II. CLASSIFICATION OF COMPOSITE PROPOSITIONS

39. Classification of Complex Propositions. -- Rigorously speaking, a composite, or better, a complex, proposition is an enunciation which includes several simple propositions.

The authors of Port-Royal enumerate six types of proposition in which the complexity is manifest, and four in which it is more or less latent: We will define them and establish the conditions of truth in each.

I. The first six are the copulative, disjunctive, conditional, causal, relative and discretive.

(1) The copulative proposition is that which includes many subjects and many attributes joined by an affirmative or negative conjunction, and or nor. This proposition is true only if its parts are true.

(2) Disjunctive propositions state an incompatibility at the same time as an alternative, as: Every free action is morally good or bad.

The condition of truth in these propositions is that the two parts of the disjunction should be mutually opposed and should admit of no middle term.

(3) Conditional propositions consist of two parts connected by if; the first, which contains the condition, is called the antecedent; the second, the consequent. E. g.: If the soul is spiritual (antecedent), it is immortal (consequent).

For the truth of these propositions we have to consider only the truth of the consequence: the falsity of both parts does not hinder the proposition, as a conditional proposition, from being true. E. g.: If the soul of animals were spiritual, it would he immortal.

(4) The causal proposition contains two propositions joined by some word indicating a cause -- because, etc.

Reduplicative propositions also belong to this class. E. g.: Evil, as such, is not the object of the will.

For the truth of these propositions it is not enough that the two parts should be true; one part must also be the real cause of the other.

(3) Relative propositions express a connection. E. g.: As the life so is the death.

Their truth depends on the correctness of the connection.

(6) Adversative, or discretive, propositions include several different judgments separated by some such particle as but, yet, nevertheless, etc. E. g.: Not on riches, but on virtue, depends happiness.

The truth of these propositions depends on the truth of their parts and of the opposition between them.

II. Four types of apparently simple, but really complex, propositions.

(1) Exclusive propositions, which assert that an attribute belongs to but one subject, as: God alone is to be loved for Himself.

(2) Exceptive propositions affirm an attribute of a subject, but with the exception of some subdivisions of that subject. E. g.: Excess is possible in all the virtues except in the love of God.

(3) Comparative propositions say not only that a thing is so, but that it is more so or less so than some other thing. E. g.: Wisdom is more valuable than fortune.

(4) Inceptive, or desitive, propositions assert that a thing has commenced or ceased to be so: E. g.: The independence of Belgium dates from 1830.

Each of these four propositions really includes two judgments; it is not true unless the two parts are true.