Part II, Chapter 5: Of Simple and Compound Propositions
WE have said that every proposition ought to have a subject and an attribute; but it does not hence follow that it may not have more than one attribute. Those, therefore, which have, only one subject and one attribute, are called simple, and those which have more than one subject, or more than one attribute, are called compound, as when I say—" Good and evil, life and death, poverty and riches, come from the Lord”—that attribute, come from the Lord, is affirmed, not of one subject alone, but of many, to wit, of good and evil, &c.
But before explaining these compound propositions, it must be remarked there are some which appear to be so, which are, nevertheless, simple; for the simplicity of a proposition is derived from the unity of subject and attribute. Now, there are many propositions which have, properly, only one subject and one attribute, but whose subject or attribute, is a complex term, containing other propositions, which may be called incidental, which constitute only a part of the subject, or attribute, being joined by the relative pronoun who, which, whose property it is to join together many propositions so that they compose only one.
Thus when Jesus Christ says,—" He that doth the will of my Father which is in heaven, shall enter into the kingdom of heaven,”—the subject of this proposition contains two propositions, since it comprehends two verbs; but as they are joined together by who, they constitute only a part of the subject; whereas, when I say—good and evil come from the Lord—there is, properly, two subjects, since I affirm equally of the one and of the other that they come from God.
And the reason of this is, that propositions joined to others by who or which, are either propositions which are only very imperfect, as will be shown further on, or are not so much considered as propositions which we then make, but as propositions which have been made before, and which we then only conceive of as though they were simple ideas. Whence it happens that it is indifferent whether we announce these propositions by adjective nouns, or by participles without verbs, and without the relative pronoun (who, which) or with verbs and the relative pronoun; for it is the same to say—The invisible God created the visible world; Alexander, the most generous of all kings, conquered Darius. And, in either case, my principal aim is not to affirm that God is invisible, or that Alexander was the most generous of kings; but, supposing each as declared before, I affirm of God, conceived as invisible, that he created the visible world; and of Alexander, conceived as generous, that he conquered Darius.
But if I were to say—Alexander was the most qenerous of all kings, and the conqueror of Darius, it is clear that I should affirm equally of Alexander, both that he was the most generous of all kings, and that he was the conqueror of Darius. And thus it is with reason, that these last kind of propositions are called compound propositions, while the others may be termed complex propositions.
Again, it must be remarked that these complex propositions may be of two kinds, for the complexity may fall either on the matter of the proposition, that is to say, on the subject, or on the attribute, or on both, or on the form only.
1. The complexity falls on the subject when the subject is a complex term, as in this proposition—man who fears nothing is a king: the king is he who fears nothing.
Beatus ille qui procul negotiis, Ut prisca gens mortalium Paterna rura bobus exercet suis, Solutus omni foenore.
For the verb is is understood in this last proposition—beatus is the attribute, and all the rest the subject.
2d, The complexity falls on the attribute when the attribute is a complex term: as, Piety is a good which renders man happy in the greatest adversity.
Sum pius Aeneas, fama super aethera notus.
But it must be particularly noticed here, that all propositions compounded of active verbs and their objects, may be called complex, and contain, in some sort, two propositions. If I say, for example, Brutus killed a tyrant, this means Brutus killed some one, and he whom he killed was a tyrant; whence it happens that this proposition may be contradicted in two ways, either by saying—Brutus killed no one, or by saying that he whom he killed was not a tyrant. It is very important to notice this, because, when these kinds of propositions enter into argument, we sometimes prove only one part of them, and suppose the other, which often makes it necessary to reduce these arguments to a more natural form, by changing the active into the passive, in order that the part which is proved may be expressed directly, as we shall notice more at length in treating of the compound arguments, which arise from these complex propositions.
3d, Sometimes the complexity falls upon both the subject and the attribute: each being a complex term, as in this proposition—the great who oppress the poor will be punished by God, who is the protector of the oppressed.
Ille ego, qui quondam, gracili modulatus avena Carmen, et egressus silvis, vicina coegi Ut quamvis avido, parerent arva colono; Gratum opus agricolis: et nunc horrentia Martis Arma virumque cano, Trojae qui primus ab oris Italiam, fato profugus, Lavinia venit Littora.
The three first verses and a part of the fourth compose the subject of this proposition, the rest of it composes the attribute, and the affirmation is contained in the verb cano.
These are the three ways according to which propositions may be complex, in relation to their matter, that is, in relation to their subject and attribute.