METHODS OF OBTAINING AN EXPLANATION. 451 



information they implicitly contain, but we do not actually 

 create new knowledge. An unlimited amount of informa- 

 tion cannot be extracted from a limited number of truths, 

 nor can we by either of these generalising processes attain 

 from them more than their equivalent, because a true con- 

 clusion never exceeds the limits of its premises, and a 

 general statement respecting any number of facts or in- 

 stances contains only as much information on the specified 

 point as all the instances put together. 



In some cases the correct interpretation of results is 

 an easy matter, the causes or other relations of them 

 being simple and obvious ; in other cases it is a difficult 

 problem, requiring intense study and much sagacity ; and 

 in others again it is not possible to ascertain the exact ex- 

 planation, either because other scientific questions bearing 

 upon this one have not yet been settled, or because the 

 secret lies beyond our powers. One great difficulty in the 

 way of obtaining a correct explanation in some cases 

 arises frojn the fact that there are various causes, and 

 many combinations of them, and each cause may act in 

 many degrees, and be modified by various circumstances, 

 and the phenomenon may arise from a combination or 

 permutation of causes. Many cases occur where an effect 

 depends upon several causes, each of which increases its 

 magnitude ; many others happen in which the effect does 

 not take place unless all the causes are present, and it is 

 common for persons to be misled by this circumstance to 

 consider that because the effect does not take place when 

 some of the conditions are present, that those conditions 

 form no part of the cause of the phenomena. It follows also, 

 from these and other considerations, that whilst there can be 

 only one true interpretation, there may be many erroneous 

 ones, each of which may mislead us. An erroneous in- 

 terpretation may appear to agree with the facts, but that 



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