402 



ON HUMAN UNDERSTANDING. 



science of numbers ; and we seem in our own day to have another instance 

 of the same kind in the very extraordinary young calculator from America, 

 not more than eight years old.* 



I have already stated, that when we cannot immediately perceive the 

 agreement or disagreement of two or more ideas, which we are desirous of 

 bringing into comparison, we are obliged to seek out for some intervening 

 idea whose agreement or disagreement with them is obvious to us ; and 

 I have also stated, that as this general search is the immedi^ite office of 

 the faculty of reason, the knowledge thus obtained is called rational 

 KNOWLEDGE. In many cases we are so fortimate as to hit upon intervening 

 ideas whose connexion with the one, the other, or both, as in a chain 

 of perfect evidence, is clear and distinct ; and in such case, whether the 

 reasoning consist of a single step or of many, as soon as the mind is able 

 to perceive the connexion or repugnancy, the agreement or disagreement 

 of the ideas in question, the degree of rational knowledge hereby ob- 

 tained becomes equal or nearly so to intuition, and is called demonstra- 

 tion. If the proofs or intervening ideas do not quite amount to this, 

 we have necessarily an inferior degree of rational knowledge, and we 

 distinguish it by the name of belief, assent, or opinion ; and accord- 

 ing to the nature of the proofs or intermediate ideas, as decided by the 

 faculty of the judgment, the opinion is rendered indubitable, probable, 



CONJECTURAL, Or SUSPICIOUS. 



It is upon this comparison of two ideas, by means of a mediate idea 

 expressed or understood, that most of our moral information or common 

 knowledge would be found to depend, if we were to analyze it. Thus, 

 on going into the street, and hearing a man whom 1 am acquainted with, 

 asking which is the way to London Bridge, I may perhaps observe to a by- 

 stander, " that man ought to know the way." The bystander immediately 

 compares the two ideas of going to London Bridge, and the man's right to 

 know the way, but can find no connexion or agreement between them, 

 and consequently is ignorant of what I mean. He applies to me there- 

 fore, for the intermediate idea by the question " Why so ?" and I give it 

 to him by ansv/ering, " Because he has repeatedly been the same road 

 before :" and although he does not put the three ideas into the measured 

 form of the schools, which is called a syllogism, every one as regularly 

 passes through his mind, and gives him the same satisfactory information 

 as if they were to assume such order : in which case they would perhaps 

 run as follows : 



Every man who goes repeatedly the same road should know his way : 

 This man has been repeatedly the same road : 

 Therefore this man should know his way. 



It would be absurd to introduce this part of logical analysis into common 

 discourse : but it is of high use in the closet, as teaching us precision, 

 by compelling us to measure the force and value of every idea and word 

 of which a proposition consists. We are indebted to Aristotle for its 

 invention ; and though it was at one time carried to an absurd excess, it 

 has of late years been far too generally discontinued. 



The connective or intermediate idea is not always expressed either in 



♦ See " Some account of Zerah Colburn, an American child, who possesses some rery re- 

 markable powers of solving questions in arithmetic, by computation, without writing, or any 

 visible coDtTivance."— Nicholson's Journal of Nat. Phil. voL xxxiy. p, 6. 



