aristotle thought

When someone speaks truly, what makes his statement true? We tend to feel that there are two factors: meaning and fact. “Snow is white.” This sentence means that ‘snow is white’, and in fact ‘snow is white’. If he spoken ‘snow is red’, he would not have spoken truly. If the fact had been different, if snow had been red, then again he would not have spoken truly. The first sentence is logic. Logic is the systematic study of logical truths. Pressed further, we would say that a sentence is logically true if all sentences with its grammatical structure are true.

Logic is a branch of philosophy that deals with the rules of correct reasoning. Most work in the field of logic deals with a form of reasoning called an argument. An argument consists of a set of statements called premises, followed by another statement called the conclusion. If the premises support the conclusion, the argument is correct If the premises do not support the conclusion, the argument is incorrect.2

There are two types of arguments, deductive and inductive. A deductive argument is valid when the conclusion must be true if the premises are true. When the conclusion does not necessarily follow from the premises, a deductive argument is invalid. In an inductive argument, the conclusion is more or less probably true based on the premises. Because the conclusion does not follow necessarily from the premises, an inductive argument is not usually deductively valid. An inductive argument may be correct or incorrect. This article deals mainly with deductive reasoning. For more information on inductive reasoning, see Inductive method.

Logic tells us whether a deductive argument is valid or invalid. The validity of such an argument depends on the form of the argument, not on the truth of its premises. As a result, an argument that depends on false premises could be valid, and an argument based on true premises could be invalid.

The categorical syllogism is the most common form of argument in traditional deductive logic. The ancient Greek philosopher Aristotle was one of the first scholars to carry out a systematic study of the categorical syllogism.

A syllogism consists of two premises and a conclusion. A categorical syllogism is one in which every statement has one of the four forms: (1) All A are B. (2) No A are B. (3) Some A are B. (4} Some A are not B. The letters A and B, or any other letters that might be used, are terms that represent various classes of things, such as numbers, people, yellow objects, unpleasant sounds, or brown cows.

The following argument is an example of a valid categorical syllogism: "All mammals are warm-blooded. All brown cows are mammals. Therefore, all brown cows are warm-blooded. The form of this syllogism is: All A are B. All C are A. Therefore, all C are B. -

The following categorical syllogism is invalid: No stars are planets Some satellites are not planets. Therefore, some satellites are not stars. This syllogism has the following form: "No A are B. Some C are not B. Therefore, some Care not A. We can determine that this syllogism is invalid by comparing it with another syllogism that has the same form and yields a false conclusion. Such a syllogism would be: No precious stones are cheap things (true). Some diamonds are dot cheap things (true). Therefore, some diamonds are not precious stones (false)." This syllogism fails to meet the requirement that the conclusion must be true if the premises are true. Therefore, the syllogism must be invalid.

The rules of syllogisms enable us to test a categorical syllogism without considering similar examples or examining the argument's structure in detail. These rules are based on certain features that occur in all valid syllogisms and distinguish them from invalid ones. For example, one rule states that no valid syllogism has two negative premises. There are two negative premises in this syllogism: "No stars are planets. Some satellites are not planets. Therefore, some satellites are not stars. Thus, we know that this syllogism cannot be valid.

B. Aristotle’s Logical Theories
Aristotle represents the climax of Greek philosophy. Probably no one surpassed him in intellectual versatility and power of synthesis. We owe to him much of our knowledge of earlier Greek philosophy, for he was not merely a speculative thinker but also a compiler and historian. While he did not always state the opinions of his predecessors too objectively, it must be remembered that the heat of argument and his own philosophical convictions frequently carried him away. In philosophical disputes, objectivity very frequently is lacking. This is true not only in ancient times, for example, in disputes between Plato and the Sophists, and between Aristotle and Plato, but in modern times, as in the disputes between Descartes and Hobbes, Schopenhauer and Hegel, and James an Royce.

