COEXISTENCES INDEPENDENT OF CAUSATION. 127 



Agreement or Difference, or of Concomitant Varia- 

 tions (which is but a modification either of the Me- 

 thod of Agreement or of the Method of Difference) . 

 We cannot conclude that the blackness we see in 

 crows must be an invariable property of crows, merely 

 because there is nothing else present of which it can 

 be an invariable property. "We therefore inquire into 

 the truth of a proposition like " All crows are black," 

 under the same disadvantage as if, in our inquiries 

 into causation, we were compelled to let in, as one of 

 the possibilities, that the effect may in that particular 

 instance have arisen without any cause at all. 



To overlook this grand distinction was, as it seems 

 to me, the capital error in Bacon's view of inductive 

 philosophy. The principle of elimination, that great 

 logical instrument which he had the immense merit 

 of first bringing into general use, he deemed appli- 

 cable in the same sense, and in as unqualified a 

 manner, to the investigation of the coexistences, as to 

 that of the successions of phenomena. He seems to 

 have thought that as every event has a cause, or 

 invariable antecedent, so every property of an object has 

 an invariable coexistent, which he called its Form : and 

 the examples he chiefly selected for the application 

 and illustration of his method, were inquiries into 

 such Forms ; attempts to determine in what else all 

 those objects resembled, which agreed in some one 

 general property, as hardness or softness, dry ness or 

 moistness, heat or coldness. Such inquiries could 

 lead to no result. The objects seldom have any such 

 circumstance in common. They usually agree in the 

 one point inquired into, and in nothing else. A 

 great proportion of the properties which, so far as we 

 can conjecture, are the likeliest to be really ultimate, 

 would seem to be inherently properties of many 



