Philosophical Works of the Late James Frederick Ferrier/Institutes of Metaphysic (1875)/Section 3/Proposition 2
PROPOSITION II.
A PREMISS BY WHICH THE THIRD ALTERNATIVE IS ELIMINATED.
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.
OBSERVATIONS AND EXPLANATIONS.
Why this proposition is introduced.1. This proposition and the next supply the premises by means of which Proposition IV. is enabled to eliminate or get rid of the third alternative in regard to Absolute Existence—thus reducing the alternatives from three to two.
Second counter-proposition.2. Second Counter-proposition.—The contradictory is a topic which has never engaged the attention either of natural thinking or of psychological science; and therefore there is, in this case, no exact counter-proposition. At any rate, it is a mere repetition of the first, and may be laid down in the following terms: "There is no middle between knowledge and ignorance; we must either know or be ignorant of a thing, and we cannot neither know nor be ignorant of anything."
To what extent it is true. 3. Not if the thing is knowable or intelligible,—in that case, certainly, we cannot neither know it, nor be ignorant of it, but must either know it or be ignorant of it. But if the thing is absolutely unknowable or contradictory, or that which is not to be known at all, or on any terms by any intelligence, in that case, it is certain that we can neither know it nor be ignorant of it. When taken with this explanation or qualification (see preceding Prop., Obs. 6-9), the correctness of the counter-proposition may be conceded. At any rate, it is unnecessary to trouble ourselves with it any further, because the third alternative concluded for in Proposition I., which this counter-proposition rejects summarily, and without a hearing, is the very point which this system rejects after having submitted it (in Props. I. II. III. IV.) to a fair and legitimate trial. So that the system may here take credit for having raised, of its own accord, and surmounted by legitimate means, a difficulty or objection which would not have been thrown in its way, either by ordinary thinking or by psychology, If this third alternative could not have been logically got rid of, the ontology would have been brought to a stand-still.