NATURE 



49 



THURSDAY, MAY 20, 1897. 



A PHILOSOPHICAL THEORY OF SELECTION. 

 Versuch eincr philosophischen Selektionstheorie. Von 



Dr. Johannes Unbehaun aus Gotha. Pp. 150. (Jena : 



Gustav Fischer, 1896.) 



THE object of this essay is to place the theory of 

 selection on a purely deductive and abstract basis 

 as distinguished from the concrete form in which it is 

 made familiar to modern evolutionists through the writ- 

 ings of Darwin and Wallace. From the philosophical 

 point of view, it is certainly desirable that we should 

 realise that the particular kind of selection which is 

 operative in species transformation, or in the production 

 of artificial races, is only one phase of selection in the 

 abstract, and any attempt to make our ideas on this sub- 

 ject more exact will be welcome to philosophical students' 

 of evolution. It is, in fact, somewhat remarkable that, 

 while all working naturalists have now accepted the doc- 

 trine of evolution in one form or another, comparatively 

 few have attempted to examine into the philosophical 

 liasis of the principles of selection. Dr. Unbehaun's dis- 

 cussion of the subject, if not exhaustive, is at any rate 

 very suggestive, and as a contribution to a much 

 neglected aspect of the philosophy of evolution the work 

 may be safely recommended to English biologists. 



The opening part of the essay, which treats of the 

 principle of selection from the historical point of view, 

 offers very little novelty. The author comes to the con- 

 clusion that the germ of the modern theory of selection is 

 contained in the writings of the Greek philosophers. 

 Empedocles appears to have had some hazy notions of 

 the kind which did not produce much effect upon 

 Aristotle, and the first definite utterance is attributed to 

 Lucretius Carus the Epicurean. Those who take pleasure 

 in reading into the poetic flights of ancient writers the 

 discoveries of modern science, will derive interest from 

 this section. There was a time in the history of science — 

 especially in this country — when no new discovery was 

 considered worthy of credence unless it could be shown 

 to be in harmony with the views of the old philosophers. 

 Those were the days when classical studies reigned 

 supreme in our Universities, and when the would-be 

 student of science was looked down upon as a poor 

 creature. Happily for us the times have changed, and 

 no worker in science is now seriously influenced by 

 what the ancients thought. If he studies their writings, 

 it is more from the point of view of academic interest 

 than from a desire to find justification for his discoveries. 

 The author of the present work does not appear to be 

 acquainted with Prof. H. F. Osborn's most interesting 

 discussion of the history of evolution in his book entitled 

 " From the Greeks to Darwin." 



As founders of the modern theory of selection. Dr. 

 Unbehaun justly couples Darwin and Wallace. The 

 distinction between evolution or descent with modifica- 

 tion and selection is clearly grasped and emphasised by 

 the former being called " Lamarckismus," and the latter 

 " Darwinismus." Some pages are devoted to an exposi- 

 tion of the Darwinian principles, and the limited theory of 

 selection elaborated by Malthus is also explained. There 

 NO. 1438, VOL. 56] 



are not many points in this section with which we are not 

 already familiar in this country, but the author certainly 

 puts the case in a way calculated to clarify some of the 

 current notions concerning the action of selection. Thus, 

 with respect to the interpretation of the term " struggle 

 for existence," it is pointed out that there are three possi- 

 bilities, viz. struggle unaccompanied by actual extermina- 

 tion, and therefore of no effect as a selective process 

 struggle with extermination, as in ordinary natural selec- 

 tion ; and extermination without struggle, which may or 

 not produce selective action. The consideration of this 

 last contingency brings out very clearly the difference 

 between the struggle of competing organisms among 

 themselves and the struggle with external (inorganic) 

 conditions of environment. The outcome of this dis- 

 cussion is the conclusion that concurrent extermination 

 of individuals or races is indispensable for the process of 

 selection — in other words, that selection is concerned 

 only with the existence or non-existence of individuals or 

 assemblages of individuals, whether actual or potential. 



After a brief exposition of the extension of the idea of 

 selection from the organism as a whole, to the component 

 parts (Wilhelm Roux, 1881), the author discusses palaeonto- 

 logical selection, a subject which appears to be equivalent 

 to a consideration of the conditions which favour the 

 preservation of fossil remains, and for the complete 

 understanding of which it is essential to study the con- 

 ditions of preservation and destruction of animals and 

 plants going on at the present time. In connection with 

 this, there is brought forward a principle which is termed 

 lithogenetic selection (Johannes Walther, 1895), ^"d 

 which may be paraphrased by saying that, although a 

 geological formation may be laid down over a wide area 

 of the surface of the earth, the local preservation of the 

 rock material is determined by local conditions, organic 

 and inorganic. The attempts which have been made to 

 refer the processes of evolution in inorganic nature to the 

 action of selection in any form, are considered by the 

 author to have failed on account of the untenabilityof the 

 fundamental assumptions. After a summing-up of the 

 conditions essential for the formulation of a philosophical 

 theory of selection, the author discusses, in an appendix, 

 some further points of historical interest ; viz. the claims 

 of Herakleitos among the ancients, and of Kant and 

 Wells among modern writers, to have entertained the 

 idea of a struggle for existence. The utterances of the 

 Greek philosopher are considered hazy ; those of Kant 

 and Wells are, as Haeckel has already shown (1889), 

 more to the point. 



The real work of building up "a purely deductive 

 theory of selection on the most general foundation ' 

 begins in the second chapter, and selection is defined 

 (p. 34) as the process by which, out of a number of 

 objects which are in any way related to each other, some 

 undergo extinction, while others survive within the same 

 interval of time. A critical analysis of this conception 

 leads to the conclusion that, instead of through selection, 

 it is possible to approach the problem from the point of 

 view of a system of objects (organisms) having different 

 degrees of duration in time. Here, again, there may be 

 selection with or without further development, according 

 as the process is accompanied by renewal or not. In the 

 latter case, a system may become modified in its average 



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