An Examination of Darwin
In the preceding five lectures I have endeavored to give you an account of those facts, and of those reasonings from facts, which form the data upon which all theories regarding the causes of the phenomena of organic nature must be based. And, although I have had frequent occasion to quote Mr. Darwin -- as all persons hereafter, in speaking upon these subjects, will have occasion to quote his famous book on the Origin of Species -- you must yet remember that, wherever I have quoted him, it has not been upon theoretical points, or for statement is any way connected with his particular speculations, but on matters of fact, brought forward by himself, or collected by himself, and which appear incidentally in his book. If a man will make a book, professing to discuss a single question, an encyclopedia, I cannot help it.
Now, having had an opportunity of considering in this sort of way the different statements bearing upon all theories whatsoever, I have to lay before you, as fairly as I can, what is Mr. Darwin's view of the matter and what position his theories hold, when judged by the principles which I have previously laid down, as deciding our judgments upon all theories and hypotheses.
I have already stated to you that the inquiry respecting the causes of the phenomena of organic nature resolves itself into two problems -- the first being the question of the origination of living or organic beings; and the second being the totally distinct problem of the modification and perpetuation of organic beings when they have already come into existence. The first question Mr. Darwin does not touch; he does not deal with it at all; but he says: "Given the origin of organic matter -- supposing its creation to have already taken place, my object is to show in consequence of what laws and what demonstrable properties of organic matter, and of its environments, such states of organic nature as those with which we are acquainted must have come about." This, you will observe, is a perfectly legitimate proposition; every person has a right to define the limits of the inquiry which he sets before himself; and yet it is a most singular thing than in all the multifarious, and, not unfrequently, ignorant attacks which have been made upon the Origin of Species, there is nothing which has been more speciously criticized than this particular limitation. If people have nothing else to urge against the book, they say -- "Well, after all, you see Mr. Darwin's explanation of the Origin of Species is not good for much, because, in the long run, he admits that he does not know how organic matter began to exist. But if you admit any special creation for the first particle of organic matter you may just as well admit it for all the rest; five hundred or five thousand distinct creations are just as intelligible, and just as little difficult to understand, as one." The answer to these cavils in twofold. In the first place, all human inquiry must stop somewhere; all our knowledge and all our investigation cannot take us beyond the limits set by the finite and restricted character of our faculties, or destroy the endless unknown, which accompanies, like its shadow, the endless procession of phenomena. So far as I can venture to offer an opinion on such a matter, the purpose of our being in existence, the highest object that human beings can set before themselves, is not the pursuit of any such chimera as the annihilation of the unknown; but it is simply the unwearied endeavor to remove its boundaries a little further from our little sphere of action.
I wonder if any historian would for a moment admit the objection that it is preposterous to trouble ourselves about the history of the Roman Empire because we do not know anything positive about the origin and first building of the city of Rome! Would it be a fair objection to urge, respecting the sublime discoveries of a Newton or a Kepler, those great philosophers, whose discoveries have been of the profoundest benefit and service to all men -- to say to them -- "After all that you have told us as to how the planets revolve, and how they are maintained in their orbits, you cannot tell us what is the cause of the origin of the sun, moon, and stars. So what is the use of what you have done?" Yet these objections would not be one whit more preposterous than the objections which have been made to the Origin of Species. Mr. Darwin, then had a perfect right to limit his inquiry as he pleased, and the only question for us -- the inquiry being so limited -- is to ascertain whether the method of his inquiry is sound or unsound; whether he has obeyed the canons which must guide and govern all investigation, or whether he has broken them; and it was because our inquiry this evening is essentially limited to that question that I spent a good deal of time in a former lecture in endeavoring to illustrate the method and nature of scientific inquiry in general. We shall now have to put in practice the principles that I then laid down.
