It is reported that Aristotle’s writings were held by his student Theophrastus, who had succeeded Aristotle in leadership of the Peripatetic School. Theophrastus’s library passed to his pupil Neleus. To protect the books from theft, Neleus’s heirs concealed them in a vault, where they were damaged somewhat by dampness, moths and worms. In this hiding place they were discovered about 100 BCE by Apellicon, a rich book lover, and brought to Athens. They were later taken to Rome after the capture of Athens by Sulla in 86 BCE. In Rome they soon attracted the attention of scholars, and the new edition of them gave fresh impetus to the study of Aristotle and of philosophy in general. This collection is the basis of the works of Aristotle that we have today. Strangely, the list of Aristotle’s works given by Diogenes Laertius does not contain any of these treatises. It is possible that Diogenes’ list is that of forgeries compiled at a time when the real works were lost to sight.
The works of Aristotle fall under three headings: (1) dialogues and other works of a popular character; (2) collections of facts and material from scientific treatment; and (3) systematic works. Among his writings of a popular nature the only one which we possess of any consequence is the interesting tract On the Polity of the Athenians. The works on the second group include 200 titles, most in fragments, collected by Aristotle’s school and used as research. Some may have been done at the time of Aristotle’s successor Theophrastus. Included in this group are constitutions of 158 Greek states. The systematic treatises of the third group are marked by a plainness of style, with none of the golden flow of language which the ancients praised in Aristotle. This may be due to the fact that these works were not, in most cases, published by Aristotle himself or during his lifetime, but were edited after his death from unfinished manuscripts. Until Werner Jaeger (1912) it was assumed that Aristotle’s writings presented a systematic account of his views. Jaeger argues for an early, middle and late period (genetic approach), where the early period follows Plato’s theory of forms and soul, the middle rejects Plato, and the later period (which includes most of his treatises) is more empirically oriented. Aristotle’s systematic treatises may be grouped in several divisions:
§ Physical works
§ Psychological works
§ Works on natural history
§ Philosophical works
Aristotle’s writings on the general subject of logic were grouped by the later Peripatetics under the name Organon, or instrument. From their perspective, logic and reasoning was the chief preparatory instrument of scientific investigation. Aristotle himself, however, uses the term “logic” as equivalent to verbal reasoning. The Categories of Aristotle are classifications of individual words (as opposed to sentences or propositions), and include the following ten: substance, quantity, quality, relation, place, time, situation, condition, action, passion. They seem to be arranged according to the order of the questions we would ask in gaining knowledge of an object. For example, we ask, first, what a thing is, then how great it is, next of what kind it is. Substance is always regarded as the most important of these. Substances are further divided into first and second: first substances are individual objects; second substances are the species in which first substances or individuals inhere.
Notions when isolated do not in themselves express either truth or falsehood: it is only with the combination of ideas in a proposition that truth and falsity are possible. The elements of such a proposition are the noun substantive and the verb. The combination of words gives rise to rational speech and thought, conveys a meaning both in its parts and as a whole. Such thought may take many forms, but logic considers only demonstrative forms which express truth and falsehood. The truth or falsity of propositions is determined by their agreement or disagreement with the facts they represent. Thus propositions are either affirmative or negative, each of which again may be either universal or particular or undesignated. A definition, for Aristotle is a statement of the essential character of a subject, and involves both the genus and the difference. To get at a true definition we must find out those qualities within the genus which taken separately are wider than the subject to be defined, but taken together are precisely equal to it. For example, “prime,” “odd,” and “number” are each wider than “triplet” (that is, a collection of any three items, such as three rocks); but taken together they are just equal to it. The genus definition must be formed so that no species is left out. Having determined the genus and species, we must next find the points of similarity in the species separately and then consider the common characteristics of different species. Definitions may be imperfect by (1) being obscure, (2) by being too wide, or (3) by not stating the essential and fundamental attributes. Obscurity may arise from the use of equivocal expressions, of metaphorical phrases, or of eccentric words. The heart of Aristotle’s logic is the syllogism, the classic example of which is as follows: All men are mortal; Socrates is a man; therefore, Socrates is mortal. The syllogistic form of logical argumentation dominated logic for 2,000 years until the rise of modern propositional and predicate logic thanks to Frege, Russell, and others.