Augustine's ON CHRISTIAN DOCTRINE

CHAP. 29.--TO WHAT EXTENT NATURAL SCIENCE IS AN EXEGETICAL AID.

45. There is also a species of narrative resembling description, in which not a past but an existing state of things is made known to those who are ignorant of it. To this species belongs all that has been written about the situation of places, and the nature of animals, trees, herbs, stones, and other bodies. And of this species I have treated above, and have shown that this kind of knowledge is serviceable in solving the difficulties of Scripture, not that these objects are to be used conformably to certain signs as nostrums or the instruments of superstition; for that kind of knowledge I have already set aside as distinct from the lawful and free kind now spoken of. For it is one thing to say: If you bruise down this herb and drink it, it will remove the pain from your stomach; and another to say: If you hang this herb round your neck, it will remove the pain from your stomach. In the former case the wholesome mixture is approved of, in the latter the superstitious charm is condemned; although indeed, where incantations and invocations and marks are not used, it is frequently doubtful whether the thing that is tied or fixed in any way to the body to cure it, acts by a natural virtue, in which case it may be freely used; or acts by a sort of charm, in which case it becomes the Christian to avoid it the more carefully, the more efficacious it may seem to be. But when the reason why a thing is of virtue does not appear, the intention with which it is used is of great importance, at least in healing or in tempering bodies, whether in medicine or in agriculture.

46. The knowledge of the stars, again, is not a matter of narration, but of description. Very few of these, however, are mentioned in Scripture. And as the course of the moon, which is regularly employed in reference to celebrating the anniversary of our Lord's passion, is known to most people; so the rising and setting and other movements of the rest of the heavenly bodies are thoroughly known to very few. And this knowledge, although in itself it involves no superstition, renders very little, indeed almost no assistance, in the interpretation of Holy Scripture, and by engaging the attention unprofitably is a hindrance rather; and as it is closely related to the very pernicious error of the diviners of the fates, it is more convenient and becoming to neglect it. It involves, moreover, in addition to a description of the present state of things, something like a narrative of the past also; because one may go back from the present position and motion of the stars, and trace by rule their past movements. It involves also regular anticipations of the future, not in the way of forebodings and omens, but by way of sure calculation; not with the design of drawing any information from them as to our own acts and fates, in the absurd fashion of the genethliaci, but only as to the motions of the heavenly bodies themselves. For, as the man who computes the moon's age can tell, when he has found out her age today, what her age was any number of years ago, or what will be her age any number of years hence, in just the same way men who are skilled in such computations are accustomed to answer like questions about every one of the heavenly bodies. And I have stated what my views are about all this knowledge, so far as regards its utility.

CHAP. 30.--WHAT THE MECHANICAL ARTS CONTRIBUTE TO EXEGETICS.

47. Further, as to the remaining arts, whether those by which something is made which, when the effort of the workman is over, remains as a result of his work, as, for example, a house, a bench, a dish, and other things of that kind; or those which, so to speak, assist God in His operations, as medicine, and agriculture, and navigation: or those whose sole result is an action, as dancing, and racing, and wrestling;--in all these arts experience teaches us to infer the future from the past. For no man who is skilled in any of these arts moves his limbs in any operation without connecting the memory of the past with the expectation of the future. Now of these arts a very superficial and cursory knowledge is to be acquired, not with a view to practising them (unless some duty compel us, a matter on which I do not touch at present), but with a view to forming a judgment about them, that we may not be wholly ignorant of what Scripture means to convey when it employs figures of speech derived from these arts.

CHAP. 31.--USE OF DIALECTICS. OF FALLACIES.

48. There remain those branches of knowledge which pertain not to the bodily senses, but to the intellect, among which the science of reasoning and that of number are the chief. The science of reasoning is of very great service in searching into and unravelling all sorts of questions that come up in Scripture, only in the use of it we must guard against the love of wrangling, and the childish vanity of entrapping an adversary. For there are many of what are called solphisms, inferences in reasoning that are false, and yet so close an imitation of the true, as to deceive not only dull people, but clever men too, when they are not on their guard. For example, one man lays before another with whom he is talking, the proposition, "What I am, you are not." The other assents, for the proposition is in part true, the one man being cunning and the other simple. Then the first speaker adds: "I am a man;" and when the other has given his assent to this also, the first draws his conclusion: "Then you are not a man. "' Now of this sort of ensnaring arguments, Scripture, as I judge, expresses detestation in that place where it is said, "There is one that showeth wisdom in words, and is hated;"(1) although, indeed, a style of speech which is not intended to entrap, but only aims at verbal ornamentation more than is consistent with seriousness of purpose, is also called sophistical.

