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truth of the parts, but from the causal influence that the one part of it has. upon the other; for both parts may be truc, yet the proposition false, if.one part be not the cause of the other.
Some logicians refer reduplicative propositions to this place, as, men, considered as men, are rational creatures, that is, because they are men,
V. Relative propositions have their parts joined by fuch particles, as express a relation or comparison of one thing to another; as when you are silent I will speak; as much as you are worth, so much you shall be esteemed; as, is the father so is the fon; where there is no tale-bearer, contention will cease.
These are very much a-kin to conditional propofie. tions, and the truth of them depends upon the juitness of their connection.
VI. Discretive propositions are such wherein various and seemingly opposite judgments are made, whose variety or distinction is noted by the particles, but, though, yet, &C. as, travellers may change their climate but not their temper; Job was patient, though his grief was great..
The truth and goodness of a discretive propofition depends on the truth of both parts, and their contradiction to one another; for though both parts should be true, yet if there be no feeming opposition between them, it is an useless affertion, though we cannot call it a false one ; as Descartes was a philosopher, yet he was a Frenchman ; the Romans were valiant, but they fpoke Latin; both which propositions are ridiculous, for want of a seeming opposition between the parts.
Since we have declared wherein the truth and fall. hood of those compound propofitions confits, it is proper also 'to give some intimations how any of thefe propofitions when they are false may be opposed or contradicted.
"All compound propositions, except copulatives and discretives, are properly denied or contradicted when the negation affects their conjunctive particles; as, if the disjunctive proposition asserts, it is either day or night. The opponent says, it is not either day or night, or it is not necessary that 'it should be either day or
night, so the hypothetical proposition is denied by saying, it does not follow that the earth must move if the Lun be fixed.
A disjunctive proposition may be contradicted also by denying all the parts; as, it is neither day nor night.
And a causal. proposition may be denied or opposed indirectly and improperly, when either part of the proposition is denied, and it must be falfe of either part be false; but the design of the proposition being to thew the causal connection of the two parts, each part is supposed to be true, and it is not properly contra. dicted as a causal propofition, unless one part of it be denied to be the cause of the other.
As for copulatives and discretiyes, because their truth depends more on the truth of their parts, therefore these may be opposed or denied as many ways, as the parts of which they are composed may be denied; fo this copulative proposition, riches and honour are temptations to pride, may be denied by saying, riches are not temptations though honour may be : or, honour is not a temptation, though riches may be ; or, neither riches nor honour are temptations, &c.
So this discretive proposition, Job was patient, though his grief was great, is denied by saying, Job was not patient, though his grief was great : or, Job was patient, but his grief was not great: or, Job was not patient, nor was his grief great.
We proceed now to the second sort of compound propositions, viz. such whofe composition is not exprefled, but latent or concealed, yet a small attention will find two propositions included in them. Such are these that follow; .. ..
1. Exclusives ; as, the pious man alone is happy, it is only Sir Isaac Newton could find out true philo. fophy.
2. Exceptives ; as, none of the ancients but Plato well defended the soul's immortality. The protestants worship none but God.
3. Comparatives ; as, pain is the greatest affliction. No Turk was fiercer than the Spaniards at Mexico.
· Here note, that the comparative degree does not al: ways imply the positive ; as if I say a fool is better than a knave, 'this does not affirm that folly is good, but that it is a less evil than knavery.
4. Inceptives and desitiver, which relate to the begirning or ending of any thing : as, the Latin tongue is, not yet forgotten. No man before Orpheus wrote Greek verse. Peter Czar of Muscovy began to civilize his nation..
To these may be added continuatives ; as, Rome ree mains to this day, which includes at least two propofitions, viz. Rome was, and Rome is.
.. Here. let other authors spend time and pains in give ing the precise definitions of all these sorts of propofitions, which may as well be understood by their names and examples: here let them tell what their truth depends.upon, and how they are to be opposed orcon. tradicted; but a. moderate share of common sense, with a review of what is said on the former compounds, will suffice for all these purposes. without the forma lity of rules.
