232 HABIT AND INTELLIGENCE. [cHAP. 



Extension is coming wlien the use of the word science in the sense 

 of the *^f oi^^y mathematical and physical science will be extinct, 

 word or, if it survives, will survive merely as a relic of an extinct 



SC16I1C6 



habit of thought. We have already begun familiarly to 

 use such expressions as the science of language, the science 

 of history, and the science of politics : a notion still sur- 

 vives that such a use of the word science is a somewhat 

 inaccurate extension of the meaning of the word ; but I 

 believe that in another generation such expressions wiE 

 come to be used with no more sense of inaccuracy or of 

 paradox than we have when we speak of the science of 

 chemistry or the science of astronomy. 



Double It is an important truth, that perfect scientific method 



science. consists in the co-operation of the inductive and deductive 

 Induction methods ; and perfect scientific proof consists in the results 

 tion must of ^^^^ two methods coinciding. Thus in astronomy the 

 co-operate, results of induction and of deduction, that is to say of 

 observation and of calculation, coincide within very small 

 limits of error; and the same is true of the sciences of 

 sound, radiance, heat, electricity, and magnetism. None 

 of these sciences could have attained to anything at all 

 comparable to their present perfection without the use of 

 this double method : in which the calculated results of 

 theoretical deduction are checked and verified by the 

 results obtained by induction from observation and experi- 

 ment ; while at the same time, by the converse process, the 

 results obtained by induction from observation and experi- 

 ment are checked and verified by the calculated results 

 Theory of theoretical deduction.^ In language which is at once 

 vatioli'^'''^' fS'^iliai' ^^^ accurate, this is called tlie coincidence of 

 the results of theory with those of observation. As was 



1 It is usual to call the experimental result the verification of the theo- 

 retical one. According to Comte, in physical science the results of theory 

 are verified by observation or experiment ; but in historical science the 

 results are first generalized from observation, and then verified by theory 

 (the theoretical data in this case consist, of course, in the general laws of 

 human nature). This may be true, but it is not very important. The impor- 

 tant and universal truth on the subject is, that the results of the theoretical 

 and of the experimental methods each need to be verified by the other. 



