14 INTRODUCTION. 



times it stands for all the distinctively human faculties 

 taken collectively, and in antithesis to the mental faculties 

 of the brute ; while at other times it is taken to mean the 

 distinctively human faculties of intellect. 



Dr. Johnson defines it as ' the power by which man 

 deduces one proposition from another, and proceeds from 

 premises to consequences.' This definition presupposes 

 language, and therefore ignores all cases of inference not 

 thrown into the formal shape of predication. Yet even in 

 man the majority of inferences drawn by the mind never 

 emerge as articulate propositions ; so that although, as 

 we shall have occasion fully to observe in my subsequent 

 work, there is much profound philosophy in identifying 

 reason with speech as they were identified in the term 

 Logos, yet for purposes of careful definition so to identify 

 intellect with language is clearly a mistake. 



More correctly, the word reason is used to signify the 

 power of perceiving analogies or ratios, and is in this 

 sense equivalent to the term ' ratiocination,' or the faculty 

 of deducing inferences from a perceived equivalency of 

 relations. Such is the only use of the word that is 

 strictly legitimate, and it is thus that I shall use it 

 throughout the present treatise. This faculty, however, 

 of balancing relations, drawing inferences, and so of fore- 

 casting probabilities, admits of numberless degrees ; and 

 as in the designation of its lower manifestations it sounds 

 somewhat unusual to employ the word reason, I shall in 

 these cases frequently substitute the word intelligence. 

 Where we find, for instance, that an oyster profits by 

 individual experience, or is able to perceive new relations 

 and suitably to act upon the result of its perceptions, I 

 think it sounds less unusual to speak of the oyster as dis- 

 playing intelligence than as displaying reason. On this 

 account I shall use the former term to signify the lower 

 degrees of the ratiocinative faculty ; and thus in my usage 

 it will be opposed to such terms as instinct, reflex action, 

 &c., in the same manner as the term reason is so opposed. 

 This is a point which, for the sake of clearness, I desire 

 the reader to retain in his memory. I shall always speak 

 of intelligence and intellect in antithesis to instinct, emo- 



