THE MECHANICAL SYSTEM AND ITS LIMITS 367 



dependent on natural selection, a principle that it really 

 excludes. The development of civilised man is becoming 

 less and less purposive ; the fact that men are not yet 

 more short-sighted and weaker is because panmixis has 

 not yet lasted long enough to bring about conspicuous 

 degenerations, and because natural selection has not 

 entirely abandoned man even in regard to his bodily frame, 

 as in the majority of cases excessive weakness or short- 

 sightedness prevents a man from earning his living and 

 so from reproducing. The majority are always con- 

 tributing new blood to the "higher orders," and this 

 improves the corporeal debility that distinguishes the 

 latter on account of their condition and occupations. 



Science, especially, has no need of teleology, because 

 it cannot regard as facts causes that act before they are 

 themselves realised. According to the teleological view 

 the evolution of the actual organisms must aim at a 

 remote end, and this end must accomplish their trans- 

 formations. If that were so we should have to give up 

 all idea of a scientific investigation of the organic world. 

 We could not study this end, as the future does not 

 exist, and so we can never determine in what way the 

 end regulates the modifications of animals; we cannot 

 detect their real causes. 



For these reasons we must reject the teleological 

 causes that are supposed to influence the beginning 

 from the end, these " final causes " as they are called in 

 opposition to the " efficient causes," which proceed 

 gradually onward. We can safely do this, because the 

 principle of selection enables us to give a purely 



