NAMES AND PROPOSITIONS. 



been the case if it had been in any 

 degree made up of attributes not con- 

 noted by the name. The second kind 

 of imperfect definition, therefore, in 

 which the name of a class is defined 

 by any of its accidents, —that is, by 

 attributes which are not included in 

 its connotation,— has been rejected 

 from the rank of genuine Definition 

 by all logicians, and has been termed 

 Description. 



This kind of imperfect definition, 

 however, takes its rise from the same 

 cause as the other, namely, the willing- 

 ness to accept as a definition anything 

 which, whether it expounds the mean- 

 ing of the name or not, enables us to 

 discriminate the things denoted by 

 the name from all other things, and 

 consequently to employ the term in 

 predication without deviating from 

 established usage. This purpose is 

 duly answered by stating any (no 

 matter what) of the attributes which 

 are common to the whole of the class, 

 and peculiar to it ; or any combina- 

 tion of attributes which happens to 

 be peculiar to it, though separately 

 each of those attributes may be com- 

 mon to it with some other things. It 

 is only necessary that the definition 

 (or description) thus formed should 

 be convertible with the name which it 

 professes to define ; that is, should be 

 exactly co-extensive with it, being 

 predicable of everything of which it 

 is predicable, and of nothing of which 

 it is not predicable ; though the attri- 

 butes specified may have no connec- 

 tion with those which mankind had 

 in view when they formed or recog- 

 nised the class, and gave it a name. 

 The following are correct definitions 

 of Man, according to this test : Man 

 is a mammiferous animal, having (by 

 nature) two hands (for the human 

 species answers to this description, 

 and no other animal does) : Man is 

 an animal who cooks his food : Man 

 is a featherless biped. 



What would otherwise be a mere 

 description may be raised to the rank 

 of a real definition by the peculiar 

 purpose which the speaker or writer 



has in view. As was seen in the 

 preceding chapter, it may, for the 

 ends of a particular art or science, or 

 for the more convenient statement of 

 an author's particular doctrines, be 

 advisable to give to some general 

 name, without altering its denotation, 

 a special connotation, different from 

 its ordinary one. When this is done, 

 a definition of the name by means of 

 the attributes which make up the 

 special connotation, though in general 

 a mere accidental definition or de- 

 scription, becomes on the particular 

 occasion and for the particular pur- 

 pose a complete and genuine defini- 

 tion. This actually occurs with re- 

 spect to one of the preceding examples, 

 "Man is a mammiferous animal 

 having two hands," which is the 

 scientific definition of man, considered 

 as one of the species in Cuvier's dis- 

 tribution of the animal kingdom. 



In cases of this sort, though the 

 definition is stUl a declaration of the 

 meaning which in the particular in- 

 stance the name is appointed to con- 

 vey, it cannot be said that to state 

 the meaning of the word is the pur- 

 pose of the definition. The purpose 

 is not to expound a name, but a 

 classification. The special meaning 

 which Cuvier assigned to the word 

 Man, (quite foreign to its ordinary 

 meaning, though involving no change 

 in the denotation of the word,) was 

 incidental to a plan of arranging 

 animals into classes on a certain 

 principle, that is, according to a cer- 

 tain set of distinctions. And since 

 the definition of Man according to 

 the ordinary connotation of the word, 

 though it would have answered every 

 other purpose of a definition, would 

 not have pointed out the place which 

 the species ought to occupy in that 

 particular classification, he gave the 

 word a special connotation, that he 

 might be able to define it by the kind of 

 attributes on which, for reasons of scien- 

 tific convenience, he had resolved to 

 found his division of animated nature. 



Scientific definitions, whether they 

 are definitions of scientific terms, or 



