4 oo THE POPULAR SCIENCE MONTHLY 



logical problem some years since in an address that I was permitted to 

 give before the Psychological Association. I venture to emphasize this 

 problem afresh and to declare that it is a problem which the whole 

 pragmatist controversy has itself especially emphasized and has not yet 

 adequately solved. 



Again I have called attention to the difference between vaguely 

 estimated confidence and objective probability. Here is a problem 

 that once more presents psychological aspects. I shall have no time 

 to discuss them upon this occasion. The psychology of probability is, 

 however, to my mind one full of very interesting problems. 



Ill 



I have thus enumerated three of the psychological problems which 

 to my mind are emphasized by the course of the pragmatistic discussion. 

 That these problems come to my mind with a special force because of my 

 logical interest, you see. It is now my purpose to appeal to you as 

 psychologists or as students interested in the subject, to follow for a 

 few moments some further characterization especially of the first of 

 these psychological problems. I am dissatisfied in the recent discussions 

 of the psychology of reasoning with what seems to be a failure to under- 

 stand what takes place in exact deductive procedure. The current 

 prejudices as well as the hoary traditions on this subject seem to con- 

 spire to call the attention of students away from the center of the 

 problem. Without attempting to give any adequate summary of Pro- 

 fessor Pillsbury's account of the reasoning process in his recent "Psy- 

 chology of Seasoning," I may attempt by a few references to indicate 

 how inadequate some current views are to take account of what the 

 deductive process actually is. In Professor Pillsbury's " Psychology of 

 Keasoning," he distinguishes pretty sharply between the two processes 

 of inference and proof. By inference, if I understand him, he means the 

 process whereby a conclusion is suggested in such wise as to arouse more 

 or less belief. By proof he means a process whereby this belief is more 

 or less adequately tested. JSTow logicians are accustomed to use the word 

 inference in a somewhat different way from that which Professor Pills- 

 bury emphasizes. And what this way is I shall try to point out in a 

 moment. But laying inference aside for the moment, and passing to 

 the other side of the reasoning process as Professor Pillsbury defines it, 

 namely to the process of proof, the only form of deductive proof which 

 Professor Pillsbury seems to emphasize is the one that has received its 

 traditional description in the doctrine of the syllogism. The essence of 

 the traditional syllogism is, according to Professor Pillsbury, that the 

 general major premise is supposed to aid us in testing our belief in the 

 conclusion, by virtue of the fact that in the minor premise something 