The life of Aristotle’s: Aristotle was born in 384 B.C. in Stagira, a town in Thrace. His parents died when he was young, and Proxenus, who provided him with an excellent education, brought him up. When he was eighteen years old, he was sent to Athens, where he entered Plato’s Academy. It was custom in those times for people, if they could afford it, to send their sons to distant centers of learning. The Platonic Academy had already achieved a wide reputation and was regarded as an excellent school, not only for preparation in politics but also for scientific studies.

The works of Aristotle’s: Unfortunately many of the works of Aristotle have been lost. Still, what remains of his researches is quite bulky and gives evidence of his indefatigable labors. His logical treatises are called the Organon. The others works of Aritotle: Categories, On interpretation, The Prior Analytics, Posterior Analytics, The Topics, On Sophistical Refutation (part of his logical work), Physics, De Caelo (On The Heavens), On Generation and Corruption, Meteorology, On The Soul (De Anima), Short Physical Treatises (Parva Naturalia), Metaphysica, Nicomachean Ethics (On Ethics), Rhetorica, and Poetics (De Poetica).

The greatest Aristotle’s influence in logic: Aristotle’s influence, which was very great in many different fields, was greatest of all in logic. In late antiquity, when Plato was still supreme in metaphysics, Aristotle was the recognized authority in logic, and he retained the position trough-out the Middle Age. It was not until the thirteenth century that Christian philosophers accorded him supremacy in the field of metaphysics. This supremacy was largely lost after the Renaissance, but his supremacy in logic survived. Even at the present day, all reject the discoveries of modern logic, and adhere with a strange tenacity, to a system which is as definitely antiquated as Ptolemaic astronomy. This makes it difficult to do historical justice to Artistotle. His present-day influence is so inimical to clear thinking his predecessors (including Plato), or how admirable his logical works would still seem if it had been a stage in a continual progress, in stead of being (as fact it was) a dead end, followed by over two thousand years of stagnation. In dealing with the predecessors of Aristotle, it is not necessary to remind the reader that they are not verbally inspired; one can therefore praise them for their ability without being supposed to subscribe to all their doctrines. Aristotle, on the country, is still, especially in logic, a battleground, and cannot be treated in a purely historical spirit.

Islamic logic inspired primary by Aristotle’s logical corpus, the Organon. Islamic authors were also familiar with some elements in Stoic logic and linguistic theory, and their logical sources included not only Aritotle’s own works of the late Greek Aristotelian commentators, the Isagoge of Porphyry and logical writing of Galen. However, most of the logical work of Islamic philosophers remained squarely within the tradition of Aristotle’s logic, and most of their writings in this area were in the form of commentaries on Aritotle.

Aristotle’s logical theories: Let us objectively and briefly review some of the important element of Aristotelian logic. We note outset that Aristotle stresses the importance of categories. These, the highest classes into which all concepts can divide, are the immediate and analyzable constituents of thought. We cannot depart from the in making any kind of judgment about the external world. Aristotle, however, varies in specifying the number of categories. At first he mentions only eight, and later ten categories. The following is a list of categories: Substance, Quantity, Quality, Relation, Place, Time, Action, and Passivity.

In this discussion of the categories, Aristotle devoted much space to substance. As the most important and fundamental category, it is basic to all reasoning. With emphasis he points out that substance stands, above all, for an individual thing. Thus, he is distinguished from Plato, who believed universals to be real. At the same time, Aristotle used substance in another way:

“All substance appears to signify that which is individual. In the case of primary substance, this is indisputably true, for the thing is a unit. In the case of secondary substances, when we speak, for instance, of “man’ or “animal”, our form of speech gives the impression that we are here also indicating that which is individual, but the impression is not strictly true; for a secondary substance is not an individual, but a class with a certain qualification; for it is not one and single as a primary substance is; the words ‘man’, ‘animal’ are predicable of more than one subject.

