Darwin was led to study the structure and distribution of coral reefs in the Pacific Ocean, to explore the minute organizations of invertebrate animals, such as the Cirripeda, and to investigate the geology of South America, the structure of the Falkland Islands, and the volcanic islands of Australia.
In the various works in which he has given an account of these researches, he has shown himself an accomplished naturalist, and they are all written with a degree of elegance and perspicuity not very common in works of the same class. His health, we regret to say, is such as to preclude him from continuous study, but we trust that he may be long preserved to advance natural history by his experimental investigations, and may be led, by means of his own discoveries, to renounce the opinions which have so deeply offended both the naturalist and the Christian.
The views of which Mr. Darwin endeavours to establish are contained in the following passage at the end of his work:—"I believe that animals have descended from at most only four or five progenitors, and plants from an equal or lesser number. Analogy would lead one step farther, namely, to the belief that all animals have descended from some one prototype.
But analogy may be a deceitful guide. Nevertheless, all living things have much in common in their chemical composition, their germinal vesicles, their cellular structure, and their laws of growth and reproduction. We see this even in so trifling a circumstance as that the same person often similarly affects plants and animals; or that the poison secreted by the gall-fly produces monstrous growths on the wild rose or oak-tree.
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In supporting this extraordinary doctrine, Mr. Darwin devotes his first chapter to the changes produced in plants and animals "under domestication. Slight changes may also be produced from "the conditions of life," such as increased size from amount of food, colour from particular kinds of food, and perhaps thickness of fur from climate; but though such causes of variation may be numerous, yet the variations themselves are unimportant compared with those which are inherited; and hence Mr.
Darwin concludes that "if strange and rare deviations of structure are truly inherited, less strange and commoner deviations may be freely admitted to be inheritable. The carrier-pigeon, the short-faced tumbler, the runt, the barb, the porter, the turbit, the jacobin, the trumpeter, the fan-tail, are all described as differing in their beaks, their necks, their bodies, their feet, their tails, and even their skeletons, and to such degree, that an ornithologist, were he told that they were wild birds, would certainly, he thinks, rank them as well-defined species; and yet all of these pigeons are admitted to have been descended from the blue and barred rock-pigeon, the Columba Livia.
Now, admitting all this to be true, it is no evidence that any of the varieties constitute a new species, though the variations may have been accumulating for four thousand years. On the contrary, there is no tendency in these variations to become permanent, but rather to disappear, so that the fancy pigeon, returns to the rock-pigeon from which it descended. The same law of reversion to the original type is proved in various domesticated animals. Pallas informs us that the wild horses of the Kalmucks, when no longer taken care of by man, relapse into their untamed condition; and Dr.
Prichard states that the escaped domesticated animals—the horse, the ass, the sheep, the goat, the hog, the dog, the cat, and the gallinaceous fowls, which the Spaniards took from Europe to America, had lost all the most obvious appearances of domestication. That the changes produced by domestication effect no permanent variation amounting to a specific difference, is strikingly shown in the case of the dog, which, of all domestic animals, exhibits the most numerous and marked variations in regard to size, colour, character of hair, and form of head; yet, notwithstanding these, as Professor Owen remarks, "the naturalist detects, in the dental formula, and in the construction of the cranium, the unmistakable generic and specific characters of the Canis familiaris.
The dumb animal might teach the philosopher that unity of kind or of species is discoverable under the strongest masks of variation. Our limits will not permit us to follow our author in his attempt to show that great changes take place under the principle of artificial selection, where domestic races have been produced by man, in accumulating in certain directions useful to him, the successive variations produced by nature.
As an example of the process of natural selection, Mr. Owing to the great rapidity with which plants and animals increase and multiply, the earth would soon be covered by their progeny, if numbers of them were not destroyed during some period of their lives. Hence there is "a struggle for existence," during which superfluous life is taken, and the vigorous, the healthy, and the happy survive and multiply, while those of feebler constitutions, incapable of providing for themselves and their offspring, must annually perish.
In admitting the fact of this struggle for existence, naturalists have drawn from it the very opposite conclusion. When God saw that every living creature which he made was good, we cannot doubt that the type of each of them was perfect. The struggle for life, therefore, is to present, and not to promote a change in the original form.
The strong tiger that survives the struggle will have more of its native ferocity than its sickly congener that has perished. Nor will the Red-Indian boy that has escaped from drowning, while his brother has perished, be a less perfect Red-Indian than his father who threw him into the sea. Instead, therefore, of there being "a constant tendency in the improved descendants of any one species, to supplant and exterminate in each stage of descent their predecessors, and their original parent," there will be the very opposite tendency to preserve unimpaired the relative perfection which that species received from the Creator's hand.
