Teaching Christianity
greatest value in penetrating and solving all kinds of problems which crop up in the holy literature. All that one has to be on guard against here is a passion for wrangling and a kind of childish parade of getting the better of one's opponents. There are, after all, many forms of argument called sophisms, false conclusions from reason which frequently look so like true ones that they can deceive not only the slow-witted but even sharp minds, when they are not paying careful attention. Thus someone put this proposition to the person he was talking to: "You are not what I am." And the other agreed; it was true after all, at least to this extent that one of them was crafty, the other simple. Then the first one added, "But I am human." When the other allowed this too, he concluded, "Therefore you are not human."
Scripture, in my opinion, expresses its detestation of such trickery in argument where it says, Whoever speaks sophistically is hateful (Sir 37:20), though even ways of speaking that do not involve such tricks, but strive for effect by using more flowery and inflated language than befits a serious speaker, are called sophistical.[107]
49. True logical inferences can also lead to false conclusions, which follow from the error of the person one is arguing with; but still these inferences can be drawn by a good and learned person, to shame the one whose error they follow from, and induce him to give up his error, because if he insists on sticking to it, he will necessarily be obliged also to hold the conclusions which he rejects. The apostle, after all, was not drawing true conclusions when he said, Neither has Christ risen again, and that other thing, Our preaching is vain; vain too is your faith (1 Cor 15:13.14), and the rest that followed. These are all absolutely false conclusions, because Christ has risen again, and the preaching of those who proclaimed this was not vain, nor was the faith of those who believed it. But these conclusions validly and truly followed from the premise of those who were saying that there is no resurrection of the dead. But once you repudiate these false conclusions, which would be true if the dead do not rise again, it follows that there will be a resurrection of the dead.
So since there can be true and valid logical inferences from false as well as from true statements, it is easy to learn the rules of true and valid inference in those schools that have nothing to do with the Church. But the truth of the statements themselves has to be established by studying the holy books.[108]
32, 50. These valid rules of logic, however, have not been instituted by human beings, but observed and noted down by them, so that they can either learn or teach them, because they are inscribed in the permanent and divinely instituted rationality of the universe. Just as those, after all, who tell the story of successive ages do not themselves put those ages together, and those who point out the facts of geography, or the natures of animals or plants or stones, are not pointing out things instituted by human beings, and those who show us the stars and their motions are not showing us something instituted by themselves or anybody else; so too the one who says, "When the consequent is false, the antecedent must be false too," is saying something very true, and does not make it to be so himself, but is only pointing out that that is how it is.
This is the rule governing what we have just quoted from the apostle. The antecedent was that there is no resurrection of the dead, which is what those people were saying whose error the apostle wished to demolish. But the necessary consequent upon that antecedent statement, that there is no resurrection of the dead, is, Neither has Christ risen again; but this consequent is false, because Christ has risen again. Therefore the antecedent is also false, that there is no resurrection of the dead; accordingly there is a resurrection of the dead. This can all be put very briefly as follows: If there is no resurrection of the dead, then neither has Christ risen again; but Christ has risen again; therefore there is a resurrection of the dead.
So this rule, that if you deny the consequent you must necessarily deny the antecedent, was not instituted by human beings, but demonstrated. And it belongs to the truth or validity of logical inferences, not to the truth of propositions.
33, 51. But when we are dealing with this case of the resurrection, we find that both the rule about logical inference and the final conclusion are true. But with false propositions,[109] the truth of this rule of logic works like this. Let us suppose someone has conceded: "If a snail is an animal, it has a voice." Once this is conceded, and it is then proved that a snail does not have a voice, the conclusion follows that a snail is not an animal, because when you deny the consequent, you must necessarily deny the antecedent. This conclusion is a false statement, but it follows by a true logical inference from a falsehood that has been conceded. And so the truth of a statement or proposition stands on its own merits; but the truth of the logical inference[110] stands or falls with the opinion of the person one is dealing with, or of the point he has conceded.
