45^ 



OPERATIONS SUBSmiARY TO IICDUCTION. 



guage adapted for the investigation 

 of truth — that its terms shall each 

 of them convey a determinate and 

 tinmistakable meaning. There are, 

 however, as we have already re- 

 marked, other requisites : some of 

 them important only in the second 

 degree, but one which is fundamental, 

 and barely yields in point of import- 

 ance, if it yields at all to the quality 

 which we have already discussed at 

 so much length. That the language 

 may be fitted for its purposes, not 

 only should every word perfectly ex- 

 press its meaning, but there should 

 be no important meaning without its 

 word. Whatever we have occasion 

 to think of often, and for scientific 

 purposes, ought to have a name ap- 

 propriated to it. 



This requisite of philosophical lan- 

 guage may be considered under three 

 different heads, that number of sepa- 

 rate conditions being involved in it. 



§ 2. First, there ought to be all 

 such names as are needful for making 

 such a record of individual observa- 

 tions that the words of the record 

 shall exactly show what fact it is 

 which has been observed. In other 

 words, there should be an accurate 

 Descriptive Terminology. 



The only things which we can ob- 

 serve directly being our own sensa- 

 tions or other feelings, a complete 

 descriptive language would be one in 

 which there should be a name for 

 every variety of elementary sensation 

 or feeling. Combinations of sensa- 

 tions or feelings may always be de- 

 scribed if we have a name for each of 

 the elementary feelings which com- 

 pose them ; but brevity of descrip- 

 tion and clearness (which often de- 

 pends very much on brevity) are 

 greatly promoted by giving distinctive 

 names not to the elements alone, but 

 also to all combinations which are of 

 frequent recurrence. On this occa- 

 sion I cannot do better than quote 

 from Dr. Whewell * some of the ex- 



* History of Scientific Ideas, li. no, in. 



cellent remarks which he has made 

 on this important branch of our sub- 

 ject. 



*' The meaning of [descriptive] tech- 

 nical terms can be fixed in the first 

 instance only by convention, and can 

 be made intelligible only by present- 

 ing to the senses that which the terms 

 are to signify. The knowledge of a 

 colour by its name can only be taught 

 through the eye. No description can 

 convey to a hearer what we mean by 

 apple-green or French-grey. It might, 

 perhaps, be supposed that, in the first 

 example, the term apple, referring to 

 so familiar an object, sufficiently sug- 

 gests the colour intended. But it 

 may easily be seen that this is not 

 true ; for apples are of many different 

 hues of green, and it is only by a con- 

 ventional selection that we can appro- 

 priate the term to one special shade. 

 When this appropriation is once made, 

 the term refers to the sensation, and 

 not to the parts of the term ; for these 

 enter into the compound merely as a 

 help to the memory, whether the sug- 

 gestion be a natural connection as in 

 'apple-green,' or a casual one as in 

 * French-grey.' In order to derive 

 due advantage from technical terms 

 of the kind, they must be associated 

 immediately with the perception to 

 which they belong, and not connected 

 with it through the vague usages of 

 common language. The memory must 

 retain the sensation ; and the tech- 

 nical word must be understood as 

 directly as the most familiar word, 

 and more distinctly. When we find 

 such terms as tin-white or pinchbeck- 

 hrown, the metallic colour so denoted 

 ought to start up in our memory 

 without delay or search. 



" This, which it is most important 

 to recollect with respect to the simpler 

 properties of bodies, as colour and 

 form, is no less true with respect to 

 more compound notions. In all cases 

 the term is fixed to a peculiar mean- 

 ing by convention ; and the student, 

 in order to use the word, must be 

 completely familiar with the conven- 

 tion, so that he has no need to frame 



