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Show 150 MR. DARWIN'S WORK AND explain and the thing that upsets yon altogether. There is hardly any hypothesis in this world which has not some fact in connection with it which has not been explained, but that is a very different affair to a fact that entirely opposes your hypothesis; in this case all you can say is, that your hypothesis is in the same position as a good many others. Now, as to the third test, that there arc no other causes competent to explain the phenomena, I explained to you that one should be able to say of a hypothesis, that no other known causes than those supposccl by it are competent to give rise to the phenomena. I-Iere, I t~ink, Mr. Darwin's view is pretty strong. I really beheve that the alternative is either Darwinism or nothing, for I do not know of any rat~onal conception or theory of the organic universe which has anv scientific position at all beside Mr. Darwin's. I d~ 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 favour a thousandth part of the evidence which may be adduced in favour ?f ~r. Dar~vin~s views. Whatever may be the obJections to h1s views, certainly all others 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 argned from what was undoubtedly a true cause of s01ne of the phenomena of orao- anic natur·e • Fie Sal'd 1' t I·S 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 TilE PHENOMENA OF OHGANIC NATURE. 151 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 feet, 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 stronglybased hypothesis is nothing 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 ~fr. 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 thcmsclYes to creeds; they are bound by articles of no sort; there is not a single belief that it is not a bounden duty with thmn to hold with a light hand and to part with it, cheerfully, the moment it is really proved to be contrary to any fact, great or small. |