Chapter 64

One should know that the purpose of the logical process is to make a clear statement of proof. The proof is a syllogism, and this syllogism is made up of two true premises and the conclusion. For example, if I want to prove that the soul is immortal, I say: ‘Everything that is perpetually in motion is immortal.’ This is a premise. Then I state a second premise: ‘The soul is perpetually in motion. Then the conclusion: ‘Therefore, the soul is immortal. Each part of the premise is called a term. A term is that into which every premise is resolved. For example, the premise goes: ‘Everything that is perpetually in motion is immortal. The part ‘everything, in so far as it is a part of the premise, is called a term. The ‘that is perpetually in motion is likewise called a term, as is the ‘immortal, and also the ‘is.

One should know that all the premises must be true and that the conclusion must follow from the premises. For, if one of the premises were found to be false, or the conclusion, then it would not be a syllogism, but a paralogism. Furthermore, there is the simple word, the noun, the verbal phrase, the statement, and the term. In respect to their subject, these five do not differ from one another. Their difference is only relative. ‘Man, for example, as a simple significant term, is called a simple word; as subject, it is called a noun; as fulfilling the functions of a predicate, it is called a verbal phrase; as part of an affirmation and negation, it is called statement; and as part of a premise and of a syllogism, it is called a term.

One should know that in the premise, that is, in the affirmation and negation, the subject is called a noun, whereas the predicate is called a verbal phrase. For example, ‘the man walks is an affirmation. ‘The man is the subject, and is called noun. ‘Walks fulfills the function of a predicate, and is called a verbal phrase. In ‘Socrates is noble the subject is ‘Socrates and it is called a noun. The phrase ‘is noble fulfills the function of a predicate, and, as a part of the affirmation, is called a verbal phrase. Even though grammarians call ‘noble a complementary word, yet, to put it simply, whatever accompanies the ‘is is a verbal phrase.

It should be known that there is no difference between