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 perly drawn out, and Aristotle seems to have felt it to be the first task for one who would build up the entire fabric of knowledge, to lay down the laws of Dialectic as the art and science of method. “Dialectic,” he says, “is useful for three things: for exercise of the mind, for converse with other men, and for knowing how to question and handle the principles of philosophy.” And the object of his ‘Topics’ is, as he tells us, “to discover a method by which we shall be able to reason from probabilities on any given question, and to defend a position without being driven to contradict our own assertions.”

Properly speaking, Dialectic, as defined by Aristotle, ought not to come first in the order of sciences, for it is a kind of applied reasoning; it is reasoning applied to that which is not certain, but only probable. Therefore the general principles of reasoning should be drawn out first, and then these should be shown in application to the certainties of science, after which a subordinate branch might be added on reasoning upon probabilities. Aristotle, however, as we have said, did not set out with the conception of Logic, or the science of reasoning, as existing by itself. This only gradually dawned upon him, and it was out of his researches in Dialectic that he was led to develop the idea of Logic. It was in thinking out the rules of Dialectic that Aristotle discovered the principles of the Syllogism, and he was justly proud of the discovery. There are only two passages in all his extant writings in which he speaks of himself: one is that in which he apologises for differing from Plato, “because truth must be pre-