DROPOSITIONS are next to be considered accora
ding to their sense or signification, and thus they are distributed into true or false. A true proposition reprefents things as they are in themselves ; but if things are represented otherwise than they are in them. selves, the proposition is falfe.
Or we may describe them more particularly thus ; à true proposition joins those ideas and terms together whose objects are joined and agree, or it disjoins those ideas and terms, whose objects disagree or are disjoined; as, every bird has wings, a brute is not immortal.
- A false proposition joins thofe ideas or terms whose objects disagree, or it disjoins those whose objects agree; as, birds have no wings, brutes are immortal.
Note, It is impossible that the same proposition should be both true and false at the same time, in the same fense and in the fame respect, because a propofition is but the representation of the agreement or disagreen ment of things : now it is impossible that the same thing should be and not be, or that the same thing should agree and not agree at the same time and in the same respect. This is the first principle of human knowledge. . .
Yet fome propofitions may seem to contradict one another, though they may be both true, but in different fenfes or respects or times : as, man was immortal in paradise, and man was mortal in paradise. But there two propositions must be referred to different times; as, man before his fall was immortal, but at the fall became mortal. So we may say now, man is mortal, or, man is immortal, if we take these propositions in different respects; as, man is an immortal creature as to his foul, but mortal as to his body. A great variety of difficulties and seeming contradictions, both in holy fcripture and other writings, may be solved and explained in this manner.
This most important question on this subject is this, what is the criterion, or distinguishing mark of truth? how fhall we know when a proposition is really true or false ? there are so many disguises of truth in the world, so many falfe appearances of truth, that some fects have declared there is no possibility of distinguishe ing truth from falfhood, and therefore they have abandoned all pretences to knowledge, and maintained strenuously that knothing is to be known.
The first men of this humour made themselves famous in Greece by the name of Sceptics, that is, Seekers : they were also called Academics, borrowing their name from academia, their school or place of study. They taught that all things are uncertain, though they allowed that some are more probable than others. After there arose the fect of Pyrrhonics, named from Pyrrho their master, who would not allowione
proposition to be more probable than another ; but profeffed that all things were equally uncertain. Now all these men (as an ingenious author expresses it) were rather to be called a sect of liars than philofophers, and that cenfure is just for two reasons. (L.) because they determined concerning every proposition that it was uncertain, and believed that as a certain truth, while they profeffèd there was nothing certain, and that nothing could be determined concerning truth or falfhood; and thus their very doctrine gave itself the lie. (2). Be. cause they judged and acted as other men did in the common affairs of life; they would neither run into fire nor water, though they profeffed ignorance and uncertainty, whether the one would burn or the other drown them.
There have been some in all ages, who have too much affected this humour, who dispute against every thing, under pretence that truth has no certain mark to distinguish it. Let us therefore inquire, what is the general criterion of truth ? and in order to this, it is proper to consider what is the reason why we affent to those propositions, which contain the most certain and indubitable truths, such as these, the whole is, greater than a part ; two and three make five.
The only reason why we believe those propositions. to be trur, is because the ideas of the subject and predicates appear with so much clearness and strength of evidence to agree to each other, that the mind cannct help discerning the agreement, and cannot doubt of the truth of them, but is constrained to judge them true. So when we compare the ideas of a circle and a triangle, or the ideas of an oyster and a butterfly, we see such an evident disagreement between them, that we are sure that the butterfly is not an oysterį nor is a triangle a circle. There is nothing but the evidence of the agreement, or disagreement between two ideas, that make us affirm or deny the one or the other.
Now it will follow from thence that a clear and dis. tinct perception or full evidence of the agreement and disagreement of our ideas to one another, or to things, is a certain criterion of truth : for fince our minds and sof such a make, that where the evidence is exceeding