The reason, though, why an inference is truly drawn that is in itself false is, as we said above, to make the person whose error we wish to correct be sorry for having maintained the antecedent, when he sees that its consequent has to be rejected. From all this it will now be easy to understand how, just as you can have true conclusions in false propositions, so too it is possible to have false conclusions in true propositions. Thus suppose someone has made the proposition, "If this man is just, he is good," and it has been conceded; and then that he has added the minor premise, "but he is not just"; and that when this has been granted too, he has drawn the conclusion, "therefore he is not good." Here, even though all the statements may be true, it is for all that not a truly or validly drawn conclusion. It is not, you see, the case that in the same way as when you deny the consequent you have to deny the antecedent, so when you deny the antecedent you have to deny the consequent. Because it is true when we say, "If he is an orator, he is a human being"; but if we then deny the first part of this proposition and say, "But he is not an orator," it will not be a true consequent, when you infer, "Therefore he is not a human being."
34, 52. That is why it is one thing to know the rules of logical relationships, another to know the truth of statements and propositions. The first involves learning what the meaning is of "consequent," "non-consequent," "repugnant." "If he is an orator, he is a human being" is a consequent proposition; "If he is a human being, he is an orator" is an inconsequent one, a non sequitur; "If he is a human being, he is a quadruped" is a repugnant one. So here a judgment is being made about the logical inference or relationship. As regards the truth of statements or propositions, on the other hand, it is the statements in themselves, not their logical relationships that have to be considered. But when uncertain statements are joined to true and certain ones in valid logical relationships, they themselves are bound also to become certain.
But some people are so proud of themselves when they have grasped the truth of logical relationships that they think it is the truth of the statements themselves. And again there are some who hold onto the truth of a statement, but belittle themselves because they are ignorant of the laws of inference, though surely the person who knows that there is a resurrection of the dead is superior to the one who knows that it is a consequent proposition, that if there is no resurrection of the dead, then neither has Christ risen again.
35, 53. Again, although knowledge of how to define terms, to distinguish and distribute them, is often applied to false matters, it is not for all that false in itself, nor was it instituted by human beings, but discovered in the very nature and intelligibility of things. Yes, of course, the poets have been in the habit of applying it in telling their fanciful tales and voicing their erroneous opinions, and so have false philosophers and even heretics, that is to say false Christians; but this does not mean that it is false that the art of defining, distinguishing and distributing enables one to exclude irrelevant material, and also not to overlook matters that are relevant to the subject. This is true, even if the points that are defined and distributed are not true.
After all, we even define falsehood itself, when we say that falsehood means the signification of something that is not in fact as it is signified, or give some similar definition; and the definition is true, though falsehood cannot possibly be true. We can also distinguish it and say there are two kinds of falsehood, one asserting things that could not possibly be true, the other asserting things that are not true, though they could be. Thus if you say that seven and three make eleven, you are saying what cannot possibly be true, while if you say, for example, that it rained on January 1, although in fact it did not, you are still saying something that could have happened. So the definition and distinction of falsehoods can be very true, although the falsehoods themselves, of course, cannot be true.
36, 54. There are also rules governing a more copious, elegant style of discourse, which is called eloquence, and these rules are true, even though falsehoods can be persuasively put across by means of them;[111] but because the truth also can be, it is not this capacity that is blameworthy, but the crookedness of those who make bad use of it. Because here too it was no human institution that decided that the expression of esteem would win over an audience, or that a short, clear description would put across what the speaker intends, and that variety of expression would hold the attention of his hearers without boring them. And there are all the other little rules which are still true, whether applied in the cause of falsehood or of truth, insofar as they ensure something is known or believed, or as they move people's hearts to seek or to shun things; and they have been found to be effective like this, rather than instituted in order to be effective like this.
37, 55. But when this subject is learned, it is meant to be applied not so much to understanding things, as to putting across what we have understood, while that other one about conclusions and definitions and distinctions is of the greatest help to us in understanding things, provided only the error is avoided, which leads people to think that when they have learned these things, they have learned the truth about the happy life.[112] It freqently happens, however, that people find it easier to attain those objects for the attainment of which these things are learned, than to master the knotty and thorny discipline of such rules.[113]
It's rather as if someone wishing to give you rules about how to walk were to warn you not to lift the back foot until you have put down the front one, and then were to describe in detail the right way of moving the joints of your limbs and knees. Well, what he is saying is true, and there is no other way to walk. But people find it much easier to walk by doing these things than to notice them when they do them, and to understand when they are told about them. Those, however, who cannot walk are much less interested in such prescriptions, which they are quite unable to test by experience. In the same way a bright person will often see that a conclusion is invalid much sooner than he will grasp the rules that make it so, while someone who is slow on the uptake will not see this, but still will be much less able to grasp those rules.
And often from these rules of logic and discourse we get more pleasure at the spectacle of truth at work than help