PHYSICAL SCIENCES TO SCIENCE IN GENERAL. 225 



aware tliat our predictions are founded on the described comparison. 

 Our opinion, in such cases, proceeds from a certain psychological fact 

 and not from a conscious argument, although, in the main, the mental 

 l^rocess was the same as in the instance where we predicted that the 

 newly discovered mammal would have lungs. 



The latter kind of induction, which cannot be carried out to the 

 complete form of a logical syllogism nor to the establishment of general 

 laws, plays a very great part in the lives of men. The whole development 

 of our sensations is based upon it, as can be proven by an investigation of 

 illusions. When, e. g., the nerves of our eye are disturbed by a blow, we 

 have a sensation of light, because, during our whole life, the optic nerve 

 had been affected only by light, and we had been accustomed to identify 

 the sensation of the optic nerve with the action of light, a habit which, 

 in the present case, leads us to an incorrect conclusion. The same kind 

 of induction plays the i)rincipal part in psychological processes, on ac- 

 count of the extreme complexity of the influences which determine the 

 formation of a man's character or momentary state of mind. In fact, 

 by asserting that we are free agents, i. e., that we have the power of 

 acting according to our own free will and choice, without being forced 

 by a strict, inevitable law, we deny the possibility of referring ba(;k at 

 least a part of the manifestations of our soul to an inflexible law. 



We might call this kind of induction o/'fi.sf/c f;K7?/c/io«, in contradis- 

 tinction to logical induction, which produces sharply defined, general 

 conclusions; because it is pre-eminently apparent in the finest \Yorks of 

 art. It is an essential part of artistic talent to be able to reproduce 

 the external characteristics of a character or state of mind by means of 

 words, forms, colors, or sounds, and to comprehend instinctively the 

 operations of the soul without being guided by any tangible rule. On 

 the contrary, wherever we become aware that the artist has consciously 

 worked after general rules and abstractions, we find his production 

 commonplace and our admiration ceases immediately. The works of 

 great artists, however, depict to us characters and operations of the 

 mind with such vivacity, such profusion of individual traits, and such 

 convincing truthfulness, that they seem superior to real life, because 

 no disturbing influences have entered. 



When we examine the sciences with regard to themanner in which con- 

 clusions must be drawn in each, we are struck ])y a fundamental diifer- 

 ence between the natural and the mental sciences. In the natural 

 sciences, induction may usually be continued until we obtain decided 

 general rules and laws, while in the mental sciences deductions from 

 psychological tact preponderate. So in the historical sciences, the 

 sources of facts must first be verified, and, when the facts are estab- 

 lished, the more difficult and more important labor begins of investi- 

 gating the complicated and various motives of peoples and individuals. 

 Both must be done chiefly through psychological consideration. The 

 psychological sciences, in so far as they have to do with the explanation 

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