404 OPERATIONS SUBSIDIARY TO INDUCTION, 



respecting the usage of language, but respecting the properties of things, 

 and even the origin of those properties. And lience every enlarge- 

 ment of our knowledge of the objects to which the name is applied, 

 is liable to suggest an improvement in the definition. It is impossible 

 to frame a perfect set of definitions on any subject, until the theory of 

 the subject is perfect ; and as science makes progi-ess, its definitions 

 ■are also progressive. 



§ 4. The discussion of Definitions, in so far as it does not turn upon 

 the use of words, but upon the properties of things, Mr. Whewell calls 

 the Explication of Conceptions. The act of ascertaining, better than 

 before, in what particulars any phenomena which are classed together 

 agree, Mr. Whewell in his technical phraseology calls, unfolding the 

 general conception in virtue of which they are so classed. Making 

 allowance for what appears to me the darkening and misleading ten- 

 dency of this mode of expression, several of his remarks are so much 

 to the purpose, that I shall take the liberty of transcribing them. 



He observes,* that many of the controversies which have had an 

 important share in the formation of the existing body of science, have 

 " assumed the form of a battle of Definitions. For example, the 

 inquiry concerning the laws of falling bodies, led to the question 

 Vi^hether the proper definition of a tmiform force is that it generates a 

 velocity proportional to the space from rest, or to the time. The con- 

 troversy of the vis viva was, what was the proper definition of the 

 meastire of force. A principal question in the classification of minerals 

 is, what is the definition of a mineral species. Physiologists have 

 endeavored to throw light on their subject by defining organization, 

 or some similar teiTU." Questions of the same nature are still open 

 respecting the definitions of Specific , Heat, Latent Heat, Chemical 

 Combination, and Solution. 



._ " It is very important for us to observe, that these controversies 

 have never been questions of insulated and arhitrary definitions, as 

 men seem ofi;en tempted to imagine them to have been. In all cases 

 there is. a tacit, assumption of some proposition which is to be expressed 

 by means of the definition and which gives it its impor-tance. The 

 dispute concerning the definition thus acquires a real value, and be- 

 comes a question concerning true and false. Thus in the discussion. 

 of the question. What is a uniform force ? it was taken for granted 

 that gravity is a uniform force. In the debate of the vis viva, it was 

 assumed that in the mutual action of bodies the whole effect of the 

 force is unchanged. In the zoological definition of species (that it 

 coixsists of individuals which have, or may have, sprung from the same 

 parents,) it is presumed that individuals so related resemble each othei 

 more than those which are excluded by such a definition ; or, perhaps, 

 that species so defined have permanent and definite differences. A 

 definition of organization, or of some other term, which was not em- 

 ployed to express some principle, would be of no value. 

 !■• " The establishment, therefore, of a right definition of a term, may 

 be a useful step in the explication of our conceptions ; but this will be 

 the case then only when we have under our consideration some prop- 

 osition in which the term is employed. For then the question really 



♦ Phil, of the Ind. Sc. ii., 177-9. 



