Darwin

by Gamaliel Bradford

We have already enlarged under observation on the essential quality of accuracy, and it may simply be added that accuracy is doubly important in all experiments for a theoretical purpose. Accuracy, complete, detailed, mathematical exactitude, was Darwin’s hobby, and the minuteness of his record constantly exemplifies it.

Also, to confirm their accuracy experiments have to be repeated. Goethe remarks with justice that it is not necessary to travel all over the world to make sure that the sky is everywhere blue,[470] and no doubt there are repetitions that are vain and superfluous. But many difficult and delicate researches have to be gone over again and again that the minutest detail may be complete; and the process may involve months of tedious delay. Darwin’s unfailing care, both to repeat and to avoid repetition, is well indicated in his son’s comment: ‘Although he would patiently go on repeating experiments where there was any good to be gained, he could not endure having to repeat an experiment which ought, if complete care had been taken, to have succeeded the first time.’[471] Here too, one cannot appreciate how immense and thorough his experimentation was without looking through such books as the ‘Animals and Plants under Domestication’ or ‘The Power of Movement in Plants.’ The endless repetition of slightly varied combinations to test a difficult or remote conclusion makes one feel how persistent and inexhaustible the patience was. And after all the years of repeated and varied research and investigation he writes the almost pathetic epilogue six months before his death: ‘I wish that I had enough strength and spirit to commence a fresh set of experiments, and publish the results, with a full recantation of my errors when convinced of them.’[429]

Finally, experiments have to be not only made, but recorded, and the accuracy, so essential with all scientific observation, is above all essential here, since the omission of a link in the record may be ruinous to the continuity of the logical chain. It is peculiarly characteristic of Darwin that he wanted the record of error and mistake as well as of success. ‘I remember,’ says his son, ‘how strongly he urged the necessity of keeping the notes of experiments which failed, and to this rule he always adhered.’[430] The value of preserving and comparing apparently insignificant and meaningless notes is sometimes brought out, as in a special case of orchids: ‘I had given up the case as hopeless, until summing up my observations, the explanation presently to be given, and subsequently proved by repeated experiments to be correct, suddenly occurred to me.’[431] Long experience of his own mistakes and failures induces extreme scepticism as to the results of others: ‘The difficulty is to know what to trust.’[352] Even when he has taken the greatest pains, the scepticism often lingers and forces him to repeat although with an identical result: ‘Notwithstanding the care taken and the number of trials made, when in the following year I looked merely at the results, without reading over my observations, I again thought that there must have been some error, and thirty-five fresh trials were made with the weakest solution; but the results were as plainly marked as before.’[353] And thus the long series of packed, closely printed volumes forms an amazing record of a life of zealous, persistent, curious experimentation from beginning to end.

III

Now let us look a little more closely at the stuff and quality of Darwin’s logical processes, considered as such. He himself often complains of the slowness and difficulty of his thinking. It is hard for him to arrange his thoughts, he says, hard for him to get them into the lucid and effective order which carries conviction with it, almost enforces conviction by the power of its own movement. He says of one of his critics: ‘He admits to a certain extent Natural Selection, yet I am sure does not understand me. It is strange that very few do, and I am become quite convinced that I must be an extremely bad explainer.’[354]

It is worth while to note the comments of Huxley, as one of Darwin’s staunchest friends and supporters, on his reasoning faculty and processes. When Romanes lauds Darwin’s colossal intellect, Huxley is inclined to protest: ‘Colossal does not seem to me to be the right epithet for Darwin’s intellect. He had a clear, rapid intelligence, a great memory, a vivid imagination, and what made his greatness was the strict subordination of all these to the love of truth.’[355] Elsewhere Huxley adds: ‘Exposition was not Darwin’s forte—and his English is sometimes wonderful. But there is a marvelous dumb sagacity about him and he gets to truth by ways as dark as those of the Heathen Chinee.’[356] Of ‘The Origin of Species’ Huxley writes: ‘It is one of the hardest books to understand thoroughly that I know of.’[357] And again, more amply: ‘Long occupation with the work has led the present writer to believe that “The Origin of Species” is one of the hardest of books to master, and he is justified in this conviction by observing that although the “Origin” has been close on thirty years before the world, the strangest misconceptions of the essential nature of the theory therein advocated are still put forth by serious writers.’[358] Critics less friendly to Darwin than Huxley have spoken still more strongly.

