A Class Room Logic / Deductive and Inductive, with Special Application to the Science and Art of Teaching

by George Hastings McNair

4. SPECIAL CANONS OF THE FOUR FIGURES.

As a deductive exercise in clear, logical thought, the indirect proof involved in establishing certain principles underlying the four figures, is of immense value. On no account should this section be omitted. The mere fact that it appears to be a difficult section is proof positive that the student is in need of just such exercises.

Canons of the first figure.

(1) The minor premise must be affirmative.

(2) The major premise must be universal.

Problem: The minor premise must be affirmative.

Data: Given the form of the first figure, which is,

M — G

S — M

S — G