March 28, 1902.] 



SCIENCE. 



487 



11. Illusions and hallucinations do not 

 show that the world I know is unreal, nor 

 do they show that its reality is relative to 

 me. 



Deceptions and illusions and hallucina- 

 tions are not unreal. They are matters of 

 fact of which the physiologist and the 

 pathologist and the physician are finding 

 out the meaning, and finding too a way to 

 make use of this meaning, by scientific dis- 

 covery, while common folks mistake their 

 meaning, just as we mistake the meaning 

 of other matters of fact when we think we 

 know more than we have found out. 



Comprehension is the gathering in of 

 generalizations into a hypothesis, but while 

 any plausible hypothesis may satisfy idle 

 curiosity, it has no scientific status unless 

 it leads to the discovei-y of facts and the 

 control of nature. 



When the ignorant man who has lost his 

 foot feels the sensation which he has 

 learned to call pain in his toes, he says his 

 foot is uneasy in its grave. When the 

 learned philosopher tells him his pain is 

 an illusion, he may justly declare that he 

 knows his OAvn feelings better than any one 

 else, however learned. The pain is real, 

 but when he satisfies himself with the 

 notion that his foot is uneasy, he mistakes 

 a hypothesis for a fact, like the philoso- 

 pher, while the man of science discovers 

 that the sensory nerve is irritated some- 

 where else than at its endings in the toes. 



12. Instead of showing that rue can never 

 know anything as it really is, may not the 

 notion that knoitiedge is comprehension he 

 a new illustration of the fallacy of the 

 undistributed middle? 



We comprehend things when we know 

 Ihem, but it does not follow that when we 

 comprehend them we know them, for 

 knowledge may be comprehension and 

 something more. 



The resemblances between things are 

 summarized by classifying or comprehend- 



ing them, but Locke has reminded us that 

 knowledge is the discovery of resemblances 

 and differences. So far as we know 

 nature, it exhibits universal order in end- 

 less diversity ; not order here aaid diversity 

 there, but order in diversity. Can we 

 imow any two things are alike without 

 knowing they are different? We may, for 

 some purpose of our own, fix our attention 

 upon the order of nature, neglecting the 

 diversity, but things do not cease to be 

 because they do not, for the time, seem to 

 concern us. 



Are the order of nature and the diver- 

 sity of nature either two things or one 

 thing seen from two standpoints? Are 

 they not rather two narrow and imperfect 

 views of the natural world which lies be- 

 fore our eyes? Have we any way to find 

 out either the unity of nature or the diver- 

 sity of nature except scientific discovery? 

 ]\'Iay not the notion that while we discover 

 the laws of nature, we deduce from these 

 laws the diversity of nature, and our con- 

 trol of nature, be an illustration of the fal- 

 lacy of the undistributed middle? Is a 

 scientific law anything more than a sum- 

 mary of past experience, joined to confi- 

 dence in the continuity of nature? Do we 

 ever know that we can foresee or control 

 nature, even in repeating the simplest sci- 

 entific experiment, until we have suc- 

 ceeded ? 



13. Biological science is pecxdiarly fitted 

 for calling to our attention the diversity 

 of nature. 



While analytical science is making mar- 

 vellous revelations of the order which per- 

 vades the apparent disorder of nature, 

 showing us, by the method of analysis and 

 generalization, the most astonishing proof 

 of order and regularity in the course of 

 events which had seemed to be chaotic, bio- 

 logical science is continually recalling to 

 our attention the divei-sity of the statis- 

 tical data, and making equally marvellous 



