CHAPTEK XXIV. 



EMPIRICAL KNOWLEDGE, EXPLANATION, AND PREDICTION. 



Inductive investigation, as we have seen, consists in tlie 

 union of hypothesis and experiment, deductive reasoning 

 being the link by which experimental results are made to 

 confirm or confute the hyi3othesis. Now when we consider 

 this relation between hypothesis and experiment it is 

 obvious that we may classify our knowledge under four 

 heads. 



(i) We may be acquainted with facts which have not 

 yet been brought into accordance with any hypotliesis. 

 Such facts constitute what is called Eminrical Knowledge. 



(2) Another extensive portion of our knowledge consists 

 of facts wliich having been first observed empirically, 

 liave afterwards been brought into accordance with other 

 facts by an hypothesis concerning the general laws apply- 

 ing to them. This portion of our knowledge may be said 

 to be co:j)lained, reasoned, or generalised. 



('3) In the third })]ace comes the collection of facts, minor 

 in numher, but most important as regards their scieutitic 

 interest, which have been anticipated by theory and after- 

 wards verilied by experiment. 



(4) Lastly, tlierc exists knowledge which is accepted 

 solely on the ground of theory, and is incapable of experi- 

 mental confirmation, at least with the instrumental means 

 in our possession. 



It is a work of much interest to compare and illustrate 

 the relative extent and value of these i'our groups of know- 

 ledge. We shall observe that as a general rule a great 

 brunch of science originates in facts observed accideut;illy, 



