538 FALLACIES. 



cause. To this class belong his speculations, and those of so many others 

 after him, tending to infer the order of the universe, not from observation, 

 but by a priori reasoning from supposed qualities of the Godhead. This 

 sort of inference was probably never can-ied to a greater length than it 

 was in one particular instance by Descartes, when, as a proof of one of his 

 physical principles, that the quantity of motion in the universe is invaria- 

 ble, he had recourse to the immutability of the Divine Nature. Reason- 

 ing of a very similar character is, however, nearly as common now as it 

 was in his time, and does duty largely as a means of fencing off disagree- 

 able conclusions. Writers have not yet ceased to oppose the theory of 

 divine benevolence to the evidence of physical facts, to the principle of 

 population for example. And people seem in general to think that they 

 have used a very powerful argument, when they have said, that to suppose 

 some proposition true, would be a reflection on the goodness or wisdom of 

 the Deity. Put into the simplest possible terms, their argument is, "If it 

 had depended on me, I would not have made the proposition true, there- 

 fore it is not true." Put into other words, it stands thus: " God is perfect, 

 therefore (what I think) perfection must obtain in nature." But since in 

 reality every one feels that nature is very far from perfect, the doctrine is 

 never applied consistently. It furnishes an argument which (like many 

 others of a similar character) people like to appeal to when it makes for 

 their own side. Nobody is convinced by it, but each appears to think 

 that it puts religion on his side of the question, and that it is a useful 

 weapon of offense for wounding an adversary. 



Although several other varieties of a priori fallacy might probably be 

 added to those here specified, these are all against which it seems neces- 

 sary to give any special caution. Our object is to open, without attempt- 

 ing or affecting to exhaust, the subject. Having illustrated, therefore, this 

 first class of Fallacies at sufticient length, I shall proceed to the second. 



CHAPTER IV. 



FALLACIES OF OBSERVATION. 



§ 1. From the Fallacies which are properly Prejudices, or presumptions 

 antecedent to, and superseding, proof, we pass to those which lie in the in- 

 correct performance of the proving process. And as Pi'oof, in its widest 

 extent, embraces one or more, or all, of three processes, Observation, Gen- 

 eralization, and Deduction, we shall consider in their order the errors ca- 

 pable of being committed in these three operations. And first, of the first 

 mentioned. 



A fallacy of misobservation may be either negative or positive ; either 

 Non- observation or Mai -observation. It is non-observation, when all the 

 error consists in overlooking, or neglecting, facts or particulars which 

 ought to have been observed. It is nial- observation, when something is 

 not simply unseen, but seen wrong; when the fact or phenomenon, instead 

 of being recognized for what it is in reality, is mistaken for something else. 



§ 2. Non-observation may either take place by overlooking instances, or 

 by overlooking some of the circumstances of a given instance. If we were 

 to conclude that a fortune-teller was a true prophet, from not adverting 

 to the cases in which his predictions had been falsified by the event, this 



