536 FALLACIES. 



question, but to that fallacy combined with another natural prejudice already- 

 adverted to, that a thing can not 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 rath- 

 er of its presence to our organs, must of necessity resemble very closely the 

 outward object itself. To fulfill 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 im- 

 age or representation of it, was the direct object of perception. Dr. Reid 

 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 pro- 

 duce them; in opposition to the natural prejudice which led people to as- 

 similate 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 exam- 

 ple. And the value of the service which he thus rendered to popular philos- 

 ophy 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 gen- 

 erality of the philosophers who preceded him, and especially to Locke and 

 Hume ; for if they did not themselves consciously fall into the error, unques- 

 tionably 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, Avhich occupies so 

 great a space in the Nomim Organum, the inquisitio informam calidi, the 

 conclusion which he favors is that heat is a kind of motion ; meaning of 

 course not the feeling of heat, but the conditions of the feeling ; meaning, 

 therefore, only that wherever there is heat, there must first be a particu- 

 lar kind of motion ; but he makes no distinction in his language between 

 these two ideas, expressing himself as if heat, and the conditions of heat, 

 were one and the same thing. So the elder Darwin, in the beginning of 

 his Zoonomia, says, " The word idea has various meanings in the writers of 

 metaphysics ; it is here used simply for those notions of external things 

 which our organs of sense bring us acquainted with originally " (thus far 

 the proposition, though vague, is unexceptionable in meaning), " and is de- 

 fined a contraction, a motion, or .configuration, of the fibres which constitute 

 the immediate organ of sense." Our notions, a configuration of the fibres ! 

 What kind of logician must he be who thinks that a phenomenon is defined 

 to be the condition on which he supposes it to depend ? Accordingly he 

 says soon after, not that our ideas are caused by, or consequent on, certain 

 organic phenomena, but " our ideas are animal motions of the organs of 

 sense." And this confusion runs through the four volumes of the Zoono- 

 mia; the reader never knows whether the writer is speaking of the effect, 

 or of its supposed cause ; of the idea, a state of mental consciousness, or of 

 the state of the nerves and brain which he considers it to presuppose. 



I have given a variety of instances in which the natural prejudice, that 

 causes and their effects must resemble one another, has operated in pi-actice 

 so as to give rise to serious errors. I shall now go further, and produce 