I stated to you in substance, if not in words, that wherever there are complex masses of phenomena to be inquired into, whether they be phenomena of the affairs of daily life or whether they belong to the more abstruse and difficult problems laid before the philosopher, our course of proceeding in unraveling that complex chain of phenomena, with a view to get at its cause, is always the same; in all cases we must invent an hypothesis; we must place before ourselves some more or less likely supposition respecting that cause, and then, having assumed an hypothesis, having supposed a cause for the phenomena in question, we must endeavor, on the one hand, to demonstrate our hypothesis, or, on the other, to upset and reject it altogether, by testing it in three ways. We must, in the first place, be prepared to prove that the supposed causes of the phenomena exist in nature; that they are what the logicians call vera causae -- true causes -- in the next place, we should be prepared to show that the assumed causes of the phenomena are competent to produce such phenomena as those which we wish to explain by them; and in the last place, we ought to be able to show that no other known causes are competent to produce these phenomena. If we can succeed in satisfying these three conditions we shall have demonstrated our hypothesis; or rather I ought to say we shall have proved it as far as certainty is possible for us; for, after all, there is no one of our surest convictions which may not be upset, or at any rate modified, by a further accession of knowledge. It was because it satisfied these conditions that we accepted the hypothesis as to the disappearance of the teapot and spoons in the case I supposed in a previous lecture; we found that our hypothesis on that subject was tenable and valid, because the supposed cause existed in nature, because it was competent to account for the phenomena, and because no other known cause was competent to account for them; and it is upon similar grounds that any hypothesis you choose to name is accepted in science as tenable and valid.
What is Mr. Darwin's hypothesis? As I apprehend it -- for I have put it into a shape more convenient for common purposes than I could find verbatim in his book -- as I apprehend it, I say, it is that all the phenomena of organic nature, past and present, result from, or are caused by, the interaction of those properties of organic matter, which we have called atavism and variability, with the conditions of existence, or, in other words -- given the existence of organic matter, its tendency to transmit its properties, and its tendency occasionally to vary; and, lastly, given the conditions of existence by which organic matter is surrounded -- that these put together are the causes of the present and of the past conditions of organic nature.
Such is the hypothesis as I understand it. Now let us see how it will stand the various tests which I laid down just now. In the first place, do these supposed causes of the phenomena exist in nature? Is it the fact that, in nature, these properties of organic matter -- atavism and variability -- and those phenomena which we have called the conditions of existence -- is it true that they exist? Well, of course, if they do not exist, all that I have told you in the last three or four lectures must be incorrect, because I have been attempting to prove that they do exist, and I take it that there is abundant evidence that they do exist; so far, therefore, the hypothesis does not break down.
But in the next place comes a much more difficult inquiry: are the causes indicated competent to give rise to the phenomena of organic nature? I suspect that this is indubitable to a certain extent. It is demonstrable, I think, as I have endeavored to show you, that they are perfectly competent to give rise to all the phenomena which are exhibited by races in nature. Furthermore, I believe that they are quite competent to account for all that we may call purely structural phenomena which are exhibited by species in nature. On that point also I have already enlarged somewhat. Again, I think that the causes assumed are competent to account for most of the physiological characteristics of species and I not only think that they are competent to account for them, but I think that they account for many things which otherwise remain wholly unaccountable and inexplicable, and I may say incomprehensible. For a full exposition of the grounds on which this conviction is based, I must refer you to Mr. Darwin's work; all that I can do now is to illustrate what I have said by two or three cases taken almost at random.
I drew your attention, on a previous evening, to the facts which are embodied in our systems of classification, which are the results of the examination and comparison of the different members of the animal kingdom one with another. I mentioned that the whole of the animal kingdom is divisible into five subkingdoms; that each of these subkingdoms is again divisible into provinces; that each province may be divided into classes, and the classes into the successively smaller groups, orders, families, genera, and species.
Now, in each of these groups the resemblance in structure among the members of the group is closer in proportion as the group is smaller. Thus, a man and a worm are members of the animal kingdom in virtue of certain apparently slight, though really fundamental, resemblances which they present. But a man and a fish are members of the same subkingdom Vertebrate because they are much more like one another than either of them is to a worm, or a snail, or any members of the other subkingdoms. For similar reasons men and horses are arranged as members of the same class, Mammalia; men and apes as members of the same order, Primates; and if there were any animals more like men than they were like any of the apes, and yet different from men in important and constant particulars of their organization, we should rank them as members of the same family, or of the same genus, but as of distinct species.
That it is possible to arrange all the varied forms of animal into groups, having this sort of singular subordination one to the other, is a very remarkable circumstance; but, as Mr. Darwin remarks, this is a result which is quite to be expected, if the principles which he lays down be correct ...