Such is a brief and very imperfect notice of the processes by which, according to Mr. Darwin, species are so changed that, since the first act of creative power, man has risen from a primordial atom , through the numerous stages of plant, fish, fowl, and quadruped. If this speculation has any evidence to support it, it will be found in the history of organized beings during the several thousand years of the historic period.
Facts and fancies in hospital infection.
In the course of this long period, no change of species has taken place and no new species has appeared. The bird and beasts of Egypt, as preserved in her ancient tombs, have experienced no change in their specific character during the two, three, or four thousand years that have elapsed since the artist prepared their mummies for preservation. Though the large runt pigeon, with its massive beak and its huge feet, differs from its blue and barred progenitor the rock, it is a pigeon still. Though the slender Italian greyhound has a strange contrast with the short-legged bull-dog, they are both dogs in their teeth and in their skull.
The mouse, even, has not been transmuted into the cat, nor the hen into the turkey, nor the duck into the goose, nor the hawk into the eagle, and still less the monkey into the man. When the highest instinct has passed into the lowest reason, when the chatter of the parrot has risen into speech, and when the lion on his forest throne has addressed his subjects in the vernacular of man, we may then submit to the imputation of an ignoble origin.
The Almighty, however, as if foreseeing the degradation of His image, seems, as stated by Cuvier to have provided the Egyptian embalmers to refute the speculation. That strange and whimsical people, by embalming with so much care the brutes which were the objects of their stupid adoration, have left us, in their sacred grottoes, cabinets of zoology almost complete. Climate has conspired with art to preserve the bodies from corruption, and we can now assure ourselves with our own eyes what was the state of a good number of species three thousand years ago.
The salmon still mounts the river barrier, as when the Roman soldiers named it the leaper, when they first saw it in the streams of Gaul; and the polypus and the sponge, and other inhabitants of the Mediterranean, exhibit the peculiar properties which were noticed in them by Aristotle. In tracing the formation and growth of coral reefs in Florida, M.
Agassiz has shown that eight thousand years are required to raise one of these coral reefs or walls from its foundation to the surface of the ocean; and as there are four wall reefs round the southern extremity of Florida, the first of these must be thirty thousand years of age, and yet all of them are built by the same identical species.
These interesting facts, and others equally demonstrative of the immutability of species, are admitted to be difficulties by Mr. Darwin himself and his only reply to them is, that more time is wanted than the age of Egyptian tombs, or even that of the coral reef, for the transmutations which he advocates. Fortunately for our argument, there have been more animals ambalsmed than those of Egypt. The plants and animals which nature has preserved in the cementeries of primeval times speak the same language as those in the Egyptian tombs, and we must now appeal to them in search of any evidence of a transmutation of species.
Geologists have agreed in dividing the crust of the earth into three different formations; namely, Primary , Secondary , and Tertiary , or, to use the more expressive names, Palaeozoic , or the strata containing the most ancient forms of life; Mesozoic , or those containing less ancient forms; and Cenozoic , or those containing more recent forms. The thickness of these different masses is as follows:—. Paleaozoic strata, about. Mesozoic " ". In the lowest of the paleozoic strata, namely, the Cambrian, there are no traces of plants or animals.
In the next strata, the lower Silurian, trilobites and cephalopods cuttle-fish are found. In the upper Silurian, the earliest fishes appear. In the lower mesozoic strata, or Sub-Oolitc, birds and marsupial mammals are found. In the lower strata of the cenozoic , the London clay, bats, dolphins, bees, etc. In its middle formations, the coralline rag, the ape, dog, lion, elephant, ox, whale, etc. In this long range of created life, from its commencement with the trilobites and cuttle-fishes in the lower Silurian strata, to the occupation of the earth by man, there is not one fact indicating the transition of one species to another.
Darwin himself confesses that the intermediate varieties are wanting, that "Geology assuredly does not reveal any such finely graduated organic chain;" and that "this is the most obvious and grave objection to his theory. He denies that life began in the lower Silurian strata. In thus maintaining "the imperfection of the geological record," in consequence chiefly of only a small portion of the globe having been explored with care, Mr.
For he may ask in vain where are the numberless transitorial links which must formerly have connected the closely allied or representative species found in the several stages of the same great formations. Darwin, and if they were all supplied according to his hypothesis, it would still present some important facts utterly subversive of his views. The existence of such creatures as the trilobites and the cephalopods or cuttle-fishes in the Silurian formations, with organs of sensation of the most perfect kind, is an unanswerable difficulty in the development theory.
Darwin is sorely puzzled with the transition of organs. The correction for the aberration of light is said, on high authority, not to be perfect even in that most perfect organ, the eye. Now it is quite true that the correction for the aberration of colour is not complete in the human or in any known eye. But, notwithstanding this, vision is perfect. The uncorrected colour is never seen in using that organ, and consequently the human eye, as the organ of vision, is perfect , and therefore not the result of natural selection.
