NECESSITY AND CAUSALITY.
NECESSITY.
1. Beings are divided into two c∞∞lasses: necessary and contingent; necessary being is that which cannot but be; contingent is that which may be and cease to be. In these definitions every thing is said; but their laconism does not permit all that is expressed in them to be easily understood. Necessity and contingency may refer to different aspects and give rise to very diverse considerations. This makes a careful analysis of the ideas expressed by them necessary.
2. What is meant by necessity? In general that is called necessary which cannot but be; but the expressioncannot, may be taken in different senses: in a moral sense, as when we say: I cannot but fulfil this duty; in a physical, as in this proposition; a paralytic cannot move himself; and in a metaphysical sense, as: A triangle cannot be a quadrilateral. In the first example, the obstacle is founded on a law; in the second, it arises from nature; in the third, it follows from the essence of the things. In all these suppositions, necessity implies the impossibility of the contrary, and this impossibility results from the necessity.
3. Hence it follows that the ideas necessity and impossibility are correlative, and that is metaphysically necessary whose opposite is metaphysically impossible. Impossibility consists in the exclusion of one thing by another; thus, "a circular triangle is impossible," means the same as "thenature of a triangle excludes the nature of a circle." In all impossibility, therefore, there is a term denied; as in all necessity there is a term affirmed; the metaphysically necessary is that whose opposite is contradictory; the existence of the absurd is impossible, the non-existence of the necessary is absurd. It is contradictory for a triangle to have four sides; and it is absurd for a triangle not to have three angles.
4. In the purely ideal order we see many necessities without any relation to existence; such are all geometrical truths. Even in the real order we conceive many hypothetical necessities in contingent beings: such are those which are obtained by applying absolute principles to any hypothesis furnished by experience. The principle of contradiction serves in an infinity of cases to found a certain necessity even in contingent beings. There is no absolute necessity of the existence of extended beings; but on the supposition that they exist, it is necessary for them to have the properties proceeding from extension.
5. In no finite being can there be an absolute necessity; the only necessity which it can have is hypothetical. The relation of its essential attributes is necessary; but, as its essence does not exist necessarily, whatever is necessary in it is so only hypothetically, that is, on the supposition that it exists.
6. We must then distinguish two necessities: one absolute, the other hypothetical. The latter relates to the essences of things, abstracting their existence, although implying it as a condition, and supposing another necessary as the ground of its possibility;[72]the former relates to the existence of the thing. The absolutely necessary is that whose existence is absolutely necessary.
7. The essence of the necessary being must contain existence; its idea must involve the idea of existence, not only logical and conceptual, but also realized.
8. We can conceive the existence of the necessary being distinct from its essence, but the reason of this is in the imperfection of the idea, which with us is not intuitive, but discursive; and consequently, we can distinguish between the logical order and the real order.
Here we find the defect of Descartes' argument by which he pretends to demonstrate the existence of God from the fact that the predicate, existence, is included in the idea of a necessary and infinite being. The idea of necessary being involves existence, but not real existence, only logical and conceptual; since after we have the idea of the necessary being, it still remains to be proved that there is an object which corresponds to this idea; the predicate belongs to the subject according to the manner in which the subject is taken, and as this is only in the purely ideal order, the predicate is also purely ideal.
9. The reality of the necessary idea cannot be demonstrated from its idea alone; but it may be demonstrated with complete evidence by introducing into the argument other elements which experience furnishes us.
Something exists; at least ourselves; at least this perception which we have in this act; at least the appearance of this act. I leave aside for the present all the questions disputed between the dogmatists and the skeptics; I only suppose adatumwhich no one can deny me, though he carry skepticism to the utmost exaggeration. When I say that something exists, I only mean to affirm that not every thing is a pure nothing.
If something exists, something has always existed, or there is no moment in which it could be said with truth: there is nothing. If such a moment of universal nothingness had ever been, nothing would now exist, there nevercould have been any thing. Let us imagine a universal and absolute nothingness; I then ask: Is it possible that any thing should come from nothing? Evidently not; therefore on the supposition of universal nothingness reality is absurd.
10. Therefore something has always existed, with a cause, without a condition on which it depends; therefore there is a necessary being. Its existence is supposed always, without relation to any hypothesis; therefore itsnot-beingis always excluded under all conditions; therefore there exists an absolutely necessarybeing, that is, a being whosenot-beingimplies a contradiction.
11. Summing up the doctrine which precedes, we may say:
I. That we have the idea of a necessary being.
II. That we deduce its existence from its idea alone.
III. That in order to demonstrate the existence of a necessary being, it is sufficient to know that something exists.
IV. We know by experience that something exists; for experience presents to us, if nothing else, the existence of our own thought.