Classics in the History of Psychology
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Christopher D. Green
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By Francis Bowen (1860)
First published in Memoirs of the
communicated March 27, April 10 and
Reprinted in G. Daniels (Ed.) (1968). Darwinism comes to
Posted May 2004
[Note from the Daniels edition: In the omitted portion of this article, Bowen reduced the Darwinian theory into the five assertions of ·which he said it consisted. The first two, the fact that individuals vary, and the fact that variations could be inherited, Bowen was ready to grant with only minor reservations. His real criticism begins with the third point.]
3. But with whatever success the doctrine of Inherited Variation may be applied to explain the existence of Varieties, it is certain that the origin of Species can be accounted for on the Development Theory, if at all, only by Cumulative Variation, -- that is, only by supposing a vast number of Inherited Variations to be successively superinduced one upon another. Doubts have been raised upon this point only on account of ambiguity in the meaning of words, or from want of agreement as to the principles of classification. Many races, both of animals and vegetables, appear to be so nearly allied to each other, that certain naturalists consider them as mere Varieties; others persist in considering them as so many distinct Species. Mr. Darwin himself remarks that the distinction between Varieties and Species is "entirely vague and arbitrary";… Fortunately we do not need, so far as our main question is concerned, to enter into the intricacies of this discussion. The advocates of the Development Theory undertake to prove that all Species of animals, even those differing most widely from each other, "have descended from at most four or five progenitors, and plants from an equal or lesser number." Putting aside altogether, therefore, the much debated question whether the several races of men are only Varieties, or are so many distinct Species, and the same question with respect to dogs, there is no doubt that men and dogs belong respectively to different Species. And generally, putting aside the question whether the offspring of certain races when crossed are entirely sterile or only partially so, there is no doubt that animals or plants belong to distinct Species when they cannot be crossed or made to interbreed at all. It is enough to say, then, that only Cumulative Variation -- and that of a vast number of successive steps -- will account for the common origin of animals which will not copulate with each other, or of plants which cannot be crossed.
Now, on this cardinal point, which contains the essence of the Development Theory, since all the other questions involved in it are of no substantive importance, so far as what may be called the Philosophy of Creation is concerned, the direct evidence fails altogether, and we are left exclusively to the guidance of conjecture and analogy and estimates of what is possible for all that we know to the contrary. It is not even pretended that we have any direct proof, either from observation or testimony, that two Species so distinct that they will not interbreed have yet sprung from common ancestors. On the contrary, Mr. Danvin's own supposition is, that the process of developing two entirely distinct Species out of a third is necessarily so gradual and protracted as to require a quasi eternity for its completion, so that only a small portion of it could have been accomplished during the limited period of man's existence upon the earth.
In the absence of any direct proof, then, it remains to be inquired if there are sufficient grounds of probability, reasoning from analogy and the principles of inductive logic, for believing that all Species of animals and plants map have originated from three or four progenitors. In speaking of the amount and frequency of Individual Variation, Mr. Darwin and his followers abuse the word tendency. After heaping up as many isolated examples of it as they can gather, they assert the legitimate inference from such cases to be, that the Species tends to vary, leaving out of view the fact that a vastly larger number of individuals of the same Species do not vary, but conform to the general type. And though only one out of a hundred of these Individual Variations is transmitted by inheritance, yet, after collecting as many instances of such transmission as they can find, they affirm that a Variation tends to become hereditable. But it is not so. Tendency is rightly inferred only from the majority of cases; a small minority of favorable instances merely shows the tendency to be the other way. Thus, the cars do not tend to run off the track, although one train out of a thousand may be unlucky enough to do so; but the general law is, that they remain on the track. Otherwise, people would not risk their lives in them.... The advocates of the Development Theory violate the first principles of inductive logic, by founding their induction not, as they should do, on the majority -- the great majority -- of cases, but on the exceptions, the accidents. Their whole proceeding is an attempt to establish a philosophy of nature, or a theory of creation, on anomalies, -- on rare accidents, -- on lusus naturae.
