LESSON 17

Rejection of the Opinions that Everything Is True and False, and that Everything Is at Rest and in Motion

Chapter 8: 1012a 29-1012b 31

             393. With these points settled it is evident that the theories which have been expressed univocally and about all things cannot be true as some affirm them to be. Now some say that nothing is true (for they say that there is nothing to prevent all statements from being like the statement that the diagonal of a square is commensurable with one of its sides), and others say that everything is true. These views are almost the same as that of Heraclitus; for he who says that all things are true and all false admits both views apart from his own words. Hence, if those are impossible, these also must be impossible.

             394. Further, it is evident that there are contradictories which cannot be true at the same time. Nor can they all be false, though this would seem more possible from what has been said.

             395. But in opposing all such views it is necessary to postulate, as has been stated in the above discussion (332), not that something is or is not, but that a word signifies something. Hence it is necessary to argue from a definition, once we have accepted what truth and falsity mean. But if to say what is true is merely to deny what is false, not everything can be false. For one part of a contradiction must be true.

             396. Again, if everything must be either affirmed or denied, both cannot be false; for one part of a contradiction is false.

             397. And the view commonly expressed applies to all such theories--they destroy themselves; for he who says that everything is true makes the contrary of his own statement true, and thus makes his own not true; for the contrary denies that it is true. And he who says that everything is false makes his own statement false. But if the former makes an exception of the contrary statement, saying that it alone is not true, and the latter makes an exception of his own statement, saying that it is not false, still they will have to consider the truth and falsity of an infinite number of statements. For he who says that a true statement is true is right; and this process will go on to infinity.

             398. Now it is evident that those who say that all things are at rest do not speak the truth, and neither do those who say that all things are in motion.

             399. For if all things are at rest, the same thing will always be true and false; but this seems to be something that changes, for he who makes a statement at one time was not and again will not be.

             400. And if all things are in motion, nothing will be true, and so everything will be false. But it has been shown that this is impossible.

             401. Further, it must be some being which is changed; for change is from something to something.

             402. But it is not true that all things are at rest or in motion sometimes, and nothing always; for there is something which always moves the things that are being moved, and the first mover is itself immovable.

COMMENTARY

             736. He argues dialectically against certain positions which stem from those mentioned above. First (393:C 736), he argues against certain men who destroy the principles of logic; and second (398:C 744), against certain men who destroy the principles of natural philosophy ("Now it is evident").

             For first philosophy should argue dialectically against those who deny the principles of the particular sciences, because all principles are based on the principle that an affirmation and a negation are not true at the same time, and that there is no intermediate between them. Now these principles are the most specific principles of this science, since they depend on the concept of being, which is the primary subject of this branch of philosophy. But the true and the false belong specifically to the study of logic; for they depend on the kind of being which is found in the mind, with which logic deals; for truth and falsity exist in the mind, as is stated in Book VI of this work (558:C 1231). Motion and rest, on the other hand, belong properly to the study of natural philosophy, because nature is defined as a principle of motion and of rest. Now the error made about truth and falsity is a result of the error made about being and nonbeing, for truth and falsity are defined by means of being and non-being, as has been said above. For there is truth when one says that what is, is, or that what is not, is not; and falsity is defined in the opposite way. And similarly the error made about rest and motion is a result of the error made about being and non-being; for what is in motion as such does not yet exist, whereas what is at rest already is. Hence, when the errors made about being and non-being have been removed, the errors made about truth and falsity and rest and motion will then also be removed.

             737. Regarding the first part of this division he does two things. First (393:C 737), he gives the erroneous opinions about truth and falsity. Second (394:C 739), he criticizes these opinions ("Further, it is evident").

             Thus he says (393) that, "with these points settled," i.e., with the foregoing points established which have to be used against the paradoxical positions mentioned above, it is obviously impossible that the views of some men should be true, namely, that we must form an opinion "univocally," i.e., think in the same way, about all things, so that we should say that all things are equally true or equally false. For some thinkers said that nothing is true but everything false, and that there is nothing to prevent us from saying that all statements are just as false as the statement (which is false) that the diameter of a square is commensurate with one of its sides. But others have said that all things are true. Statements of the latter kind are a result of the opinion of Heraclitus, as has been pointed out (362:C 684); for he said that a thing is and is not at the same time, and from this it follows that everything is true.

             738. And lest perhaps someone might say that besides these opinions there is also a third one, which states that everything is both true and false at the same time, he replies, as though meeting a tacit objection, that anyone who maintains this opinion also maintains both of the foregoing ones. Hence, if the first two opinions are impossible, the third must also be impossible.

             739. Further, it is evident (394).

             Then he presents arguments against the foregoing opinions, and the first of these is as follows: it is evident that there are certain contradictories which cannot be true at the same time or false at the same time, for example, the true and not-true, being and non-being. This can be better understood from what has been said. Therefore, if one of these two contradictories must be false and the other true, not all things can be true or all false.

