34 THE SCIENCE OF LOGIC 



an achievement of the modern mind, we must not infer that it 

 was entirely unknown to the ancients. That to modern thought 

 the honour was reserved of seizing upon the full significance of 

 the method, and of applying it with such marked success, even 

 the most ardent defenders of Aristotle and the Scholastics need 

 not deny. 1 But that the principle of this method was known 

 to the latter, their works give unmistakable evidence. 

 And, firstly, let us turn to Aristotle himself: 



&quot;Repeated sensations,&quot; he writes, &quot;leave impressions in the memory, 

 and these engender experience (tpnfipia) ; experience suggests abstraction, 

 which separates from the particular instances the one in relation with the 

 many (TO iv napa ra TroXXa), that is to say, the universal. But the abstract 

 put in relation with an indefinite number of individuals, is a principle of 

 science and of art&quot;. 2 



Turning, now, to St. Thomas s full and lucid commentary 3 on 

 the passage just quoted, it would be difficult to find a plainer 

 illustration of the modern inductive Method of Agreement : A 

 physician has learned by repeated experiences that a certain herb has 

 cured several patients of fever. From these experiences he 

 ascends to the apprehension of the universal principle that &quot; this 

 kind of herb cures patients afflicted with this kind of fever&quot;. St. 

 Thomas does not explicitly state the principle, or examine the 

 process by which the ascent is made ; obviously, however, it is 

 not made by enumeration of instances, complete or incomplete. 



1 Ueberweg rightly remarks that &quot; The recognition of the full significance of 

 the inductive method in the sciences was reserved for modern times &quot; (System der 

 Logik, 127). 



3 Post. Anal., ii., 19, (5). 



3 &quot; Ex memoria multoties facta circa eamdem rem in diversis tamen singulari- 

 bus, fit experimentum : quia experimentum [^uirtipfa] nihil aliud videtur, quam accipere 

 aliquid ex multis in memoria retentis. Sed, tamen, experimentum indiget aliqua 

 ratiocinatione circa particularia, per quam confertur unum ad aliud, quod est pro- 

 prium rationis. Puta, cum talis recordatur quod talis herba multoties sanavit 

 multos a febre, dicitur esse experimentum quod talis herba sit sanativa febris. 

 Ratio autem non sistit in experimento particularium ; sed ex multis particularibus 

 in quibus expertus sit, accipit unum commune quod firmatur in anima, et considerat 

 illud absque consideratione alicujus singularium, et hoc accipit ut principium artis 

 et scientiae. Puta, diu medicusconsideravit hanc herbam sanasse Socratem febrien- 

 tem, et Platonem, et multos alios singulares homines ; cum autem sua consideratio 

 ad hoc ascendit quod talis species herbae sanat febrientem simpliciter, hoc accipitur 

 ut quaedam regula artis medicinae &quot; (St. Thomas, in loc. cit.). It will be observed 

 that there is no mention here of &quot; Inductio &quot; but only of &quot; Experimentum &quot;. It is 

 significant, too, that these passages from Aristotle and St. Thomas are from the 

 Posterior Analytics, i.e. from that part of the Organon which treats of Certain Science, 

 while the passages quoted above in reference to enumerative induction complete 

 and incomplete are taken from the Prior Analytics and the Topics, i.e. the parts 

 that refer, the one to the formal side of reasoning, the other to probable arguments. 



