LESSON 6

Four Senses of the Term Necessary. Its First and Proper Sense Immobile Things, though Necessary, Are Exempted from Force

Chapter 5: 1015a 20-1015b 15

             416. Necessary means that without which, as a contributing cause, a thing cannot be or live; for example, breathing and food are necessary to an animal because it cannot exist without them.

             417. And it also means that without which the good for man cannot be or come to be, and that without which one cannot get rid of or remain free of some evil; for example, the drinking of some drug is necessary in order that one may not be in distress, and sailing to Aegina is necessary in order that one may collect money.

             418. Again, it means what applies force and force itself, and this is something which hinders and prevents, in opposition to desire and choice. For that which applies force is said to be necessary, and for this reason anything necessary is also said to be lamentable, as Evenus says, "For every necessary thing is mournful." And force is a kind of necessity, as Sophocles says, "But force compels me to do this." And necessity seems to be something blameless, and rightly so, for it is contrary to motion which stems from choice and from knowledge.

             419. Again, we say that anything which cannot be otherwise is necessarily so.

             420. And from this sense of the term necessary all the other senses are derived. For whatever is forced is said either to do or to undergo something necessary when it cannot do something according to its inclination as a result of force, as if there were some necessity by reason of which the thing could not be otherwise. The same thing applies to the contributing causes of life and of good. For when in the one case good, and in the other life or being, is impossible without certain contributing causes, these are necessary; and this cause is a kind of necessity.

             421. Further, demonstration belongs to the class of necessary things, because whatever has been demonstrated in the strict sense cannot be otherwise. The reason for this is the principles, for the principles from which a syllogism proceeds cannot be otherwise.

             422. Now of necessary things some have something else as the cause of their necessity and others do not, but it is because of them that other things are necessary. Hence what is necessary in the primary and proper sense is what is simple, for this cannot be in more ways than one. Therefore it cannot be in one state and in another; otherwise there would be more ways than one. If, then, there are any beings which are eternal and immobile, in them nothing forced or contrary to nature is found.

COMMENTARY

             827. Having distinguished the different senses of the terms which signify causes, the Philosopher now gives the different senses of a term which designates something pertaining to the notion of cause, i.e., the term necessary; for a cause is that from which something else follows of necessity. In regard to this he does two things. First (416:C 827), he distinguishes the different senses of the term necessary. Second (420:C 836), he reduces all of these to one primary sense ("And from this sense").

             In the first part (416) he gives four senses in which the term necessary is used. First, it means that without which a thing cannot be or live; and even when this is not the principal cause of a thing, it is still a contributing cause. Breathing, for example, is necessary to an animal which breathes, because it cannot live without this. And while breathing is not the [principal] cause of life, none the less it is still a contributing cause inasmuch as it helps to restore what is lost and prevents the total consumption of moisture, which is a cause of life. Hence things of this kind are said to be necessary because it is impossible for things to exist without them.

             828. And it also means (417).

             Then he gives a second sense in which things are said to be necessary. He says that in a second way those things are said to be necessary without which some good cannot be or come about, or some evil be avoided or expelled. For example, we say that "the drinking of some drug," i.e., a laxative medicine, is necessary, not because an animal cannot live without it, but because it is required to expel something, namely, an evil, illness, or even to avoid it. For this is necessary "in order that one may not be in distress," i.e., to avoid being ill. And similarly "sailing to Aegina," i.e., to a definite place, is necessary, not because a man cannot exist without this, but because he cannot acquire some good, i.e., money, without doing this. Hence, such a voyage is said to be necessary in order to collect a sum of money.

             829. Again, it means (418).

             Here he gives a third sense in which things are said to be necessary. He says that anything which exerts force, and even force itself, is termed necessary. For force is said to be necessary, and one who is forced is said to do of necessity whatever he is compelled to do. He shows what is meant by something that exerts force both in the case of natural beings and in that of beings endowed with will. In natural beings there is a desire for or an inclination toward some end or goal, to which the will of a rational nature corresponds; and for this reason a natural inclination is itself called an appetite. For both of these, i.e., both the desire of a natural inclination and the intention of the will, can be hindered and prevented--hindered in carrying out a motion already begun, and prevented from initiating motion. Therefore, that is said to be forced "which is done in opposition to desire," i.e., against the inclination of a natural being; and it is "something that hinders choice," i.e., the end intended in executing a voluntary motion already begun, and also something that prevents it from beginning. Another text says, "and this is according to impetuousness," i.e., according to impulse. For force is found when something is done through the impulse of an external agent and is opposed to the will and power of the subject. And that is forced which is done as a result of an impulse applying force.

             830. Now from this definition of the forced he draws two conclusions. The first is that everything forced is sad or mournful. He proves this by using the statement of a certain poet or teacher, saying that everything which is necessary or forced is sad or lamentable; for force is a kind of necessity, as the poet Sophocles says: "Force," i.e., necessity, "compelled me to do this." For it has been said (418:C 829) that force is something which hinders the will; and things which are opposed to the will cause sorrow, because sorrow has to do with things which happen to us against our will.

