336 FALLACIES. 



tence not solely to the fallacy in question, but to that fallacy 

 combined with another natural prejudice already adverted to, 

 that a thing cannot act where it is not. In both doctrines it 

 is assumed that the phenomenon which takes place in us when 

 we see or touch an object, and which we regard as an effect of 

 that object, or rather as its presence to our organs, must of 

 necessity resemble very closely the outward object itself. To 

 fulfil this condition, the Epicureans supposed that objects were 

 constantly projecting in all directions impalpable images of 

 themselves, which entered at the eyes and penetrated to the 

 mind ; while modern metaphysicians, though they rejected 

 this hypothesis, agreed in deeming it necessary to suppose 

 that not the thing itself, but a mental image or representation 

 of it, was the direct object of perception. Dr. Keid had to 

 employ a world of argument and illustration to familiarize 

 people with the truth, that the sensations or impressions on 

 our minds need not necessarily be copies of, or bear any 

 resemblance to, the causes which produce them ; in opposition 

 to the natural prejudice which led people to assimilate the 

 action of bodies upon our senses, and through them upon our 

 minds, to the transfer of a given form from one object to 

 another by actual moulding. The works of Dr. Reid are even 

 now the most effectual course of study for detaching the mind 

 from the prejudice of which this was an example. And the 

 value of the service which he thus rendered to popular philo- 

 sophy, is not much diminished although we may hold, with 

 Brown, that he went too far in imputing the "ideal theory" 

 as an actual tenet, to the generality of the philosophers who 

 preceded him, and especially to Locke and Hume : for if they 

 did not themselves consciously fall into the error, unquestion- 

 ably they often led their readers into it. 



The prejudice, that the conditions of a phenomenon must 

 resemble the phenomenon, is occasionally exaggerated, at least 

 verbally, into a still more palpable absurdity ; the conditions 

 of the thing are spoken of as if they were the very thing 

 itself. In Bacon's model-inquiry, which occupies so great a 

 space in the Novum Organumyihe inquisitio informam calidi, 

 the conclusion which he favours is that heat is a kind of 



