Book 7
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Dialectic (they hold) falls under two heads: subjects of discourse and language. And the subjects fall under the following headings: presentationsThe word φαντασία (= appearance or appearing) is a technical term in Stoic logic for which no one English equivalent is as yet unanimously adopted. It denotes the immediate datum of consciousness or experience, whether presented to sense or in certain cases to the mind. Hence presentation is nearer than perception or impression. It might be thought to correspond to Locke’s simple ideas, for which Hume substituted impressions and ideas; but this is hardly so; for φαντασίαι are given as it were from without, and then with them as materials the mind itself constructs general notions and concepts. and the various products to which they give rise, propositions enunciated and their constituent subjects and predicates, and similar terms whether direct or reversed, genera and species, arguments too, moods, syllogisms and fallacies whether due to the subject matter or to the language;
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these including both false and true and negative arguments, sorites and the like, whether defective, insoluble, or conclusive, and the fallacies known as the Veiled, or Horned, No man, and The Mowers.
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The second main head mentioned above as belonging to Dialectic is that of language, wherein are included written language and the parts of speech, with a discussion of errors in syntax and in single words, poetical diction, verbal ambiguities, euphony and music, and according to some writers chapters on terms, divisions, and style.
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The study of syllogisms they declare to be of the greatest service, as showing us what is capable of yielding demonstration; and this contributes much to the formation of correct judgements, and their arrangement and retention in memory give a scientific character to our conception of things.
