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PREFACE. 



This book makes no pretence of giving to the world a new 

 theory of our intellectual operations. Its claim to attention, if it 

 possess any, is grounded on the fact that it is an attempt not to 

 supersede, but to embody and systematize, the best ideas which 

 have been either promulgated on its subject by speculative writers, 

 or conformed to by accurate thinkers in their scientific inquiries. 



To cement together the detached fragments of a subject, never 

 yet treated as a whole ; to harmonize the true portions of discordant 

 theories, by supplying the links of thought necessary to connect 

 them, and by disentangling them from the errors with which they 

 are always more or less interwoven ; must necessarily require a 

 considerable amount of original speculation. To other originality 

 than this, the present work lays no claim. In the existing state of 

 the cultivation of the sciences, there would be a very strong pre- 

 sumption against any one who should imagine that he had effected 

 a revolution in the theory of the investigation of truth, or added 

 any fundamentally new process to the practice of it. The im- 

 provement which remains to be effected in methods of philoso- 

 phizing (and the author believes that they have much need of 

 improvement) can only consist in performing, more systematically 

 and accurately, operations with which, at least in their elementary 

 form, the human intellect in some one or other of its employments 

 is already familiar. 



In the portion of the work which treats of Ratiocination, the 

 author has not deemed it necessary to enter into technical details 

 which may be obtained in so perfect a shape from the existing 

 treatises on what is termed the Logic of the Schools. In the con- 

 tempt entertained by many modern philosophers for the syllogistic 

 art, it will be seen that he by no means participates ; although the 

 scientific theory on which its defence is usually rested appears to 

 him eri'oneous : and the view which he has suggested of the nature 

 and functions of the Syllogism may, perhaps, afford the means of 



