RELATION OF SOCIOLOGY TO BIOLOGY. 327 



Characteristic Ideas. — Such, then, is the hierarchy of science 

 and the mutual relations of the several orders. Now, each group of sci- 

 ences, as Whewell has shown, has its own characteristic fundamental 

 idea or ideas. For example, the fundamental ideas of mathematics — 

 the ideas underlying all its operations — are tliose of mimher and quan- 

 tity. The fundamental idea of mechanical and physical sciences is that 

 of physical force. The fundamental idea peculiar to chemistry and 

 underlying all its distinctive phenomena is that of affinity. The fun- 

 damental idea underlying all the distinctive phenomena of biology is 

 that of life. Subordinate ideas under these general heads we shall call, 

 after Comte, doctrines. 



Characteristic Methods. — Again, each group of sciences has also 

 its characteristic method. The characteristic method of mathematics 

 is that of notation. We are all familiar with the wonderful power of 

 this method. By the use of a few figures, viz., the numeral digits, hav- 

 ing each a value of its own and another depending on position, a few 

 symbols, a and b, x and y, connected by signs, + ^^^ — ^"d =, the 

 veriest schoolboy may quickly solve problems which would defy the 

 unassisted efforts of the greatest genius. The characteristic method of 

 physics and chemistry is experiment : without the use of this potent 

 instrument these sciences could not advance a step. The characteristic 

 method of biological sciences is the method of comparison. The use 

 of this method we will illustrate after a while. 



Now, each group, after it once enters the hierarchy, besides its own 

 characteristic ideas and methods, uses freely and with the greatest 

 advantage all the ideas and methods of the lower sciences, but espe- 

 cially those of the science immediately below, and with which, there- 

 fore, it is immediately connected. Thus chemistry uses the charac- 

 teristic ideas and methods of physics and mathematics, but espe- 

 cially of physics. Biology, besides its own characteristic ideas and 

 methods, uses freely the methods and ideas of chemistry — physics 

 and mathematics — but especially those of chemistry. If there be any 

 other still higher science, it must use with the greatest advantage 

 the ideas and methods of all lower sciences, but especially those of 

 biologv. 



Again : although the ideas and methods of the lower groups are 

 imported into the higher groups and freely used there, yet we acquire 

 clear conceptions of such ideas and doctrines, and expertness in the 

 use of such methods, only in the group where they are native and 

 characteristic. Thus, each group of sciences becomes the appropriate 

 school for its own characteristic doctrines and methods. For example, 

 physics uses freely the method of notation, but mathematics is the 

 true school of this method. Biology uses experiment, but physics is 

 the true school of this method. If there be any other still higher sci- 

 ence which shall use the doctrines of life and the method of compari- 

 son, the cultivators of that science should first acquire clear concep- 