I feel that Huxley’s judgment is too severe. It is true that Darwin had not the admirable gift of logical, lucid exposition which made Huxley himself one of the most luminous of scientific writers. But even when Darwin’s reasoning is most complex and difficult, there is a notable quality of sincerity and single-mindedness, which wins and retains your confidence. He seems somehow to have an exceptional power of taking you into his mental processes, and to make you think and see and feel as he does. If you feel that he may be wrong, it is because he feels that he may be wrong himself.

It is profitable to examine a little more in detail some illustrations of Darwin’s scientific theorizing. The great central doctrine of evolution, with its buttressing support of natural selection, will fill our next chapter, but there are several lesser developments of speculation which deserve notice. I need hardly say that we are not in any way discussing the validity of the theories in the abstract, but simply Darwin’s fashion of framing, holding, and sustaining them.

There is first the theory as to the formation of coral reefs. At an early period in his career Darwin conceived the idea that these reefs were produced by the subsidence of the ocean bed and the steady building up of the coral insects toward the surface. He himself admits that this theory was the most deductive of all that he ever urged and the least founded in the beginning upon a wide and careful investigation of fact. Alexander Agassiz, who, after extensive research, was not disposed to accept it, wrote: ‘Darwin’s observations were all theoretical, based upon chartographic study in his house, a very poor way of doing, and that’s the way all his coral reef work has been done.’[359] And the theory has met with strenuous opposition from many quarters, though one critic says in regard to it: ‘Be it true or not, be it a competent explanation or not, no matter. In influence on geology it has been as far-reaching as the doctrine of natural selection has been on biology.’[360] But Darwin himself clung to it to the end, meeting objections with vast ingenuity and reiterating his positions with ampler and more penetrating arguments. Yet through all the persistence there is the readiness at any moment to see the other side. ‘I must still adhere to my opinion, that the atolls and barrier reefs in the middle of the Pacific and Indian Oceans indicate subsidence, but I fully agree with you that such cases as that of the Pellew Islands, if of at all frequent occurrence, would make my general conclusions of very little value. Future observers must decide between us.’[361] And he writes frankly to Alexander Agassiz: ‘If I am wrong, the sooner I am knocked on the head and annihilated so much the better.’[362]

Another instance of Darwin’s zeal and ingenuity in reasoning is the theory of sexual selection, devised to meet some difficulties in his general argument. Many animals have certain so-called secondary sexual characteristics, that is, characteristics affecting one sex only yet not directly involved in the reproductive process. Darwin believed that these characteristics were largely developed through the working of natural selection upon the basis of the preference of one sex for individuals of the other for mating purposes. That is to say, the splendor of the male peacock’s tail made him more attractive to the female and therefore more successful with her. There were numerous and obvious difficulties in this view, as the assumption of a fine æsthetic sense in comparatively lowly organized creatures, and it was energetically disputed from the start. Wallace, Darwin’s ardent fellow-thinker and coadjutor, was anything but favorable to it. Yet Darwin’s faith was never really shaken. He persisted to the end, making new experiments and investigations, and meeting his adversaries’ contentions with vast and varied resource. In ‘The Descent of Man’ he wrote: ‘For my own part I conclude that of all the causes which have led to the differences in external appearance between the races of man, and to a certain extent between man and the lower animals, sexual selection has been the most efficient.’[363] Nevertheless, it is fascinating to see him reveal the doubt and the questioning that were inwrought with conviction in his mind. He writes to Wallace: ‘I grieve to differ from you, and it actually terrifies me and makes me constantly distrust myself.’[364] Again: ‘You will be pleased to hear that I am undergoing severe distress about protection and sexual selection; this morning I oscillated with joy towards you; this evening I have swung back to my [old] position, out of which I fear I shall never get.’[365] And he sums up the process with a general remark of the largest and most fruitful bearing: ‘I sometimes marvel how truth progresses, so difficult is it for one man to convince another, unless his mind is vacant. Nevertheless, I myself to a certain extent contradict my own remark, for I believe far more in the importance of protection than I did before reading your articles.’[366]