Upon Mr. Darwin's principle the ear is not perfect, because it is insensible to the music of the spheres or the lense imperfect because it cannot discover every shade of colour. An over-sensitive ear would be destroyed by the sounds to which nature subjects it, and a touch sensitive to colour would be torture to its possessor. Natural selection, however, under Mr. Darwin's guide, may reconcile these difficulties, and the eye of the future may be furnished with crystalline lenses doubly or triply achromatic.
Our author himself sometimes stands aghast before his own opinions. He declares that "the belief that an organ so perfect as the eye could have been formed by natural selection is more than enough to stagger any one ;" but what can he say when he learns what he ought to have known, that the lens of the cuttle-fish, one of the earliest of animals, is as perfect and more complex even than that of man. The crystalline lens of the Sepia Loligo differs from that of all other animals in being a compound lens, consisting of a principal lens of a paraboloidal form, deeply convex behind, and slightly convex before, united to a meniscus with a predomination convexity placed in front of it.
The concave face of the meniscus is kept in contact with the slightly convex face of the principal lens by means of a transparent cartilaginous ring, so that the lens actually consists of three separate parts. In all other lenses the lamina: are composed of fibres, but in the Loligo they are films having a fibrous structure, radiating from the pole of the posterior surface of the lens. This rather curious failure to explore alternatives is by no means confined to atomic theory; it is widespread throughout the entire fabric of physical science.
The First Postulate of Relativity is a striking example. The real substance of the Relativity Theory is contained in the postulates of the constant velocity of light and the equivalence of gravitational and inertial mass. The validity of these postulates is firmly established; actually they are not postulates at all, they are experimental facts, the authenticity of which most physicists were willing to concede even before Einstein incorporated them into his theory. The First Postulate, on the other hand, is simply a principle of impotence. As such it cannot contribute anything of a positive nature to the theory; it merely serves the purpose of evading the contradiction which otherwise exists between the constant velocity of light and the Newtonian concept of motion.
Furthermore, it does not even do a very good job of meeting this quite modest requirement. In the first place, this postulate, which seems rather plausible in application to linear motion, falls flat in application to rotational motion, where the existence of a velocity can often be detected by external means. For instance, we can tell that the galaxies are rotating, and we can even get a general idea as to the relative magnitudes of their rotational velocities, simply by looking at them. This situation has never been reconciled with the First Postulate. The duty of the former is to explain facts; the duty of the latter is to explain away facts.
From a strictly logical standpoint, the best policy would probably be just to accept the fact that a contradiction exists, and to look upon attempts at explanation, such as the First Postulate, simply as interesting speculations, until some fully satisfactory explanation finally does appear. Essentially, this is what is being done in the field of radiation, where there is a similar contradiction between the wave and particle aspects of the photon.
Here the physicists, as James B. In view of the historical background and the general feeling that even a poor explanation is better than none, a frank recognition of the true situation may be to much to expect. There is no valid excuse, however, for failing to explore the possible alternative explanations. Obviously such alternatives exist. Within the framework of accepted ideas as to the nature of space and time the constant velocity of light is definitely in conflict with the concept of absolute motion. Something therefore has to be modified in order to conform with the observed facts, but this does not mean that the absolute motion concept necessarily has to be jettisoned.
It is equally possible to modify the currently accepted space-time concepts and retain absolute motion. A great many other similar instances of failure to explore alternatives could be cited, but in such cases as those described thus far the fault has been primarily a failure to recognize the existence of the alternatives. This is a serious and costly oversight, to be sure, but criticizing it amounts to essentially nothing more than contending that scientists ought to do a better job: a contention which, even if true, is rather pointless.
But in addition to those instances where the alternatives have gone unrecognized, there are many situations in which the existence of alternatives is realized, but where some one of the possible alternative explanations is arbitrarily selected and proclaimed as an established fact. Unlike the failure to recognize the alternatives, which can be excused on the ground that the human brain is far from being a perfect instrument, this equally costly practice of investing pure assumptions with the habiliments of positive facts is wholly unnecessary and inexcusable.
Yet at the same time that a host of scientific authorities are proclaiming this theory as a firmly established and incontestable experimental fact, practically every elementary physics textbook admits that it is actually nothing more than an arbitrary selection from among several possible alternative explanations of the observed facts. The experiments simply show that if a particle is subjected to an unchanged electric or magnetic force, the resulting acceleration decreases at high velocities and approaches a limit of zero at the velocity of light.
