Scientific.

Otago Witness, Issue 1296, 30 September 1876, Page 3

Scientific.

THE OTAGO INSTITUTE.

THE INDUCTIVE METHOD AS APPLIED TO THE THEORY OF DESCENT.

The second of the series of popular lectures in connection with the Otago Institute was held on the 18th in the University Hall, which wa3 filled, the audience including a large number of ladies. The President of the Institute, Mr Robert Gillies, was in the cbaii. Captain Hutton was the lecturer, and he chose for his topic the above subject. The following is a condensed report of the lecture, which waa a verbal one : — By the terra inductive method is meant the process by which the laws of nature are discovered and proved. We begin by ,the observation of facts, and from these we form empirical laws, which are observed uniformities. We then try to explain these laws by hypotheses. If more than one hypothesis is suggested as an explanation, we decide between them by means of what Lord Bacon calls the crucial instances. We then proceed io ascertain whether more than one cause is involved, which we do by two methods, the first of which is called that of difference, and the second that of residues. We then proceed to the verification of the hypothesis. This is done by proof of gradation, and by the explanation of other empirical laws collected from pauses or phenomena different from those on which the original induction was based. If the hypothesis be verified, it then becomes a theory. Now, let us apply thid to the theory of descent with modification. The theory of descent asserts that all animals and plants have descended from a common stock, and that the present diversity of form is owing to the gradual variation from the parental type. It has nothing to do with the cause of variation, nor with the cause of divergence of character. By the analysis of the facts of anatomy a classification is established which shows that animals are associated in groups, which branch from each other, like twigs, and boughs from the stem of a tree ; the higher and more specialized groups forming the twigs, the lower and more generalised ones forming the stern. This is called the classificatory tree. Erom an analysis of the facts of palaeontology we compile the successional tree, which, although imperfect, agrees in all its main points with the classificatory tree. That is, the more generalised forms have preceded in time the more speciaUsed ones. From this analysis of the facts of anatomy and paleontology we arrive at the following empirical law — "Animals have come into existence upon a gradual ascending scale. " Two hypotheses have been put forward to explain this law. The one is a special creation upon a plan : the other is called descent with a modification. No other hypothesis is possible. We now come to test these two hypotheses by means of crucial instances. The difficulty of this particular proof is that one of the hypotheses is avowedly supernatural, and the only way to dispose of a supernatural hypothesis is to show that accepting it would lead to results which its acceptors could not adopt ; in fact to a reductio ad absurdam. This brings me to the most disagreeable part of the whole address. It is very distasteful to me to have to show that that the acceptance of such a hypothesis brings about an absurd idea of the Creator. I shall, therefore, try_ to pass over this portion of my subject as qiucidy as possible. But it is necessary to insist upon it as long as men, like the Bishop of Dunedin and Professor Salmond, who spoke here on the last evening, say that they see no reason why special creation should not be true. So long as thay maintain that it will be necessary for us to show that the hypothesis which they put forward leads to 'absurdities. From numerous instances, I will select the following as crucial tests. The Oceanic Islands, when first discovered, are always imperfectly stocked ; they are subsequently better stocked byjnan. I next select a case of the phenomena called rudimentary organs. In the young calf, canine teeth are found, which afterwards disappear. I will now take a case under the head of useless organs. In the kalcapo, of New Zealand, we have a bird which, although it possesses large wings, yet cannot use them, because its pectoral muscles are too weak. Again, in the upland goose, of Patagonia, we find a bird which has web feet, but yet never goes near the water. Then, in nature, there are many imperfect adaptations. For instance, on the Pampas of the La Plata thex*e is a woodpecker, which never sees a tree. These and many other examples which might be given, show that if we adopt the special creation hypothesis, we should have to suj>poae that the Creator did not always put the right thing in the right place j that he was a bad workman, and wasted his materials ; that be was often subject to fits of absence of mind, and that he was fond ot practical jokes, giving men reason, and at the same time creating a lot of deceptions to lead that reason astray. For if the web feet of the upland goose are supposed to be only an intellectual puzzle, then we shall have to extend the principle farther— to fossils, for example— and we would have to suppose that they were only sports of nature, and not realty dead animals. It is more than a puzzle, it is a deception. This is really the logical proof of the hypothesis of the theory of descent. For if one of these two hypotheses must be true, and if the adopting that of a special creation would lead to the results which I have mentioned, it follows that the theory of descent must be the true one. But in order to show that it can be thoroughly established, we will subject it to the whole of the proofs akeady mentioned under the head of the inductive method. We will jDroceed to ascertain whether there are any plurality of causes — that is to say, whether it is possible for the two hypotheses to conjoin. We commence this examination by the method of difference. If we compare Europe with New Zealand, we will find that the former contains a number of terrestrial mammals, while the latter has none. We know by experience that New Zealand is capable of supporting mammals, as many of them have been introduced into the Colony. And the only material point of difference between the two countries ii this resyect is that in Europe we find fossil mammals, while in New_ Zealand we do not. Comparing Australia with Europe and New Zoaland, we find that it con tains mammals, all of which are marsupial,but none of the higher forms. From these instances we see that where the antecedents of the former existence of certain mammals are excluded, the phenomenon of the present existence of allied mammals does not occur, consequently it must be the cause, or the indispensable part of the cause, of the phenomena. This means that the theory of descent is necessary for the explanation and existence of these mammals, while the special creation hypothesis is quite unnecessary. Again, let us compare the babits of the paradise duck and the blue duck of New Zealand. The paradise duck, when it has young ones, on being alarmed, feigns to be wounded, in order to draw attention away from them. The blue duck never makes such an attempt. What, now, is the essential difference between these two animals. The paradise duck belongs to a genus distributed over Europe, Asia, and Australia, where mammals exist, and against which it has to. defend its young. The blue duck, on the contrary, belongs to a genus, found in. no other

