Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/489

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461



PROPOSITION II.


A PREMISS BY WHICH THE THIRD ALTERNATIVE IS ELIMINATED.


Whatever we neither know nor are ignorant of is the contradictory.


DEMONSTRATION.

If that which we neither know nor are ignorant of were not the contradictory, it would be knowable; because whatever is not contradictory is knowable. But if it (that viz., which we neither know nor are ignorant of) were knowable, we must either know it or be ignorant of it. If we know it, we cannot neither know it nor be ignorant of it; and if we are ignorant of it, we cannot neither know it nor be ignorant of it. Therefore whatever we neither know nor are ignorant of cannot be knowable; and not being knowable, it must be the contradictory; because everything except the contradictory is knowable. Consequently, whatever we neither know nor are ignorant of, is, and must be, the contradictory.