20 SCIENTIFIC METHOD 



the most potent kind of explanation. He takes Newton's 

 explanation of Kepler's Laws by gravitation as an ex- 

 ample. But he misunderstood Newton's method, by 

 describing it as if it explained the facts of planetary 

 motion by making a hypothesis of gravitation as cause 

 and then deducing from it the facts. Now, Newton may 

 have made a hypothesis beforehand according to the 

 story of the apple. But hypothesis of a cause and 

 hypothetical deduction of facts are not the method of 

 Newton's Principia, which makes no hypothesis of 

 gravitation, and does not use gravity to the sun as 

 cause to deduce planetary motions as facts, but, on the 

 contrary, uses planetary motions as facts to deduce 

 gravity to the sun as their cause. The explanatory 

 method of Newton is neither hypothetical nor synthetic, 

 but scientific and analytic. 



Mill failed to discriminate between analytic and 

 synthetic deduction, and as a consequence did not 

 perceive that frequently in the history of science the 

 original order of discovery is analytic and the order 

 of teaching synthetic. Thus, when once Newton had 

 used planetary motions to deduce gravitation, gravitation 

 was then used to deduce planetary motions, inversely. But 

 from imperfect appreciation of the extraordinary power 

 of deduction, Mill misunderstood analysis and synthesis, 

 as well as their connexion. On the one hand he sub- 

 stitutes hypothetical deduction for analysis. On the 

 other hand, missing the analytic foundation of synthesis, 

 he represents synthetic deduction as also hypothetical. 

 He has had immense influence even on his opponents. 

 The result is that, since the publication of his Logic, 

 hypothesis has been ridden to death ; and many scientific 

 inferences are misrepresented as mere hypothesis to 

 explain facts, which are really perfectly scientific deduc- 



