DEDUCTIVE LAW OF MAI^'s OEIGIN. 357 



the central nervous system of this new species of mammal 

 could possibly consist of a ventral cord with an oesopha- 

 geal collar as in the insects, or of scattered pairs of 

 knots as in the moUuscs, or that its heart could be many- 

 chambered as in flies, or one-chambered as in the tunicates. 

 This completely certain and safe conclusion, although it is 

 not based upon any direct experience, is a deductive con- 

 clusion. In the same way, as I have shown in a previous 

 chapter, Goethe, from the comparative anatomy of mammals, 

 established the general inductive conclusion that they all 

 possess a mid jawbone, and afterwards drew from it the 

 special deductive conclusion that man, who in all other 

 respects does not essentially differ from other mammals, 

 must also possess a like mid jawbone. He maintained this 

 conclusion without having actually seen the human mid jaw- 

 bone, and only proved its existence subsequently by actual 

 observation (vol. i. p. 84). 



The process of induction is a logical system of forming 

 conclusions /rom the special to the general, by which we 

 advance from many individual experiences to a general 

 law; deduction, on the other hand, draws a conclusion 

 from the general to the special, from a general law of 

 nature to an individual case. Thus the Theory of Descent 

 is, without doubt, a great inductive law, empirically based 

 upon aU the biological experience cited above; the pithe- 

 coid theory, on the other hand, which asserts that man has 

 developed out of lower, and in the first place out of ape- 

 like mammals, is a deductive law inseparably connected 

 with the general iaductive law. 



The pedigree of the human race, the approximate outlines 

 of which I gave in the last chapter but one, of course 



