« SebelumnyaLanjutkan »
THE THEORY OF DEVELOPMENT. Upon the study of living and fossil organisms, their processes and relations, external and internal, is based the series of inductions embodied in the theory of development. Development is the evolution of organisms by natural process. For ages its principles have been employed by breeder and horticulturist to improve old and originate new varieties. What man does only by working in obedience to natural law, nature accomplishes of itself, environment replacing man as the external factor. A tendency to vary is part of every organism, and this internal, physiological tendency responds to external change. But environment does not originate variation any more than the canal originates the stream which it directs. Heredity is the fact that offspring resemble parent, variation that they differ from parent. The efficient causes of resemblance and variation are unknown, save that they are physiological and not physical, dynamic and not mechanical.
Overproduction expresses the observation that many more individuals are produced than there is food or room for; hence arises a struggle for existence in which the weaker individuals perish and the stronger survive. This is the survival of the fittest or natural selection. The survival results because of greater ability to cope with and conquer adverse conditions of existence. This natural selection by which organisms are brought into harmony with environment is a negative result, since it operates only by suppressing weaker individuals. Thus each generation propagates from its best and each becomes more perfect than the preceding, just as in producing the race. horse, man selected the fleetest horses and bred from them; of the progeny the fleetest were in turn paired, and so on till the present result has been attained. Those results that are per. manently helpful to the individual become developed by use and the variation is transmitted in an intensified form to de. scendants. Functions perfect organs, actions develop instinct, organisms are differentiated and specialized, brought into harmony with their respective surroundings, and species are created. The intermediate varieties, being less strongly characterized-weaker, are for the most part blotted out, and series which once connected species are lost.
Since the several factors are always operating and environment (climate, amount of food, etc.), is ever and gradually changing, “species” are not fixed but are constantly responding to new conditions. “Species” and “varieties,” therefore, are relative terms. Species, like individuals, succeed one another in serial lines. Successive ages, geology teaches, have produced increasingly specialized forms. The physical conditions gradually improving, from primal germs through the ages have developed all species past and present,—such is the teaching of the theory. Geographic zoology and botany evidence that species are variable and that many intermediate races and varieties now exist. Asa Gray says: “I have been at the making and unmaking of far too many species to retain any overweening confidence in their definiteness and stability. I believe that they bave only a relative fixity and permanence."
Variation, overproduction, struggle for existence, survival of the fittest-these are the facts of Development. That from primal germs, by increasing specializations and adaptations, has come the present wealth of organic species, is the theory, the series of inductions, based on those facts. It accounts for the greatest number of phenomena, appears eminently reasonable, is compatible with and explains other science, and is accepted by the great body of scientific workers. Like Design it is not strictly demonstrable, but as a matter of induction its probability is so overwhelming that it is considered established.
THE BEARING OF DEVELOPMENT ON TELEOLOGY.
Accepting the theory of development, what is its bearing upon Design? Have vegetables and animals “ paved the earth with intentions," as Gray asserts, or is the materialist correct in claiming that in and of itself Development is sufficient to account for all the changes and improvements resulting in present species; that purely natural processes having accounted for adaptations, design is only an appearance ?
Nature, they say, is the grand worker, matter and force the two elements of the universe. The eye, for example, is not the result of wise forethought, not an instrument designed for the purpose of seeing. It has become an instrument of vision
simply and only because light and other external influences operated on the tendency of antecedent ocelli to vary. All adaptations and contrivances are accounted for when their physical antecedents are traced back to their supposed origin. The marvelous correspondence of organ and function no longer exhibit design since environment, directing through ages the tendency to vary, harmonizes them one to another. So with instinct, and with species.
In short, all natural harmonies are only the working of unconscious, unintelligent, impersonal nature.
The same sys. tem of natural law everywhere pervading the universe causes equally the pebble and the eye. The same immutable law manifested in gravitation falls the stone, --manifested in Development produces the human hand. There is no more intelli. gence shown in one than the other. The special adaptations of the band to its uses are “not any more available as evidence of design than the adaptations of a river to the bed which it has itself been the means of excavating." Law, immutable law, nothing but law! Briefly, this is the position of the materialist who lays claim to evolution. It is plausible, it has gained more than a limited hearing.
