FALLACIES OF SIMPLE INSPECTION. 351 



among the objects in nature which obtains among our 

 ideas of them. That if we always think of two things 

 together, the two things must always exist together. 

 That if one thing makes us think of another as pre- 

 ceding or following it, that other must precede it or 

 follow it in actual fact. And conversely, that when 

 we cannot conceive two things together they cannot 

 exist together, and that their combination may, with- 

 out further evidence, be rejected from the list of 

 possible occurrences. 



Few persons, I am inclined to think, have reflected 

 upon the great extent to which this fallacy has pre- 

 vailed, and prevails, in the actual beliefs and actions of 

 mankind. For a first illustration of it, we may refer 

 to a large class of popular superstitions. If any one 

 will examine in what circumstance most of those 

 things agree, which in different ages and by different 

 portions of the human race have been considered as 

 omens or prognostics of some interesting event, whe- 

 ther calamitous or fortunate ; he will find them very 

 generally characterized by this peculiarity, that they 

 cause the mind to think of that, of which they are 

 therefore supposed to forebode the actual occurrence. 

 " Talk of the devil, and he will appear," has passed 

 into a proverb. Talk of the devil, that is, raise the 

 idea, and the reality will follow. In times when the 

 appearance of that personage in a visible form was 

 thought to be no uncommon occurrence, it has doubt- 

 less often happened to persons of vivid imagination 

 and susceptible nerves, that talking of the devil has 

 caused them to fancy they saw him ; as, even in our 

 incredulous days, listening to ghost stories predisposes 

 us to see ghosts: and thus, as a prop to the a priori 

 fallacy, there might come to be added an auxiliary 

 fallacy of mal-observation, with one of false genera- 