“Yet species and genus do not merely indicate quality, like the term ‘white’; ‘white’ indicate quality and nothing further, but species and genus determine the quality with reference to a substance: they signify substance qualitatively differentiated. The determinate qualification covers a larger field in the case of the genus than in that of the species: he who uses word ‘animal’ is herein using a word of wider extension than he who uses the word ‘man’.

Aristotle was famous as “the father of logic”. Although according K. Berten, the term of “logic” is not from Aristotle. In the ancient work, the term of “logic” first arose in Cicero era ((first century B.C.), but in meaning “rhetoric”. Alexander Aphrodisiac (the Early Third century) was first person have used word “logic”. Aristotle used term ‘analitica” and “dialectica” in his books Topica (explain about dialectic), Analytica priora and analytica posteriora (explain about analytic). Aristotle’s work about logic is Organon.

The fundamental logical unit, Aristotle asserted, is syllogism. An example of the Aristotelian syllogism is the following:

“All Nazis were anti-Semitic”, “Hitler was a Nazi”, Therefore, “Hitler was anti-Semitic”.

The first proposition constitutes the major premise. That second, the minor premise; and the conclusion are contained in the statement, “Hitler was anti-Semitic” Aristotle demonstrated how various forms of the syllogism could be obtained. The syllogism itself he believed is based on the law of self-contradiction and the law of excluded middle.

For the another example: All men are mortal (Major premise), Socrates is a man (Minor premise), Therefore, Socrates is mortal (Conclusion). Alternatively: All men are mortal, All Greek is man, Therefore: All Greeks are mortal.

To some extent, as Bertrand Russell has often pointed out, Aristotle had too much faith in the syllogism, for he held that all deductive arguments can be reduced to the syllogism. Yet, mathematics, which is based on deduction, can get along very well without the use of syllogism. Furthermore, the syllogism is not helpful when it becomes necessary to discover new truths. It merely describes the relationship between propositions. Thus, a syllogism can be valid regardless of the truth of its assertion. For example, we might say: “All German are warmongers. Frittz Schmids is a German. Therefore, Fritz Schmids is a warmonger.” From a formal standpoint, the argument is perfectly valid although its truth can scarcely be maintained.

Aristotle does not distinguish between these two forms; this, as we shall see later, is mistake.
Other forms are: No fishes are rational, all sharks are fishes, and therefore no sharks are rational. All men are rational; some animals are men, there for some animals are rational. No Greek are black, some men are Greek, therefore some men are not black.

There are some inferences that can be made from a single premise. From “some men are mortal’ we can infer that ‘some mortals are men.’ According to Aristotle, this can be also inferred from ‘all men are mortal’. From ‘no gods are mortal’, we can infer ‘no mortals are gods’, but from ‘some men are not mot Greeks’ it does not follow that ‘some Greeks are not men.’

Critics to Aristotle Logic: This system was the beginning of formal logic, and as such, was both important and admirable. However, considered as the end, not the beginning, of formal logic, it is open to three kinds of criticism:

(1) Formal defect within the system itself.
Let us begin with the two statements ‘Socrates is a man’ and ‘all Greeks are men’. It is necessary to make a sharp distinction, between these two, which is not done in Aristotelian logic. The statement ‘all Greeks are men’ is commonly interpreted as implying that there are Greeks; without this implication, some of Aristotle’s syllogism are not valid. Take for instance: ‘All Greeks are men’, ‘All Greeks are white’, therefore ‘some men are white’. This is valid if there are Greeks, but not otherwise. If I were to say: ‘All golden mountains are mountains, all golden mountains are golden, there fore some mountains are golden,’ my conclusion would be false, though in some sense my premises would be true. If we are explicit, we must therefore divide the one statement ‘all Greek are men’ into two, one saying ‘there are Greeks’, and the other saying ‘if anything is a Greek it is man’.

