3^ 



INDUCTION. 



in chemistry simple substances, or 

 elementary natural agents, are the 

 only ones, any of whose properties 

 can with certainty be considered 

 ultimate ; and of these the ultimate 

 properties are probably much more 

 numerous than we at present recog- 

 nise, since every successful instance 

 of the resolution of the properties of 

 their compounds into simpler laws, 

 generally leads to the recognition of 

 properties in the elements distinct 

 from any previously known. The 

 resolution of the laws of the heavenly 

 motions established the previously 

 unknown ultimate property of a mu- 

 tual attraction between all bodies: 

 the resolution, so far as it has yet 

 proceeded, of the laws of crystallisa- 

 tion, of chemical composition, elec- 

 tricity, magnetism, &c., points to 

 various polarities, ultimately inherent 

 in the particles of which bodies are 

 composed ; the comparative atomic 

 weights of different kinds of bodies 

 were ascertained by resolving into 

 more general laws the uniformities 

 observed in the proportions in which 

 substances combine with one another ; 

 and so forth. Thus although every 

 resolution of a complex uniformity 

 into simpler and more elementary 

 laws has an apparent tendency to 

 diminish the number of the ultimate 

 properties, and really does remove 

 many properties from the list ; yet, 

 (since the result of this simplifying 

 process is to trace up an ever greater 

 variety of different effects to the same 

 agents,) the farther we advance in 

 this direction, the greater number of 

 distinct properties we are forced 

 to recognise in one and the same 

 object : the co-existences of which 

 properties must accordingly be ranked 

 among the ultimate generalities of 

 nature. 



§ 3. There are, therefore, only two 

 kinds of propositions which assert 

 uniformity of co-existence between 

 properties. Either the properties 

 depend on causes, or they do not. If 

 they do, the proposition which affirms 



them to be co- existent is a derivative 

 law of co-existence between effects, 

 and until resolved into the laws of 

 causation on which it depends, is an 

 empirical law, and to be tried by the 

 principles of induction to which such 

 laws are amenable. If, on the other 

 hand, the properties do not depend on 

 causes, but are ultimate properties ; 

 then if it be true that they invariably 

 co-exist, they must all be ultimate 

 properties of one and the same Kind ; 

 and it is of these only that the co- 

 existences can be classed as a peculiar 

 sort of laws of nature. 



When we aflfirm that all crows are 

 black, or that all negroes have woolly 

 hair, we assert an uniformity of co- 

 existence. We assert that the pro- 

 perty of blackness, or of having woolly 

 hair, invariably co-exists with the 

 properties which, in common language, 

 or in the scientific classification that 

 we adopt, are taken to constitute the 

 class crow, or the class negro. Now, 

 supposing blackness to be an ultimate 

 property of black objects, or woolly 

 hair an ultimate property of the ani- 

 mals which possess it ; supposing that 

 these properties are not results of 

 causation, are not connected with 

 antecedent phenomena by any law ; 

 then if all crows are black, and all 

 negroes have woolly hair, these must 

 be ultimate properties of the Kind 

 croio or negro, or of some Kind which 

 includes them. If, on the contrary, 

 blackness or woolly hair be an effect 

 depending on causes, these general 

 propositions are manifestly empirical 

 laws ; and all that has already been 

 said respecting that class of generali- 

 sations may be applied without modi- 

 fication to these. 



Now, we have seen that in the case 

 of all compounds — of all things, in 

 short, except the elementary sub- 

 stances and primary powers of nature 

 — the presumption is, that the pro- 

 perties do really depend upon causes ; 

 and it is impossible in any case what- 

 ever to be certain that they do not 

 We therefore should not be safe in 

 claiming for any generalisation re- 



