§ 543. The major and minor terms are called the Extremes, as opposed to the Mean or Middle Term. § 544. The premiss in which the major term is compared with the middle is called the Major Premiss. § 545. The other premiss, in which the minor term is compared with the middle, is called the Minor Premiss. § 546. The order in which the premisses occur in a syllogism is indifferent, but it is usual, for convenience, to place the major premiss first. § 547. The following will serve as a typical instance of a syllogism-- Middle term Major term \ Major Premiss. All mammals are warm-blooded | Antecedent > or Minor term Middle term | Premisses Minor Premiss. All whales are mammals / Minor term Major term \ Consequent or .'. All whales are warm-blooded > Conclusion. § 548. The reason why the names 'major, 'middle' and 'minor' terms were originally employed is that in an affirmative syllogism such as the above, which was regarded as the perfect type of syllogism, these names express the relative quantity in extension of the three terms. [Illustration] § 549. It must be noticed however that, though the middle term cannot be of larger extent than the major nor of smaller extent than the minor, if the latter be distributed, there is nothing to prevent all three, or any two of them, from being coextensive. § 550. Further, when the minor term is undistributed, we either have a case of the intersection of two classes, from which it cannot be told which of them is the larger, or the minor term is actually larger than the middle, when it stands to it in the relation of genus to species, as in the following syllogism-- All Negroes have woolly hair. Some Africans are Negroes. .'. Some Africans have woolly hair. [Illustration] § 551. Hence the names are not applied with strict accuracy even in the case of the affirmative syllogism; and when the syllogism is negative, they are not applicable at all: since in negative propositions we have no means of comparing the relative extension of the terms employed. Had we said in the major premiss of our typical syllogism, 'No mammals are cold-blooded,' and drawn the conclusion 'No whales are cold-blooded,' we could not have compared the relative extent of the terms 'mammal' and 'cold-blooded,' since one has been simply excluded from the other. [Illustration] § 552. So far we have rather described than defined the syllogism. All the products of thought, it will be remembered, are the results of comparison. The syllogism, which is one of them, may be so regarded in two ways-- (1) As the comparison of two propositions by means of a third. (2) As the comparison of two terms by means of a third or middle term.