The latter statement is purely hypothetical, and does not imply that there are Greeks. This purely formal error was a source of errors in metaphysics and theory of knowledge. Metaphysical errors arose through supposing that ‘all men’ is the subject of ‘all men are mortal’. It made it possible to hold that, in some sense, ‘all men’ denotes an entity of the same short as that denoted by ‘Socrates’. This led Aristotle to say that in a sense a species is a substance. He is careful to qualify this statement, but his followers, especially Porphyry, showed less caution. Another error into which Aristotle falls through this mistake is to think that a predicate of a predicate can be a predicate of the original subject. If I say, ‘Socrates is Greek, all Greeks are human’, Aristotle thinks that ‘human’ is a predicate of ‘Greek’, while ‘Greeks is a predicate of ‘Socrates’, and obviously ‘human’ is a predicate of ‘Socrates’. However, in fact ‘human’ is not a predicate of ‘Greeks’. The distinction between names and predicate, or in metaphysical language, between particulars and universals, is thus blurred, with disastrous consequence philosophy.

(2) Over-estimation of the syllogism.
The syllogism is only one kind of deductive argument. In mathematics, which is wholly deductive, syllogism sharply ever occurs.
(3) Over-estimation of deduction.
The Greeks in general attached more importance to deduction as a source of knowledge than modern importance to deduction as a source of knowledge than modern philosophers do. In this respect, Aristotle was less at fault than Plato was; he repeatedly admitted the importance of induction, and he devoted considerable attention to the question; how do we know the first premises from which deduction must start? Nevertheless, he, likes other Greeks, gave undue prominence to deduction is his theory of knowledge.

C. Conclusion
Significance of Aristotle’s logic. What is the lasting significance of Aristotle’s logic? (1) Through it, he provided a rational discipline for philosophy. He showed that all speculation involves logical consistency and must be based on definite logical principles (2) He outlined the elements of deductive logic and described the fallacies which arise in various arguments (3) He discussed the nature of scientific demonstration and in this respect gave voice to the ideal of Greek science, which was interested in rational understanding rather than in experimentation. (4) He made a distinction between (a) deduction, which starts with general principles and derives facts from it and (b) induction, which starts with particulars and then arrives at a generalization. (5) He made a clear distinction between validity and truth: validity is concerned with the form of logic where as truth deals with the content of logic. (6) He laid down excellent rules for definition, and they can still be used today. Finally, (7) he laid the foundation for the complete classification of the sciences.

References and Further Reading

Aulary, Delasy, al-Fikr, al-‘Araby, Beirut: Dar al-Fikr al-Banany, 1982.

Badawy, Abd al-Rahman, al-Turats al-Yunany fi al-Hadharah al-Islamiyah, Beirut: Dar
al-Qalam, 1980.

Bertens, . K, Sejarah Filsafat Yunani, Yogyakarta: Kanisius, 1975.

Craig, Edward & Floridi, Luciano (Editors), Routledge’s Encyclopedia of Islamic
Philosophy, London & New York: Routledge, 1998.

Fakhry, Majid, Sejarah Filsafat Islam: Sebuah Peta Kronologis (Translated from A Short
Introduction to Islamic Philosophy, Theology and Mysticism, Bandung: Mizan,
2001.

Hatta, Mohammad, Alam Pikiran Yunani, Jakarta: UI-Press & Tintamas, 1986.

Leamen, Oliver, Pengantar Filsafat Islam: Sebuah Pendekatan Tematis (Translated from
A Brief Introduction to Islamic Philosophy), Bandung: Mizan, 2001

Mayer, Frederick, A History of Ancient & Medieval Philosophy, California: San
Francisco: American Book Company,1950.

Muthahhari, Murtadha, Ilmu Manthiq (translated from part of Asynai ba Ulume Islame),
Lampung: YAPI, 1990.

Quine, W.V., Philosophy of Logic, London: Prentice-Hall, Inc, 1970.

Russel, Bertrand , History of Western Philosphy, London: Unwin Paperbacks, 1979.

Shaliba, Ahmad, Tarikh al-Falsafah al-‘Arabiyah, Beirut: Dar al-Kitab al-Banany, 1973.

www.Mywebpages.comcast.net/fandrews27/PA9Logic.htm