sod 



:p'allacies. 



his luch in possessing a particular gal- 

 vanic battery ; if this battery, as far 

 as Davy was concerned, had itself 

 been an accident, and not (as in point 

 of fact it was) desired and obtained 

 by him for the purpose of ensuring 

 the testimony of experience to his 

 principles, and in order to bind down 

 material nature under the inquisition 

 of reason, and force from her, as by 

 torture, unequivocal answers to 'pre- 

 pared and preconceived questions, — 

 3'et still they would not have been 

 talked of or described as instances of 

 luck, but as the natural results of his 

 admitted genius and known skill. But 

 should an accident have disclosed 

 similar discoveries to a mechanic at 

 Birmingham or Sheffield, and if the 

 man should grow rich in consequence, 

 and, partly by the envy of his neigh- 

 bours and partly with good reason, 

 be considered by them as a man below 

 par in the general powers of his under- 

 standing ; then, ' O what a lucky fel- 

 low ! Well, Fortune does favour fools 

 -^that's for certain ! It is always so ! ' 

 And forthwith the exclaimer relates 

 half a dozen similar instances. Thus 

 accumulating the one sort of facts and 

 never collecting the other, we do, as 

 poets in their diction, and quacks of 

 all denominations do in their reason- 

 ing, put a part for the whole." 



This passage very happily sets forth 

 the manner in which, under the loose 

 mode of induction which proceeds per 

 enumerationem simpUcem, not seeking 

 for instances of such a kind as to be 

 decisive of the question, but generalis- 

 ing from any which occur, or rather 

 which are remembered, opinions grow 

 up with the apparent sanction of ex- 

 perience, which have no foundation in 

 the laws of nature at all. "Itaque 

 recte respond it ille," (we may say 

 with Bacon,*) "qui cum suspensa 

 tabula in templo ei monstraretur 

 eorum, qui vota solverant, quod nau- 

 f ragii periculo elapsi sint, atque inter- 

 rogando premeretur, anne tum qxiidem 

 Deorum numen agnosceret, qusesivit 



* Kcv. Org., Aph. 46. 



denuo, At uhi sunt iUi depicti qui post 

 vota nuncupata perierunt 1 Eadem 

 ratio est fere omnis superstitionis, ut 

 in Astrologicis, in Somniis, Ominibus, 

 Nemesibus, et hujusmodi ; in quibus, 

 homines delectati hujusmodi vanita- 

 tibus, advertunt eventus, ubi implen- 

 tur ; ast ubi fallunt, licet multo fre- 

 quentius, tamen negligunt, et praete-: 

 reunt." And he proceeds to say, that 

 independently of the love of the m.ar- 

 vellous, or any other bias in the in-' 

 clinations, there is a natural tendency 

 in the intellect itself to this kind of 

 fallacy, since the mind is more moved 

 by affirmative instances, though nega- 

 tive ones are of most use in philoso- 

 phy : " Is tamen humano intellectui 

 error est proprius et perpetuus, ut 

 magis moveatur et excitetur Affirma- 

 tivis quam Negativis ; cum rite et 

 ordine sequum se utrique praebere de- 

 beat ; quin contra, in omni Axiomate 

 vero constituendo, major vis est in- 

 stantise negativae." 



But the greatest of all causes of 

 non - observation is a preconceived 

 opinion. This it is which, in all 

 ages, has made the whole race of 

 mankind, and every separate section 

 of it, for the most part unobservant 

 of all facts, howev*>r abundant, even 

 when passing under their own eyes, 

 which are contradictory to any first 

 appearance or any received tenet. 

 It is worth while to recall occasion- 

 ally to the oblivious memorj* of man- 

 kind some of the striking instances 

 in which opinions that the simplest 

 experiment would have shown to be 

 erroneous continued to be entertained 

 because nobody ever thought of try- 

 ing that experiment. One of the 

 most remarkable of these was exhi- 

 bited in the Copernican controversy. 

 The opponents of Copernicus argued 

 that the earth did not move, because 

 if it did, a stone let fall from the top 

 of a high tower would not reach the 

 ground at the foot of the tower, but 

 at a little distance from it, in a con- 

 trary direction to the earth's course ; 

 in the same manner (said they) as, if 

 a ball is let drop from the mast-head 



