COEXISTENCES INDEPENDENT OF CAUSATION. 347 



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 wore 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 

 eiTor in Bacon's view of inductive philosophy. The principle of elim- 

 ination, that gi"eat logical instrument which he had the immense merit 

 of first bringing into general use, ho deemed applicable in the same 

 sense and in as unqualified a manner, to the investigation of the coex- 

 istences, as to that of the successions of phenomena. He .seercts 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 applica- 

 tion and illustration of his method, were inquiries into such Forms; 

 attempts to determine in what else all those objects x'esembled, which 

 agreed in some one general property, as hardness or softness, dryness 

 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 different Kinds of things, not allied in any other 

 respect. And as for the properties which, being effects of causes, we 

 are able to give some account of, they have generally nothing to do 

 with the ultimate resemblances or diversities in the objects themselves, 

 but depend upon some outward circumstances, under the influence of 

 which any objects whatever are capable of manifesting those proper- 

 ties : as is emphatically the case with those favorite subjects of Bacon's 

 scientific inquiries, hotness and coldness ; as well as with hardness 

 and softness, solidity and fluidity, and many other very conspicuous 

 qualities. 



In the absence, then, of any universal law of coexistence, similar 

 to the universal law of causation which regulates sequence, we are 

 thrown back upon the unscientific induction of the ancients, per enu- 

 mcrationem simplicem, nhi non rcperitxir instantia contradict or ia. The 

 reason we have for believing that all crows are black, is simply that we 

 have seen and heard of many black crows, and never of one of any 

 other color. It remains to be considered how far this evidence can 

 reach, and how we are to measure its strength in any given case. 



§ 5. It sometimes hap])ens that a mere change in the ,mode of ver- 

 bally enunciating a question, although nothing is really added to the 

 meaning expressed, is of itself a considerable step towards its solution. 

 This, I think, happens in the present instance. The degree of cer-: 

 tainty of any generalization which rests upon no other evidence than 

 the agreement, so far as it goes, of all past observation, is but another 

 phrase for the degi-ee of improbability that an exception, if it existed, 

 could have hitherto remained unobserved. The reason for believing 

 that all crows are black, is measured by the improbability that crows 

 of any other color should have existed to the present time without our 

 being aware of it. Let us state the question in this last mode, and 

 coiisider what is implied in the supposition that there raay be crows 