part of the world except New Zealand. It is, in fact, one of our old identities, and has lived in New Zealand only, and consequently haa never had to protect its young from the attacks of mammals. This # proves > that the paradise duck has inherited its instincts from parents which Jived in countries inhatitedlby mammals, but as the species is only found in New Zealand we must assume that it has been derived by descent with a modification from those of Europe and Asia. Special creation will not explain this in any way. With regard to the method of residues, all that can be said is that there is no residual phenomena. The theory of descent will explain everything that may be legitimately expected from it. We now proceed to'verify the hypothesis by the two tests already pointed out. It is necessary, by way of a preliminary observation, to remaik that descent with a modification is a known cause and that no limits to variation have been proved. Variation has been experimentally investigated by the breeding of domestic animals. It has been found that variations may be produced quite as great as between the different natural genera. We have therefore no reason fco distrust it as an efficient cause. Take now the proof by gradation. It has been shown by paleontologists in Germany that the spined ammonites of the middle Jarassic period were gradually developed from the ribbed ammonites of the lower Jurassic. The proof of this is complete. That the transition between the two species is not found is owing to the imperfection of the palseontological record. A few instances only are all that could be expected at present. I will now proceed with the proof of the explanation which I gave of empirical laws. We have two large classes of phenomena quite distinct from those xipon which the original induction was based. They are the phenomena of variability and of geographical distribution of animals. It will be only necessary to take a tew cases out of a number which might be brought forward. It has been found that, if any animal has an abnormally developed organ — that is, more developed than in any other species of the same genus — such organ is particularly subject to excessive variation. This is easily explained by the theory of descent. Because the abnormally developed organ, which is not found in other members cf the same genus, necessarily implies its recent development, and consequently it has 7iot had time to become constant by means of inheritance. It is also found that specific characters are more variable than generic characters; that each genera contains variable species; that each genera is composed of closely allied species j that species closely allied to other species have restricted ranges. All these empirical laws are easily explained by the theory of descent. But by the special creation _ hypothesis they remain enigmas. We will take one more example from the geographical distribution. Oceanic Islands, that is, Hands separated from the mainland by a great expanse of ocean, contain a large number of plants and animals which are to be found nowhere else, but though .distinct they are_ closely related to animals and plants on the mainland. Descent with a modification readily explains how animals and plants having become isolated, have changed gradually from their brothers which remain upon the mainland ; whereas if we accept the hypothesis of a special creation, we should have to suppose that the creatiye power had been far more active in small islands than upon continents. We have thus seen thai the theory of descent complies with all the tests invented by logicians to try the truth of a theory, and tha proof of it is a 8 complete as that of any other physical theory, and is certainly conclusive as on the geological theory. — (Applause. ) The Rev. Dr Stuart : I wish to make a remark or two, and I will put what I have to say in the form of a question to Captain Hutton. He started by telling us that all vegetables and animals are derived from one common stock. In my humble judgment he did not show us that, and there is also another important point to which I expected he would have alluded to, that is, to explain how the vegetable passed into the animal. He told us a great "many things about varieties and how they are produced, but it seems to me that the elementarylesson of the whole business is the common origin of vegetables and animals. If that can be shown we would have to admit all that follows. I would like if he would make that clear to us.

. Mr Puenell explained that the fundamental defect in the inductive method of reasoning was that it assumes sequences to be causes and effects.

Professor Coughtret pointed out that Darwin, and those who upheld his theory, maintained that transition did , not take place rapidly, but gradually, in the course of time. In reply to what Dr Stuart had said, he observed that it was a noted fact that when animals and vegetables were traced to their lowest j)oints they come to creatures which could not be differentiated even by the aid of the most powerful miscroscope. He suggested that, looking at the importance of the subject, the discussion should be adjourned until another evening.

The Chairman: I will now call upon Captain Hutton to reply. Dr Stuart : I have a hundred questions yet to ask. Such is the best method to get at the truth.

The Chairman : It would probably be brought out by Dr Stuart taking up the other side of the question on one of those popular evenings. lam afraid that it would be difficult to get the meeting together again. It is but fair that Captain Hutton be allowed to reply to the questions put by Dr Stuart, and that it will rest with the Council of the Institute to say whether the sublect cen be considered on another evening.

The Rev. R. L. Stanford said that he held, with Captain Hutton, that the theory answered all the formulas which had been laid down by the lecturer. He (Mr Stanford) considered it unanswerable and irrefragably true. Captain Hutton, in reply, remarked that Dr Stuart had asked how the vegetable had passed into the animal. He did not exactly think that that was what Dr Stuart meant. " How did it pass in?" He would reply that he did not know, nor did not know the cause, but they presumed that it did pass in. They also presumed that all animals and plants had come from a common stock, because they found, on dissecting and studying them, that the facts of anatomy showed that they were all connected. They could not be expected to prove each particular case, because if they covild do that, then it would not be a theory at all, but an absolute fact.

The Chairman : Ladies and Gentlemen, I will not detain you a moment. I regret that I have not had the opportunity of saying a few words on this subject, but there is one thing which I will say. lam forcibly reminded of what is related of St. Augustine when the theory of the world being circular was first put forth. There was a great controversy about the matter, and, on being applied to,, he said — "I do not see anything in Scripture against the world being round ; but if it is round, then the people on the other side will be sticking like flies upon it. They therefore cannot belong to the same race as we, and cannot cohae under the scheme of redemption. Therefore the theory cannot be true." That is an illustration of the arguments brought forward against (Evolution,