Classical Syllogisms in Logic Teaching

This paper focuses on the challenges of introducing classical syllogisms in university courses in elementary logic and human reasoning. Using a program written in Prolog+CG, some empirical studies have been carried out involving three groups of students in Denmark; one group of philosophy students and two groups of students of informatics. The skills of the students in syllogistic reasoning before and after the logic courses have been studied and are discussed. The empirical observations made with the program make it possible to identify syllogisms which are found difficult by the students, and to identify others which the students find easier to handle. It is discussed why certain syllogisms are more difficult than others to assess correctly with respect to validity. The results are compared with findings from earlier studies in the literature. As in other studies, it is shown that the test persons have a tendency correctly to assess valid syllogisms as such more often than correctly assessing invalid syllogisms as such. It is also investigated to what extent the students have improved their skills in practical reasoning by attending the logic courses. Finally, some open questions regarding syllogistic reasoning are discussed.