Page images
PDF
EPUB

rules ; and if we would gain a just and precise idea of every universal, particular and indefinite expreffion, we must not only consider the particular idiom of the lan. guage, but the time, the place, the occasion, the cir. cumstances of the matter spoken of, and thus penetrate as far as possible into the design of the speaker or writer..

[merged small][merged small][ocr errors]

T H EN a proposition is considered with regard

VV; to its copula, it may be divided into affirmative and negative ; for it is a copula joins, or disjoins the two ideas. Others .call this: a division of proposition according to their quality

An affirmative proposition is when the idea of the pre-dicate, is supposed to agree to the idea of the subject, and is joined to it by the word is, or are, which are the copula ; as, all men are sinners. But when the predicate is not supposed to agree with the subject, and is disjoined from it by the particles. is not, are not, C. the proposition is negative : as, man is not innocenti, or, no man is innocent. In an affirmative proposition : we aflert one thing to belong to another, and as it 'were, unite them in thought and word; in negative propositions .we. separate, one thing from another, and deny their agreement. . It may become something odd, that two ideas or terms are said to be disjoined as well as joined by a copula :.. bur if we can but suppose the negative partie cles do really belong to the copula of negative proposi.tions, it takes away the harshness of the expression; and to make it yet softer, we may consider that the predicate and subject may be properly said to be joined in a form of words as a proposition, by connective particles in grammar or logic, though they are disjoined in their sense and signification. Every youth who has

learned his grammar, knows there are fuch words as disjunctive conjunctions.

Several things are worthy of our notice on this subject.

Note 1. As there are some terms or words, and ideas, (as I have shewn before) concerning which it is hard to determine whether they are negative or pofitive, so there are some propofitions concerning which it may be difficult to say, whether they affirm or deny; as, when we fay, Plato was no fool : Cicero was no unskilful orator : Cæfar made no expedition to Muscovy : an oyster has no part like an eel; It is not neceffary for a physician to speak French, and for a physician to speak French is needless. The sense of these proposia tions is very plain and easy, though logicians might squabble perhaps a whole day, whether they should fank them under the names of negative or affirmative..

Note 2. In Latin and English two negatives joined. in one sentence make an affirmative ; as when we de. clare, no man is not mortal, it is the same as though we said, man is mortal, but in Greek, and oftentimes in French, two negatives make but a stronger denial.

Note 3: If the mere negative term, not, be added to the copula of an universal affirmative proposition, it reduces it to a particular negative; as, all men are not wise, signifies the same as, some men are not wise.

Note 4. In all affirmative propositions, the predicate is taken in its whole comprehension ; that is, every effential part and attribute of it is affirmed concerning the subject; as when I say, a true christian is an honelt man, every thing that belongs to honesty is affirmed concerning a true christian.

Notes. In all negative propositions the predioate is. taken in its whole extension that is, every species and individual thät is contained in the general idea of the predicate, is utterly denied concerning the subject ; lo in this propofition, a spirit is not an animal, we exclude all sorts and kinds and particular animals whatsoever from the idea of a spirit.

From these two last remarks we may derive this ina ference, that we ought to attend to the entire comprehenfion of our ideas, and to the universal extenfion of

them, as far as we have proper capacity for it, before we grow too confident in our affirming or denying any thing, which may have the least darkness, doubt or dife ficulty attending it: it is the want of that attention that betrays us into many mistakes.

SECT. III:

Of the Opposition and Conversion of Propositions.

NY two ideas being joined or disjoined in varie A ous forms will afford us several propositions : all thele may be distinguished according to their quantity. and their quality * into four, which are marked or de noted by the letters A, E, I, O, thus :

Α

[ Universal affirmative..

Universal negative. 1 ? denotes a {

3 Particular aflirmative..

[ Particular negative. according to these ola Latin rhymes

Asferit A, Negat E, verum generaliter amba;
Ajerit I, Negat 0, sed particulariter ambo.

This may be exemplified by these two ideas, a. Vine and a Tree.

A Every Vine is a Tree..
I E No Vine is a Tree.

I Some Vine is a Tree.
O Some Vine is not a Trees

The logicians.of the schools have written many large trifles concerning the oppolation and conversion of propoe fitions. It will be sufficient here to give a few brief hints of these things, that the learner may not be utterly ignorant of them.

* The reader Mould remember here, that a proposition according to its quantity is called universal or particular, and according to its quality, it is either affirmative or negative.

Propositions which are made of the same subject and predicate are said to be opposite, when that which is denied in one is affirmed in the other, either in whole or in part, without any consideration whether the propositions be true or no.

If they differ both in quantity and quality, they are said to be contradictory ; as, A Every Vine is a . Tree .. These can never be both true, or O Some Vine is not ? both false at the same time.

a Tree. · If two universals differ in quality, they are contraries; as, A Every Vine is

a Tree... (These can never be both true toge. E No Vine is a ther, but they may be both false.

. Tree.

If two particular propofitions differ in quality, they are subcontraries; as, I Some Vine is an Tree.

These may be both true together, Some Vine is not but they can never be both false. a Tree.

Both particular and universal propositions which agree in quality, but not in quantity, are called subaltern, though these are not properly opposite, as

A Every Vine is a Tree.

I Some Vine is a Tree. Or thus :

E No Vine is a Tree.

O Some Vine is not a Tree. The canons of subaltern propofitions are usually reckoned these three, (viz) (I). If any universal propofition be true, the particular will be true also, but not on the contrary, And (2.) If a particular propofition be false; the universal must be false, but not on the contrary. (3.) Subaltern propositions, whether universal or particular, may sometimes be both true, and sometimes both false.

The conversion of propoßtions is when the subject

and predicate change their places with preservation of the truth. This may be done with conftant certainty in all universal negatives and particular affirmatives; as, no spirit is an animal, may be converted, no animal is a spirit; and some tree is a vine, may be converted, some vine is a tree. But there is more formal trifling in this sort of discourse than there is of folid improvement, because this sort of conversion arises merely from the form of words, as connected in a proposition, rather than from the matter.

Yet it may be useful to observe, that there are some propositions, which by reason of the ideas or matter of which they are composed may be converted with constant truth : such are those propositions whose predicate is a nominal or real definition of the subject, or the difference of it, or a property of the fourth kind, or a superlative degree of any property or quality whatsoever, or in short, wheresoever the predicate and the subject have exactly the same extension or the same comprehension; as, every vine is a tree bearing grapes; and every tree bearing grapes is a vine : religion is the truest wisdom, and the truest wisdom is religion : Julius Cæsar was the first emperor of Rome; and the first emperor of Rome was Julius Cæfar. These are the propositions which are properly convertible, and they are called reciprocal propositions.

SECT. IV.
Of pure and modal Propohtions.

ANOTHER division of propositions among the

A scholastic writers is into pure and modal. This may be called (for distinction lake) a division according to the predicate.

When a proposition merely expresses that the predicate is connected with the subject, it is called a pure proposition; as, every true christian is an honest man.

« PreviousContinue »