Freedom in Science and Teaching. - Ernst Haeckel (mobi reader txt) 📗

for certain of gravitation, of the attraction of mass, of its effects at great distances, and so on? Newton's theory of gravitation is regarded as the most important and certain theory of physics, and yet gravitation itself is a hypothesis. Then, as to the other branches of physics—electricity and magnetism. The whole scheme of these important sciences rests on the hypothesis of "electric fluidity," or of imponderable matter of which the existence is nothing less than proved. Or optics? Optics certainly appertain to the most important and completest branch of physics, and yet the undulatory theory of light, which we accept now as the indispensable basis of optics, rests on an unproved hypothesis, on the subjective assumption of an ethereal medium, whose existence no one is in a position to prove objectively in any way. Nay, further, before Young set up the undulatory theory of light, for a hundred years the emanation theory as taught by Newton obtained exclusively in physics; a theory which at the present day is universally regarded as untenable. In our opinion the mighty Newton won the greatest honours in the development of the science of optics, inasmuch as he was the first to connect and explain the vast mass of objective optical facts by a subjective and pregnant hypothesis. But, according to Virchow's view, Newton on the contrary transgressed greatly by teaching this erroneous hypothesis; for even in "exact" physics none but "independent and certain facts" are to be taught and established by "experiment as the highest means of proof." Physics as a whole, as resting on mere unproved hypotheses, may be indeed an object of inquiry but not of teaching.

Of course the same is true of chemistry; nay, this stands on much weaker feet, and is even less proved than physics. The whole theoretical side of chemistry is an airy structure of hypotheses such as does not exist in any other science. In the last three decades we have seen a whole series of the most different theories rapidly succeed each other, none of which can be positively proved, though at least one of them is taught by every professor of chemistry. But what is worst of all, the common basis of all the most dissimilar chemical theories, viz., the atomic theory, is as unproved and unprovable as any hypothesis can be. No chemist has ever seen an atom, but he nevertheless considers the mechanism of atoms as the highest term of his science, he nevertheless describes and constructs the connection of atoms in their various combinations as though he had them before him on the dissecting-table! All the conceptions which we possess as to chemical structure and the affinities of matter, are subjective hypotheses, mere conceptions as to the position and changes of position of the various atoms, whose very existence is incapable of proof. Away, then, with chemistry from our schools! The chemist must only describe the properties of the different elements and those combinations which can be put before the pupil as ascertained facts founded in experiment, "the highest means of proof." Everything that goes beyond this is mischievous, particularly every suggestion as to the essence and chemical constituents of bodies; matters as to which, in the nature of things, we can only form uncertain hypotheses. For as all chemistry, viewed as a system of doctrine, rests solely on such hypotheses, it may be indeed a subject of investigation but not of teaching.

Having thus convinced ourselves that chemistry as well as physics, those "exact sciences," those "mechanical" bases of all other sciences, rest on mere unproved hypotheses, and so must not be taught, we may make short work of the other faculties. For they collectively are more or less historical sciences and dispense wholly or in part with even those half-exact, fundamental principles on which physics and chemistry are based. In the first place, there is that grand, historical, natural science, geology; the great doctrine of the structure and composition, the origin and development of our globe. According to Virchow this too must be limited to the description of ascertained facts, such as the structure of mountain masses, the character of the fossils they contain, the formation of crystals, and so forth. But not for the world must anything be taught as to the evolution of this globe; for this rests from beginning to end on unproved hypotheses. For even to the present day the Plutonic and Neptunic theories are disputing the field, and to this day we know not as to many of the most important rocks, whether they originated by the agency of fire or of water. The new and remarkable discoveries of the great Challenger-expedition threaten to subvert a great many geological notions which had long been regarded as certain. Then again, as to fossils. Who can prove with any certainty that these petrifactions are in truth the fossilised remains of extinct organisms? They may be—as many distinguished naturalists of even the last century maintained—marvellous sports of nature, mysterious "Lusus naturæ," or mere rough, inorganic models of the labouring Creator into which He subsequently "breathed the breath of life;" or perhaps "stone-flesh" (caro fossilis) brought into existence, on the dead rocks by the "fertilising air" (aura seminalis), and so forth.

