DEDUCTIVE LAW OF MAN’S ORIGIN. 357 
the central nervous system of this new species of mammal 
could possibly consist of a ventral cord with an cesopha- 
geal collar as in the insects, or of scattered pairs of 
knots as in the molluscs, 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. 1. p. 84). 
The process of ~mduction is a logical system of forming 
conclusions from 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 all 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 inductive law. 
The pedigree of the human race, the approximate outlines 
of which I gave in the last chapter but one, of course 
