DIALECTIC, the art of separating a sub ject into its parts by discussion. It thus in cludes both the use of reason and speech, and is the process of defining an idea or principle and testing the definition by showing all the consequences, both positive and negative, that it involves.
Aristotle is reported to have said that Zeno the Eleatic was the father of dialectic. The justification of this remark is found in the fact that Zeno defends the position of his school by showing through a process of reasoning the ab surd and contradictory results that follow from the conceptions defended by their opponents. With Socrates dialectic is an art of investigat ing a subject by means of conversation carried on by two or more persons, each of whom con tributes something to the result, proposing defi nitions, or calling attention to certain aspects of the subject, or certain negative cases that had been overlooked. Thus Xenophon ('Memora bilia,' Chap. v.) tells us that Socrates said that dialectic was so called because it is an inquiry pursued by persons who take counsel together, separating the subjects considered according to their kinds. Plato extends the use of the term and makes it the art of working up by a method ological procedure of thought to a knowledge of the highest principles of things. As he says bk. v.), it is the method by which *reason avails itself of hypotheses, not as first principles, but as general hypotheses, that is, as stepping-stones and helps whereby it may force its way up to something not hypothetical and arrive at the first principles of all things and seize it in its grasp." For Plato then dialectic is the term used to describe all logical thinking.
Aristotle, however, does not use the term to cover his art of logical demonstration from necessary principles, but ascribes to it a lower place, describing it as the method of dealing with what is merely probable, or of arriving at what is most likely to be true in cases when cer tain demonstration is impossible.
The term dialectic has also frequently been used in ancient and modern times to denote an empty or sophistical art of playing with words or operating with concepts that have no real meaning or content. Thus Kant in the 'Critique of Pure Reason) employs the word in this sense to denote *the false pretense of knowledge that is based on illegitimate concepts that have no real basis in experience.* He names the third main division of his work 'Transcendental Dialectic,) and devotes it to a systematic exposure of the emptiness and futility of this form of reasoning. Hegel, on the other hand, uses the term to describe the true method of the development of thought. According to him there is in thought an in ternal principle of development in virtue of which it moves through three stages— from a thesis or positive position to the antithesis or negative view that is contradictory of the start ing-point, then finally to the synthesis or recon ciliation of the two opposing views. Hegel develops this into a universal method of pro cedure, regarding it as a process that exhibits both the development of the thought-process and also nature of reality, and pointing out illus trations of its course in history and in many departments of life and thought.