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INDUCTION, ANCIENT AND MODERN.

THE

HE growth of the inductive sciences is one of the notes of

modern research. The very word science, once appropriated to deductive or a priori knowledge, is now claimed as the exclusive property of inductive or a posteriori knowledge. Some of our modern treatises on Logic give far more space to inductive than to deductive Logic, and regard it as far more important. Observation and experiment take a prominence in modern systems that was quite unknown to the ancients. The laws of right observation and trustworthy experiment are examined and sifted with a carefulness of detail and a strictness of inquiry to which Aristotle and St. Thomas were wholly strangers. Laws and canons are laid down for their employment; the methods which are to regulate them are represented as the very groundwork of philosophy. The once cherished principles of the Dictum de omni et nullo and the a priori laws of thought are relegated to an unhonored obscurity. This change dates from Bacon and Locke. It does not concern us to trace its origin or the cause of its development. It is enough to say that as men turned their thoughts from laws received upon authority to those which were framed as the result of human experience, or indeed, as all authority began to be regarded as built up from below, rather than as coming down from above, it was but natural that the new constructive process should assume an importance it had never enjoyed before, and that unquestioning obedience to prevailing laws should be exchanged for a very critical inquiry into the validity and source of those laws. And when the new school of theology and philosophy had decided that they came from below, rather than from above, that they were the elected representatives of the people, rather than the appointed vicegerents of God, that they were true because everywhere of force, and not everywhere of force because true, it was but right and proper that their election should be challenged by the scientific inquirer, and that their authority should be subjected to the most approved principles of impartial and unbiased research.

Has the change been one which has strengthened truth, or one which has induced new and plausible forms of error? The answer to this question requires a very careful distinction between the various fields of knowledge. As regards things of a purely material nature and the laws that govern them, it cannot be denied that we owe an enormous debt to the Baconian induction and its further development by subsequent writers. Nearly all our modern discoveries are due to it, and to the stimulus that it has given to the physical and mechanical sciences,—not merely to botany, chemistry, zoology; not merely to the sciences that deal with light, heat, and motion, but in the loftier tenets of medicine, hygiene, astronomy, history, ethnology, philology,—the new method has given an impulse to human activity that has changed the whole face of the world. The rapid growth of large cities, colonization, the decline in the warlike and the increase in the commercial spirit, the lower rate of mortality by reason of sanitary improvements and of the advance of medical knowledge, the decrease in crimes of violence and in lawless oppression of the poor, and many other changes, which amount to an unseen and gradual revolution, are in a great measure due to the development of the inductive method.

Yet in all this there is a counterbalancing loss which must not be overlooked. Even in the material development the gain is not unmixed; large cities have their disadvantages, and these of no mean order; the growth of a commercial spirit involves the danger of the growth of a selfish and a narrow spirit; the improvements in hygiene and medicine keep alive those who would in old times have died off in their sickly youth, and their unhealthy offspring hand on a weakly constitution in their turn to the next generation; if lawlessness has diminished, there is, on the other hand, a lower morality in the modern city than in the villages of former times, and the social critic may well be puzzled, as he weighs the advantages against the disadvantages, to say whether the effect of our material advance has on the whole been for the better or for the worse.

But there is another aspect under which we have to regard it. We have to ask whether the inductive spirit, as it is called, is calculated, on the whole, to strengthen or relax man's grasp of truth, whether the temper that has been introduced really promotes man's rational development, whether it increases or diminishes the number of important and practical principles possessed by him for the regulation of his conduct and the direction of his life to its true end, whether it is a temper that places him in his proper relation to God and teaches him the true end of his existence. We have to inquire, moreover, whether it is favorable or unfavorable to Revelation and to supernatural truth, whether its methods are suitable means to be employed by one who is looking out to discover what religion it is to which God has given His divine sanction, and outside of which all else are false and self-contradictory.

These questions will be very differently answered by those without and those within the Catholic Church. The latter, while they acknowledge the services, the enormous services rendered by the methods of modern inductive research, cannot but recognize their danger when once they are allowed to claim the almost exclusive possession of the field of truth. It is the discrediting of a priori truth, the knocking out of sight of the true basis of certitude, the abolition of all absolute certainty resulting from the domination of this new spirit, that alarms the Catholic. He dreads a deluge of the stream which, within proper limits and in moderate amount, would fertilize and refresh the face of the earth.

We have, therefore, to consider the relation of the ancient and modern induction, and how far we ought to give in to the claims of the latter to be the dominant method of modern logic. We will begin by glancing at the question historically, in order that we may see if there is in our two great authorities, Aristotle and St. Thomas, any recognition of modern induction and the methods by which it is safeguarded. We will then carefully examine the distinction between the induction of ancient and that of modern times, and lay down the laws and canons which regulate the one and the other. This portion of our inquiry is no unimportant one, and one, too, beset with difficulties. We have to steer our course between the Scylla of a narrow and blind indifference to the value of the new discovery, and the Charybdis of a too great devotion to a hungry monster that seeks to swallow up all truth in its rapid and all-devouring vortex.