But I am wrong! for with regard to petrifactions, Virchow is in the highest degree speculative, and accepts without any hesitation the rash hypothesis that fossils are actually the remains of extinct organisms, although no "certain proof" whatever can be offered in its favour, and although experiment, the "highest means of proof," has never yet produced a single fossil. According to him these are actual "objective, material evidences," only here we must go no further than certain experience teaches us, and base no subjective conclusions on these objective facts. Thus, for instance, in the long series of the mesozoic formations, in the different strata of the Trias, Jurassic, and Chalk formations, for the deposition of which a lapse of many millions of years has been required, we find absolutely no remains of fossil mammalia beyond lower jaws; seek where we will, nothing is anywhere to be found but lower jaws, and no other bones whatever. The simple reasons of this striking imperfection of the palæontological record have been clearly expounded by Lyell, Huxley, and others. (Comp. my "History of Creation," vol. ii. p. 32.) These great investigators, in accordance with all other palæontologists, have demonstrated that these jaw-bones of the mesozoic period are the remains of mammalia, accurately speaking of marsupials, on the simple ground that the nether jaws of the extant recent marsupials show a similar characteristic form with the fossil ones. They therefore unhesitatingly assume that the rest of the bones in the bodies of these extinct animals corresponded to those of living mammals. But this is a quite inadmissible hypothesis devoid of any "certain proof!" Where, then, are the other bones? Let us see them! till then we decline to believe in them. According to Virchow, we ought rather to assume that the lower jaw was the only bone in the body of these extraordinary beasts. Are there not, in fact, snails, in which an upper jaw is the only representation of a skeleton.

We cannot omit taking this opportunity of casting a side glance at the very hazardous position which Virchow, in total opposition to his boasted cool scepticism, has taken up in anthropology as it is called, now his favourite branch of science. In his Munich address he tells us that he is pursuing the study of anthropology with delight, and then asserts that "the quarternary man" is an universally-accepted fact. Quite apart from this statement, we have seen that Virchow can never attain to a profound and really scientific study of anthropology simply for this reason, that he is lacking in that comprehensive knowledge of comparative morphology which is indispensable to it; nay, comparative anatomy and ontogenesis must be, according to him, unpermitted speculations and the phylogenesis of man, the key to all the most important questions of anthropology, being based upon these, is devoid of all certain proof. All the more must we wonder at the speculative levity with which even the sceptic Virchow in the "Primeval History of Man" and "Fossil Anthropology," embarks in the most hazardous conjectures, and gives out uncertain, subjective hypotheses as certain, objective facts.

There is, in fact, at the present day no department of science in which the wildest and most untenable hypotheses have blossomed out so freely as in anthropology and ethnology, so-called. All the phylogenetic hypotheses which I myself have put forward in my "Evolution of Man" as to the animal ancestry of man, or in my "Natural History of Creation" as to the affinities of animal races—all the other genealogical hypotheses which are now advanced by numerous zoologists and botanists as to the phylogenetic evolution of the animal and plant worlds—all these hypotheses together, which Virchow rejects in a lump, are, critically considered as hypotheses, far better grounded in facts, far better supported by facts, than the majority of those innumerable airy and fanciful hypotheses with which, for the last twelve years, the "Archiv für Anthropologie" and "Zeitschrift für Ethnologie," edited by Virchow and Bastian, have filled their columns. This last periodical has at least the merit of being a tolerably consistent opponent of the doctrine of evolution, while in the former, during twelve years, essays on both sides have been mixed up in cheerful confusion. And how fanciful are the short-sighted hypotheses which there blossom forth from the mixed mass of facts, chaotically flung together. Only think of the disputes over the stone age, bronze age, and iron age; think of the motley discussions as to the varieties of skull-conformation and their significance; on the races of man, the migrations of peoples and the like. Most of these very intricate historical problems are far more buried in obscurity, and the hypotheses to explain them dispense far more largely with any basis of facts, than is the case with our phylogenetic hypotheses; for these are more or less "objectively" based on the facts of comparative anatomy and ontogenesis.

But no one of these historical hypotheses is so daring, so little "certainly proved," as the group of very various and contradictory hypotheses which have been put forward as to the antiquity and first appearance of the human species; and Virchow asserts positively "The pleistocene man is an universally accepted fact. The tertiary man is, on the other hand, a problem, though indeed a problem which is already under substantial discussion!" As if the distinction between the tertiary and quarternary periods were not itself a geological hypothesis, and as if the significance of the fossil animal-remains, which play the largest part in it, did not also rest on mere hypotheses which escape all certain proof! Where, then, is the actual experiment "as the highest means of proof," which gives evidence for these "certain facts"? The whole discussion in general about pre-historic man, which Virchow has mixed up with his Munich address (pp. 30, 31), is the clearest evidence of the uncritical spirit in which he deals with these historical problems as "exact natural sciences." He assures us that "not one single ape's skull, nor skull of an anthropoid ape, has ever been found which could actually have belonged to a human owner! and he adds this sentence, in italics, "We cannot teach, for we cannot regard it as a real acquisition of science, that man is descended from the ape or from any other animal!" Then evidently no alternative remains but that he is descended from a god, or from a clod!

But let us go over the rest of the sciences to see what, according to Virchow, may be taught in each without endangering the safety of science. In the whole department of biology, as well as in zoology—including anthropology—and in