A = PBC ꖌ pBc;
but these alternatives cannot be reduced, and the proposition is quite different from
A = BC ꖌ Bc.
Illustrations of the Indirect Method.
A great variety of arguments and logical problems might be introduced here to show the comprehensive character and powers of the Indirect Method. We can treat either a single premise or a series of premises.
Take in the first place a simple definition, such as “a triangle is a three-sided rectilinear figure.” Let
A = triangle
B = three-sided
C = rectilinear figure,
then the definition is of the form
A = BC.
If we take the series of eight combinations of three letters in the Logical Alphabet (p. [94]) and strike out those which are inconsistent with the definition, we have the following result:—