« PreviousContinue »
necessity when the meaning is exactly the same in each
With comparative terms this kind of inference will seldom be applicable; thus from “a cottage is a building,” we cannot infer “a huge cottage is a huge building," since a cottage may be large when compared with other cottages, but not with buildings generally.
Immediate Inference by Complex Conception is closely similar to the last, and consists in employing the subject 6 and predicate of a proposition as parts of a more com
plex conception. From “all metals are elements,” I can pass to “a mixture of metals is a mixture of elements.” From a horse is a quadruped” I infer “the skeleton of a horse is the skeleton of a quadruped.” But here again the reader must beware of applying the process where the new complex conception has a different meaning in the subject and predicate. Thus, from “all Protestants are Christians,” it does not follow that “ a majority of Protestants are a majority of Christians," nor that “the most excellent of the Protestants is the most excellent of the Christians."
The student is recommended to render himself familiar with all the transformations of propositions, or immediate inferences described in this lesson; and copious examples are furnished for the purpose. It is a good exercise to throw the same proposition through a series of changes, so that it comes out in its original form at last, and thus proves the truth of all the intermediate changes; but should conversion by limitation have been used, the original universal proposition cannot be regained, but only the particular proposition corresponding to it.
On Immediate Inference, Archbishop Thomson,
Outline of the Laws of Thought, $S 85–92.
LOGICAL ANALYSIS OF SENTENCES.
PROPOSITIONS as they are usually to be found in written or spoken compositions seldom exhibit the simple form, the conjunction of a subject, copula, and predicate, which we have seen to be the proper logical construction. Not only is the copula often confused with the predicate, but several propositions may be combined into one grammatical sentence. For a full account of the analysis of sentences I shall refer to several excellent little works devoted to the subject; but I will here attempt to give a sketch of the various ways in which a sentence may be constructed.
So often is the copula united to the predicate in ordinary language, that the grammarian treats the proposition as composed of only two parts, the subject and predicate, or verb. Thus the proposition, “ The sun rises,” apparently contains nothing but a subject “the sun,” and a predicate “rises;” but the proposition is really equivalent to “the sun is rising,” in which the copula is distinctly shown. We shall, therefore, consider the verb or grammatical predicate as containing both copula and logical predicate. In Latin one single word may combine all the three parts of the proposition, as in sum, “I am ;" and the celebrated exclamation of Cæsar, Veni, vidi, vici, “I came, I saw, I conquered," contains three distinct and complete propositions in three words. These peculiar cases only arise, however, from the parts of the proposition having been blended together and dis
guised in one word ; and in the Latin sum, the letter m is a relic of the pronoun me, which is the real subject of the proposition. If we had a perfect acquaintance with the Grammar of any language it would probably not contradict the logical view of a sentence, but would perhaps explain how the several parts of the complete proposition had become blended and apparently lost, just as the words will and not are blended in the colloquial“ I wont.”
A grammatical sentence may contain any number of distinct propositions, which admit of being separated but which are combined together for the sake of brevity. In the sentence,
“Art is long and Time is fleeting," there are two distinct subjects, Art and Time, and two predicates, “long" and "fleeting,” so that we have simply two propositions connected by the conjunction and. We may have however several distinct subjects with one and the same predicate; as in
“Thirty days hath September,
April, June, and November.” In this well-known couplet the predicate “having thirty days” is placed first for the sake of emphasis, and there are four subjects, September, April, &c., of each of which it is affirmed. Hence these lines really contain four distinct propositions.
Again, there may be one subject with a plurality of predicates, so that several different propositions are asserted without the repetition of the subject and copula. Thus the sentence
“Nitrogen is a colourless, tasteless, inodorcus gas, slightly lighter than air,” contains one subject only, Nitrogen, but four or five predicates; it is plainly equivalent to “Nitrogen is colourless,” “Nitrogen is tasteless," “Nitrogen is a gas," and so on.
Lastly, we may have several subjects and several
predicates all combined in the same sentence, and with only one copula, so that each predicate is asserted of each subject; and a great number of distinct propositions are condensed into one brief sentence. Thus in the sentence, “Iron, Copper, Lead and Zinc are abundant, cheap and useful metals, we have evidently four subjects, and we may be said to have four predicates, “abundant,” “cheap," "useful,” and “metal.” As there is nothing to prevent our applying each predicate to each subject the sentence really contains 16 distinct propositions in only 11 words; thus “Iron is abundant,” Iron is cheap," “Copper is abundant,” “ Copper is cheap," and so on. In the curious sentence,
“ Hearts, tongues, figures, scribes, bards, poets, cannot think, speak, cast, write, sing, number, his love to Antony*,
*," Shakspeare has united six subjects and six predicates, or verbs, so that there are, strictly speaking, six times six or thirty-six propositions.
In all the cases above noticed the sentence is said to be compound, and the distinct propositions combined together are said to be coordinate with each other, that is of the same order or kind, because they do not depend upon each other, or in any way affect each other's truth. The abundance, cheapness, or utility of iron need not be stated in the same sentence with the qualities of copper, lead or zinc; but as the predicates happen to be the same, considerable trouble in speaking or writing is saved by putting as many subjects as possible to the same set of predicates. It is truly said that brevity is the soul of wit, and one of the great arts of composition consists in condensing as many statements as possible into the fewest words, so long as the meaning is not confused thereby.
Antony and Cleopatra, Act III. Sc. 2.
Propositions are however combined in a totally different manner when one proposition forms a part of the subject or predicate of the other. Thus in the sentence, “The man who is upright need not fear accusation,” there are two verbs, and two propositions, but one of these only describes the subject of the other; “who is upright" evidently restricts the application of the predicate “need not fear accusation” to a part of the class
The meaning of the whole sentence might be expressed in the form
“The upright man need not fear accusation.” And it is clearly seen that the clause or apparent proposition is substituted for an adjective. Such a clause or proposition is called subordinate, because it merely assists in the formation of the principal sentence, and has no meaning apart from it; and any sentence containing a subordinate clause is said to be complex. Almost any part of a sentence may thus be replaced by a subordinate clause. Thus in “Oxygen and Nitrogen are the gases which form the largest part of the atmosphere,” there is a subordinate clause making part of the predicate, and the meaning might be expressed nearly as well in this way, “Oxygen and Nitrogen are the gases forming the largest part of the atmosphere."
In the case of a modal proposition (see p. 69), or one which states the manner in which the predicate belongs to the subject, the mode may be expressed either by an adverb, or by a subordinate clause. “As a man lives so he dies” is such a proposition; for it means, "a man dies as he lives,” and “as he lives” is equivalent to an adverb; if he lives well, he dies well; if he lives badly, he dies badly. Adverbs or adverbial clauses may also specify the time, place, or any other circumstance concerned in the truth of the main proposition.
Assuming the reader to be acquainted with the gram