July 2, 1909] 



SCIENCE 



21 



25 presidents of the United States " 23 of 

 whom were country bred, or were brought up 

 under what the census terms rural conditions." 

 This fact is without significance for two rea- 

 sons. First, the total 25 is so small that the 

 probable error is necessarily too large to give 

 a conclusion in a statistical discussion of this 

 kind. Second, and equally important, their 

 birth records must be taken in terms of the 

 total proportion of the population dwelling in 

 the country and rural districts in the early 

 days when these men were born. The fact 

 that " about 36 per cent, of our population 

 actually live on the farm at the present time " 

 has nothing to do with the question. The 

 same criticism applies to the figures concern- 

 ing United States senators. He has shown no 

 ratio over the expected for the rural regions in 

 terms of population distribution, at the time 

 of their birth, some fiity or sixty years ago. 



I shall look forward with expectancy to the 

 other statistics which Mr. Spillman hopes to 

 present, and am very glad that he takes an 

 interest in these questions. I agree with him 

 that " the matter must rest here until further 

 statistics are available " ; but in the meantime 

 I shall feel much confidence in the indications 

 which have been furnished me as drawn from 

 a list of some sixteen thousand, more or less 

 notable persons, out of the vast population of 

 the United States. 



Frederick Adams Woods 



Brookline, Mass., 

 May 17, 1909 



FAIR PLAY AND TOLERATION IN CRITICISM 



To that large number who accept the jus- 

 tice, the value and the need of the recent 

 criticism by Blackwelder of the geological 

 fallacies dressed out as facts in Lowell's book 

 on Mars as the abode of life, some reply will 

 seem called for to offset before the general 

 scientific public the personal, befogging and 

 dogmatic rejoinder which it evoked in a recent 

 issue of Science from one not a geologist.' 

 In this connection some preliminary statement 

 may well be made as to the kind of articles 



^ " Fair Play and Toleration in Science," by T. 

 J. J. See, professor of mathematics, U. S. Navy, 

 Science, Vol. XXIX., pp. 858-60, May 28, 1909. 



which in the mind of the writer seem to call 

 for certain kinds of criticism. This appears 

 the more necessary since to some all criticism 

 seems out of place and to indicate a carping 

 disposition, while others would hold that spe- 

 cialists are too lax in permitting to pass un- 

 challenged many works which are highly erro- 

 neous but whose character is evident to the 

 specialist only. 



Destructive criticism is to all constructive 

 workers in science a disagreeable task, yet one 

 which should often be regarded as a duty, 

 especially to imiversity teachers, since such 

 are deeply interested in the general diffusion 

 of knowledge and should be equally concerned 

 in the prevention of that diffusion of error 

 which, unless vigorously combated, takes the 

 place of truth. 



All research work, even by properly quali- 

 fied men, must necessarily contain some per- 

 centage of error which is eliminated by fur- 

 ther advances in knowledge, but which fre- 

 quently serves a most valuable purpose in 

 stimulating to further and more exact ob- 

 servation and analysis. Such work, addressed 

 to specialists, is always worthy of more praise 

 than criticism, and a proper review will always 

 seek out the parts of value and give them more 

 prominence than those features which in the 

 mind of the reviewer may seem open to ques- 

 tion or even to miss the truth. It is not such 

 research work which is here under discussion. 



Advancement of knowledge, however, im- 

 plies not only abstruse technical researches, 

 but popular expositions of the same which 

 shall carry a vivid conception of the principles 

 and results to the intelligent but unprofes- 

 sional public, consisting of laymen as well as 

 workers in other branches of knowledge. Such 

 work when well done is regarded by scientists 

 in general as of the very highest educational 

 value, and many eminent men have contrib- 

 uted a part of their time to the development 

 of popular science. In fact, no small part of 

 the eminence of some of the best known and 

 highly regarded men of science is due to their 

 work in what may be called the popular field, 

 since it reaches those whose professional in- 

 terests are in other branches. It is obvious 



