358 FALLACIES. 



in degree. On this subject what appeared necessary was 

 said in the chapter on the Limits to the Explanation of Laws 

 of Nature; hut as the fallacy is even in our own times a 

 common one, I shall touch on it somewhat further in this 

 place. 



When we say that the force which retains the planets in 

 their orbits is resolved into gravity, or that the force which 

 makes substances combine chemically is resolved into elec- 

 tricity, we assert in the one case what is, and in the other 

 case what might, and probably will ultimately, be a legiti- 

 mate result of induction. In both these cases, motion is 

 resolved into motion. The assertion is, that a case of motion, 

 which was supposed to be special, and to follow a distinct 

 law of its own, conforms to and is included in the general 

 law which regulates another class of motions. But, from 

 these and similar generalizations, countenance and currency 

 have been given to attempts to resolve, not motion into 

 motion, but heat into motion, light into motion, sensation 

 itself into motion ; states of consciousness into states of the 

 nervous system, as in the ruder forms of the materialist philo- 

 sophy ; vital phenomena into mechanical or chemical processes, 

 as in some schools of physiology. 



Now I am far from pretending that it may not be capable 

 of proof, or that it will not be an important addition to our 

 knowledge if proved, that certain motions in the particles of 

 bodies are among the conditions of the production of heat or 

 light; that certain assignable physical modifications of the 

 nerves may be the conditions not only of our sensations or 

 emotions, but even of our thoughts ; that certain mechanical 

 and chemical conditions may, in the order of nature, be suffi- 

 cient to determine to action the physiological laws of life. 

 All I insist upon, in common with every thinker who enter- 

 tains any clear idea of the logic of science, is, that it shall 

 not be supposed that by proving these things one step would 

 be made towards a real explanation of heat, light, or sensa- 

 tion ; or that the generic peculiarity of those phenomena can 

 be in the least degree evaded by any such discoveries, however 



