10 INTRODUCTION. 



the observance of the laws which it is the province of logic to 

 investigate. If the conclusions are just, and the knowledge 

 real, those laws, whether known or not, have heen observed. 



6. We need not, therefore, seek any farther for a solu 

 tion of the question, so often agitated, respecting the utility 

 of logic. If a science of logic exists, or is capable of existing, 

 it must be useful. If there be rules to which every mind 

 consciously or unconsciously conforms in every instance in 

 which it infers rightly, there seems little necessity for dis 

 cussing whether a person is more likely to observe those rules, 

 when he knows the rules, than when he is unacquainted with 

 them. 



A science may undoubtedly be brought to a certain, not 

 inconsiderable, stage of advancement, without the application 

 of any other logic to it than what all persons, who are said to 

 have a. sound understanding, acquire empirically in the course 

 of their studies. Mankind judged of evidence, and often 

 correctly, before logic was a science, or they never could have 

 made it one. And they executed great mechanical works 

 before they understood the laws of mechanics. But there are 

 limits both to what mechanicians can do without principles of 

 mechanics, and to what thinkers can do without principles of 

 logic. A few individuals, by extraordinary genius, or by the 

 accidental acquisition of a good set of intellectual habits, may 

 work without principles in the same way, or nearly the same 

 way, in which they would have worked if they had been in 

 possession of principles. But the bulk of mankind require 

 either to understand the theory of what they are doing, or to 

 have rules laid down for them by those who have understood 

 the theory. In the progress of science from its easiest to its 

 more difficult problems, each great step in advance has usually 

 had either as its precursor, or as its accompaniment and neces 

 sary condition, a corresponding improvement in the notions 

 and principles of logic received among the most advanced 

 thinkers. And if several of the more difficult sciences are 

 still in so defective a state ; if not only so little is proved, but 

 disputation has not terminated even about the little which 



