78 SCIENCE PROGRESS 



of the males of military age are taken off to war under conscrip- 

 tion, whilst a smaller section, and that the weakly section, remains 

 behind, and this process is said to be " reversed selection," i.e. 

 it is the unfit instead of the fit who are predominantly selected 

 for fatherhood. It may be reversed selection, but also it may 

 not be, because fortunately not all who go to the war are killed, 

 and until we know both the quantity and quality of those who 

 return we cannot decide whether the whole process is reversed 

 selection or not. The problem may be best expressed algebrai- 

 cally. Let A be the males of military age who remain civilians. 

 This group consists of a small number of seriously defective 

 persons (with regard to this small minority the pessimists have 

 a strong case), of a considerable number who are naturally 

 weakly in various respects, and of another section of men who 

 possess weaknesses which are merely acquired and are therefore, 

 ex hypothesis not heritable. Moreover, in the exceptional case of 

 Great Britain, voluntary service swells the size of A by a large 

 addition of those who are fit for service, but who do not enlist — 

 the men with private responsibilities that they feel unjustified in 

 leaving, the indifferent, political dissentients, Quakers, and so 

 forth. Let B represent the entire body of soldiers. B then 

 passes through the dangers of war, and we will represent the 

 survivors, fortunately a large majority in very recent wars, by 

 the letter M. Now I have not seen it anywhere definitely stated, 

 but there appears to underlie the argument of the pessimists a 

 tacit assumption that the average level of inborn capacities will 

 be the same in M as in B. If that were true, then of course the 

 average quality of A + M would be lower than that of A + B. 

 I may say in parenthesis that the problem is not really one of 

 simple averages, because even Darwinians admit that the 

 offspring of A, even if A married only women as inferior as 

 themselves, would tend somewhat to revert towards the racial 

 mean, but for the moment we will ignore that incalculable com- 

 plication. Now in so far as some of the members of A possess 

 definite heritable defects which are wholly absent from B, it is 

 no doubt true that the quality of M is identical with that of B, 

 though even here there may be a variable liability to develop 

 some of the defects. But with other characteristics, in which 

 there is a gradation of inborn variation — muscular strength, the 

 endurance of fatigue, height, strength of nerve, etc. — the case is 

 quite otherwise. It is a legitimate assumption that war exercises 