The further conclusion that the decrease in acceleration is due to an increase in mass is a pure assumption that has no factual foundation whatever. It should be emphasized that, so far as the present issue is concerned, it is immaterial whether this assumption of an increase in mass at high velocities is ultimately found valid or not valid. The important point is that as matters now stand, we do not know what the ultimate verdict will be, and if the assumption happens to be wrong, which is not at all unlikely, the prevailing arbitrary refusal to consider any alternative places an almost impassible roadblock in the way of further progress.
Nothing dampens the enthusiasm of the research worker more, or constitutes a greater obstacle to recognition of the right answer if the researcher does ultimately find it in spite of everything, than this practice of building pure assumptions up to the status of articles of faith whose validity must not be questioned.
This is not intended to imply that there is anything inherently wrong about making assumptions. Newton thought that there was, and he expressed some rather critical opinions about hypotheses in general, but an examination of his work shows that he actually utilized them rather freely.
The truth is that we have no option but to use assumptions, unless we restrict our inquiries to the regions accessible to direct observation. The only method that is available for investigating phenomena in inaccessible regions is to make some assumption, then determine what consequences will result in the observable regions if the assumption is valid, and finally compare these theoretical consequences with the results of observation or measurement. We may legitimately take the stand, therefore, that assumptions are indispensable tools of science.
The trouble starts only when the distinction between assumptions and facts is allowed to break down. There are, of course, many kinds of assumptions in scientific practice, and the arbitrary selection from among equally possible alternatives is neither the most prevalent nor the most dangerous. As pointed out in a previous chapter, the latter distinction belongs to the postulates which deny the validity of established physical principles in application to the special classes of phenomena under consideration.
The most common is the ad hoc assumption invented for the purpose of overcoming some specific obstacle in the theoretical development. Nothing more than a very elementary knowledge of human nature is required for a full understanding of the immense popularity that the privilege of making such assumptions now enjoys.
No scientist likes to face the prospect of spending long years of effort in a fruitless endeavor to solve a difficult problem, and few can achieve such perfect scientific detachment that they are able to contemplate with equanimity the necessity of giving up a cherished concept or theory of long standing. But here is a marvelous device by which the scientist can circumvent both of these distasteful prospects as if by magic.
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The ad hoc assumption is the morphine of the scientific world. When used sparingly and in the appropriate circumstances it is invaluable, but when it is used indiscriminately the results are disastrous. Common prudence certainly calls for the exercise of a careful control over any device which is so open to abuse: a close scrutiny of the alleged justification for the assumption, an insistence on adequate study of all possible alternatives, and above all, a permanent and sharply defined line of demarcation between assumptions and positively established facts.
But present practice is just the reverse. The scientist who solves a problem receives no more credit than the one who postulates that a solution is impossible; indeed our highest honors are reserved for those who construct evasive postulates of a particularly novel and ingenious character. Furthermore, the current tendency is to elevate these ingenious assumptions to a level where they are on a par with, or even superior to, the established facts.
The most vicious aspect of the present incredibly liberal policy with respect to the employment of ad hoc assumptions is that it perpetuates basic errors when they are once made. The facts that have been brought out in the preceding pages with respect to the nuclear hypothesis provide a graphic illustration of this point. Here is a hypothesis whose antecedents could never have survived any kind of a critical examination, and whose consequences have been one long story of continued and repeated conflict with observed facts and established principles.
The mere layman, in his innocence, might think that somewhere along the line someone would suggest that it would be simpler to drop the nuclear idea than to force the rest of physical theory through such a painful series of contortions. But no, the theorist tells us, this is unthinkable.
Facts and Fancies in Modern Science (Illustrated Edition)
Back on page one of The Book it says that Rutherford discovered the nucleus in and this, like the laws of the Medes and Persians, cannot be changed. And as long as there are no restrictions on the use of ad hoc assumptions, it will not be changed unless through the agency of some irreverent work such as this , since the question always comes up in this form: Shall we make another assumption or shall we abandon our entire theoretical structure? An important class of non-factual material that is all too often confused with fact consists of extrapolations from the known to the unknown regions.
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Here again, the process itself is not open to criticism. Extrapolation is a sound and indispensable tool of science, and as long as the products of the extrapolation process are recognized for what they actually are, this device serves a very useful purpose.
Facts and fancies in modern science by Sir John William Dawson - Free Ebook
As brought out earlier, we must use assumptions in order to deal with regions beyond the reach of direct observation, but if we had to make our assumptions completely at random, the amount of work that would have to be done to test one hypothesis after another until we just happened to hit on the right one would make scientific research practically impossible.
Extrapolation is the device that we use to determine the kind of assumption which has the greatest probability of being correct. Let us assume, for example, that we are doing some work which involves the melting point of iron under pressures on the order of those existing at the center of the earth. We have no direct knowledge of the behavior of matter under such high pressures and we therefore have no option but to make an assumption of some kind.