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CHAPTER IV. 

 FALLACIES OF OBSERVATION. 



I. FROM the fallacies which are properly Preju- 

 dices, or presumptions antecedent to, and superseding, 

 proof, we pass to those which lie in the incorrect per- 

 formance of the proving process. And as Proof, in 

 its widest extent, embraces one or more or all of 

 three processes, Observation, Generalization, and 

 Deduction ; we shall consider in their order the errors 

 capable of being committed in these three operations. 

 And first, of the first mentioned. 



A fallacy of misobservation may be either nega- 

 tive or positive; either Non-observation or Mai- obser- 

 vation. It is non-observation, when all the error 

 consists in overlooking, or neglecting, facts or particu- 

 lars which ought to have been observed. It is mal- 

 observation, when something is not simply unseen, 

 but seen wrong ; when the fact or phenomenon, 

 instead of being recognised 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 would be non-observa- 

 tion of instances : but if we overlooked or remained 

 ignorant of the fact that in cases where the predictions 

 had come true, he had been in collusion with some 

 one who had given him the information on which they 



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