[§ 6.]
Venn’s Method of Diagrams.
Let us represent “not-x” by “x′”.
Mr. Venn’s Method of Diagrams is a great advance on the above Method.
He uses the last of the above Diagrams to represent any desired relation between x and y, by simply shading a Compartment known to be empty, and placing a + in one known to be occupied.
Thus, he would represent the three Propositions “Some x are y”, “No x are y”, and “All x are y”, as follows:—
[pg175]It will be seen that, of the four Classes, whose peculiar Sets of Attributes are xy, xy′, x′y, and x′y′, only three are here provided with closed Compartments, while the fourth is allowed the rest of the Infinite Plane to range about in!