This single objection is fatal to Mr. Darwin's theory, which depends on the accumulation, one upon another, of many successive instances of departure from the primitive type. For if even Individual Variation appears only in one case out of a hundred, -- and all naturalists will admit this proportion to be as large as the facts will warrant, -- and if, out of the cases in which it does appear, not more than one in a hundred is perpetuated by inheritance, then should a second Variation happen, what chance has it of leaping upon the back of one of the former class: The chance is one out of 100 X 100 X 100 = 1,000,000. And the chance of a third Variation being added to a second, which in turn has been cumulated upon a first, will be one out of 100 raised to the fourth power, or 100,000,000. It is not necessary to carry the computation any further, especially as Mr. Darwin states that the process of development can be carried out "only by the preservation and accumulation of infinitesimally small inherited modifications." Of course, the interval between two Species so distinct that they will, not interbreed could be bridged over only by a vast number of modifications thus minute; and on this calculation of the chances, the time required for the development of one of these Species out of the other would lack no characteristic of eternity except its name. But the theory requires us to believe that this process has been repeated an indefinite number of times, so as to account for the development of all the Species now in being, and of all which have become extinct, out of four or five primeval forms. If the indications from analogy, on which the whole speculation is based, are so faint that the work cannot have been completed except in an infinite lapse of years, these indications practically amount to nothing. The evidence which needs to be multiplied by infinity before it will produce conviction, is no evidence at all.
4. What is here called the "Struggle for Life" is only another name for the familiar fact, that every Species of animal and vegetable life has its own Conditions of Existence, on which its continuance and its relative numbers depend. Remove any one of these Conditions, and the whole Species must perish; abridge any of them, and the number of individuals in the Species must be lessened. The intrusion of a new race which is more prolific, more powerful, more hardy, or in any way better adapted to the locality, may gradually crowd out some of its predecessors, or restrict them within comparatively narrow bounds. Thus the introduction of the Norway rat has banished the former familiar plague of our households and barns from many of its old haunts, and probably reduced the whole number in this Species to a mere fraction of what it once was. Civilized man also has successfully waged war against many ferocious or noxious animals, and probably exterminated some of them. But the appearance of a rival or hostile race is not the only cause of such diminution or extinction. A change in the physical features of a given district may partially or entirely depopulate it, without the necessary introduction of any new-comers. The drying up or filling up of a lake is necessarily fatal to all its aquatic tribes. The gradual submergence of an island or a continent must exterminate, sooner or later, all the native Species which were peculiar to it. And at the utmost, the failure of any Condition of Existence, whatever may be its character, only leaves vacant ground for the future introduction or creation of new forms of life, without tending in the slightest degree to bring such new forms into existence.
5. Natural Selection, also, as already remarked, has nothing to do with the origin of Species, and, in its abstract form, is only the statement of a truism. Of course, when two or more Species crowd each other, the more prolific or the more vigorous, other things being equal, is more likely to gain possession of the disputed ground, and thus to diminish the numbers of the other or oblige it to migrate, or, in rare cases, to kill it out altogether. But this last supposition is a conceivable rather than a probable result. All observation goes to show, that every Species retains a very persistent hold upon life, however feeble may be the tenure of existence for its individual members. Its numbers may be materially diminished; it may be forced to shift its ground, and to suffer in consequence some slight change in its habits; (Mr. Darwin himself tells us of upland geese and of woodpeckers where there are no trees); it may be driven into holes and corners; but somehow it still survives. Utter extinction of a Species is one of the rarest of all events; not half a dozen cases can be enumerated which are known to have taken place since man's residence upon the earth. And these, surely, are a very insufficient basis on which to found a theory embracing all forms of life. Yet man is the greatest exterminator the world has ever known. His physical powers, coupled with the use of reason by which they are multiplied a thousand-fold, enables him to wage internecine war with comparative ease against nearly every race that molests him. Only the insect tribes, through their immense numbers and their littleness, can successfully defy him; and these not always. In his Struggle for Life, all other creatures, animal or vegetable, must retreat or perish. Yet how few has he rooted out altogether! But the Development Theory requires us to believe that this process of extinction, guided by Natural Selection, has been repeated well-nigh to infinity. Not only all the races which are now found only in their stone coffins, but countless others,-"the interminable number of intermediate forms which must have existed" as connecting links, and a still greater crowd of other Varieties not intermediate, but gross, rude, and purposeless in their formation, -- the unmeaning creations of an unconscious cause, -- must all have perished, each through its own peculiar repetition of a series of events so infrequent that we can hardly compute the chances of their happening at all.