Now, as to the third test, that there are no other causes competent to explain the phenomena, I explained to you that one should be able to say of an hypothesis that no other known causes than those supposed by it are competent to give rise to the phenomena. Here, I think, Mr. Darwin's view is pretty strong. I really believe that the alternative is either Darwinism or nothing, for I do not know of any rational conception or theory of the organic universe which has any scientific position at all beside Mr. Darwin's. I do not know of any proposition that has been put before us with the intention of explaining the phenomena of organic nature which has in its favor a thousandth part of the evidence which may be adduced in favor of Mr. Darwin's views. Whatever may be the objections to his view, certainly all other theories are absolutely out of court.
Take the Lamarckian hypothesis, for example. Lamarck was a great naturalist, and to a certain extent went the right way to work; he argued from what was undoubtedly a true cause of some of the phenomena of organic nature. He said it is a matter of experience that an animal may be modified more or less in consequence of its desires and consequent actions. Thus, if a man exercise himself as a blacksmith, his arms will become strong and muscular; such organic modification is a result of this particular action and exercise. Lamarck thought that by a very simple supposition based on this truth he could explain the origin of the various animal species; he said, for example, that the short-legged birds which live on fish had been converted into the long-legged waders by desiring to get the fish without wetting their feathers, and so stretching their legs more and more through successive generations. If Lamarck could have shown experimentally that even races of animals could be produced in this way, there might have been some ground for his speculations. But he could show nothing of the kind, and his hypothesis has pretty well dropped into oblivion, as it deserved to do. I said in an earlier lecture that there are hypotheses and hypotheses, and when people tell you that Mr. Darwin's strongly based hypothesis is noting but a mere modification of Lamarck's, you will know what to think of their capacity for forming a judgment on this subject.
But you must recollect that when I say I think it is either Mr. Darwin's hypothesis or nothing; that either we must take his view or look upon the whole of organic nature as an enigma, the meaning of which is wholly hidden from us; you must understand that I mean that I accept it provisionally, in exactly the same way as I accept any other hypothesis. Men of science do not pledge themselves to creeds; they are bound by articles of no sort; there is not a single belief that it is not a bounden duty with them to hold with a light hand and to part with cheerfully the moment it is really proved to be contrary to any fact, great or small. And if, in course of time, I see good reasons for such a proceeding, I shall have no hesitation in coming before you and pointing out any change in my opinion without finding the slightest occasion to blush for so doing. So I say that we accept this view, as we accept any other, so long as it will help us, and we feel bound to retain it only so long as it will serve our great purpose -- the improvement of man's estate and the widening of his knowledge. The moment this, or any other conception, ceases to be useful for these purposes, away with it to the four winds; we care not what becomes of it!
But to say truth, although it has been my business to attend closely to the controversies roused by the publication of Mr. Darwin's book, I think that not one of the enormous mass of objections and obstacles which have been raised is of any very great value, except that sterility case which I brought before you just now. All the rest are misunderstandings of some sort, arising either from prejudice or want of knowledge or still more from want of patience and care in reading the work.
For you must recollect that it is not a book to be read with as much ease as its pleasant style may lead you to imagine. You spin through it as if it were a novel the first time you read it, and think you know all about it; the second time you read it you think you know rather less about it; and the third time you are amazed to find how little you have really apprehended its vast scope and objects. I can positively say that I never take it up without finding in it some new view, or light, or suggestion that I have not noticed before. That is the best characteristic of a thorough and profound book; and I believe this feature of the Origin of Species explains why so many persons have ventured to pass judgment and criticisms upon it which are by no means worth the paper they are written on.
Before concluding these lectures there is one point to which I must advert -- though, as Mr. Darwin has said nothing about man in his book, it concerns myself rather than him -- for I have strongly maintained on sundry occasions that if Mr. Darwin's views are sound, they apply as much to man as to the lower mammals, seeing that it is perfectly demonstrable that the structural differences which separate man from the apes are not greater than those which separate some apes from others. There cannot be the slightest doubt in the world that the argument which applies to the improvement of the horse form an earlier stock, or of ape from ape, applies to the improvement of man from some simpler and lower stock than man. There is not a single faculty -- functional or structural, moral, intellectual, or instinctive -- there is no faculty whatever that is not capable of improvement; there is no faculty whatsoever which does not depend upon structure, and as structure tends to vary, it is capable of being improved.
