An examination of Sir William Hamilton's philosophy Volume 2; and of the principal philosophical questions discussed in his writings

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1865 Excerpt: ...a bare negation of man, but includes the positive attribute of being an animal, which X may possibly not be. It might be said, with more plausibility, that the Law of Excluded Middle is the principle of Disjunctive Reasoning. Thus, in the last example, "X is either a man or a brute" may be a conclusion from two premises, that X is an animal, and that every animal is either a man or a brute: the latter of which is a disjunctive judgment grounded on the Law of Excluded Middle. But it is not the fact that all disjunctive conclusions are inferred from premises of this nature. Having been told that A has lost a son, I conclude that either B, C, or D (A having no other sons) is dead: what kind of reasoning is this? Disjunctive, surely: it has a disjunctive premise, and leads to a disjunctive conclusion. But the disjunctive premise (Every son of A is either B, C, or D) does not rest on the Law of Excluded Middle, or on any necessity of thought; it rests on my knowledge of the individual fact. The third Law, however, like the two others, is one of the principles of all reasonings, being the generalization of a process which is liable to be required in all of them. As the Doctrine of Contradiction authorizes us to substitute for the assertion of either of two contradictory propositions, the denial of the other, so the doctrine of Excluded Middle empowers us to substitute for the denial of either of two contradictory propositions, the assertion of the other. Thus all the three principles which our author terms the Fundamental Laws of Thought, are universal postulates of Reasoning; and as such, are entitled to the conspicuous position which our author assigns to them in Logic: though it is evident that they ought not to be placed at the very beginning of the...