It is easy to see why the extermination of a Species, even upon the conditions of Mr. Darwin's theory, should be so infrequent. He holds that all the races which have originated upon the earth since the primeval act of creation first grudgingly threw only four or five seeds of existence into the ground, have been shaded into each other by gradations so slight as to be nearly imperceptible. Differing so slightly from each other, the advantage possessed by any one of them in the Struggle for Life must have been almost indefinitely small. But a peculiarity important enough to preserve those who have it, while whole Species must die out because they have it not, cannot be thus trifling in character. It must have been one of grave moment; not a slight Variation, but a jump. The successive development of new races -- itself, as we have seen, an extremely slow process -- must have been continued through numerous steps before the divergence resulting from it could have been serious enough to enable one of the divergent stocks to overcome and exterminate the other. Numerous Species of the same genus now coexist, often within the bounds of a not very extended territory, without any one of them showing any tendency to supplant or exterminate another. Thus, South Africa is the country par excellence of the antelope; about fifty species of this animal have been found there, many of them very abundant, notwithstanding the numerous Carnivora that prey upon them, and yet none of them showing any tendency to die out before civilized man came thither and brought gunpowder along with him.
Natural Selection can operate only upon races previously brought into being by other causes. In itself, it is powerless either to create or exterminate. In the Development Theory, its only function is, when the number of different Species is so far multiplied that they crowd upon each other, and the extinction of one or more becomes inevitable (if we can conceive of such a case), then to make the selection, or to determine which shall be the survivors and which the victims. As individuals of the same Species, the same Variety, and even of the same flock, certainly differ much from each other in strength, swiftness, courage, powers of endurance, and other qualities, Natural Selection has an undoubted part to play, when the struggle comes for such a flock, in determining which of its members shall succumb. But that it ever plays a corresponding part in the grand contest of Species imagined by Mr. Darwin, is a supposition resting upon no evidence whatever, but only upon the faint presumption afforded by the fact, that certain Species at widely separated times have become extinct, through what causes we know not; and therefore, for all that we know to the contrary, Natural Selection may have had something to do with their disappearance. This is to found a theory, not upon knowledge, but upon ignorance. If such reasoning be legitimate, we are entitled to affirm that the moon is inhabited by men "whose heads do grow beneath their shoulders." It may be so, for all we know to the contrary. This review of the state of the evidence upon each of Mr. Darwin's five points is enough to show that the testimony fails entirely just where it is most wanted. Facts and arguments are accumulated where they are of little or no avail, because the conclusions to which they tend, when properly limited and qualified, are admitted and familiar principles in science. But the theory of the Origin of Species by Cumulative Variation which is all that is peculiar to this form of the transmutation hypothesis, rests upon no evidence whatever, and has a great balance of probabilities against it. Individual Variation, the Struggle for Life, and Natural Selection, each within clearly defined limits, are acknowledged facts, which still leave the main question in the philosophy of creation precisely where it was before; and even the doctrine of Inherited Variation relates only to the origin of Varieties, which is a distinct question, and one of subordinate importance and interest, except to naturalists. Mr. Darwin has invented a new scheme of cosmogony, and finds that, like other cosmogonies, it is a blank hypothesis, not susceptible either of proof or disproof, and needing an eternity for its development. There is nothing new in such a speculation of what is possible in an infinite lapse of years. This latest form of the speculation has no advantage over the one first propounded some three thousand years ago; -- that a chaos of atoms, moving about fortuitously in infinite space, may have happened, in an eternity, to settle into the present kosmos; for the chance of order and fitness is at least one out of an infinite number of chances of disorder and confusion; and in an infinite series of years, this solitary chance must sooner or later be realized....
Every such speculation must be rejected, because it is self-contradictory. It professes to develop a Theory of Creation, -- to explain the beginning of things; and in order to do so, it is obliged to assume that the present or ordinary succession of phenomena, the common sequence of causes and effects which we every day witness, has continued from eternity; -- that is, that there never was any Creation, and that the universe never began to be. It professes to untie the knot, and ends by denying that there is any knot to untie. Mr. Darwin is too imaginative a thinker to be a safe guide in natural science; he has unconsciously left the proper ground of physics and inductive science, and busied himself with questions of cosmogony and metaphysics.