Is it true? Is this the legitimate bearing of Development on teleology? In reply it is said :
Development does not preclude Design. Like all science the theory of development has to do with second or efficient causes, known and unknown. For this reason it cannot account for the beginning of things. Development implies material to be evolved and forces by which it is done, but itself neither orig. inates nor explains that origin. The laws of development do not account for, but are only manifested in matter by the movements of force. To claim that life is the adjustment of inner to outer relations says nothing, since this adjustment is just what is calling for explanation. Mr. Darwin did not pretend to account for the origin of sensation or life.
Design is not excluded by supposing that Development explains all processes by which adaptations are evolved, even back to the first life-gerin. Not accounting when or how materials and forces originated, Development has no reason to give why in those beginnings the factors by which design is accomplished should not have been implanted. If intention existed in the first germ, undesigned formation cannot develop from it, since the extent of the implanted intention can be read only at the completion of such development. Nothing less than the oak is the measure of the acorn. That only an oak will come from an acorn is certain, --can be accurately predicted. In some way the plan for the product, since certain and predictable, is enfolded in the seed. Because true that the result of each developed acorn is an oak, is it not evident that the tree is a predetermined result? In like manner is it not eminently reasonable that other results,—adaptations and contrivances,—should be implanted in primal germs ? Certainly, Development does not preclude Design.
Development presupposes Design. Such intricate combinations of force as are known to be employed in producing the infinite variety of organic adaptations presuppose that immutable laws, working individually, could not produce such results; other. wise, by the law of parsimony, nature would employ them. This harmonious working of a complex of efficient causes, producing unified results in adaptations, indicates a coördinating power, which cannot be force, since force is precisely what is coutrolled, nor an efficient cause because such are the very things whose combination is to be explained. This first cause, working from a higher level, combines and manipulates secondary causes under proper circumstances of space and time and produces such results as presuppose this first cause to be an intelligent Designer.' Therefore, while Development is the summation of those processes—variation, overproduction, strug. gle for existence, survival of the fittest, etc.,which physically considered produce adaptation, it presupposes other factors which itself does not explain, and accountable for only on the supposition of Design.
Development is presupposed by Design. That is, if there is design it would probably be accomplished by means of tbe processes of Development. Design (in any fair sense of the word) must proceed from a conscious, intelligent Designer, who to realize his purposes in nature must have will to choose and power to accomplish.
As the preceding section shows, Development does not preclude an intelligent First Cause. However impossible immediate creation when we consider Development as cognizant only of secondary or efficient cause, this First Cause, manipulating matter and force, may have resources not inconsistent with efficient cause and so be able to create immediately. So long as the induction of a First Cause be valid, the possibility of immediate creation cannot be absolutely denied. There is nothing, however, a priori against mediate creation, since absolute immutability of law may be the most perfect means by which intelligence could accomplish it purposes. If it be said that laws are not things but statements, it is replied that they express natural relations—that if nature is true they are true.
Immutable law and uniformity of nature are expressions for the observed harmony and regularity of natural phenomena. Results in nature which are now brought to pass are by natural process. We observe only uniformity in present methods of creation. There is every probability that in the production of past phenomena the same methods prevailed. The veracity of nature necessitates the conviction that like results in nature are produced by like means. All the instances of adaptations now going on are by natural process or Development. Hence the presumption that all adaptations in nature were so produced and the conviction-supported by all science which is based on the fact of uniformity in nature,—that if adaptations realize design it is by mediate creation. In other words, design in adaptations presupposes Development.
The induction of a process of creation between organic result and origin therefore in no wise destroys the evidence of design, but only that former postulate of teleology, immediate creation. In inorganic nature, geology has conclusively shown that seas, continents, etc., were slowly evolved. Their immediate creation no longer finds acceptance. The evidence in nature that the simplest means are always employed in the attainment of an end (the law of parsimony), declares against supernatural means 80 long as there are natural ones. So in organic nature, Development declares unnatural and improbable the assumption -for it is nothing more, -of immediate creation. The weight of evidence is all on one side. There is but one choice for the