FALLACIES OF OBSERVATION. 



513 



committed no otherwise than by mis- 

 taking for conception what is in fact 

 inference. We have formerly shown 

 how intimately the two are blended 

 in almost everything which is called 

 observation, and still more in every 

 Description.* What is actually on 

 any occasion perceived by our senses 

 being so minute in amount, and gene- 

 rally so unimportant a portion of the 

 state of facts which we wish to ascer- 

 tain or to communicate, it would be 

 absurd to say that either in our ob- 

 servations or in conveying their result 

 to others, we ought not to mingle in- 

 ference with fact ; all that can be 

 said is, that when we do so we ought 

 to be aware of what we are doing, 

 and to know what part of the asser- 

 tion rests on consciousness, and is 

 therefore indisputable, what part on 

 inference, and is therefore question- 

 able. 



One of the most celebrated ex- 

 amples of an universal error pro- 

 duced by mistaking an inference for 

 the direct evidence of the senses was 

 the resistance made, on the ground 

 of common sense, to the Copernican 

 system. People fancied they saw the 

 sun rise and set, the stars revolve in 

 circles round the pole. We now 

 know that they saw no such thing ; 

 what they really saw was a set of ap- 

 pearances equally reconcilable with 

 the theory they held and with a to- 

 tally different one. It seems strange 

 that such an instance as this, of the 

 testimony of the senses pleaded with 

 the most entire conviction in favour 

 of something which was a mere infer- 

 ence of the judgment, and, as it turned 

 out, a false inference, should not have 

 opened the eyes of the bigots of com- 

 mon sense, and inspired them with a 

 more modest distrust of the compe- 

 tency of mere ignorance to judge the 

 conclusions of cultivated thought. 



In proportion to any person's defi- 

 ciency of knowledge and mental culti- 

 vation is generally his inability to 

 discriminate between his inferences 



* Supra, p. 42». 



and the perceptions on which they 

 were grounded. Many a marvellous 

 tale, many a scandalous anecdote, 

 owes its origin to this incapacity. 

 The narrator relates, not what he 

 saw or heard, but the impression 

 which he derived from what he saw 

 or heard, and of which perhaps the 

 greater part consisted of inference, 

 though the whole is related not as 

 inference but as matter of fact. The 

 difficulty of inducing witnesses to 

 restrain within any moderate limits 

 the intermixture of their inferences 

 with the narrative of their percep- 

 tions is well known to experienced 

 cross-examiners ; and still more is 

 this the case when ignorant persons 

 attempt to describe any natural phe- 

 nomenon. " The simplest narrative," 

 says Dugald Stewart,* '*of the nio.<t 

 illiterate observer involves more or 

 less of hypothesis ; nay, in general it 

 will be found that, in proportion to 

 his ignorance, the greater is the num- 

 ber of conjectural principles involved 

 in his statements. A village apothe- 

 cary (and, if possible, in a still greater 

 degree, an experienced nurse) is sel- 

 dom able to describe the plainest case 

 without employing a phraseology of 

 which every word is a theory ; where- 

 as a simple and genuine specifica- 

 tion of the phenomena which mark 

 a particular disease, a specification 

 unsophisticated by fancy or by pre- 

 conceived opinions, may be regarded 

 as unequivocal evidence of a mind 

 trained by long and successful study 

 to the most difficult of all arts, that 

 of the faithful interpretation of na- 

 ture." 



The universality of the confusion 

 between perceptions and the infer- 

 ences drawn from them, and the 

 rarity of the power to discriminate 

 the one from the other, ceases to sur- 

 prise us when we consider that in the 

 far greater number of instances the 

 actual perceptions of our senses are of 

 no importance or interest to us except 

 as marks from which we infer some- 



' Elements of the Philosophy of the Mind, 

 ToL ii. cU. 4, sect. 5. 



2^ 



