to uncover more information related.