Well, I have taken a good deal of pains at various times to prove this, and I have endeavored to meet the objections of those who maintain that the structural differences between man and the lower animals are of so vast a character and enormous extent that even if Mr. Darwin's views are correct, you cannot imagine this particular modification to take place. It is, in fact, an easy matter to prove that, so far as structure is concerned, man differs to no greater extent from the animals which are immediately below him than these do from other members of the same order. Upon the other hand, there is no one who estimates more highly than I do the dignity of human nature, and the width of the gulf in intellectual and moral matters which lies between man and the whole of the lower creation.
But I find this very argument brought forward vehemently be some. "You say that man has proceeded from a modification of some lower animal, and you take pains to prove that the structural differences which are said to exist in his brain do not exist at all, and you teach that all functions, intellectual, moral, and others, are the expression or the result, in the long run, of structures and of the molecular forces which they exert." It is quite true that I do so.
"Well, but," I am told at once, somewhat triumphantly, "you say in the same breath that there is a great moral and intellectual chasm between man and the lower animals. How is this possible when you declare that moral and intellectual characteristics depend on structure, and yet tell us that there is no such gulf between the structure of man and that of the lower animals?"
I think that objection is based upon a misconception of the real relations which exist between structure and function, between mechanism and work. Function is the expression of molecular forces and arrangements, no doubt; but does it follow from this that variation in function so depends upon variation in structujre that the former is always exactly proportioned to the latter? If there is no such relation, if the variation in function which follows on a variation in structure may be enormously greater than the variation of the structure, then, you, see the objection falls to the ground.
Take a couple of watches -- made by the same maker, and as completely alike as possible; set them upon the table, and the function of each -- which is its rate of going -- will be performed in the same manner, and you shall be able to distinguish no difference between them; but let me take a pair of pincers, and if my hand is steady enough to do it, let me just lightly crush together the bearings of the balance wheel, or force to a slightly different angle the teeth of the escarpment of one of them, and of course you know the immediate result will be that the watch, so treated, from that moment will cease to go. But what proportion is there between the structural alteration and the functional result? Is it not perfectly obvious that the alteration is of the minutest kind, yet that, slight as it is, it has produced an infinite difference in the performance of the functions of these two instruments?
Well, now, apply that to the present question. What is it that constitutes and makes man what he is? What is it but his power of language -- that language giving him the means of recording his experience -- making every generation somewhat wiser than its predecessor -- more in accordance with the established order of the universe?
What is it but this power of speech, of recording experience, which enables men to be men -- looking before and after and, in some dim sense, understanding the working of this wondrous universe -- and which distinguishes man from the whole of the brute world? I say that this functional difference is vast, unfathomable, and truly infinite in its consequences; and I say, at the same time, that it may depend upon structural differences which shall be absolutely inappreciable to us with our present means of investigation. What is this very speech that we are talking about? I am speaking to you at this moment, but if you were to alter, in the minutest degree, the proportion of the nervous forces now active in the two nerves which supply the muscles of my glottis, I should become suddenly dumb. The voice is produced only so long as the vocal cords are parallel; and these are parallel only so long as certain muscles contract with exact equality; and that again depends on the equality of action of those two nerves I spoke of. So that a change of the minutest kind in the structure of one of these nerves, or in the structure of the part in which it originates, or of the supply of blood to that part, or of one of the muscles to which it is distributed, might render all of us dumb. But a race of dumb men, deprived of all communication with those who could speak, would be little indeed removed from the brutes. And the moral and intellectual difference between them and ourselves would be practically infinite, though the naturalist should not be able to find a single shadow of even specific structural difference.
But let me dismiss this question now, and, in conclusion, let me say that you may go away with it as my mature conviction that Mr. Darwin's work is the greatest contribution which has been made to biological science since the publication of the Regne Animal of Cuvier, and since that of the History of Development of von Baer. I believe that if you strip it of its theoretical part it still remains one of the greatest encyclopedias of biological doctrine that any one man ever brought forth; and I believe that, if you take it as the embodiment of an hypothesis, it is destined to be the guide of biological and psychological speculation for the next three or four generations.