             740. But in opposing (395).

             He gives the second argument. He says that in opposing "these views," or positions, "it is necessary to postulate," or request, not that someone should admit that something either is or is not in reality, as has been stated above (332:C 611), because this seems to be begging the question, but that he should admit that a word signifies something. Now if this is not granted, the dispute comes to an end; but if it is granted, it is then necessary to give definitions, as has already been stated above (332:C 611). Hence we must argue against these thinkers by proceeding from definitions, and in the case of the present thesis we must do this especially by considering the definition of falsity. Now if truth consists merely in affirming what it is false to deny, and vice versa, it follows that not all statements can be false, because either the affirmation or the negation of something must be true. For obviously truth consists simply in saying that what is, is, or in saying that what is not, is not; and falsity consists in saying that what is, is not, or in saying that what is not, is. Hence it is clear that it is true to say that that is of which it is false that it is not, or to say that that is not of which it is false that it is; and it is false to say that that is of which it is true that it is not, or to say that that is not of which it is true that it is. Thus from the definition of truth and falsity it is clear that not all things are false. And for the same reason it is clear that not all things are true.

             741. Again, if everything (396).

             Here he gives the third argument, which runs thus: it is clear from what has been said above that we must either affirm or deny something of each thing since there is no intermediate between contradictories. It is impossible, then, for everything to be false. And by the same reasoning it is proved that it is impossible for everything to be true, i.e., by reason of the fact that it is impossible both to affirm and to deny something at the same time.

             742. And the view (397).

             He gives the fourth argument: all of the foregoing statements, or opinions, face this unreasonable result--they destroy themselves. This is "the view commonly expressed," i.e., a frequently heard statement made by all; and thus another text says, "It happens that it is commonly held." He proves this view as follows: anyone who says that everything is true makes the contrary of his own opinion true. But the contrary of his own opinion is that his own opinion is not true. Therefore he who says that everything is true says that his own opinion is not true; and thus he destroys his own opinion. Similarly it is evident that he who says that everything is false also says that his own opinion is false.

             743. And because someone could say that he who claims that everything is true makes an exception of the one contrary to his own statement, or bars it from what holds universally (and the same thing applies to one who says that everything is false), he therefore rejects this answer. He says that, if the one who says that everything is true makes his own contrary opinion an exception, saying that it alone is not true, and if the one who says that everything is false makes his own opinion an exception, saying that it alone is not false, none the less it follows that they will be able "to consider," or bring forward, an infinite number of true statements against those who hold that all are false, and an infinite number of false statements against those who hold that all are true. For granted that one opinion is true, it follows that an infinite number are true. And granted that one opinion is false, it follows that an infinite number are false. For if the position, or opinion, that Socrates is sitting is true, then the opinion that it is true that Socrates is sitting will also be true, and so on to infinity. For he who says that a true statement is true is always right; and he who says that a false statement is true is always wrong; and this can proceed to infinity.

             744. Now it is (398).

             He argues against those who destroy the principles of nature, i.e., motion and rest, and in regard to this he does three things.

             First, he mentions the falsity of these opinions, saying that it is evident, from what has been said above, that neither the opinion which states that everything is in motion, nor the one which states that everything is at rest, is true.

             745. For if all things (399).

             Second, he shows that these opinions are false. First of all he shows that the opinion which holds that everything is at rest is false; for if everything were at rest, nothing would then be changed from the state in which it sometimes is. Hence, whatever is true would always be true, and whatever is false would always be false. But this seems to be absurd; for the truth and falsity of a proposition is changeable. Nor is this to be wondered at, because the man who has an opinion or makes a statement at one time was not and now is and again will not be.

             746. Second, he uses two arguments to show that the opinion which holds that all things are in motion is false. He gives the first (400) where he says, "And if all things." It is as follows. If all things are in motion and nothing is at rest, nothing will be true in the world; for what is true already exists, but what is in motion does not yet exist. Hence everything must be false. But this is impossible, as has been shown (395:C 740).

             747. Further, it must be (401).

             He gives the second argument, and it runs thus: everything that is undergoing change is necessarily a being, because everything that is being changed is being changed from something to something else, and everything that is being changed in something else belongs to the subject that is undergoing change. Hence it is not necessary to say that everything in the subject undergoing change is being changed, but that there is something which remains. Hence not everything is in motion.

             748. But it is not (402).

             He gives the third argument, and it disposes of a false opinion which could arise from what has been said above. For, since not all things are in motion nor all at rest, someone could therefore think that all things are sometimes in motion and sometimes at rest. In disposing of this opinion he says that, it is not true that all things are sometimes in motion and sometimes at rest, for there are certain movable things which are always being moved, namely, the celestial bodies above us, and there is a mover, namely, the first, which is always immovable and ever in the same state, as has been proved in Book VIII of the Physics.