             831. The second conclusion is that anything which is necessary is rightly said to be without blame or reproach. For it is said that necessity deserves forgiveness rather than blame; and this is true because we deserve to be blamed only for the things which we do voluntarily and for which we may also be reasonably rebuked. But the kind of necessity which pertains to force is opposed to the will and to reason, as has been stated (418:C 829); and thus it is more reasonable to say that things done by force are not subject to blame.

             832. Again, we say (419).

             He gives a fourth sense in which things are said to be necessary. He says that being in such a state that it cannot be otherwise we also call necessary, and this is what is necessary in an absolute sense. Things necessary in the first senses, however, are necessary in a relative sense.

             833. Now whatever is absolutely necessary differs from the other types of necessity, because absolute necessity belongs to a thing by reason of something that is intimately and closely connected with it, whether it be the form or the matter or the very essence of a thing. For example, we say that an animal is necessarily corruptible because this is a natural result of its matter inasmuch as it is composed of contraries; and we say that an animal is necessarily capable of sensing because this is a result of its form; and we also say that an animal is necessarily a living sensible substance because this is its essence.

             834. However, the necessity of something which is necessary in a relative sense and not absolutely depends on an extrinsic cause. And there are two kinds of extrinsic causes--the end and the agent. The end is either existence taken absolutely, and the necessity taken from this end pertains to the first kind; or it is well disposed existence or the possession of some good and necessity of the second kind is taken from this end.

             835. Again, the necessity which comes from an external agent pertains to the third kind of necessity. For force exists when a thing is moved by an external agent to something which it has no aptitude for by its own nature. For if something is disposed by its own nature to receive motion from an external agent, such motion will not be forced but natural. This is evident in the motion of the celestial bodies by separate substances, and in that of lower bodies by higher ones.

             836. And from this (420).

             Here he reduces all of the senses in which things are necessary to one; and in regard to this he does three things. First (420:C 836), he shows that all the types of necessity found in reality pertain to this last type. Second (421:C 838), he shows that necessity in matters of demonstration is taken in this last sense ("Further, demonstration"). Third (422:C 839), he draws a corollary from what has been set down above ("Now of necessary things").

             He accordingly says, first (420), that all the other senses of the term necessary are somehow referred to this last sense. He makes this clear, first, with reference to the third way in which things are said to be necessary. For whatever is forced is said to do or to undergo something of necessity on the grounds that it cannot act through its own power because of the force exerted on it by an agent; and this is a kind of necessity by which it cannot be otherwise than it is.

             837. Then he shows that the same thing is true of the first and second ways in which things are said to be necessary: in the first way with reference to the causes of living and being absolutely, and in the second with reference to the causes of good. For the term necessary was so used in these other ways: in one way to designate that without which a thing cannot be well off, and in the other to designate that without which a thing cannot live or exist. Hence that cause without which a thing cannot live or exist or possess a good or avoid an evil is said to be necessary; the supposition being that the primary notion of the necessary derives from the fact that something cannot be otherwise.

             838. Further, demonstration (421).

             Then he shows that the necessary in matters of demonstration is taken from this last sense, and this applied both to principles and to conclusions. For demonstration is said to be about necessary things, and to proceed from necessary things. It is said to be about necessary things because what is demonstrated in the strict sense cannot be otherwise. He says "demonstrated in the strict sense" in order to distinguish this from what is demonstrated by the kind of demonstration which refutes an opponent, and does not strictly demonstrate. In the fourth book (331:C 609) he called this an ad hominem argument. In demonstrations of this kind which refute an opponent we conclude to the impossible from certain impossible premises. But since in demonstrations the premises are the causes of the conclusion, for demonstrations in the strict sense are productive of science and this is had only by way of a cause, the principles from which a syllogism proceeds must also be necessary and thus cannot be otherwise than they are. For a necessary effect cannot come from a non-necessary cause.

             839. Now of necessary things (422).

             Here he draws three conclusions from the points set down above, one of which follows from the other. The first is that, since in demonstrations the premises are the causes of the conclusion and both of these are necessary, it follows that some things are necessary in one of two ways. For there are some things whose necessity is caused by something else, and there are others whose necessity has no cause; and such things are necessary of themselves. This is said against Democritus, who claimed that we must not look for the causes of necessary things, as is stated in Book VIII of the Physics.

             840. The second conclusion is that, since there must be one first necessary being from which other beings derive their necessity (for there cannot be an infinite regress in causes, as was shown in the second book [152:C 301]), this first necessary being, which is also necessary in the most proper sense because it is necessary in all ways, must be simple. For composite things are changeable and thus can be in more ways than one. But things which can be in more ways than one can be now in one way and now in another, and this is opposed to the notion of necessity; for that is necessary which cannot be otherwise. Hence the first necessary being must not be now in one way and now in another, and consequently cannot be in more ways than one. Thus he must be simple.

             841. The third conclusion is that, since the forced is something which is moved by an external agent in opposition to its own nature, and necessary principles are simple and unchangeable, as has been shown (422:C 840), therefore if there are certain eternal and unchangeable beings, as the separate substances are, in them there must be nothing forced or contrary to their nature. He says this lest a mistake should be made in the case of the term necessity, since it is predicated of immaterial substances without implying on this account that anything forced is found in them.