212 SCIENCE PROGRESS 



the opinion that prevails to this clay in Oxford and among 

 logicians the world over; and Aristotle's system of Logic has 

 been accepted as impeccable for two thousand years. It is true 

 that there have been a very few sceptics and scoffers, from 

 Sextus Empiricus in the third century a.d. to Peter Ramus and 

 Sennertius in the sixteenth ; but they had no followers, and 

 their influence was neglectable. If a consensus of authority 

 could establish the truth of any doctrine, no doubt the truth 

 of traditional Logic would be unquestionable; but a consensus 

 of authority alone, even of two thousand years of practical 

 unanimity, is not enough to establish the truth of a doctrine. 

 There is conclusive proof that it is not. Not for two thousand 

 years only, but for six thousand years, and not the Western 

 nations only, but also the highly intellectual civilisations of 

 India and China, accepted as unquestionably true the doctrines 

 of judicial astrology. As in the case of Logic, these doctrines 

 were from time to time questioned by isolated sceptics, such as 

 Aristarchus of Samos, Martianus Capella, Favorinus, Juvenal, 

 and others, but, as in the case of Logic, these exceptional pro- 

 tests carried no weight and exercised no influence. Down to 

 the time of Milton, who often uses astrological phraseology, 

 and even down to Dryden, himself a convinced astrologer, the 

 doctrines of judicial astrology were accepted with practical 

 unanimity. The belief in witchcraft was even more ancient 

 and more widespread, yet who believes in it now? It is 

 difficult now to find any adherent either of witchcraft or judicial 

 astrology, and at some future time it will be difficult to find 

 any one who is interested in the doctrines of Logic, except as 

 a matter of historical curiosity. How far off this future may be 

 it is impossible to say, but I hope to do something to hasten 

 its advent. 



The impossibilities of Logic are many, and to cover the whole 

 field, to surmount them all, and to show that every one is 

 merely a bogey, requires a volume of considerable size. Such 

 a book I have written, and no logician has ventured to deny 

 that I have achieved his impossibilities. I select here but a few, 

 and I take them from the central and most important doctrine of 

 Logic, the doctrine of the syllogism. 



The central doctrine of Logic is that there is only one mode 

 of reasoning or inference, only one way in which we can reason 

 from premisses to a conclusion, and that this is by means of 