49. There are also valid processes of reasoning which lead to false conclusions, by following out to its logical consequences the error of the man with whom one is arguing; and these conclusions are sometimes drawn by a good and learned man, with the object of making the person from whose error these consequences result, feel ashamed of them and of thus leading him to give up his error when he finds that if he wishes to retain his old opinion, he must of necessity also hold other opinions which he condemns. For example, the apostle did not draw true conclusions when he said, "Then is Christ not risen," and again, "Then is our preaching vain, and your faith is also vain;"(1) and further on drew other inferences which are all utterly false; for Christ has risen, the preaching of those who declared this fact was not in vain, nor was their faith in vain who had believed it. But all these false inferences followed legitimately from the opinion of those who said that there is no resurrection of the dead. These inferences, then, being repudiated as false, it follows that since they would be true if the dead rise not, there will be a resurrection of the dead. As, then, valid conclusions may be drawn not only from true but from false propositions, the laws of valid reasoning may easily be learnt in the schools, outside the pale of the Church. But the truth of propositions must be inquired into in the sacred books of the Church.

CHAP. 32.--VALID LOGICAL SEQUENCE IS NOT DEVISED BUT ONLY OBSERVED BY MAN.

50. And yet the validity of logical sequences is not a thing devised by men, but is observed and noted by them that they may be able to learn and teach it; for it exists eternally in the reason of things, and has its origin with God. For as the man who narrates the order of events does not himself create that order; and as he who describes the situations of places, or the natures of animals, or roots, or minerals, does not describe arrangements of man; and as he who points out the stars and their movements does not point out anything that he himself or any other man has ordained;--in the same way, he who says, "When the consequent is false, the antecedent must also be false," says what is most true; but he does not himself make it so, he only points out that it is so. And it is upon this rule that the reasoning I have quoted from the Apostle Paul proceeds. For the antecedent is, "There is no resurrection of the dead,"--the position taken up by those whose error the apostle wished to overthrow. Next, from this antecedent, the assertion, viz., that there is no resurrection of the dead, the necessary consequence is, "Then Christ is not risen." But this consequence is false, for Christ has risen; therefore the antecedent is also false. But the antecedent is, that there is no resurrection of the dead. We conclude, therefore, that there is a resurrection of the dead. Now all this is briefly expressed thus: If there is no resurrection of the dead, then is Christ not risen; but Christ is risen, therefore there is a resurrection of the dead. This rule, then, that when the consequent is removed, the antecedent must also be removed, is not made by man, but only pointed out by him. And this rule has reference to the validity of the reasoning, not to the truth of the statements.

CHAP. 33.--FALSE INFERENCES MAY BE DRAWN FROM VALID REASONINGS, AND VICE VERSA.

51. In this passage, however, where the argument is about the resurrection, both the law of the inference is valid, and the conclusion arrived at is true. But in the case of false conclusions, too, there is a validity of inference in some such way as the following. Let us suppose some man to have admitted: If a snail is an animal, it has a voice. This being admitted, then, when it has been proved that the snail has no voice, it follows (since when the consequent is proved false, the antecedent is also false) that the snail is not an animal. Now this conclusion is false, but it is a true and valid inference from the false admission. Thus, the truth of a statement stands on its own merits; the validity of an inference depends on the statement or the admission of the man with whom one is arguing. And thus, as I said above, a false inference may be drawn by a valid process of reasoning, in order that he whose error we wish to correct may be sorry that he has admitted the antecedent, when he sees that its logical consequences are utterly untenable. And hence it is easy to understand that as the inferences may be valid where the opinions are false, so the inferences may be unsound where the opinions are true. For example, suppose that a man propounds the statement, "If this man is just, he is good," and we admit its truth. Then he adds, "But he is not just;" and when we admit this too, he draws the conclusion, "Therefore he is not good." Now although every one of these statements may be true, still the principle of the inference is unsound. For it is not true that, as when the consequent is proved false the antecedent is also false, so when the antecedent is proved false the consequent is false. For the statement is true, "If he is an orator, he is a man." But if we add, "He is not an orator," the consequence does not follow, "He is not a man."

CHAP. 34.--IT IS ONE THING TO KNOW THE LAWS OF INFERENCE, ANOTHER TO KNOW THE TRUTH OF OPINIONS.

52. Therefore it is one thing to know the laws of inference, and another to know the truth of opinions. In the former case we learn what is consequent, what is inconsequent, and what is incompatible. An example of a consequent is, "If he is an orator, he is a man;" of an inconsequent, "If he is a man, he is an orator;" of an incompatible, "If he is a man, he is a quadruped." In these instances we judge of the connection. In regard to the truth of opinions, however, we must consider propositions as they stand by themselves, and not in their connection with one another; but when propositions that we are not sure about are joined by a valid inference to propositions that are true and certain, they themselves, too, necessarily become certain. Now some, when they have ascertained the validity of the inference, plume themselves as if this involved also the truth of the propositions. Many, again, who hold the true opinions have an unfounded contempt for themselves, because they are ignorant of the laws of inference; whereas the man who knows that there is a resurrection of the dead is assuredly better than the man who only knows that it follows that if there is no resurrection of the dead, then is Christ not risen.

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