Induction in its widest sense is, according to Aristotle, a process by which we mount up from the particular to the universal.' This may be done in three different ways.

1. The particulars may be the occasion which enables us to recognize a universal a priori law. They put before us in concrete form two ideas, the identity of which we might not have been able to recognize in the abstract. If we tell a man ignorant of Euclid that the exterior angle of every plane triangle is exactly equal to the two interior and remote angles, he does not instinctively recognize the truth of our statement. But if we draw first one triangle and then another, and prove it to him mathematically, he is able to mount up to the universal law. Even a single instance is sufficient to make it plain to him when once he sees that the proof is independent of the kind of triangle of which there is question, and that it holds good whether the triangle be equiangular, isosceles or scalene, obtuse-angled or right-angled or acuteangled. This, however, is scarcely induction in the strict meaning of the word, for the argument is rather through and from the particular instance or instances to the universal.

11παγωγή ή από των καθ' έκαστον επί πα καθόλου έθοδος. Αr. Τom. Ι. 12.

Induction in its strict sense is based upon the particulars, and argues from them, not through them. It is any process by which we are enabled to affirm or deny respecting the universal subject something that we have already attained or denied of the several particulars contained under it. It naturally is divided into two different kinds, which furnish us with the second and third of the various meanings of the word.

1. Complete induction, in which all the particulars are enumerated.

2. Incomplete induction, in which only a portion of the particulars are enumerated, but from this portion a conclusion is drawn which covers those not enumerated.

Complete induction, is the exact reverse of the deductive process; as in the latter we argue from the universal subject to each and all of the particulars contained under it, so in the former we argue from each and all of the particulars to the universal subject. Aristotle defines it as proving the major term of the middle by means of the minor, as opposed to deductive inference, which proves the major of the minor by means of the middle. For instance:

Saul, David, and Solomon were men of remarkable achievements. But Saul, David, and Solomon were all the kings of the whole of Palestine, therefore all the kings of the whole of Palestine were men of remarkable achievements; or,

Nettles, pellitories, figs, mulberries have flowers with a single perianth. But nettles, pellitories, figs, and mulberries are all the flowers belonging to the order urticea, therefore all the plants in the order urticeæ have flowers with a single perianth.

In these syllogisms the names of the individuals or of the lowest species are the minor term, inasmuch as they come under the class to which they immediately belong; and though collectively they are identical with it in extension, yet they have a certain inferiority to it because it is always possible that some pert historical or botanical or other discovery might add another to the list of kings who ruled over the whole of Palestine, or to the urticea plants, or to any other enumeration of particulars coming under a universal. Hence in an inductive argument middle and minor change places, or rather that which is minor in point of possible extension stands as the middle term, because in actual extension it is the equal of the middle term, which, in this kind of argument, humbly resigns its rights and takes the place of the minor term of the syllogism.

Is the inductive syllogism a legitimate one? We must look at the import of the proposition. The import of a proposition is,

that it states the existence of such a connection between the two objects of thought, that in whatever individuals you find the one you will find the other. When we apply this test to the major premiss, we find it to be a true proposition. Wherever Saul, etc., are found as objects of thought, there one shall also find remarkable achievements. But it is not similarly applicable to the minor; it is not true that wherever we find possible kings of all Israel, there we shall find Saul, etc.; it is only true in the case of the actual kings as known to us. This weak point comes out when we fix our attention on the copula. All the kings of the whole of Palestine were Saul, David, and Solomon, means not that the ideas of Saul, David and Solomon are present wherever the idea of king of the whole of Palestine is present as an object of thought, but merely that in point of fact the class of all the kings of the whole of Palestine is made up of these individuals. This is not the logical meaning of the copula, and at once creates the opposition between the syllogism and induction of which Aristotle speaks, and the anomaly which he mentions respecting the middle term. This, moreover, accounts for the further anomaly of a universal conclusion in figure 3, although this anomaly may be avoided by transposing the terms of the minor premiss.

Is complete induction of any practical usefulness? Yes, it has the same function as deduction. It renders implicit knowledge explicit. We are enabled to realize what we had not realized before, to trace a universal law where we had not previously suspected one. It brings out some universal characteristic of a class, or teaches us to recognize those who are bound together as members of that class, by the possession in common of a peculiarity which before we had only recognized as belonging to the individuals. It is true that this sort of induction per enumerationem simplicem does not establish any connection by way of cause and effect between the common property and the common class.

It may be a matter of chance that all the kings who ruled the whole of Palestine were distinguished men, or that all the urticeæ have a single perianth. But it is, at all events, a suggestive fact, and leads us to question ourselves whether there must not have been some reason why the kings in question had remarkable gifts or the flowers one perianth only.

For instance, if we go into the room of a friend, and find his library consists of ten books and ten only, and on examining them find that they are, one and all, books describing travels in China or Japan, a complete induction enables us to lay down the proposition:

All our friend's books are books of travels in China and Japan. This suggests to us a train of thought that would never have

VOL. XIII.-32

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